Science.gov

Sample records for synthesis gas

  1. Gas Phase Nanoparticle Synthesis

    NASA Astrophysics Data System (ADS)

    Granqvist, Claes; Kish, Laszlo; Marlow, William

    This book deals with gas-phase nanoparticle synthesis and is intended for researchers and research students in nanomaterials science and engineering, condensed matter physics and chemistry, and aerosol science. Gas-phase nanoparticle synthesis is instrumental to nanotechnology - a field in current focus that raises hopes for environmentally benign, resource-lean manufacturing. Nanoparticles can be produced by many physical, chemical, and even biological routes. Gas-phase synthesis is particularly interesting since one can achieve accurate manufacturing control and hence industrial viability.

  2. Oxygenates vs. synthesis gas

    SciTech Connect

    Kamil Klier; Richard G. Herman; Alessandra Beretta; Maria A. Burcham; Qun Sun; Yeping Cai; Biswanath Roy

    1999-04-01

    Methanol synthesis from H{sub 2}/CO has been carried out at 7.6 MPa over zirconia-supported copper catalysts. Catalysts with nominal compositions of 10/90 mol% and 30/70 mol% Cu/ZrO{sub 2} were used in this study. Additionally, a 3 mol% cesium-doped 10/90 catalyst was prepared to study the effect of doping with heavy alkali, and this promoter greatly increased the methanol productivity. The effects of CO{sub 2} addition, water injection, reaction temperature, and H{sub 2}/C0 ratio have been investigated. Both CO{sub 2} addition to the synthesis gas and cesium doping of the catalyst promoted methanol synthesis, while inhibiting the synthesis of dimethyl ether. Injection of water, however, was found to slightly suppress methanol and dimethyl ether formation while being converted to CO{sub 2} via the water gas shift reaction over these catalysts. There was no clear correlation between copper surface area and catalyst activity. Surface analysis of the tested samples revealed that copper tended to migrate and enrich the catalyst surface. The concept of employing a double-bed reactor with a pronounced temperature gradient to enhance higher alcohol synthesis was explored, and it was found that utilization of a Cs-promoted Cu/ZnO/Cr{sub 2}O{sub 3} catalyst as a first lower temperature bed and a Cs-promoted ZnO/Cr{sub 2}O{sub 3} catalyst as a second high-temperature bed significantly promoted the productivity of 2-methyl-1-propanol (isobutanol) from H{sub 2}/CO synthesis gas mixtures. While the conversion of CO to C{sub 2+} oxygenates over the double-bed configuration was comparable to that observed over the single Cu-based catalyst, major changes in the product distribution occurred by the coupling to the zinc chromite catalyst; that is, the productivity of the C{sub 1}-C{sub 3} alcohols decreased dramatically, and 2-methyl branched alcohols were selectively formed. The desirable methanol/2-methyl oxygenate molar ratios close to 1 were obtained in the present double

  3. High pressure synthesis gas conversion

    SciTech Connect

    Not Available

    1992-01-01

    A high pressure gas phase fermentation system has been constructed for the biological production of ethanol from coal synthesis gas. The reactors in the system consist of a 650 mL continuous stirred tank reactor and a 1 L continuous column reactor. The reactors are designed for individual or dual operation in series or parallel, with continuous gas and liquid feed. The system is housed in a constant temperature, explosion-proof room, equipped with gas leak detectors.

  4. Synthesis gas method and apparatus

    SciTech Connect

    Kelly, Sean M.; Kromer, Brian R.; Litwin, Michael M.; Rosen, Lee J.; Christie, Gervase Maxwell; Wilson, Jamie; Kosowski, Lawrence W; Robinson, Charles

    2015-11-06

    A method and apparatus for producing a synthesis gas product having one or more oxygen transport membrane elements thermally coupled to one or more catalytic reactors such that heat generated from the oxygen transport membrane element supplies endothermic heating requirements for steam methane reforming reactions occurring within the catalytic reactor through radiation and convention heat transfer. A hydrogen containing stream containing no more than 20 percent methane is combusted within the oxygen transport membrane element to produce the heat and a heated combustion product stream. The heated combustion product stream is combined with a reactant stream to form a combined stream that is subjected to the reforming within the catalytic reactor. The apparatus may include modules in which tubular membrane elements surround a central reactor tube.

  5. Synthesis gas method and apparatus

    SciTech Connect

    Kelly, Sean M.; Kromer, Brian R.; Litwin, Michael M.; Rosen, Lee J.; Christie, Gervase Maxwell; Wilson, Jamie R.; Kosowski, Lawrence W.; Robinson, Charles

    2013-01-08

    A method and apparatus for producing a synthesis gas product having one or more oxygen transport membrane elements thermally coupled to one or more catalytic reactors such that heat generated from the oxygen transport membrane element supplies endothermic heating requirements for steam methane reforming reactions occurring within the catalytic reactor through radiation and convention heat transfer. A hydrogen containing stream containing no more than 20 percent methane is combusted within the oxygen transport membrane element to produce the heat and a heated combustion product stream. The heated combustion product stream is combined with a reactant stream to form a combined stream that is subjected to the reforming within the catalytic reactor. The apparatus may include modules in which tubular membrane elements surround a central reactor tube.

  6. Biological conversion of synthesis gas culture development

    SciTech Connect

    Klasson, K.T.; Basu, R.; Johnson, E.R.; Clausen, E.C.; Gaddy, J.L.

    1992-03-01

    Research continues on the conversion of synthesis by shift reactions involving bacteria. Topics discussed here include: biological water gas shift, sulfur gas utilization, experimental screening procedures, water gas shift studies, H{sub 2}S removal studies, COS degradation by selected CO-utilizing bacteria, and indirect COS utilization by Chlorobia. (VC)

  7. Alternative fuels and chemicals from synthesis gas

    SciTech Connect

    Unknown

    1998-08-01

    The overall objectives of this program are to investigate potential technologies for the conversion of synthesis gas to oxygenated and hydrocarbon fuels and industrial chemicals, and to demonstrate the most promising technologies at DOE's LaPorte, Texas, Slurry Phase Alternative Fuels Development Unit (AFDU). The program will involve a continuation of the work performed under the Alternative Fuels from Coal-Derived Synthesis Gas Program and will draw upon information and technologies generated in parallel current and future DOE-funded contracts.

  8. ALTERNATIVE FUELS AND CHEMICALS FROM SYNTHESIS GAS

    SciTech Connect

    Unknown

    1999-01-01

    The overall objectives of this program are to investigate potential technologies for the conversion of synthesis gas to oxygenated and hydrocarbon fuels and industrial chemicals, and to demonstrate the most promising technologies at DOE's LaPorte, Texas, Slurry Phase Alternative Fuels Development Unit (AFDU). The program will involve a continuation of the work performed under the Alternative Fuels from Coal-Derived Synthesis Gas Program and will draw upon information and technologies generated in parallel current and future DOE-funded contracts.

  9. Alternative Fuels and Chemicals From Synthesis Gas

    SciTech Connect

    1998-07-01

    The overall objectives of this program are to investigate potential technologies for the conversion of synthesis gas to oxygenated and hydrocarbon fuels and industrial chemicals, and to demonstrate the most promising technologies at DOE's LaPorte, Texas, Slurry Phase Alternative Fuels Development Unit (AFDU). The program will involve a continuation of the work performed under the Alternative Fuels from Coal-Derived Synthesis Gas Program and will draw upon information and technologies generated in parallel current and future DOE-funded contracts.

  10. ALTERNATIVE FUELS AND CHEMICALS FROM SYNTHESIS GAS

    SciTech Connect

    Unknown

    1999-07-01

    The overall objectives of this program are to investigate potential technologies for the conversion of synthesis gas to oxygenated and hydrocarbon fuels and industrial chemicals, and to demonstrate the most promising technologies at DOE's LaPorte, Texas, Slurry Phase Alternative Fuels Development Unit (AFDU). The program will involve a continuation of the work performed under the Alternative Fuels from Coal-Derived Synthesis Gas Program and will draw upon information and technologies generated in parallel current and future DOE-funded contracts.

  11. ALTERNATIVE FUELS AND CHEMICALS FROM SYNTHESIS GAS

    SciTech Connect

    Unknown

    2000-10-01

    The overall objectives of this program are to investigate potential technologies for the conversion of synthesis gas to oxygenated and hydrocarbon fuels and industrial chemicals, and to demonstrate the most promising technologies at DOE's LaPorte, Texas, Slurry Phase Alternative Fuels Development Unit (AFDU). The program will involve a continuation of the work performed under the Alternative Fuels from Coal-Derived Synthesis Gas Program and will draw upon information and technologies generated in parallel current and future DOE-funded contracts.

  12. ALTERNATIVE FUELS AND CHEMICALS FROM SYNTHESIS GAS

    SciTech Connect

    1999-10-01

    The overall objectives of this program are to investigate potential technologies for the conversion of synthesis gas to oxygenated and hydrocarbon fuels and industrial chemicals, and to demonstrate the most promising technologies at DOE's LaPorte, Texas, Slurry Phase Alternative Fuels Development Unit (AFDU). The program will involve a continuation of the work performed under the Alternative Fuels from Coal-Derived Synthesis Gas Program and will draw upon information and technologies generated in parallel current and future DOE-funded contracts.

  13. High pressure synthesis gas fermentation

    SciTech Connect

    Not Available

    1991-01-01

    Construction of the high pressure gas phase fermentation system is nearing completion. All non-explosion proof components will be housed separately in a gas-monitored plexiglas cabinet. A gas-monitoring system has been designed to ensure the safety of the operations in case of small or large accidental gas releases. Preliminary experiments investigating the effects of high pressure on Clostridium 1jungdahlii have shown that growth and CO uptake are not negatively affected and CO uptake by an increased total pressure of 100 psig at a syngas partial pressure of 10 psig.

  14. Method for the production of synthesis gas

    SciTech Connect

    Deuser, N.; Diemer, P.

    1982-09-28

    Crude gas obtained through partial oxidation of carboncontaining material is subjected to catalytic conversion in an apparatus containing a moistening-demoistering system connected by means of a combined water circulation. To reduce the required amount of steam and process heating, a partial stream of water coming from the moistener is branched off, heated by indirect heat exchange with converted, hot synthesis gas, and then united with the partial stream of water coming from the demoistener for re-delivery to the moistener.

  15. High pressure synthesis gas fermentation

    SciTech Connect

    Not Available

    1992-01-01

    The construction of the high pressure gas phase fermentation system has been completed. Photographs of the various components of the system are presented, along with an operating procedure for the equipment.

  16. Process for production desulfurized of synthesis gas

    DOEpatents

    Wolfenbarger, James K.; Najjar, Mitri S.

    1993-01-01

    A process for the partial oxidation of a sulfur- and silicate-containing carbonaceous fuel to produce a synthesis gas with reduced sulfur content which comprises partially oxidizing said fuel at a temperature in the range of 1900.degree.-2600.degree. F. in the presence of a temperature moderator, an oxygen-containing gas and a sulfur capture additive which comprises a calcium-containing compound portion, a sodium-containing compound portion, and a fluoride-containing compound portion to produce a synthesis gas comprising H.sub.2 and CO with a reduced sulfur content and a molten slag which comprises (1) a sulfur-containing sodium-calcium-fluoride silicate phase; and (2) a sodium-calcium sulfide phase.

  17. Biological conversion of synthesis gas

    SciTech Connect

    Clausen, E.C.

    1993-04-10

    A continuous stirred tank reactor with and without sulfur recovery has been operated using Chlorobium thiosulfatophilum for the conversion of H[sub 2]S to elemental sulfur. In operating the reactor system with sulfur recovery, a gas retention time of 40 min was required to obtain a 100 percent conversion of H[sub 2]S to elemental sulfur. Essentially no SO[sub 4][sup 2[minus

  18. Numerical simulation of synthesis gas incineration

    NASA Astrophysics Data System (ADS)

    Kazakov, A. V.; Khaustov, S. A.; Tabakaev, R. B.; Belousova, Y. A.

    2016-04-01

    The authors have analysed the expediency of the suggested low-grade fuels application method. Thermal processing of solid raw materials in the gaseous fuel, called synthesis gas, is investigated. The technical challenges concerning the applicability of the existing gas equipment developed and extensively tested exclusively for natural gas were considered. For this purpose computer simulation of three-dimensional syngas-incinerating flame dynamics was performed by means of the ANSYS Multiphysics engineering software. The subjects of studying were: a three-dimensional aerodynamic flame structure, heat-release and temperature fields, a set of combustion properties: a flare range and the concentration distribution of burnout reagents. The obtained results were presented in the form of a time-averaged pathlines with color indexing. The obtained results can be used for qualitative and quantitative evaluation of complex multicomponent gas incineration singularities.

  19. Method and apparatus for producing synthesis gas

    DOEpatents

    Hemmings, John William; Bonnell, Leo; Robinson, Earl T.

    2010-03-03

    A method and apparatus for reacting a hydrocarbon containing feed stream by steam methane reforming reactions to form a synthesis gas. The hydrocarbon containing feed is reacted within a reactor having stages in which the final stage from which a synthesis gas is discharged incorporates expensive high temperature materials such as oxide dispersed strengthened metals while upstream stages operate at a lower temperature allowing the use of more conventional high temperature alloys. Each of the reactor stages incorporate reactor elements having one or more separation zones to separate oxygen from an oxygen containing feed to support combustion of a fuel within adjacent combustion zones, thereby to generate heat to support the endothermic steam methane reforming reactions.

  20. Biological conversion of synthesis gas

    SciTech Connect

    Ackerson, M.D.; Clausen, E.C.; Gaddy, J.L.

    1993-01-05

    Syngas is known to contain approximately 1 percent H[sub 2]S, along with CO[sub 2], C0[sub 2], H[sub 2] and CH[sub 4]. Similarly, the syngas may become contaminated with oxygen, particularly during reactor start-up and during maintenance. Previous studies with the water-gas shift bacterium Rhodospirillum rubrum have shown that the bacterium is tolerant of small quantities of oxygen, but the effects of oxygen on CO-consumption are unknown. Similarly, R. rubrum is known to be tolerant of H[sub 2]S, with high concentrations of H[sub 2]S negatively affecting CO-uptake. Batch experiments were thus carried out to determine the effects of H[sub 2]S and O[sub 2] on CO-uptake by R. rubrum. The results of these experiments were quantified by using Monod equations modified by adding terms for CO, H[sub 2]S and O[sub 2] inhibition. The techniques used in determining kinetic expressions previously shown for other gas-phase substrate bacterial systems including R. rubrum were utilized.

  1. Biological conversion of synthesis gas

    SciTech Connect

    Klasson, K.T.; Basu, R.; Johnson, E.R.; Clausen, E.C.; Gaddy, J.L.

    1992-03-01

    Mass transfer and kinetic studies were carried out for the Rhodospirillum rubrum and Chlorobium thiosulfatophilum bacterial systems. R. rubrum is a photosynthetic anaerobic bacterium which catalyzes the biological water gas shift reaction: CO + H[sub 2]0 [yields] CO[sub 2] + H[sub 2]. C. thiosulfatophilum is also a H[sub 2]S and COS to elemental sulfur. The growth of R. rubrum may be satisfactorily carried out at 25[degree] and 30[degree]C, while CO uptake and thus the conversion of CO best occurs at temperatures of either 30[degree], 32[degree] or 34[degree]C. The rate of conversion of COs and H[sub 2]O to CO[sub 2] and H[sub 2]S may be modeled by a first order rate expression. The rate constant at 30[degree]C was found to be 0.243 h[sup [minus]1]. The growth of C. thiosulfatophilum may be modeled in terms of incoming light intensity using a Monod equation: [mu] = [sub 351] + I[sub o]/[sup 0.152]I[sub o]. Comparisons of the growth of R. rubrum and C. thiosulfatophilum shows that the specific growth rate of C. thiosulfatophilum is much higher at a given light intensity.

  2. High temperature desulfurization of synthesis gas

    DOEpatents

    Najjar, Mitri S.; Robin, Allen M.

    1989-01-01

    The hot process gas stream from the partial oxidation of sulfur-containing heavy liquid hydrocarbonaceous fuel and/or sulfur-containing solid carbonaceous fuel comprising gaseous mixtures of H.sub.2 +CO, sulfur-containing gases, entrained particulate carbon, and molten slag is passed through the unobstructed central passage of a radiant cooler where the temperature is reduced to a temperature in the range of about 1800.degree. F. to 1200.degree. F. From about 0 to 95 wt. % of the molten slag and/or entrained material may be removed from the hot process gas stream prior to the radiant cooler with substantially no reduction in temperature of the process gas stream. In the radiant cooler, after substantially all of the molten slag has solidified, the sulfur-containing gases are contacted with a calcium-containing material to produce calcium sulfide. A partially cooled stream of synthesis gas, reducing gas, or fuel gas containing entrained calcium sulfide particulate matter, particulate carbon, and solidified slag leaves the radiant cooler containing a greatly reduced amount of sulfur-containing gases.

  3. Process for producing dimethyl ether from synthesis gas

    DOEpatents

    Pierantozzi, R.

    1985-06-04

    This invention pertains to a Fischer Tropsch process for converting synthesis gas to an oxygenated hydrocarbon with particular emphasis on dimethyl ether. Synthesis gas comprising carbon monoxide and hydrogen are converted to dimethyl ether by carrying out the reaction in the presence of an alkali metal-manganese-iron carbonyl cluster incorporated onto a zirconia-alumina support.

  4. Process for producing dimethyl ether form synthesis gas

    DOEpatents

    Pierantozzi, Ronald

    1985-01-01

    This invention pertains to a Fischer Tropsch process for converting synthesis gas to an oxygenated hydrocarbon with particular emphasis on dimethyl ether. Synthesis gas comprising carbon monoxide and hydrogen are converted to dimethyl ether by carrying out the reaction in the presence of an alkali metal-manganese-iron carbonyl cluster incorporated onto a zirconia-alumina support.

  5. High pressure synthesis gas conversion. Final report

    SciTech Connect

    Not Available

    1993-05-01

    The purpose of this research project is to build and test a high pressure fermentation system for the production of ethanol from synthesis gas. The fermenters, pumps, controls, and analytical system were procured or fabricated and assembled in our laboratory. This system was then used to determine the effects of high pressure on growth and ethanol production by Clostridium ljungdahlii. The limits of cell concentration and mass transport relationships were found in CSTR and immobilized cell reactors (ICR). The minimum retention times and reactor volumes were found for ethanol production in these reactors. A maximum operating pressure of 150 psig has been shown to be possible for C. ljungdahlli with the medium of Phillips et al. This medium was developed for atmospheric pressure operation in the CSTR to yield maximum ethanol concentrations and thus is not best for operation at elevated pressures. It is recommended that a medium development study be performed for C. ljungdahlii at increased pressure. Cell concentration, gas conversion and product concentration profiles were presented for C. ljungdahlii as a function of gas flow rate, the variable which affects bacterium performance the most. This pressure was chosen as a representative pressure over the 0--150 psig operating pressure range for the bacterium. Increased pressure negatively affected ethanol productivity probably due to the fact that medium composition was designed for atmospheric pressure operation. Medium development at increased pressure is necessary for high pressure development of the system.

  6. Alternative fuel and chemicals from synthesis gas

    SciTech Connect

    1996-05-01

    Development of a reliable and cost-effective method of wax/catalyst separation is a key step toward a commercially viable slurry reactor process with iron oxide-based catalyst for Fischer-Tropsch (F-T) synthesis of hydrocarbon transportation fuels. Although a variety of suitable catalysts (including, for example, cobalt-based catalysts) are available, iron oxide-based catalysts are preferred for coal-derived, CO-rich syngas because, in addition to catalyzing the F-T reaction, they simultaneously catalyze the reaction stifling CO to H{sub 2}, obviating a separate shift process block and associated costs. Because of the importance of development of this wax/catalyst separation, a study was initiated in February 1991. P. Z. Zhou of Burns and Roe reviewed the status of F-T wax/catalyst separation techniques. This led to the selection of a filtration system for the separation. Pilot tests were conducted by Mott Porous Metal Products in 1992 to develop this system. Initial results were good, but problems were encountered in follow-up testing. As a result of the testing, a filter was selected for use on the pilot plant. In LaPorte, Texas, APCI has been operating a pilot plant for the development of various synthesis gas technologies with DOE and industry support. The APCI F-T program builds on the DOE-sponsored laboratory-scale work by Mobil, reported in the mid-1980s, which used an iron oxide catalyst to produce high-quality F-T liquids in relatively compact reactors. Separation of the catalyst solids from the wax still represents a challenge. In the summer of 1992, testing of the selected filter was begun as part of the pilot plant testing. The filter performed poorly. Separation of the catalyst was primarily by sedimentation. It was recommended that the wax/catalyst separation be developed further.

  7. Evaluation of Reformer Produced Synthesis Gas for Emissions Reductions in Natural Gas Reciprocating Engines

    SciTech Connect

    Mark Scotto

    2010-05-30

    Rolls-Royce Fuel Cell Systems (US) Inc. (RRFCS) has developed a system that produces synthesis gas from air and natural gas. A near-term application being considered for this technology is synthesis gas injection into reciprocating engines for reducing NO{sub x} emissions. A proof of concept study using bottled synthesis gas and a two-stroke reciprocating engine showed that injecting small amounts of high-flammable content synthesis gas significantly improved combustion stability and enabled leaner engine operation resulting in over 44% reduction in NO{sub x} emissions. The actual NO{sub x} reduction that could be achieved in the field is expected to be engine specific, and in many cases may be even greater. RRFCS demonstrated that its synthesis gas generator could produce synthesis gas with the flammable content that was successfully used in the engine testing. An economic analysis of the synthesis gas approach estimates that its initial capital cost and yearly operating cost are less than half that of a competing NO{sub x} reduction technology, Selective Catalytic Reduction. The next step in developing the technology is an integrated test of the synthesis gas generator with an engine to obtain reliability data for system components and to confirm operating cost. RRFCS is actively pursuing opportunities to perform the integrated test. A successful integrated test would demonstrate the technology as a low-cost option to reduce NO{sub x} emissions from approximately 6,000 existing two-stroke, natural gas-fired reciprocating engines used on natural gas pipelines in North America. NO{sub x} emissions reduction made possible at a reasonable price by this synthesis gas technology, if implemented on 25% of these engines, would be on the order of 25,000 tons/year.

  8. Evaluation of Reformer Produced Synthesis Gas for Emissions Reductions in Natural Gas Reciprocating Engines

    SciTech Connect

    Mark V. Scotto; Mark A. Perna

    2010-05-30

    Rolls-Royce Fuel Cell Systems (US) Inc. (RRFCS) has developed a system that produces synthesis gas from air and natural gas. A near-term application being considered for this technology is synthesis gas injection into reciprocating engines for reducing NOx emissions. A proof of concept study using bottled synthesis gas and a two-stroke reciprocating engine showed that injecting small amounts of highflammables content synthesis gas significantly improved combustion stability and enabled leaner engine operation resulting in over 44% reduction in NOx emissions. The actual NOx reduction that could be achieved in the field is expected to be engine specific, and in many cases may be even greater. RRFCS demonstrated that its synthesis gas generator could produce synthesis gas with the flammables content that was successfully used in the engine testing. An economic analysis of the synthesis gas approach estimates that its initial capital cost and yearly operating cost are less than half that of a competing NOx reduction technology, Selective Catalytic Reduction. The next step in developing the technology is an integrated test of the synthesis gas generator with an engine to obtain reliability data for system components and to confirm operating cost. RRFCS is actively pursuing opportunities to perform the integrated test. A successful integrated test would demonstrate the technology as a low-cost option to reduce NOx emissions from approximately 6,000 existing two-stroke, natural gas-fired reciprocating engines used on natural gas pipelines in North America. NOx emissions reduction made possible at a reasonable price by this synthesis gas technology, if implemented on 25% of these engines, would be on the order of 25,000 tons/year.

  9. Plasma reforming of glycerol for synthesis gas production.

    PubMed

    Zhu, Xinli; Hoang, Trung; Lobban, Lance L; Mallinson, Richard G

    2009-05-28

    Glycerol can be effectively converted to synthesis gas (selectivity higher than 80%) with small amounts of water or no water using plasmas at low temperature and atmospheric pressure, without external heating. PMID:19436906

  10. High pressure synthesis gas conversion. Task 1, System construction

    SciTech Connect

    Not Available

    1992-01-01

    A high pressure gas phase fermentation system has been constructed for the biological production of ethanol from coal synthesis gas. The reactors in the system consist of a 650 mL continuous stirred tank reactor and a 1 L continuous column reactor. The reactors are designed for individual or dual operation in series or parallel, with continuous gas and liquid feed. The system is housed in a constant temperature, explosion-proof room, equipped with gas leak detectors.

  11. Autothermal Reforming of Natural Gas to Synthesis Gas

    SciTech Connect

    Steven F. Rice; David P. Mann

    2007-04-13

    This Project Final Report serves to document the project structure and technical results achieved during the 3-year project titled Advanced Autothermal Reformer for US Dept of Energy Office of Industrial Technology. The project was initiated in December 2001 and was completed March 2005. It was a joint effort between Sandia National Laboratories (Livermore, CA), Kellogg Brown & Root LLC (KBR) (Houston, TX) and Süd-Chemie (Louisville, KY). The purpose of the project was to develop an experimental capability that could be used to examine the propensity for soot production in an Autothermal Reformer (ATR) during the production of hydrogen-carbon monoxide synthesis gas intended for Gas-to-Liquids (GTL) applications including ammonia, methanol, and higher hydrocarbons. The project consisted of an initial phase that was focused on developing a laboratory-scale ATR capable of reproducing conditions very similar to a plant scale unit. Due to budget constraints this effort was stopped at the advanced design stages, yielding a careful and detailed design for such a system including ATR vessel design, design of ancillary feed and let down units as well as a PI&D for laboratory installation. The experimental effort was then focused on a series of measurements to evaluate rich, high-pressure burner behavior at pressures as high as 500 psi. The soot formation measurements were based on laser attenuation at a view port downstream of the burner. The results of these experiments and accompanying calculations show that soot formation is primarily dependent on oxidation stoichiometry. However, steam to carbon ratio was found to impact soot production as well as burner stability. The data also showed that raising the operating pressure while holding mass flow rates constant results in considerable soot formation at desirable feed ratios. Elementary reaction modeling designed to illuminate the role of CO2 in the burner feed showed that the conditions in the burner allow for the direct

  12. Integrated production of fuel gas and oxygenated organic compounds from synthesis gas

    DOEpatents

    Moore, Robert B.; Hegarty, William P.; Studer, David W.; Tirados, Edward J.

    1995-01-01

    An oxygenated organic liquid product and a fuel gas are produced from a portion of synthesis gas comprising hydrogen, carbon monoxide, carbon dioxide, and sulfur-containing compounds in a integrated feed treatment and catalytic reaction system. To prevent catalyst poisoning, the sulfur-containing compounds in the reactor feed are absorbed in a liquid comprising the reactor product, and the resulting sulfur-containing liquid is regenerated by stripping with untreated synthesis gas from the reactor. Stripping offgas is combined with the remaining synthesis gas to provide a fuel gas product. A portion of the regenerated liquid is used as makeup to the absorber and the remainder is withdrawn as a liquid product. The method is particularly useful for integration with a combined cycle coal gasification system utilizing a gas turbine for electric power generation.

  13. Homogeneously catalyzed synthesis gas transformations to oxygenate fuels

    SciTech Connect

    Mahajan, D.; Mattas, L.; Sanchez, J.

    1992-04-01

    At Brookhaven National Laboratory (BNL), the ongoing oxygenates synthesis program is addressing the catalytic synthesis gas conversion to liquid fuels and fuel additives. The major thrust of this effort is to enhance carbon conversion, reaction rates, product selectivity and overall process efficiency. To this effect, a series of liquid phase homogeneous catalysts have been developed and successfully utilized in the synthesis of methanol and other oxygenates. This paper identifies advantages and uncertainties associated with these newly developed catalysts. The effect of system parameters on the overall process scheme is discussed.

  14. Conversion of synthesis gas with iron-containing catalyst

    SciTech Connect

    Butter, S.A.; Chester, A.W.

    1981-03-10

    A method is disclosed for the conversion of synthesis gas to a liquid hydrocarbon product having a boiling range of less than 400* F. at a 90% overhead utilizing a novel catalyst prepared from a water-insoluble organic iron compound. The novel method involves contacting synthesis gas with a single particle catalyst containing iron, a crystalline acidic aluminosilicate zeolite having a silica-to-alumina ratio of at least 12, a pore size greater than about 5 angstrom units, and a constraint index of about 1 to 12, and a matrix. The catalyst does not contain promoters.

  15. Solid fuel volatilization to produce synthesis gas

    DOEpatents

    Schmidt, Lanny D.; Dauenhauer, Paul J.; Degenstein, Nick J.; Dreyer, Brandon J.; Colby, Joshua L.

    2014-07-29

    A method comprising contacting a carbon and hydrogen-containing solid fuel and a metal-based catalyst in the presence of oxygen to produce hydrogen gas and carbon monoxide gas, wherein the contacting occurs at a temperature sufficiently high to prevent char formation in an amount capable of stopping production of the hydrogen gas and the carbon monoxide gas is provided. In one embodiment, the metal-based catalyst comprises a rhodium-cerium catalyst. Embodiments further include a system for producing syngas. The systems and methods described herein provide shorter residence time and high selectivity for hydrogen and carbon monoxide.

  16. Activation of catalysts for synthesizing methanol from synthesis gas

    DOEpatents

    Blum, David B.; Gelbein, Abraham P.

    1985-01-01

    A method for activating a methanol synthesis catalyst is disclosed. In this method, the catalyst is slurried in an inert liquid and is activated by a reducing gas stream. The activation step occurs in-situ. That is, it is conducted in the same reactor as is the subsequent step of synthesizing methanol from a methanol gas stream catalyzed by the activated catalyst still dispersed in a slurry.

  17. Scale study of direct synthesis of dimethyl ether from biomass synthesis gas.

    PubMed

    Lv, Yongxing; Wang, Tiejun; Wu, Chuangzhi; Ma, Longlong; Zhou, Yi

    2009-01-01

    We investigated the synthesis of dimethyl ether (DME) from biomass synthesis gas using a kind of hybrid catalyst consisting of methanol and HZSM-5 zeolite in a fixed-bed reactor in a 100 ton/year pilot plant. The biomass synthesis gas was produced by oxygen-rich gasification of corn core in a two-stage fixed bed. The results showed that CO conversions reached 82.00% and 73.55%, the selectivities for DME were 73.95% and 69.73%, and the space-time yields were 124.28 kg m(-3) h(-1) and 203.80 kg m(-3) h(-1) when gas hourly space velocities were 650 h(-1) and 1200 h(-1), respectively. Deoxidation and tar removal from biomass synthesis gas was critical to the stable operation of the DME synthesis system. Using single-pass synthesis, the H(2)/CO ratio improved from 0.98-1.17 to 2.12-2.22. The yield of DME would be increased greatly if the exhaust was reused after removal of the CO(2). PMID:19393311

  18. Biodesulfurization of flue gases using synthesis gas delivered as microbubbles

    SciTech Connect

    Selvaraj, P.T.; Bredwell, M.D.; Little, M.H.; Kaufman, E.N.

    1997-03-01

    In this study, the authors have focused research on utilizing a gas mixture containing 36% H{sub 2}, 47% CO, 10% CO{sub 2}, 5% CH{sub 4} and a balance of N{sub 2} as a model coal synthesis gas as a low-cost feedstock for sulfate-reducing bacteria cultures. Coal synthesis gas will be readily available in power plants and the biological utilization of syn-gas as a carbon and energy source produces no organic end product that has to be processed prior to its disposal. Coal synthesis gas is, however, sparingly soluble in aqueous phase. This process utilizing SRB with syn-gas feedstock may be mass transfer limited and methods to enhance the mass transport have been investigated. A CSTR with cell recycle and a trickle bed reactor with cells immobilized in BIO-SEP{trademark} polymeric beads were operated with syn-gas feedstock to obtain maximum productivity for SO{sub 2} reduction to H{sub 2}S. The CSTR reactor was then fed with syn-gas as microbubbles in an effort to improve the mass transfer properties. With syn-gas fed as microbubbles, productivity in the CSTR increased from 1.2 to 2.1 mmol/h {center_dot} L in 33 h. This has been observed at the same biomass concentration of 5 g/L. This shows the mass transport limitation in the above process. In the trickle bed reactor, maximum productivity of 8.8 mmol/h {center_dot} L was achieved with less carbon and energy requirements (1 mol H{sub 2} and 1.2 mol CO per mol of SO{sub 2}) indicating better surface to volume ratio with cells immobilized in the pores of polymeric beads.

  19. Synthesis gas production by mixed conducting membranes with integrated conversion into liquid products

    DOEpatents

    Nataraj, Shankar; Russek, Steven Lee; Dyer, Paul Nigel

    2000-01-01

    Natural gas or other methane-containing feed gas is converted to a C.sub.5 -C.sub.19 hydrocarbon liquid in an integrated system comprising an oxygenative synthesis gas generator, a non-oxygenative synthesis gas generator, and a hydrocarbon synthesis process such as the Fischer-Tropsch process. The oxygenative synthesis gas generator is a mixed conducting membrane reactor system and the non-oxygenative synthesis gas generator is preferably a heat exchange reformer wherein heat is provided by hot synthesis gas product from the mixed conducting membrane reactor system. Offgas and water from the Fischer-Tropsch process can be recycled to the synthesis gas generation system individually or in combination.

  20. Synthesis and deposition of metal nanoparticles by gas condensation process

    SciTech Connect

    Maicu, Marina Glöß, Daniel; Frach, Peter; Schmittgens, Ralph; Gerlach, Gerald; Hecker, Dominic

    2014-03-15

    In this work, the synthesis of Pt and Ag nanoparticles by means of the inert gas phase condensation of sputtered atomic vapor is presented. The process parameters (power, sputtering time, and gas flow) were varied in order to study the relationship between deposition conditions and properties of the nanoparticles such as their quantity, size, and size distribution. Moreover, the gas phase condensation process can be combined with a plasma enhanced chemical vapor deposition procedure in order to deposit nanocomposite coatings consisting of metallic nanoparticles embedded in a thin film matrix material. Selected examples of application of the generated nanoparticles and nanocomposites are discussed.

  1. Process for production of synthesis gas with reduced sulfur content

    DOEpatents

    Najjar, Mitri S.; Corbeels, Roger J.; Kokturk, Uygur

    1989-01-01

    A process for the partial oxidation of a sulfur- and silicate-containing carbonaceous fuel to produce a synthesis gas with reduced sulfur content which comprises partially oxidizing said fuel at a temperature in the range of 1800.degree.-2200.degree. F. in the presence of a temperature moderator, an oxygen-containing gas and a sulfur capture additive which comprises an iron-containing compound portion and a sodium-containing compound portion to produce a synthesis gas comprising H.sub.2 and CO with a reduced sulfur content and a molten slag which comprises (i) a sulfur-containing sodium-iron silicate phase and (ii) a sodium-iron sulfide phase. The sulfur capture additive may optionally comprise a copper-containing compound portion.

  2. NOVEL REACTOR FOR THE PRODUCTION OF SYNTHESIS GAS

    SciTech Connect

    Vasilis Papavassiliou; Leo Bonnell; Dion Vlachos

    2004-12-01

    Praxair investigated an advanced technology for producing synthesis gas from natural gas and oxygen This production process combined the use of a short-reaction time catalyst with Praxair's gas mixing technology to provide a novel reactor system. The program achieved all of the milestones contained in the development plan for Phase I. We were able to develop a reactor configuration that was able to operate at high pressures (up to 19atm). This new reactor technology was used as the basis for a new process for the conversion of natural gas to liquid products (Gas to Liquids or GTL). Economic analysis indicated that the new process could provide a 8-10% cost advantage over conventional technology. The economic prediction although favorable was not encouraging enough for a high risk program like this. Praxair decided to terminate development.

  3. Biological conversion of synthesis gas. Topical report: Economic evaluations

    SciTech Connect

    Clausen, E.C.; Gaddy, J.L.

    1993-09-01

    The purpose of the proposed research is to develop a technically and economically feasible process for biologically producing H{sub 2} from synthesis gas while, at the same time, removing harmful sulfur gas compounds. Six major tasks are being studied: culture development, where the best cultures are selected and conditions optimized for simultaneous hydrogen production and sulfur gas removal; mass transfer and kinetic studies in which equations necessary for process design are developed; bioreactor design studies, where the cultures chosen in Task 1 are utilized in continuous reaction vessels to demonstrate process feasibility and define operating conditions; evaluation of biological synthesis gas conversion under limiting conditions in preparation for industrial demonstration studies; process scale-up where laboratory data are scaled to larger-size units in preparation for process demonstration in a pilot-scale unit; and economic evaluation, where process simulations are used to project process economics and identify high cost areas during sensitivity analyses. The purpose of this report is to present economic evaluations for H{sub 2} production from synthesis gone by Rhodospirillum rubrum. Cases are presented with and without light requirements and in stirred tank and immobilized cell reactors. In addition, economic information is presented for isolate ERIH{sub 2} (from Engineering Resources, Inc.) in the two reactors with and without H{sub 2} recovery.

  4. Combined Gas-Liquid Plasma Source for Nanoparticle Synthesis

    NASA Astrophysics Data System (ADS)

    Burakov, V. S.; Kiris, V. V.; Nevar, A. A.; Nedelko, M. I.; Tarasenko, N. V.

    2016-09-01

    A gas-liquid plasma source for the synthesis of colloidal nanoparticles by spark erosion of the electrode material was developed and allowed the particle synthesis regime to be varied over a wide range. The source parameters were analyzed in detail for the electrical discharge conditions in water. The temperature, particle concentration, and pressure in the discharge plasma were estimated based on spectroscopic analysis of the plasma. It was found that the plasma parameters did not change signifi cantly if the condenser capacitance was increased from 5 to 20 nF. Purging the electrode gap with argon reduced substantially the pressure and particle concentration. Signifi cant amounts of water decomposition products in addition to electrode elements were found in the plasma in all discharge regimes. This favored the synthesis of oxide nanoparticles.

  5. Biological conversion of synthesis gas. Limiting conditions/scale-up

    SciTech Connect

    Basu, R.; Klasson, K.T.; Takriff, M.; Clausen, E.C.; Gaddy, J.L.

    1993-09-01

    The purpose of this research is to develop a technically and economically feasible process for biologically producing H(sub 2) from synthesis gas while, at the same time, removing harmful sulfur gas compounds. Six major tasks are being studied: 1. Culture development, where the best cultures are selected and conditions optimized for simultaneous hydrogen production and sulfur gas removal; 2. Mass transfer and kinetic studies in which equations necessary for process design are developed; 3. Bioreactor design studies, where the cultures chosen in Task 1 are utilized in continuous reaction vessels to demonstrate process feasibility and define operating conditions; 4. Evaluation of biological synthetic gas conversion under limiting conditions in preparation for industrial demonstration studies; 5. Process scale-up where laboratory data are scaled to larger-size units in preparation for process demonstration in a pilot-scale unit; and 6. Economic evaluation, where process simulations are used to project process economics and identify high cost areas during sensitivity analyses.

  6. Biological conversion of synthesis gas. Topical report: Bioreactor studies

    SciTech Connect

    Basu, R.; Klasson, K.T.; Clausen, E.C.; Gaddy, J.L.

    1993-09-01

    The purpose of the proposed research is to develop a technically and economically feasible process for biologically producing H{sub 2} from synthesis gas while, at the same time, removing harmful sulfur gas compounds. Six major tasks are being studied: culture development, where the best cultures are selected and conditions optimized for simultaneous hydrogen production and sulfur gas removal; mass transfer and kinetic studies in which equations necessary for process design are developed; bioreactor design studies, where the cultures chosen in Task 1 are utilized in continuous reaction vessels to demonstrate process feasibility and define operating conditions; evaluation of biological synthesis gas conversion under limiting conditions in preparation for industrial demonstration studies; process scale-up where laboratory data are scaled to larger-size units in preparation for process demonstration in a pilot-scale unit; and economic evaluation, where process simulations are used to project process economics and identify high cost areas during sensitivity analyses. The purpose of this report is to present results from bioreactor studies involving H{sub 2} production by water gas shift and H{sub 2}S removal to produce elemental sulfur. Many of the results for H{sub 2} production by Rhodospirillum rubrum have been presented during earlier contracts. Thus, this report concentrates mainly on H{sub 2}S conversion to elemental sulfur by R. rubrum.

  7. ISOBUTANOL-METHANOL MIXTURES FROM SYNTHESIS GAS

    SciTech Connect

    Enrique Iglesia

    1998-09-01

    Isobutanol is potential as a fuel additive or precursor to methyl tert-butyl ether (MTBE). Alkali-promoted Cu/ZnO/Al{sub 2}O{sub 3} and Cu/MgO/CeO{sub 2} materials have been found to catalyze the formation of isobutanol from CO and H{sub 2} at temperatures (573-623 K) that allow their use in slurry reactors. Our studies focus on the mechanism and structural requirements for selective isobutanol synthesis on these types of catalysts. Alkali promoted Cu/MgO/CeO{sub 2}, Cu/MgO/ZnO, and CuZnAlO{sub x} materials and their individual components Cu/MgO, MgO/CeO{sub 2}, MgO and CeO{sub 2} have been prepared for the use in kinetic studies of alcohol coupling reactions, in identification of reaction intermediates, and in isobutanol synthesis at high pressures. These samples were prepared by coprecipitation of mixed nitrate solutions with an aqueous solution of KOH (2M) and K{sub 2}CO{sub 3} (1M) at 338 K at a constant pH of 9, except for Cs-Cu/ZnO/Al{sub 2}O{sub 3} at a pH of 7, in a well-stirred thermostated container. The precipitate was filtered, washed thoroughly with dioinized water at 303 K in order to remove residual K ions, and dried at 353 K overnight. Dried samples were calcined at 723 K, except for Cs-Cu/ZnO/Al{sub 2}O{sub 3} at 623 K, for 4 h in order to form the corresponding mixed oxides. Alkali addition (K or Cs) was performed by incipient wetness using K{sub 2}CO{sub 3} (0.25 M) and CH{sub 3}COOCs (0.25 M) aqueous solutions. The crystallinity and phase structures of resulting materials were analyzed by powered X-ray diffraction.

  8. Catalyst for converting synthesis gas to liquid motor fuels

    DOEpatents

    Coughlin, Peter K.

    1986-01-01

    The addition of an inert metal component, such as gold, silver or copper, to a Fischer-Tropsch catalyst comprising cobalt enables said catalyst to convert synthesis gas to liquid motor fuels at about 240.degree.-370.degree. C. with advantageously reduced selectivity of said cobalt for methane in said conversion. The catalyst composition can advantageously include a support component, such as a molecular sieve, co-catalyst/support component or a combination of such support components.

  9. Enhanced catalyst for converting synthesis gas to liquid motor fuels

    DOEpatents

    Coughlin, Peter K.

    1986-01-01

    The conversion of synthesis gas to liquid molar fuels by means of a cobalt Fischer-Tropsch catalyst composition is enhanced by the addition of molybdenum, tungsten or a combination thereof as an additional component of said composition. The presence of the additive component increases the olefinic content of the hydrocarbon products produced. The catalyst composition can advantageously include a support component, such as a molecular sieve, co-catalyst/support component or a combination of such support components.

  10. Combustion synthesis of tin dioxide nanocomposites for gas sensing applications

    NASA Astrophysics Data System (ADS)

    Bakrania, Smitesh Dhirajlal

    The current work focuses on understanding the mechanisms controlling tin dioxide (SnO2) nanoparticle morphology in combustion synthesis systems and how nanoarchitecture affects performance of solid-state gas sensors. A range of analytical methods (including transmission and scanning electron microscopy, x-ray diffraction, nitrogen absorption, and XEDS) were used to characterize the materials properties as a function of the combustion synthesis conditions. A novel method of generating tin dioxide materials was developed which provides a new degree of control over SnO2 morphology; including spherical, nanorod and encapsulated particle architectures. A simplified model for particle formation based on characteristic times was developed to identify the physical and chemical processes affecting the morphologies observed using transmission electron microscope imaging. The SnO2 nanoparticles evolve from primary particles sizes of 7 nm to 14 nm through the synthesis region, and the results indicate interparticle collision and sintering are the dominant mechanisms in determining particle size and morphology for the flame conditions studied. Metal acetates were used to create metal/SnO 2 nanocomposite materials, and the processes controlling gold acetate decomposition in particular were explored. The results of the studies suggest a relationship between the precursor crystallite size and the product nanoparticles. The well-characterized SnO2 particles were evaluated as the active materials for gas-sensing. Sensor sensitivity and time response to carbon monoxide in dry air was used to investigate microstructure-performance links. Excellent sensitivity (3 7, based on the ratio of the resistance of the sensor in air to the resistance in the target gas) and time response (4--20 seconds) were demonstrated for the thin film gas sensors. Fabrication studies demonstrated the sensor performance was a strong function of the film deposition method. A novel method for manufacturing

  11. Synthesis of organic geochemical data from the Eastern Gas Shales

    SciTech Connect

    Zielinski, R. E.; McIver, R. D.

    1982-01-01

    Over 2400 core and cuttings samples of Upper Devonian shales from wells in the Appalachian, Illinois, and Michigan Basins have been characterized by organic geochemical methods to provide a basis for accelerating the exploitation of this unconventional, gas-rich resource. This work was part of a program initiated to provide industry with criteria for locating the best areas for future drilling and for the development of stimulation methods that will make recovery of the resource economically attractive. The geochemical assessment shows that the shale, in much of the Appalachian, Illinois, and Michigan Basins is source rock that is capable of generating enormous quantities of gas. In some areas the shales are also capable of generating large quantities of oil as well. The limiting factors preventing these sources from realizing most of their potential are their very low permeabilities and the paucity of potential reservoir rocks. This geochemical data synthesis gives direction to future selection of sites for stimulation research projects in the Appalachian Basin by pinpointing those areas where the greatest volumes of gas are contained in the shale matrix. Another accomplishment of the geochemical data synthesis is a new estimate of the total resource of the Appalachian Basin. The new estimate of 2500 TCF is 25 percent greater than the highest previous estimates. This gives greater incentive to government and industry to continue the search for improved stimulation methods, as well as for improved methods for locating the sites where those improved stimulation methods can be most effectively applied.

  12. Synthesis of Isobutene and Isobutane from Synthesis Gas. A Literature Review Since 1992

    SciTech Connect

    Petkovic, Lucia M.; Ginosar, Daniel M.

    2012-04-01

    The isosynthesis reaction is commonly referred as the reaction that converts selectively synthesis gas to isobutene and isobutane. The main feature of this reaction is the production of branched hydrocarbons in higher proportion with respect to linear hydrocarbons than expected from thermodynamic equilibrium and with a molecular weight distribution favoring iso-C4 hydrocarbons. This article reviews and summarizes isosynthesis research results reported in the open scientific literature with emphasis on the articles published in the last two decades.

  13. High pressure synthesis gas conversion. Task 3: High pressure profiles

    SciTech Connect

    Not Available

    1993-05-01

    The purpose of this research project was to build and test a high pressure fermentation system for the production of ethanol from synthesis gas. The fermenters, pumps, controls, and analytical system were procured or fabricated and assembled in our laboratory. This system was then used to determine the effects of high pressure on growth and ethanol production by C. 1jungdahlii. The limits of cell concentration and mass transport relationships were found in CSTR and immobilized cell reactors (ICR). The minimum retention times and reactor volumes were found for ethanol production in these reactors.

  14. OPTIMIZING SYNTHESIS GAS YIELD FROM THE CROSS DRAFT GASIFICATION OF WOODY BIOMASS

    EPA Science Inventory

    Biomass can be gasified to yield synthesis gas, tars, and ash. The process is governed by a number of parameters such as the temperature of the gasifying medium (in this case air), and the moisture content of the feedstock. Synthesis gas from gasifying wood pellets was collected ...

  15. Synthesis gas solubility in Fischer-Tropsch slurry: Final report

    SciTech Connect

    Chao, K.C.; Lin, H.M.

    1988-01-01

    The objective is to investigate the phase equilibrium behavior of synthesis gases and products in a Fischer-Tropsch slurry reactor. A semi-flow apparatus has been designed and constructed for this purpose. Measurements have been made for hydrogen, cabon monoxide, methane, ethane, ethylene, and carbon dioxide in a heavy n-paraffin at temperatures from 100 to 300)degree)C and pressures 10 to 50 atm. Three n-paraffin waxes: n-eicosane (n-C/sub 20/), n-octacosane )n-C/sub 28/), and n-hexatriacontane (n-C/sub 36/), were studied to model the industrial wax. Solubility of synthesis gas mixtures of H/sub 2/ and CO in n-C/sub 28/ was also determined at two temperatures (200 and 300)degree)C) for each of three gas compositions (40.01, 50.01, and 66.64 mol%) of hydrogen). Measurements were extended to investigate the gas solubility in two industrial Fischer-Tropsch waxes: Mobilwax and SASOL wax. Observed solubility increases in the order: H/sub 2/, CO, CH/sub 4/, CO/sub 2/, C/sub 2/H/sub 4/, C/sub 2/H/sub 6/, at a given temperature pressure, and in the same solvent. Solubility increases with increasing pressure for all the gases. Lighter gases H/sub 2/ and CO show increased solubility with increasing temperature, while the heavier gases CO/sub 2/, ethane, and ethylene show decreased solubility with increasing temperature. The solubility of methane, the intermediate gas, changes little with temperature, and shows a shallow minimum at about 200)degrees)C or somewhat above. Henry's constant and partial molal volume of the gas solute at infinite dilution are determinedfrom the gas solubility data. A correlation is developed from the experimental data in the form on an equation of state. A computer program has been prepared to implement the correlation. 19 refs., 66 figs., 39 tabs.

  16. DESIGN, SYNTHESIS, AND MECHANISTIC EVALUATION OF IRON-BASED CATALYSIS FOR SYNTHESIS GAS CONVERSION TO FUELS AND CHEMICALS

    SciTech Connect

    Jian Xu; Enrique Iglesia

    2004-03-31

    This project explores the extension of previously discovered Fe-based catalysts with unprecedented Fischer-Tropsch synthesis rate, selectivity, and ability to convert hydrogen-poor synthesis gas streams typical of those produced from coal and biomass sources. Contract negotiations between the U.S. Department of Energy and the University of California were completed on December 9, 2004. During this first reporting period, we have modified and certified a previously decommissioned microreactor, ordered and installed a budgeted gas chromatograph, developed and reviewed safe operating procedures and data analysis methods, and reproduced successfully previous synthetic protocols and catalytic performance of catalytic materials based on Fe-Zn-Cu-K oxide precursors synthesized using precipitation methods, drying using surface-active agents, and activated in synthesis gas within Fischer-Tropsch synthesis tubular reactors.

  17. Gas-phase synthesis of magnetic metal/polymer nanocomposites

    NASA Astrophysics Data System (ADS)

    Starsich, Fabian H. L.; Hirt, Ann M.; Stark, Wendelin J.; Grass, Robert N.

    2014-12-01

    Highly magnetic metal Co nanoparticles were produced via reducing flame spray pyrolysis, and directly coated with an epoxy polymer in flight. The polymer content in the samples varied between 14 and 56 wt% of nominal content. A homogenous dispersion of Co nanoparticles in the resulting nanocomposites was visualized by electron microscopy. The size and crystallinity of the metallic fillers was not affected by the polymer, as shown by XRD and magnetic hysteresis measurements. The good control of the polymer content in the product nanocomposite was shown by elemental analysis. Further, the successful polymerization in the gas phase was demonstrated by electron microscopy and size measurements. The presented effective, dry and scalable one-step synthesis method for highly magnetic metal nanoparticle/polymer composites presented here may drastically decrease production costs and increase industrial yields.

  18. Gas-phase synthesis of magnetic metal/polymer nanocomposites.

    PubMed

    Starsich, Fabian H L; Hirt, Ann M; Stark, Wendelin J; Grass, Robert N

    2014-12-19

    Highly magnetic metal Co nanoparticles were produced via reducing flame spray pyrolysis, and directly coated with an epoxy polymer in flight. The polymer content in the samples varied between 14 and 56 wt% of nominal content. A homogenous dispersion of Co nanoparticles in the resulting nanocomposites was visualized by electron microscopy. The size and crystallinity of the metallic fillers was not affected by the polymer, as shown by XRD and magnetic hysteresis measurements. The good control of the polymer content in the product nanocomposite was shown by elemental analysis. Further, the successful polymerization in the gas phase was demonstrated by electron microscopy and size measurements. The presented effective, dry and scalable one-step synthesis method for highly magnetic metal nanoparticle/polymer composites presented here may drastically decrease production costs and increase industrial yields. PMID:25422410

  19. Catalyst for converting synthesis gas to light olefins

    DOEpatents

    Rao, V. Udaya S.; Gormley, Robert J.

    1982-01-01

    A catalyst and process for making same useful in the catalytic hydrogenation of carbon monoxide in which a silicalite support substantially free of aluminum is soaked in an aqueous solution of iron and potassium salts wherein the iron and potassium are present in concentrations such that the dried silicalite has iron present in the range of from about 5 to about 25 percent by weight and has potassium present in an amount not less than about 0.2 percent by weight, and thereafter the silicalite is dried and combined with amorphous silica as a binder for pellets, the catalytic pellets are used to convert synthesis gas to C.sub.2 -C.sub.4 olefins.

  20. Thermodynamic Study of Transformation of Methane to Synthesis Gas Over Metal Oxides

    NASA Astrophysics Data System (ADS)

    Roohi, P.; Alizadeh, R.; Fatehifar, E.

    2015-01-01

    A metal oxide reduction-water splitting cycle is a new developing method to produce synthesis gas without using a catalyst. In the reduction stage, metal oxide reduction and methane activation are combined in an efficient and energy-saving process using methane as a reducing agent. In this study, the effect of temperature and reductant (oxidant) amount on the equilibrium composition of products, graphitic carbon formation, yield of synthesis gas (water splitting stage), and produced ratio are thermodynamically investigated. This investigation includes metal oxides of zinc, tin, cobalt, and nickel. The results show that the synthesis gas is produced simultaneously with gaseous zinc, molten tin, solid cobalt, and solid nickel for those metal oxides in the reduction process. In the case of tin oxide, the feasibility of the graphitic carbon formation is less than the other oxides. The maximum yield of synthesis gas occurs in the stoichiometric molar ratio of methanothermal reduction reactions. From the methane consumption point of view, zinc oxide has a much higher synthesis gas yield. Finally, it is proposed that cobalt and nickel oxides can be used only in the reduction stage to produce synthesis gas and reduced metals due to low equilibrium conversion in the water splitting stage. The metal oxide reduction-water splitting cycle can be developed as an environmentally friendly technology for synthesis gas production over metal oxides.

  1. Biological upgrading of coal-derived synthesis gas: Final report

    SciTech Connect

    Barik, S.; Johnson, E.R.; Ko, C.W.; Clausen, E.C.; Gaddy, J.L.

    1986-10-01

    The technical feasibility of the biological conversion of coal synthesis gas to methane has been demonstrated in the University of Arkansas laboratories. Cultures of microorganisms have been developed which achieve total conversion in the water gas shift and methanation reactions in either mixed or pure cultures. These cultures carry out these conversions at ordinary temperatures and pressures, without sulfur toxicity. Several microorganisms have been identified as having commercial potential for producing methane. These include a mixed culture of unidentified bacteria; P. productus which produces acetate, a methane precursor; and Methanothrix sp., which produces methane from acetate. These cultures have been used in mixed reactors and immobilized cell reactors to achieve total CO and H/sub 2/ conversion in a retention time of less than two hours, quite good for a biological reactor. Preliminary economic projections indicate that a biological methanation plant with a size of 5 x 10/sup 10/ Btu/day can be economically attractive. 42 refs., 26 figs., 86 tabs.

  2. Gas-Phase Combustion Synthesis of Nonoxide Nanoparticles in Microgravity

    NASA Technical Reports Server (NTRS)

    Axelbaum, R. L.; Kumfer, B. M.; Sun, Z.; Chao, B. H.

    2001-01-01

    Gas-phase combustion synthesis is a promising process for creating nanoparticles for the growing nanostructure materials industry. The challenges that must be addressed are controlling particle size, preventing hard agglomerates, maintaining purity, and, if nonoxides are synthesized, protecting the particles from oxidation and/or hydrolysis during post-processing. Sodium-halide Flame Encapsulation (SFE) is a unique methodology for producing nonoxide nanoparticles that addresses these challenges. This flame synthesis process incorporates sodium and metal-halide chemistry, resulting in nanoparticles that are encapsulated in salt during the early stages of their growth in the flame. Salt encapsulation has been shown to allow control of particle size and morphology, while serving as an effective protective coating for preserving the purity of the core particles. Metals and compounds that have been produced using this technology include Al, W, Ti, TiB2, AlN, and composites of W-Ti and Al-AlN. Oxygen content in SFE synthesized nano- AlN has been measured by neutron activation analysis to be as low as 0.54wt.%, as compared to over 5wt.% for unprotected AlN of comparable size. The overall objective of this work is to study the SFE process and nano-encapsulation so that they can be used to produce novel and superior materials. SFE experiments in microgravity allow the study of flame and particle dynamics without the influence of buoyancy forces. Spherical sodium-halide flames are produced in microgravity by ejecting the halide from a spherical porous burner into a quiescent atmosphere of sodium vapor and argon. Experiments are performed in the 2.2 sec Drop Tower at the NASA-Glenn Research Center. Numerical models of the flame and particle dynamics were developed and are compared with the experimental results.

  3. Synthesis of dimethyl ether and alternative fuels in the liquid phase from coal-derived synthesis gas. Final technical report

    SciTech Connect

    Not Available

    1993-02-01

    Through the mid-1980s, Air Products has brought the liquid phase approach to a number of other synthesis gas reactions where effective heat management is a key issue. In 1989, in response to DOE`s PRDA No. DE-RA22-88PC88805, Air Products proposed a research and development program entitled ``Synthesis of Dimethyl Ether and Alternative Fuels in the Liquid Phase from Coal Derived Syngas.`` The proposal aimed at extending the LPMEOH experience to convert coal-derived synthesis gas to other useful fuels and chemicals. The work proposed included development of a novel one-step synthesis of dimethyl ether (DME) from syngas, and exploration of other liquid phase synthesis of alternative fuel directly from syngas. The one-step DME process, conceived in 1986 at Air Products as a means of increasing syngas conversion to liquid products, envisioned the concept of converting product methanol in situ to DME in a single reactor. The slurry reactor based liquid phase technology is ideally suited for such an application, since the second reaction (methanol to DME) can be accomplished by adding a second catalyst with dehydration activity to the methanol producing reactor. An area of exploration for other alternative fuels directly from syngas was single-step slurry phase synthesis of hydrocarbons via methanol and DME as intermediates. Other possibilities included the direct synthesis of mixed alcohols and mixed ethers in a slurry reactor.

  4. ALTERNATIVE FUELS AND CHEMICALS FROM SYNTHESIS GAS. FINAL QUARTERLY STATUS REPORT

    SciTech Connect

    1999-04-01

    The overall objectives of this program are to investigate potential technologies for the conversion of synthesis gas to oxygenated and hydrocarbon fuels and industrial chemicals, and to demonstrate the most promising technologies at DOE's LaPorte, Texas, Slurry Phase Alternative Fuels Development Unit (AFDU). The program will involve a continuation of the work performed under the Alternative Fuels from Coal-Derived Synthesis Gas Program and will draw upon information and technologies generated in parallel current and future DOE-funded contracts.

  5. ALTERNATIVE FUELS AND CHEMICALS FROM SYNTHESIS GAS. FINAL QUARTERLY STATUS REPORT NO. 10

    SciTech Connect

    1998-11-01

    The overall objectives of this program are to investigate potential technologies for the conversion of synthesis gas to oxygenated and hydrocarbon fuels and industrial chemicals, and to demonstrate the most promising technologies at DOE's LaPorte, Texas, Slurry Phase Alternative Fuels Development Unit (AFDU). The program will involve a continuation of the work performed under the Alternative Fuels from Coal-Derived Synthesis Gas Program and will draw upon information and technologies generated in parallel current and future DOE-funded contracts.

  6. Ion transport membrane reactor systems and methods for producing synthesis gas

    SciTech Connect

    Repasky, John Michael

    2015-05-12

    Embodiments of the present invention provide cost-effective systems and methods for producing a synthesis gas product using a steam reformer system and an ion transport membrane (ITM) reactor having multiple stages, without requiring inter-stage reactant injections. Embodiments of the present invention also provide techniques for compensating for membrane performance degradation and other changes in system operating conditions that negatively affect synthesis gas production.

  7. Synthesis of carbon nanoparticles from commercially available liquified petroleum gas

    NASA Astrophysics Data System (ADS)

    Nandiyanto, A. B. D.; Fadhlulloh, M. A.; Rahman, T.; Mudzakir, A.

    2016-04-01

    The aim of this study was to synthesize carbon nanoparticles (CNPs) from commercially available liquefied petroleum gas (LPG). In the research procedure, LPG was reacted with air to construct CNPs. To confirm the successful synthesis of CNPs, we conducted several sample analyses: Gas Chromatography-Mass Spectrometry (GC-MS), Transmission Electron Microscope (TEM), X-ray Diffraction (XRD), and Infrared Spectra (FTIR). We also varied LPG and oxygen mole ratios at 0.8; 2.4; 4.8; and 7.2. The GC-MS results indicated the composition of LPG was propane (58.90%), isobutane (18.35%), butane (22.26%), and butane, 2-methyl (0.48%). The TEM results showed that the particles were spheres with sizes of between 25 and 35 nm. The sizes of particles were controllable, depending on the mole ratio. The XRD results showed mole ratios of LPG and oxygen of 0.80 and 2.40 were natural graphite, whereas the mole ratios of 4.80 and 7.20 were hexagonal graphite. FT-IR results showed CNPs have absorption peaks at wave number (i) 752 (C-H bend sp2); (ii) 835 (C=C); (iii) 1274 (C-O-C vibration); (iv) 1400 and 1600 (C-C stretch aromatic); (v) 2800 (C-H sp2); (vi) 2900 (CH sp3); (vii) 3100 (C-H aromatic); and (viii) 3400 cm-1 (O-H). From the FTIR analysis results, the sample contained allotrope graphite due to detection of peaks at 1400 and 1600 cm-1 (C-C stretch aromatic) and 3100 cm-1 (C-H aromatic).

  8. Bendable Zeolite Membranes: Synthesis and Improved Gas Separation Performance.

    PubMed

    Wang, Bo; Ho, W S Winston; Figueroa, Jose D; Dutta, Prabir K

    2015-06-23

    Separation and sequestration of CO2 emitted from fossil energy fueled electric generating units and industrial facilities will help in reducing anthropogenic CO2, thereby mitigating its adverse climate change effects. Membrane-based gas separation has the potential to meet the technical challenges of CO2 separation if high selectivity and permeance with low costs for large-scale manufacture are realized. Inorganic zeolite membranes in principle can have selectivity and permeance considerably higher than polymers. This paper presents a strategy for zeolite growth within the pores of a polymer support, with crystallization time of an hour. With a thin coating of 200-300 nm polydimethylsiloxane (PDMS) on the zeolite-polymer composite, transport data for CO2/N2 separation indicate separation factors of 35-45, with CO2 permeance between 1600 and 2200 GPU (1 GPU = 3.35 × 10(-10) mol/(m(2) s Pa)) using dry synthetic mixtures of CO2 and N2 at 25 °C. The synthesis process results in membranes that are highly reproducible toward transport measurements and exhibit long-term stability (3 days). Most importantly, these membranes because of the zeolite growth within the polymer support, as contrasted to conventional zeolite growth on top of a support, are mechanically flexible.

  9. Plasma reforming and partial oxidation of hydrocarbon fuel vapor to produce synthesis gas and/or hydrogen gas

    DOEpatents

    Kong, Peter C.; Detering, Brent A.

    2003-08-19

    Methods and systems for treating vapors from fuels such as gasoline or diesel fuel in an internal combustion engine, to form hydrogen gas or synthesis gas, which can then be burned in the engine to produce more power. Fuel vapor, or a mixture of fuel vapor and exhaust gas and/or air, is contacted with a plasma, to promote reforming reactions between the fuel vapor and exhaust gas to produce carbon monoxide and hydrogen gas, partial oxidation reactions between the fuel vapor and air to produce carbon monoxide and hydrogen gas, or direct hydrogen and carbon particle production from the fuel vapor. The plasma can be a thermal plasma or a non-thermal plasma. The plasma can be produced in a plasma generating device which can be preheated by contact with at least a portion of the hot exhaust gas stream, thereby decreasing the power requirements of the plasma generating device.

  10. Plasma Reforming And Partial Oxidation Of Hydrocarbon Fuel Vapor To Produce Synthesis Gas And/Or Hydrogen Gas

    DOEpatents

    Kong, Peter C.; Detering, Brent A.

    2004-10-19

    Methods and systems are disclosed for treating vapors from fuels such as gasoline or diesel fuel in an internal combustion engine, to form hydrogen gas or synthesis gas, which can then be burned in the engine to produce more power. Fuel vapor, or a mixture of fuel vapor and exhaust gas and/or air, is contacted with a plasma, to promote reforming reactions between the fuel vapor and exhaust gas to produce carbon monoxide and hydrogen gas, partial oxidation reactions between the fuel vapor and air to produce carbon monoxide and hydrogen gas, or direct hydrogen and carbon particle production from the fuel vapor. The plasma can be a thermal plasma or a non-thermal plasma. The plasma can be produced in a plasma generating device which can be preheated by contact with at least a portion of the hot exhaust gas stream, thereby decreasing the power requirements of the plasma generating device.

  11. Carbon dioxide capture and use: organic synthesis using carbon dioxide from exhaust gas.

    PubMed

    Kim, Seung Hyo; Kim, Kwang Hee; Hong, Soon Hyeok

    2014-01-13

    A carbon capture and use (CCU) strategy was applied to organic synthesis. Carbon dioxide (CO2) captured directly from exhaust gas was used for organic transformations as efficiently as hyper-pure CO2 gas from a commercial source, even for highly air- and moisture-sensitive reactions. The CO2 capturing aqueous ethanolamine solution could be recycled continuously without any diminished reaction efficiency.

  12. Gas-Phase Combustion Synthesis of Aluminum Nitride Powder

    NASA Technical Reports Server (NTRS)

    Axelbaum, R. L.; Lottes, C. R.; Huertas, J. I.; Rosen, L. J.

    1996-01-01

    Due to its combined properties of high electrical resistivity and high thermal conductivity aluminum nitride (AlN) is a highly desirable material for electronics applications. Methods are being sought for synthesis of unagglomerated, nanometer-sized powders of this material, prepared in such a way that they can be consolidated into solid compacts having minimal oxygen content. A procedure for synthesizing these powders through gas-phase combustion is described. This novel approach involves reacting AlCl3, NH3, and Na vapors. Equilibrium thermodynamic calculations show that 100% yields can be obtained for these reactants with the products being AlN, NaCl, and H2. The NaCl by-product is used to coat the AlN particles in situ. The coating allows for control of AlN agglomeration and protects the powders from hydrolysis during post-flame handling. On the basis of thermodynamic and kinetic considerations, two different approaches were employed to produce the powder, in co-flow diffusion flame configurations. In the first approach, the three reactants were supplied in separate streams. In the second, the AlCl3 and NH3 were premixed with HCl and then reacted with Na vapor. X-ray diffraction (XRD) spectra of as-produced powders show only NaCl for the first case and NaCl and AlN for the second. After annealing at 775 C tinder dynamic vacuum, the salt was removed and XRD spectra of powders from both approaches show only AlN. Aluminum metal was also produced in the co-flow flame by reacting AlCl3 with Na. XRD spectra of as-produced powders show the products to be only NaCl and elemental aluminum.

  13. Techno-economic analysis for the evaluation of three UCG synthesis gas end use approaches

    NASA Astrophysics Data System (ADS)

    Nakaten, Natalie; Kempka, Thomas; Burchart-Korol, Dorota; Krawczyk, Piotr; Kapusta, Krzysztof; Stańczyk, Krzysztof

    2016-04-01

    Underground coal gasification (UCG) enables the utilization of coal reserves that are economically not exploitable because of complex geological boundary conditions. In the present study we investigate UCG as a potential economic approach for conversion of deep-seated coals into a synthesis gas and its application within three different utilization options. Related to geological boundary conditions and the chosen gasification agent, UCG synthesis gas composes of varying methane, hydrogen, nitrogen, carbon monoxide and carbon dioxide amounts. In accordance to its calorific value, the processed UCG synthesis gas can be utilized in different manners, as for electricity generation in a combined cycle power plant or for feedstock production making use of its various chemical components. In the present study we analyze UCG synthesis gas utilization economics in the context of clean electricity generation with an integrated carbon capture and storage process (CCS) as well as synthetic fuel and fertilizer production (Kempka et al., 2010) based on a gas composition achieved during an in situ UCG trial in the Wieczorek Mine. Hereby, we also consider chemical feedstock production in order to mitigate CO2 emissions. Within a sensitivity analysis of UCG synthesis gas calorific value variations, we produce a range of capital and operational expenditure bandwidths that allow for an economic assessment of different synthesis gas end use approaches. To carry out the integrated techno-economic assessment of the coupled systems and the sensitivity analysis, we adapted the techno-economic UCG-CCS model developed by Nakaten et al. (2014). Our techno-economic modeling results demonstrate that the calorific value has a high impact on the economics of UCG synthesis gas utilization. In the underlying study, the synthesis gas is not suitable for an economic competitive electricity generation, due to the relatively low calorific value of 4.5 MJ/Nm³. To be a profitable option for electricity

  14. Autothermal reforming of natural gas to synthesis gas:reference: KBR paper #2031.

    SciTech Connect

    Mann, David; Rice, Steven, D.

    2007-04-01

    This Project Final Report serves to document the project structure and technical results achieved during the 3-year project titled Advanced Autothermal Reformer for US Dept of Energy Office of Industrial Technology. The project was initiated in December 2001 and was completed March 2005. It was a joint effort between Sandia National Laboratories (Livermore, CA), Kellogg Brown & Root LLC (KBR) (Houston, TX) and Sued-Chemie (Louisville, KY). The purpose of the project was to develop an experimental capability that could be used to examine the propensity for soot production in an Autothermal Reformer (ATR) during the production of hydrogen-carbon monoxide synthesis gas intended for Gas-to-Liquids (GTL) applications including ammonia, methanol, and higher hydrocarbons. The project consisted of an initial phase that was focused on developing a laboratory-scale ATR capable of reproducing conditions very similar to a plant scale unit. Due to budget constraints this effort was stopped at the advanced design stages, yielding a careful and detailed design for such a system including ATR vessel design, design of ancillary feed and let down units as well as a PI&D for laboratory installation. The experimental effort was then focused on a series of measurements to evaluate rich, high-pressure burner behavior at pressures as high as 500 psi. The soot formation measurements were based on laser attenuation at a view port downstream of the burner. The results of these experiments and accompanying calculations show that soot formation is primarily dependent on oxidation stoichiometry. However, steam to carbon ratio was found to impact soot production as well as burner stability. The data also showed that raising the operating pressure while holding mass flow rates constant results in considerable soot formation at desirable feed ratios. Elementary reaction modeling designed to illuminate the role of CO{sub 2} in the burner feed showed that the conditions in the burner allow for the

  15. Polyoxometalate-mediated electron transfer-oxygen transfer oxidation of cellulose and hemicellulose to synthesis gas.

    PubMed

    Sarma, Bidyut Bikash; Neumann, Ronny

    2014-08-01

    Terrestrial plants contain ~70% hemicellulose and cellulose that are a significant renewable bioresource with potential as an alternative to petroleum feedstock for carbon-based fuels. The efficient and selective deconstruction of carbohydrates to their basic components, carbon monoxide and hydrogen, so called synthesis gas, is an important key step towards the realization of this potential, because the formation of liquid hydrocarbon fuels from synthesis gas are known technologies. Here we show that by using a polyoxometalate as an electron transfer-oxygen transfer catalyst, carbon monoxide is formed by cleavage of all the carbon-carbon bonds through dehydration of initially formed formic acid. In this oxidation-reduction reaction, the hydrogen atoms are stored on the polyoxometalate as protons and electrons, and can be electrochemically released from the polyoxometalate as hydrogen. Together, synthesis gas is formed. In a hydrogen economy scenario, this method can also be used to convert carbon monoxide to hydrogen.

  16. DEVELOPMENT OF ALTERNATIVE FUELS AND CHEMICALS FROM SYNTHESIS GAS

    SciTech Connect

    Peter J. Tijrn

    2003-05-31

    This Final Report for Cooperative Agreement No. DE-FC22-95PC93052, the ''Development of Alternative Fuels and Chemicals from Synthesis Gas,'' was prepared by Air Products and Chemicals, Inc. (Air Products), and covers activities from 29 December 1994 through 31 July 2002. The overall objectives of this program were to investigate potential technologies for the conversion of synthesis gas (syngas), a mixture primarily of hydrogen (H{sub 2}) and carbon monoxide (CO), to oxygenated and hydrocarbon fuels and industrial chemicals, and to demonstrate the most promising technologies at the LaPorte, Texas Alternative Fuels Development Unit (AFDU). Laboratory work was performed by Air Products and a variety of subcontractors, and focused on the study of the kinetics of production of methanol and dimethyl ether (DME) from syngas, the production of DME using the Liquid Phase Dimethyl Ether (LPDME{trademark}) Process, the conversion of DME to fuels and chemicals, and the production of other higher value products from syngas. Four operating campaigns were performed at the AFDU during the performance period. Tests of the Liquid Phase Methanol (LPMEOH{trademark}) Process and the LPDME{trademark} Process were made to confirm results from the laboratory program and to allow for the study of the hydrodynamics of the slurry bubble column reactor (SBCR) at a significant engineering scale. Two campaigns demonstrated the conversion of syngas to hydrocarbon products via the slurry-phase Fischer-Tropsch (F-T) process. Other topics that were studied within this program include the economics of production of methyl tert-butyl ether (MTBE), the identification of trace components in coal-derived syngas and the means to economically remove these species, and the study of systems for separation of wax from catalyst in the F-T process. The work performed under this Cooperative Agreement has continued to promote the development of technologies that use clean syngas produced from any one of a

  17. Alternative fuels and chemicals from synthesis gas. Fourth quarterly report, 1994

    SciTech Connect

    1997-10-01

    The overall objectives of this program are to investigate potential technologies for the conversion of synthesis gas to oxygenated and hydrocarbon fuels and industrial chemicals, and to demonstrate the most promising technologies at DOE`s LaPorte, Texas, Slurry Phase Alternative Fuels Development Unit (AFDU). The program will involve a continuation of the work performed under the Alternative Fuels from Coal-Derived Synthesis Gas Program and will draw upon information and technologies generated in parallel current and future DOE-funded contracts.

  18. Performance of trickle-bed bioreactors for converting synthesis gas to methane

    SciTech Connect

    Kimmel, D.E.; Klasson, K.T.; Clausen, E.C.; Gaddy, J.L.

    1991-12-31

    Carbon monoxide, H{sub 2}, and CO{sub 2} in synthesis gas can be converted to CH{sub 4} by employing a triculture of Rhodospirillum rubrum, Methanosarcina barkeri, and Methanobacterium formicicum. Trickle-bed reactors have been found to be effective for this conversion because of their high mass-transfer coefficients. This paper compares results obtained for the conversion of synthesis gas to CH{sub 4} in 5-cm- and 16.5-cm-diameter trickle-bed reactors. Mass-transfer and scale-up parameters are defined, and light requirements for R. rubrum are considered in bioreactor design.

  19. Catalyst for selective conversion of synthesis gas and method of making the catalyst

    DOEpatents

    Dyer, Paul N.; Pierantozzi, Ronald

    1986-01-01

    A Fischer-Tropsch (F-T) catalyst, a method of making the catalyst and an F-T process utilizing the catalyst by which synthesis gas, particularly carbon-monoxide rich synthesis gas is selectively converted to higher hydrocarbons of relatively narrow carbon number range. In general, the selective and notably stable catalyst, consists of an inert carrier first treated with a Group IV B metal compound (such as zirconium or titanium), preferably an alkoxide compound, and subsequently treated with an organic compound of an F-T metal catalyst, such as cobalt, iron or ruthenium carbonyl. Reactions with air and water and calcination are specifically avoided in the catalyst preparation procedure.

  20. High pressure synthesis gas fermentation, January 15, 1991--April 14,1991

    SciTech Connect

    Not Available

    1991-01-01

    The components of synthesis gas can be converted into ethanol by the bacterium Clostridium ljunfdahlii, Strain PETC. This microorganism achieves complete conversion of synthesis gas and gives stoichiometric yields of ethanol with high energy efficiency. The reaction rate and bioreactor size are the controlling factors in the commercialization of this process.Synthesis gas fermentations are mass transfer limited due to the very low gas solubilities. It has been demonstrated that reaction rate is proportional to pressure at least up to 10 atm, the limit of existing experimental equipment. The equivalent retention time at 10 atm can be reduced to three minutes. It is felt that retention times of a few seconds are possible and can be demonstrated at higher pressures. With such short equivalent reaction times, the reactor volume for large scale alcohol production becomes nominal and commercial application is assured. The objective of this project is to construct and test a high pressure fermentation system for the production of ethanol from synthesis gas. This system will be fabricated and assembled and the unit used to define the effects of elevated pressure on the growth and performance of C. ljungdahlii. The limits of cell concentration and mass transport relationships will be found in immobilized cell and stirred tank reactors. Minimum retention times and reactor volumes will be found for ethanol production in these reactors.

  1. High pressure synthesis gas fermentation, January 15, 1991--April 14,1991

    SciTech Connect

    Not Available

    1991-12-31

    The components of synthesis gas can be converted into ethanol by the bacterium Clostridium ljunfdahlii, Strain PETC. This microorganism achieves complete conversion of synthesis gas and gives stoichiometric yields of ethanol with high energy efficiency. The reaction rate and bioreactor size are the controlling factors in the commercialization of this process.Synthesis gas fermentations are mass transfer limited due to the very low gas solubilities. It has been demonstrated that reaction rate is proportional to pressure at least up to 10 atm, the limit of existing experimental equipment. The equivalent retention time at 10 atm can be reduced to three minutes. It is felt that retention times of a few seconds are possible and can be demonstrated at higher pressures. With such short equivalent reaction times, the reactor volume for large scale alcohol production becomes nominal and commercial application is assured. The objective of this project is to construct and test a high pressure fermentation system for the production of ethanol from synthesis gas. This system will be fabricated and assembled and the unit used to define the effects of elevated pressure on the growth and performance of C. ljungdahlii. The limits of cell concentration and mass transport relationships will be found in immobilized cell and stirred tank reactors. Minimum retention times and reactor volumes will be found for ethanol production in these reactors.

  2. Design, Synthesis, and Mechanistic Evaluation of Iron-Based Catalysis for Synthesis Gas Conversion to Fuels and Chemicals

    SciTech Connect

    Enrique Iglesia

    2004-09-30

    This project explores the extension of previously discovered Fe-based catalysts with unprecedented Fischer-Tropsch synthesis rate, selectivity, and ability to convert hydrogen-poor synthesis gas streams typical of those produced from coal and biomass sources. Contract negotiations were completed on December 9, 2004. During the first reporting period, we certified a microreactor, installed required analytical equipment, and reproduced synthetic protocols and catalytic performance previously reported. During this second reporting period, we have prepared and tested several Fe-based compositions for Fischer-Tropsch synthesis and tested the effects of product recycle under both subcritical and supercritical conditions. These studies established modest improvements in rates and selectivities with light hydrocarbon recycle without any observed deleterious effects, opening up the opportunities for using of recycle strategies to control temperature profiles in fixed-bed Fe-based Fischer-Tropsch synthesis reactors without any detectable kinetic detriment. In a parallel study, we examined similar effects of recycle for cobalt-based catalysts; marked selectivity improvements were observed as a result of the removal of significant transport restrictions on these catalysts. Finally, we have re-examined some previously unanalyzed data dealing with the mechanism of the Fischer-Tropsch synthesis, specifically kinetic isotope effects on the rate and selectivity of chain growth reactions on Fe-based catalysts.

  3. Effects of carrier gas dynamics on single wall carbon nanotube chiral distributions during laser vaporization synthesis.

    PubMed

    Landi, Brian J; Raffaelle, Ryne P

    2007-03-01

    We report on the utility of modifying the carrier gas dynamics during laser vaporization synthesis to alter the single wall carbon nanotube (SWNT) chiral distribution. SWNTs produced from an Alexandrite laser using conventional Ni/Co catalysts demonstrate marked differences in chiral distributions due to effects of helium gas and reactor chamber pressure, in comparison to conventional subambient pressures and argon gas. Optical absorption and Raman spectroscopies confirm that the SWNT diameter distribution decreases under higher pressure and with helium gas as opposed to argon. Fluorescence mapping of the raw soots in sodium dodecylbenzene sulfonate (SDBS)-D2O was used to estimate the relative (n, m)-SWNT content of the semiconducting types. A predominance of type II structures for each synthesis condition was observed. The distribution of SWNT chiral angles was observed to shift away from near-armchair configurations under higher pressure and with helium gas. These results illustrate the importance of gas type and pressure on the condensation/cooling rate, which allows for synthesis of specific SWNT chiral distributions.

  4. Direct Routes from Synthesis Gas to Ethylene Glycol.

    ERIC Educational Resources Information Center

    Dombek, B. D.

    1986-01-01

    Discusses the synthesis of ethylene glycol from carbon monoxide and hydrogen using bimetallic catalysts. Although this technology has not been implemented, it illustrates two important future trends, namely, use of bimetallic catalysts and use of coal-derived carbon monoxide and hydrogen as a new feed stock. (JN)

  5. Alternate fuels and chemicals from synthesis gas: Vinyl acetate monomer. Final report

    SciTech Connect

    Richard D. Colberg; Nick A. Collins; Edwin F. Holcombe; Gerald C. Tustin; Joseph R. Zoeller

    1999-01-01

    There has been a long-standing desire on the part of industry and the U.S. Department of Energy to replace the existing ethylene-based vinyl acetate monomer (VAM) process with an entirely synthesis gas-based process. Although there are a large number of process options for the conversion of synthesis gas to VAM, Eastman Chemical Company undertook an analytical approach, based on known chemical and economic principles, to reduce the potential candidate processes to a select group of eight processes. The critical technologies that would be required for these routes were: (1) the esterification of acetaldehyde (AcH) with ketene to generate VAM, (2) the hydrogenation of ketene to acetaldehyde, (3) the hydrogenation of acetic acid to acetaldehyde, and (4) the reductive carbonylation of methanol to acetaldehyde. This report describes the selection process for the candidate processes, the successful development of the key technologies, and the economic assessments for the preferred routes. In addition, improvements in the conversion of acetic anhydride and acetaldehyde to VAM are discussed. The conclusion from this study is that, with the technology developed in this study, VAM may be produced from synthesis gas, but the cost of production is about 15% higher than the conventional oxidative acetoxylation of ethylene, primarily due to higher capital associated with the synthesis gas-based processes.

  6. Microemulsion impregnated catalyst composite and use thereof in a synthesis gas conversion process

    DOEpatents

    Abrevaya, H.; Targos, W.M.

    1987-12-22

    A catalyst composition is described for synthesis gas conversion comprising a ruthenium metal component deposited on a support carrier wherein the average metal particle size is less than about 100 A. The method of manufacture of the composition via a reverse micelle impregnation technique and the use of the composition in a Fischer-Tropsch conversion process is also disclosed.

  7. Microemulsion impregnated catalyst composite and use thereof in a synthesis gas conversion process

    DOEpatents

    Abrevaya, Hayim; Targos, William M.

    1987-01-01

    A catalyst composition for synthesis gas conversion comprising a ruthenium metal component deposited on a support carrier wherein the average metal particle size is less than about 100 A. The method of manufacture of the composition via a reverse micelle impregnation technique and the use of the composition in a Fischer-Tropsch conversion process is also disclosed.

  8. Design, Synthesis, and Mechanistic Evaluation of Iron-Based Catalysis for Synthesis Gas Conversion to Fuels and Chemicals

    SciTech Connect

    Akio Ishikawa; Manuel Ojeda; Nan Yao; Enrique Iglesia

    2006-03-31

    This project extends previously discovered Fe-based catalysts to hydrogen-poor synthesis gas streams derived from coal and biomass sources. These catalysts have shown unprecedented Fischer-Tropsch synthesis rate, selectivity for feedstocks consisting of synthesis gas derived from methane. During the first reporting period, we certified a microreactor, installed required analytical equipment, and reproduced synthetic protocols and catalytic results previously reported. During the second reporting period, we prepared several Fe-based compositions for Fischer-Tropsch synthesis and tested the effects of product recycle under both subcritical and supercritical conditions. During the third and fourth reporting periods, we improved the catalysts preparation method, which led to Fe-based FT catalysts with the highest FTS reaction rates and selectivities so far reported, a finding that allowed their operation at lower temperatures and pressures with high selectivity to desired products (C{sub 5+}, olefins). During this fifth reporting period, we have studied the effects of different promoters on catalytic performance, specifically how their sequence of addition dramatically influences the performance of these materials in the Fischer-Tropsch synthesis. The resulting procedures have been optimized to improve further upon the already unprecedented rates and C{sub 5+} selectivities of the Fe-based catalysts that we have developed as part of this project. During this fifth reporting period, we have also continued our studies of optimal activation procedures, involving reduction and carburization of oxide precursors during the early stages of contact with synthesis gas. We have completed the analysis of the evolution of oxide, carbide, and metal phases of the active iron components during initial contact with synthesis gas using advanced synchrotron techniques based on X-ray absorption spectroscopy. We have confirmed that the Cu or Ru compensates for inhibitory effects of Zn, a

  9. Synthesis gas solubility in Fischer-Tropsch slurry

    SciTech Connect

    Huang, S.H.

    1987-01-01

    A semi-flow apparatus is designed and constructed for the measurements of gas solubilities in molten waxes. Test data of CO/sub 2//toluene mixture show excellent agreement with literature data from a static apparatus. Five gases are studied: hydrogen, carbon monoxide, methane, ethane, and carbon dioxide. Data measurements are completed for each gas in n-eicosane (C/sub 20/), n-octacosane (C/sub 28/), and in n-hexatriacontane (C/sub 36/) as well as in an industrial wax over 100 to 300/sup 0/C and 10 to 50 atm. Solubilities of gas mixtures of H/sub 2/ + CO in n-C/sub 28/ are also measured at several equilibrium gas compositions. The gas K-value, defined as the ratio of the composition in the vapor phase to that in the liquid phase, is found independent as gas compositions within experimental errors. The Krichevski-Kasarnovsky equation represents well the data of binary systems. Henry's constants and partial molar volumes of gases at infinite dilution are determined from the equation. The Redlich-Kwong-Soave equation of state is modified to describe the vapor pressures of n-paraffins up to n-C/sub 100/. The modified equation is combined with a new mixing rule, whose derivation is based on a polymer solution theory, to correlate the data, and the results are satisfactory. Furthermore, the adjustable parameter can be correlated as an asymptotical function of the solvent molecular weight except for H/sub 2/ and CO at the lowest temperature. The modified equation with correlated parameter can predict the gas mixture solubilities in n-C/sub 28/. Also, gas solubilities in a wax mixture can be predicted if the wax is treated as a pure n-paraffin with the same number average molecular weight.

  10. DESIGN, SYNTHESIS, AND MECHANISTIC EVALUATION OF IRON-BASED CATALYSIS FOR SYNTHESIS GAS CONVERSION TO FUELS AND CHEMICALS

    SciTech Connect

    Akio Ishikawa; Manuel Ojeda; Enrique Iglesia

    2005-03-31

    This project explores the extension of previously discovered Fe-based catalysts to hydrogen-poor synthesis gas streams derived from coal and biomass sources. These catalysts have previously shown unprecedented Fischer-Tropsch synthesis rate, selectivity with synthesis gas derived from methane. During the first reporting period, we certified a microreactor, installed required analytical equipment, and reproduced synthetic protocols and catalytic performance previously reported. During the second reporting period, we prepared several Fe-based compositions for Fischer-Tropsch synthesis and tested the effects of product recycle under both subcritical and supercritical conditions. During this third reporting period, we have prepared a large number of Fe-based catalyst compositions using precipitation and impregnations methods with both supercritical and subcritical drying and with the systematic use of surface active agents to prevent pore collapse during drying steps required in synthetic protocols. These samples were characterized during this period using X-ray diffraction, surface area, and temperature-programmed reduction measurements. These studies have shown that these synthesis methods lead to even higher surface areas than in our previous studies and confirm the crystalline structures of these materials and their reactivity in both oxide-carbide interconversions and in Fischer-Tropsch synthesis catalysis. Fischer-Tropsch synthesis reaction rates and selectivities with low H{sub 2}/CO ratio feeds (H{sub 2}/CO = 1) were the highest reported in the literature at the low-temperature and relatively low pressure in our measurements. Current studies are exploring the optimization of the sequence of impregnation of Cu, K, and Ru promoters, of the activation and reaction conditions, and of the co-addition of light hydrocarbons to increase diffusion rates of primary olefin products so as to increase the selectivity to unsaturated products. Finally, we are also addressing

  11. Oxygen transport membrane based advanced power cycle with low pressure synthesis gas slip stream

    DOEpatents

    Kromer, Brian R.; Litwin, Michael M.; Kelly, Sean M.

    2016-09-27

    A method and system for generating electrical power in which a high pressure synthesis gas stream generated in a gasifier is partially oxidized in an oxygen transport membrane based reactor, expanded and thereafter, is combusted in an oxygen transport membrane based boiler. A low pressure synthesis gas slip stream is split off downstream of the expanders and used as the source of fuel in the oxygen transport membrane based partial oxidation reactors to allow the oxygen transport membrane to operate at low fuel pressures with high fuel utilization. The combustion within the boiler generates heat to raise steam to in turn generate electricity by a generator coupled to a steam turbine. The resultant flue gas can be purified to produce a carbon dioxide product.

  12. Sorbents for High Temperature Removal of Arsenic from Coal-Derived Synthesis Gas

    SciTech Connect

    Alptekin, G.O.; Copeland, R.; Dubovik, M.; Gershanovich, Y.

    2002-09-20

    Gasification technologies convert coal and other heavy feedstocks into synthesis gas feed streams that can be used in the production of a wide variety of chemicals, ranging from hydrogen through methanol, ammonia, acetic anhydride, dimethyl ether (DME), methyl tertiary butyl ether (MTBE), high molecular weight liquid hydrocarbons and waxes. Syngas can also be burned directly as a fuel in advanced power cycles to generate electricity with very high efficiency. However, the coal-derived synthesis gas contains a myriad of trace contaminants that may poison the catalysts that are used in the downstream manufacturing processes and may also be regulated in power plant emissions. Particularly, the catalysts used in the conversion of synthesis gas to methanol and other liquid fuels (Fischer-Tropsch liquids) have been found to be very sensitive to the low levels of poisons, especially arsenic, that are present in the synthesis gas from coal. TDA Research, Inc. (TDA) is developing an expendable high capacity, low-cost chemical absorbent to remove arsenic from coal-derived syngas. Unlike most of the commercially available sorbents that physically adsorb arsenic, TDA's sorbent operates at elevated temperatures and removes the arsenic through chemical reaction. The arsenic content in the coal gas stream is reduced to ppb levels with the sorbent by capturing and stabilizing the arsenic gas (As4) and arsenic hydrides (referred to as arsine, AsH3) in the solid state. To demonstrate the concept of high temperature arsenic removal from coal-derived syngas, we carried out bench-scale experiments to test the absorption capacity of a variety of sorbent formulations under representative conditions. Using on-line analysis techniques, we monitored the pre- and post-breakthrough arsine concentrations over different sorbent samples. Some of these samples exhibited pre-breakthrough arsine absorption capacity over 40% wt. (capacity is defined as lb of arsenic absorbed/lb of sorbent), while

  13. Reactive gas condensation synthesis of aluminum nitride nanoparticles.

    PubMed

    Baker, Colin C; Ceylan, Abdullah; Shah, S Ismat

    2006-01-01

    Aluminum Nitride (AIN) nanoparticles were synthesized using a Reactive Gas Condensation (RGC) technique in which a mixture of ammonia (NH3) and nitrogen (N2) gases were used for the nitridation of aluminum. NH3 served as the reactive gas, while N2 served as both a carrier gas and the inert source for particle condensation. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analyses revealed that at reactive gas compositions greater than 10% NH3 in N2, samples were composed entirely of hexagonal AIN nanoparticles. Electron diffraction patterns showed single crystal hexagonal AIN structure. The particle size was controlled by varying the pressure of the gas mixture. AIN nanoparticles were dispersed in a liquid matrix to enhance thermal conductivity. Results showed that a minimal addition of AIN increased the thermal conductivity of hydrocarbon pump oil by approximately 27%. The thermal conductivity became constant after reaching a maximum above 0.01 wt% AIN. Temporal stability of AIN was studied by XRD. Samples exposed to air for extended periods of time and analyzed by XRD show no degradation of crystalline AIN nanoparticles.

  14. Natural synthesis of bioactive greigite by solid-gas reactions

    NASA Astrophysics Data System (ADS)

    Igarashi, Kensuke; Yamamura, Yasuhisa; Kuwabara, Tomohiko

    2016-10-01

    Greigite, a ferrimagnetic iron sulfide Fe(II)Fe(III)2S4, is thought to have played an essential role in chemical evolution leading to the origin of life. Greigite contains a [4Fe-4S] cluster-like structure and has been synthesized in the laboratory by liquid-state reactions. However, it is unclear how greigite can be synthesized in nature. Herein, we show that greigite is synthesized by the solid-gas reaction of Fe(III)-oxide-hydroxides and H2S. We discovered that the hyperthermophilic hydrogenotrophic methanogen Methanocaldococcus jannaschii reduced elemental sulfur, and the resulting sulfide generated greigite from hematite. The time course and pH dependence of the reaction respectively indicated the involvement of amorphous FeS and H2S as reaction intermediates. An abiotic solid-gas reaction of hematite and H2S (g) under strictly anaerobic conditions was developed. The solid-gas reaction fully converted hematite to greigite/pyrite at 40-120 °C within 12 h and was unaffected by the bulk gas phase. Similar abiotic reactions occurred, but relatively slowly, with aqueous H2S in acidulous liquids using hematite, magnetite, or amorphous FeO(OH) as starting materials, suggesting that greigite was extensively produced in the Hadean Eon as these Fe(III)-oxide-hydroxides were shown to be present or routinely produced during that era. Surprisingly, the obtained greigite induced methanogenesis and growth of hydrogenotrophic methanogens, suggesting that the external greigite crystals enhanced reactions that would otherwise require enzymes, such as [4Fe-4S] cluster-harboring membrane-bound hydrogenases. These data suggested that the greigite produced by the solid-gas and solid-dissolved gas reactions was bioactive.

  15. Evaluation of some new zeolite-supported metal catalysts for synthesis gas conversion

    SciTech Connect

    Melson, G.A.; Crawford, J.E.; Crites, J.W.; Mbadcam, K.J.; Rao, V.U.S.; Stencel, J.M.

    1982-03-01

    The use of bifunctional zeolite-based catalysts for the conversion of synthesis gas (carbon monoxide and hydrogen) to gasoline range hydrocarbons has recently attracted much attention. For example, the combination of metal oxides with the medium pore (about 6A) zeolite ZSM-5 and the use of a metal nitrate impregnated ZSM-5 catalyst have been shown to produce gasoline range hydrocarbons containing a high percentage of aromatics from synthesis gas. The production of gasoline range hydrocarbons which have a high olefin content has also been reported by using iron or cobalt impregnated ZSM-5 catalysts. The efficiency and selectivity of supported metal heterogeneous catalysts is closely related to the dispersion and particle size of the metal component and to the nature of the interaction between the metal and the support. For a particular metal, catalytic activity may be varied by changing the metal dispersion and the support, thus, the method of synthesis and any pre-treatment of the catalyst is important in the overall process of catalyst evaluation. Supported metal catalysts have traditionally been prepared by impregnation techniques that involve treatment of a support with an aqueous solution of a metal salt followed by calcination. In the Fe/ZSM-5, system, the decomposition of the iron nitrate during calcination usually produces iron oxides of relatively large crystallite size. This work was initiated in an attempt to produce highly dispersed, thermally stable supported metal catalysts which may be effective for synthesis gas conversion.

  16. Synthesis and gas separation studies of substituted polyaniline membranes

    SciTech Connect

    Su, T.M.; Kwon, A.H.; Lew, B.M.; Kaner, R.B.

    1996-10-01

    Polyaniline is a conjugated polymer that can be reversibly doped and undoped using common acids and bases. In the doped state, polyaniline is thermally and environmentally stable and electrically conducting. Polyaniline has shown promise as a gas separation membrane, however, it is limited by poor thermal processability and solvent solubility. The solvent solubility is increased for ethyl and methoxy substituted polyaniline. The smooth free-standing membranes cast from these substituted polymers exhibit an increase in gas permeability compared to the base form of polyaniline, but a decrease in selectivity.

  17. Electrochemical polishing of hydrogen sulfide from coal synthesis gas

    SciTech Connect

    Gleason, E.F.; Winnick, J.

    1995-11-01

    An advanced process has been developed for the separation of H{sub 2}S from coal gasification product streams through an electrochemical membrane. This technology is developed for use in coal gasification facilities providing fuel for cogeneration coal fired electrical power facilities and Molten Carbonate Fuel Cell electrical power facilities. H{sub 2}S is removed from the syn-gas by reduction to the sulfide ion and H at the cathode. The sulfide ion migrates to the anode through a molten salt electrolyte suspended in an inert ceramic matrix. Once at the anode it is oxidized to elemental sulfur and swept away for condensation in an inert gas stream. The syn-gas is enriched with the H{sub 2}. Order-of-magnitude reductions in H{sub 2}S have been repeatably recorded (100 ppm to 10 ppm H{sub 2}S) on a single pass through the cell. This process allows removal of H{sub 2}S without cooling the gas stream and with negligible pressure loss through the separator. Since there are no absorbents used, there is no absorption/regeneration step as with conventional technology. Elemental sulfur is produced as a by-product directly, so there is no need for a Claus process for sulfur recovery. This makes the process economically attractive since it is much less equipment intensive than conventional technology.

  18. Hematite nanoplates: Controllable synthesis, gas sensing, photocatalytic and magnetic properties.

    PubMed

    Hao, Hongying; Sun, Dandan; Xu, Yanyan; Liu, Ping; Zhang, Guoying; Sun, Yaqiu; Gao, Dongzhao

    2016-01-15

    Uniform hematite (α-Fe2O3) nanoplates exposing {001} plane as basal planes have been prepared by a facile solvothermal method under the assistance of sodium acetate. The morphological evolution of the nanoplates was studied by adjusting the reaction parameters including the solvent and the amount of sodium acetate. The results indicated that both the adequate nucleation/growth rate and selective adsorption of alcohol molecules and acetate anions contribute to the formation of the plate-like morphology. In addition, the size of the nanoplates can be adjusted from ca. 180nm to 740nm by changing the reaction parameters. Three nanoplate samples with different size were selected to investigate the gas sensing performance, photocatalytic and magnetic properties. As gas sensing materials, all the α-Fe2O3 nanoplates exhibited high gas sensitivity and stability toward n-butanol. When applied as photocatalyst, the α-Fe2O3 nanoplates show high photodegradation efficiency towards RhB. Both the gas sensing performance and the photocatalytic property of the products exhibit obvious size-dependent effect. Magnetic measurements reveal that the plate-like α-Fe2O3 particles possess good room temperature magnetic properties. PMID:26476200

  19. Nanocasting synthesis and gas-sensing behavior of hematite nanowires

    NASA Astrophysics Data System (ADS)

    Li, Danping; Zhang, Y.; Xu, Jingcai; Jin, Hongxiao; Jin, Dingfeng; Hong, Bo; Peng, Xiaoling; Wang, Panfeng; Ge, Hongliang; Wang, Xinqing

    2016-10-01

    The dispersed and uniform hematite nanowires (α-Fe2O3 NWs) with the different diameter were synthesized using SBA-15 as hard templates by the nanocasting method, and the diameter of α-Fe2O3 NWs was about 4, 6 and 8 nm, respectively. The BET surface area of α-Fe2O3 NWs changed a little, while the bandgap decreased from 2.07, 2.03 to 1.91 eV with the increasing diameter according to quantum size effect. Compared all samples, the sensitivity of α-Fe2O3 NWs based gas-sensors increased from 10.64 to 11.43 with the bandgap and BET surface area α-Fe2O3 NWs in 100 ppm ethanol at 300 °C, and the response-recovery time was also improved for the good crystallinity. It's concluded that the surface area greatly affected the gas-sensing performance of α-Fe2O3 NWs based sensors, while the bandgap and crystallinity also influenced the gas-sensing behavior to some extent. The α-Fe2O3 NWs based gas-sensors exhibited the high sensitivity, fast response-recovery and good selectivity to ethanol.

  20. Hematite nanoplates: Controllable synthesis, gas sensing, photocatalytic and magnetic properties.

    PubMed

    Hao, Hongying; Sun, Dandan; Xu, Yanyan; Liu, Ping; Zhang, Guoying; Sun, Yaqiu; Gao, Dongzhao

    2016-01-15

    Uniform hematite (α-Fe2O3) nanoplates exposing {001} plane as basal planes have been prepared by a facile solvothermal method under the assistance of sodium acetate. The morphological evolution of the nanoplates was studied by adjusting the reaction parameters including the solvent and the amount of sodium acetate. The results indicated that both the adequate nucleation/growth rate and selective adsorption of alcohol molecules and acetate anions contribute to the formation of the plate-like morphology. In addition, the size of the nanoplates can be adjusted from ca. 180nm to 740nm by changing the reaction parameters. Three nanoplate samples with different size were selected to investigate the gas sensing performance, photocatalytic and magnetic properties. As gas sensing materials, all the α-Fe2O3 nanoplates exhibited high gas sensitivity and stability toward n-butanol. When applied as photocatalyst, the α-Fe2O3 nanoplates show high photodegradation efficiency towards RhB. Both the gas sensing performance and the photocatalytic property of the products exhibit obvious size-dependent effect. Magnetic measurements reveal that the plate-like α-Fe2O3 particles possess good room temperature magnetic properties.

  1. Design, Synthesis, and Mechanistic Evaluation of Iron-Based Catalysis for Synthesis Gas Conversion to Fuels and Chemicals

    SciTech Connect

    Akio; Ishikawa; Manuel Ojeda; Nan Yao; Enrique Iglesia

    2006-09-30

    This project extends previously discovered Fe-based catalysts to hydrogen-poor synthesis gas streams derived from coal and biomass sources. These catalysts have shown unprecedented Fischer-Tropsch synthesis rates and selectivities for feedstocks consisting of synthesis gas derived from methane. During the first reporting period, we certified a microreactor, installed required analytical equipment, and reproduced synthetic protocols and catalytic results previously reported. During the second reporting period, we prepared several Fe-based compositions for Fischer-Tropsch Synthesis and tested the effects of product recycle under both subcritical and supercritical conditions. During the third and fourth reporting periods, we improved the catalysts preparation method, which led to Fe-based FT catalysts with the highest FTS reaction rates and selectivities so far reported, a finding that allowed their operation at lower temperatures and pressures with high selectivity to desired products (C{sub 5+}, olefins). During the fifth reporting period, we studied the effects of different promoters on catalytic performance, specifically how their sequence of addition dramatically influenced the performance of these materials in the Fischer-Tropsch synthesis. We also continued our studies of the kinetic behavior of these materials. Specifically, the effects of H{sub 2}, CO, and CO{sub 2} on the rates and selectivities of Fischer-Tropsch Synthesis reactions led us to propose a new sequence of elementary steps on Fe and Co Fischer-Tropsch catalysts. More specifically, we were focused on the roles of hydrogen-assisted and alkali-assisted dissociation of CO in determining rates and CO{sub 2} selectivities. During this sixth reporting period, we have studied the validity of the mechanism that we propose by analyzing the H{sub 2}/D{sub 2} kinetic isotope effect (r{sub H}/r{sub D}) over a conventional iron-based Fischer-Tropsch catalyst Fe-Zn-K-Cu. We have observed experimentally that

  2. Design, Synthesis and Mechanistic Evaluation of Iron-Based Catalysis for Synthesis Gas Conversion to Fuels and Chemicals

    SciTech Connect

    Akio Ishikawa; Manuel Ojeda; Nan Yao; Enrique Iglesia

    2007-03-31

    This project extends previously discovered Fe-based catalysts to hydrogen-poor synthesis gas streams derived from coal and biomass sources. These catalysts have shown unprecedented Fischer-Tropsch synthesis rates and selectivities for synthesis gas derived from methane. During the first reporting period, we certified a microreactor, installed required analytical equipment, and reproduced synthetic protocols and catalytic results previously reported. During the second reporting period, we prepared several Fe-based compositions for Fischer-Tropsch Synthesis and tested the effects of product recycle under both subcritical and supercritical conditions. During the third and fourth reporting periods, we improved the catalysts preparation method, which led to Fe-based materials with the highest FTS reaction rates and selectivities so far reported, a finding that allowed their operation at lower temperatures and pressures with high selectivity to desired products (C{sub 5+}, olefins). During the fifth and sixth reporting period, we studied the effects of different promoters on catalytic performance, specifically how their sequence of addition dramatically influenced the performance of these materials in the Fischer-Tropsch synthesis. We also continued our studies of the kinetic behavior of these materials during the sixth reporting period. Specifically, the effects of H{sub 2}, CO, and CO{sub 2} on the rates and selectivities of Fischer-Tropsch Synthesis reactions led us to propose a new sequence of elementary steps on Fe and Co Fischer-Tropsch catalysts. Finally, we also started a study of the use of colloidal precipitation methods for the synthesis small Co clusters using recently developed methods to explore possible further improvements in FTS rates and selectivities. We found that colloidal synthesis makes possible the preparation of small cobalt particles, although large amount of cobalt silicate species, which are difficult to reduce, were formed. During this

  3. Synthesis gas and olefins from the catalytic autothermal reforming of volatile and non-volatile liquids

    NASA Astrophysics Data System (ADS)

    Dreyer, Bradon Justin

    2007-12-01

    The research presented in this thesis develops an understanding of a clean energy process technology, catalytic partial oxidation (CPO). CPO is a process in which a carbon containing fuel, such as a hydrocarbon, is passed over a noble metal catalyst (e.g. rhodium and platinum) to efficiently generate synthesis gas (H2 and CO) and olefins (e.g. ethylene and propylene) in millisecond contact times. Chapter 1 introduces CPO and compares this technology with conventional methods for synthesis gas and olefin production. CPO has several advantages over the traditional synthesis gas and olefin production methods. One advantage includes autothermal operation, requiring no external heat input from furnaces or heat exchangers. Autothermal operation allows these reactors to be built compactly. The short contact-times associated with CPO further enable for high throughput in relatively small reactor systems, and more compact reactors typically translate to faster response times if transient operation is required. Nobel metal based CPO catalysts are also resistant to deactivation, resulting in less catalyst replacement, regeneration, and maintenance, and an increase in operating efficiency. An overview of the many applications of the chemicals produced from CPO is also presented in Chapter 1. The chemicals produced are crucial in generating valuable chemical intermediates that are eventually incorporated in consumer products, medical devices, building structures, and fertilizers. Additionally, H2 can be used as a source of energy in mobile fuel applications. Fuel cells convert H2 and O2 into electricity and water at higher efficiencies than thermal engine generators. Due to the difficulties in H2 storage, these more efficient energy generators are dependent on hydrogen obtained from synthesis gas production in compact, portable fuel reformers, such as CPO reactors. Furthermore, H2 and CO can be used in reducing environmentally harmful emissions. Particularly, the implementation

  4. Synthesis, pervaporation and gas separation studies of polyaniline blends

    SciTech Connect

    Huang, S.C.; Conklin, J.A.; Su, T.M.

    1995-12-01

    Membranes have been successfully produced from blends of polyaniline/polyacrylic acid and polyaniline/polyimide. The uniqueness of these membranes is the incorporation of {open_quotes}polymer dopants{close_quotes} in polyaniline. Conductivity measurements show that polyacrylic acid dopes the polyaniline. Pervaporation of water and water/acetic acid mixtures were performed using polyaniline and its polyacrylic acid blend. An improved flux over the polyaniline base form is observed. Polyaniline/polyimide blends were synthesized for gas permeability studies. These blends combine improved thermal stability relative to polyaniline with greater gas selectivity relative to polyimide. The blend shows an increase in permeability for all gases studied over both, polyaniline base and polyimide, while maintaining comparable separation factors.

  5. Synthesis, Characterization, and Gas Sensing Applications of WO3 Nanobricks

    NASA Astrophysics Data System (ADS)

    Xiao, Jingkun; Song, Chengwen; Dong, Wei; Li, Chen; Yin, Yanyan; Zhang, Xiaoni; Song, Mingyan

    2015-08-01

    WO3 nanobricks are fabricated by a simple hydrothermal method. Morphology and structure of the WO3 nanobricks are characterized by scanning electron microscopy and x-ray diffraction. Gas sensing properties of the as-prepared WO3 sensor are systematically investigated by a static gas sensing system. The results show that the WO3 nanobricks with defect corners demonstrate good crystallinity, and the mean edge length and wall thickness are 1-1.5 and 400 nm, respectively. The WO3 sensor achieves its maximum sensitivity to 100 ppm ethanol at the optimal operating temperature of 300 °C. Ultra-fast response time (2-3 s) and fast recovery time (4-11 s) of the WO3 sensor toward 100 ppm ethanol are also observed at this optimal operating temperature. Moreover, the WO3 sensor exhibits high selectivity to other gases such as methanol, benzene, hexane, and dichloromethane, indicating its excellent potential application as a gas sensor for ethanol detection.

  6. Design and synthesis of copper-cobalt catalysts for the selective conversion of synthesis gas to ethanol and higher alcohols.

    PubMed

    Prieto, Gonzalo; Beijer, Steven; Smith, Miranda L; He, Ming; Au, Yuen; Wang, Zi; Bruce, David A; de Jong, Krijn P; Spivey, James J; de Jongh, Petra E

    2014-06-16

    Combining quantum-mechanical simulations and synthesis tools allows the design of highly efficient CuCo/MoO(x) catalysts for the selective conversion of synthesis gas (CO+H2) into ethanol and higher alcohols, which are of eminent interest for the production of platform chemicals from non-petroleum feedstocks. Density functional theory calculations coupled to microkinetic models identify mixed Cu-Co alloy sites, at Co-enriched surfaces, as ideal for the selective production of long-chain alcohols. Accordingly, a versatile synthesis route is developed based on metal nanoparticle exsolution from a molybdate precursor compound whose crystalline structure isomorphically accommodates Cu(2+) and Co(2+) cations in a wide range of compositions. As revealed by energy-dispersive X-ray nanospectroscopy and temperature-resolved X-ray diffraction, superior mixing of Cu and Co species promotes formation of CuCo alloy nanocrystals after activation, leading to two orders of magnitude higher yield to high alcohols than a benchmark CuCoCr catalyst. Substantiating simulations, the yield to high alcohols is maximized in parallel to the CuCo alloy contribution, for Co-rich surface compositions, for which Cu phase segregation is prevented.

  7. Harnessing the Power of the Water-Gas Shift Reaction for Organic Synthesis.

    PubMed

    Ambrosi, Andrea; Denmark, Scott E

    2016-09-26

    Since its original discovery over a century ago, the water-gas shift reaction (WGSR) has played a crucial role in industrial chemistry, providing a source of H2 to feed fundamental industrial transformations such as the Haber-Bosch synthesis of ammonia. Although the production of hydrogen remains nowadays the major application of the WGSR, the advent of homogeneous catalysis in the 1970s marked the beginning of a synergy between WGSR and organic chemistry. Thus, the reducing power provided by the CO/H2 O couple has been exploited in the synthesis of fine chemicals; not only hydrogenation-type reactions, but also catalytic processes that require a reductive step for the turnover of the catalytic cycle. Despite the potential and unique features of the WGSR, its applications in organic synthesis remain largely underdeveloped. The topic will be critically reviewed herein, with the expectation that an increased awareness may stimulate new, creative work in the area.

  8. Harnessing the Power of the Water-Gas Shift Reaction for Organic Synthesis.

    PubMed

    Ambrosi, Andrea; Denmark, Scott E

    2016-09-26

    Since its original discovery over a century ago, the water-gas shift reaction (WGSR) has played a crucial role in industrial chemistry, providing a source of H2 to feed fundamental industrial transformations such as the Haber-Bosch synthesis of ammonia. Although the production of hydrogen remains nowadays the major application of the WGSR, the advent of homogeneous catalysis in the 1970s marked the beginning of a synergy between WGSR and organic chemistry. Thus, the reducing power provided by the CO/H2 O couple has been exploited in the synthesis of fine chemicals; not only hydrogenation-type reactions, but also catalytic processes that require a reductive step for the turnover of the catalytic cycle. Despite the potential and unique features of the WGSR, its applications in organic synthesis remain largely underdeveloped. The topic will be critically reviewed herein, with the expectation that an increased awareness may stimulate new, creative work in the area. PMID:27595612

  9. Design, Synthesis, and Mechanistic Evaluation of Iron-Based Catalysis for Synthesis Gas Conversion to Fuels and Chemicals

    SciTech Connect

    Akio Ishikawa; Manuel Ojeda; Enrique Iglesia

    2005-09-30

    This project extends previously discovered Fe-based catalysts to hydrogen-poor synthesis gas streams derived from coal and biomass sources. These catalysts have shown unprecedented Fischer-Tropsch synthesis rate, selectivity for feedstocks consisting of synthesis gas derived from methane. During the first reporting period, we certified a microreactor, installed required analytical equipment, and reproduced synthetic protocols and catalytic results previously reported. During the second reporting period, we prepared several Fe-based compositions for Fischer-Tropsch synthesis and tested the effects of product recycle under both subcritical and supercritical conditions. During the third reporting period, we improved the catalysts preparation method, which led to Fe-based FT catalysts with the highest FTS reaction rates and selectivities so far reported, a finding that allowed their operation at lower temperatures and pressures with high selectivity to desired products (C{sub 5+}, olefins). During this fourth reporting period, we have determined the effects of different promoters on catalytic performance. More specifically, we have found that the sequence in which promoters are introduced has a marked positive impact on rates and selectivities. Cu or Ru chemical promoters should be impregnated before K to achieve higher Fischer-Tropsch synthesis rates. The catalyst prepared in this way was evaluated for 240 h, showing a high catalytic activity and stability after an initial period of time necessary for the formation of the active phases. Concurrently, we are studying optimal activation procedures, which involve the reduction and carburization of oxide precursors during the early stages of contact with synthesis gas. Activation at low temperatures (523 K), made possible by optimal introduction of Cu or Ru, leads to lower catalyst surface area than higher activation temperatures, but to higher reaction rates, because such low temperatures avoid concurrent deactivation

  10. High-resolution aperture synthesis of molecular gas in NGC 1068

    SciTech Connect

    Planesas, P.; Scoville, N.; Myers, S.T. California Institute of Technology, Pasadena Toronto Univ. )

    1991-03-01

    High-resolution aperture synthesis imaging of NGC 1068 in the CO J = 1-0 line is presented. The major features of the molecular distribution in the central 3 kpc of the galaxy are a continuous pair of spiral arms originating from the end of the stellar bar seen in 2.2 micron images and a nuclear gas concentration of about 80 million solar masses. The total molecular gas content of the spiral arms is 5 billion solar masses; most of this gas is distributed in 38 complexes of 10 million to 700 million solar masses, with sizes ranging up to 500 pc. The large reservoir of interstellar gas seen in the spiral arms at 1.7 kpc radius may play a central role in both the abundant star formation and nuclear activity. 37 refs.

  11. Hydrothermal synthesis of self-assembled hierarchical tungsten oxides hollow spheres and their gas sensing properties.

    PubMed

    Li, Jinwei; Liu, Xin; Cui, Jiashan; Sun, Jianbo

    2015-05-20

    Hierarchical self-assembled hollow spheres (HS) of tungsten oxide nanosheets have been synthesized via a template-free hydrothermal method. Morphology evolution of the products is determined by the amount of H2C2O4 (oxalic acid) which serves as chelating agent. Structural features of the products were characterized by X-ray diffraction (XRD), and morphology was investigated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). In addition, the porous structure was analyzed using the Brunauer-Emmett-Teller (BET) approach. The synthesis mechanism of the products with self-assembled hierarchical structures was proposed. The NO2 gas sensing properties of self-assembled hierarchical WO3 HS materials were investigated, the gas sensing properties of WO3 synthesized by a variety of formulations were compared, and the possible gas sensing mechanism was discussed. The obvious enhancement of the gas sensing properties was ascribed to the structure of the hierarchical HS.

  12. Method for forming synthesis gas using a plasma-catalyzed fuel reformer

    SciTech Connect

    Hartvigsen, Joseph J; Elangovan, S; Czernichowski, Piotr; Hollist, Michele

    2015-04-28

    A method of forming a synthesis gas utilizing a reformer is disclosed. The method utilizes a reformer that includes a plasma zone to receive a pre-heated mixture of reactants and ionize the reactants by applying an electrical potential thereto. A first thermally conductive surface surrounds the plasma zone and is configured to transfer heat from an external heat source into the plasma zone. The reformer further includes a reaction zone to chemically transform the ionized reactants into synthesis gas comprising hydrogen and carbon monoxide. A second thermally conductive surface surrounds the reaction zone and is configured to transfer heat from the external heat source into the reaction zone. The first thermally conductive surface and second thermally conductive surface are both directly exposed to the external heat source. A corresponding apparatus and system are also disclosed herein.

  13. Impact of Contaminants Present in Coal-Biomass Derived Synthesis Gas on Water-gas Shift and Fischer-Tropsch Synthesis Catalysts

    SciTech Connect

    Alptekin, Gokhan

    2013-02-15

    Co-gasification of biomass and coal in large-scale, Integrated Gasification Combined Cycle (IGCC) plants increases the efficiency and reduces the environmental impact of making synthesis gas ("syngas") that can be used in Coal-Biomass-to-Liquids (CBTL) processes for producing transportation fuels. However, the water-gas shift (WGS) and Fischer-Tropsch synthesis (FTS) catalysts used in these processes may be poisoned by multiple contaminants found in coal-biomass derived syngas; sulfur species, trace toxic metals, halides, nitrogen species, the vapors of alkali metals and their salts (e.g., KCl and NaCl), ammonia, and phosphorous. Thus, it is essential to develop a fundamental understanding of poisoning/inhibition mechanisms before investing in the development of any costly mitigation technologies. We therefore investigated the impact of potential contaminants (H2S, NH3, HCN, AsH3, PH3, HCl, NaCl, KCl, AS3, NH4NO3, NH4OH, KNO3, HBr, HF, and HNO3) on the performance and lifetime of commercially available and generic (prepared in-house) WGS and FT catalysts.

  14. Process and catalyst for converting synthesis gas to liquid hydrocarbon mixture

    DOEpatents

    Rao, V. Udaya S.; Gormley, Robert J.

    1987-01-01

    Synthesis gas containing CO and H.sub.2 is converted to a high-octane hydrocarbon liquid in the gasoline boiling point range by bringing the gas into contact with a heterogeneous catalyst including, in physical mixture, a zeolite molecular sieve, cobalt at 6-20% by weight, and thoria at 0.5-3.9% by weight. The contacting occurs at a temperature of 250.degree.-300.degree. C., and a pressure of 10-30 atmospheres. The conditions can be selected to form a major portion of the hydrocarbon product in the gasoline boiling range with a research octane of more than 80 and less than 10% by weight aromatics.

  15. Synthesis, characterization and gas sensing properties of tin oxide nanopowder

    NASA Astrophysics Data System (ADS)

    Choudhary, Meenakshi; Mishra, V. N.; Dwivedi, R.

    2013-06-01

    In the present work, tin oxide nanopowder has been synthesized by solid-state reaction technique. The as-prepared pure and palladium doped (0.5 and 1%) powders have been used for the fabrication of thick film sensors. The influence of particle size of powders and morphology of the thick films has been studied on the sensing performance of thick film sensor. It is observed that the sensors produced from the SnO2 doped with 1% palladium have an excellent ability for the detection of hydrogen gas.

  16. New iron catalyst for preparation of polymethylene from synthesis gas

    DOEpatents

    Sapienza, R.S.; Slegeir, W.A.

    1988-03-31

    This invention relates to a process for synthesizing hydrocarbons; more particularly, the invention relates to a process for synthesizing long-chain hydrocarbons known as polymethylene from carbon monoxide and hydrogen or from carbon monoxide and water or mixtures thereof in the presence of a catalyst comprising iron and platinum or palladium or mixtures thereof which may be supported on a solid material, preferably an inorganic refractory oxide. This process may be used to convert a carbon monoxide containing gas to a product which could substitute for high density polyethylene.

  17. Multiscale Aspects of Modeling Gas-Phase Nanoparticle Synthesis

    PubMed Central

    Buesser, B.; Gröhn, A.J.

    2013-01-01

    Aerosol reactors are utilized to manufacture nanoparticles in industrially relevant quantities. The development, understanding and scale-up of aerosol reactors can be facilitated with models and computer simulations. This review aims to provide an overview of recent developments of models and simulations and discuss their interconnection in a multiscale approach. A short introduction of the various aerosol reactor types and gas-phase particle dynamics is presented as a background for the later discussion of the models and simulations. Models are presented with decreasing time and length scales in sections on continuum, mesoscale, molecular dynamics and quantum mechanics models. PMID:23729992

  18. Iron catalyst for preparation of polymethylene from synthesis gas

    DOEpatents

    Sapienza, Richard S.; Slegeir, William A.

    1990-01-01

    This invention relates to a process for synthesizing hydrocarbons; more particularly, the invention relates to a process for synthesizing long-chain hydrocarbons known as polymethylene from carbon monoxide and hydrogen or from carbon monoxide and water or mixtures thereof in the presence of a catalyst comprising iron and platinum or palladium or mixtures thereof which may be supported on a solid material, preferably an inorganic refractory oxide. This process may be used to convert a cabon monoxide containing gas to a product which could substitute for high density polyethylene.

  19. Catalyst and process for converting synthesis gas to liquid motor fuels

    DOEpatents

    Coughlin, Peter K.

    1987-01-01

    The addition of an inert metal component, such as gold, silver or copper, to a Fischer-Tropsch catalyst comprising cobalt enables said catalyst to convert synthesis gas to liquid motor fuels at about 240.degree.-370.degree. C. with advantageously reduced selectivity of said cobalt for methane in said conversion. The catalyst composition can advantageously include a support component, such as a molecular sieve, co-catalyst/support component or a combination of such support components.

  20. Enhanced catalyst and process for converting synthesis gas to liquid motor fuels

    DOEpatents

    Coughlin, Peter K.

    1986-01-01

    The conversion of synthesis gas to liquid molar fuels by means of a cobalt Fischer-Tropsch catalyst composition is enhanced by the addition of molybdenum, tungsten or a combination thereof as an additional component of said composition. The presence of the additive component increases the olefinic content of the hydrocarbon products produced. The catalyst composition can advantageously include a support component, such as a molecular sieve, co-catalyst/support component or a combination of such support components.

  1. Synthesis and Gas Phase Thermochemistry of Germanium-Containing Compounds

    SciTech Connect

    Nathan Robert Classen

    2002-12-31

    The driving force behind much of the work in this dissertation was to gain further understanding of the unique olefin to carbene isomerization observed in the thermolysis of 1,1-dimethyl-2-methylenesilacyclobutane by finding new examples of it in other silicon and germanium compounds. This lead to the examination of a novel phenylmethylenesilacyclobut-2-ene, which did not undergo olefin to carbene rearrangement. A synthetic route to methylenegermacyclobutanes was developed, but the methylenegermacyclobutane system exhibited kinetic instability, making the study of the system difficult. In any case the germanium system decomposed through a complex mechanism which may not include olefin to carbene isomerization. However, this work lead to the study of the gas phase thermochemistry of a series of dialkylgermylene precursors in order to better understand the mechanism of the thermal decomposition of dialkylgermylenes. The resulting dialkylgermylenes were found to undergo a reversible intramolecular {beta} C-H insertion mechanism.

  2. Removal of Mercury from Coal-Derived Synthesis Gas

    SciTech Connect

    2005-09-29

    A paper study was completed to survey literature, patents, and companies for mercury removal technologies applicable to gasification technologies. The objective was to determine if mercury emissions from gasification of coal are more or less difficult to manage than those from a combustion system. The purpose of the study was to define the extent of the mercury problem for gasification-based coal utilization and conversion systems. It is clear that in coal combustion systems, the speciation of mercury between elemental vapor and oxidized forms depends on a number of factors. The most important speciation factors are the concentration of chlorides in the coal, the temperatures in the ducting, and residence times. The collection of all the mercury was most dependent upon the extent of carbon in the fly ash, and the presence of a wet gas desulfurization system. In combustion, high chloride content plus long residence times at intermediate temperatures leads to oxidation of the mercury. The mercury is then captured in the wet gas desulfurization system and in the fly ash as HgCl{sub 2}. Without chloride, the mercury oxidizes much slower, but still may be trapped on thick bag house deposits. Addition of limestone to remove sulfur may trap additional mercury in the slag. In gasification where the mercury is expected to be elemental, activated carbon injection has been the most effective method of mercury removal. The carbon is best injected downstream where temperatures have moderated and an independent collector can be established. Concentrations of mercury sorbent need to be 10,000 to 20,000 the concentrations of the mercury. Pretreatment of the activated carbon may include acidification or promotion by sulfur.

  3. Potential of wastewater-treating anaerobic granules for biomethanation of synthesis gas.

    PubMed

    Guiot, Serge R; Cimpoia, Ruxandra; Carayon, Gaël

    2011-03-01

    Gasification of biomass produces a mixture of gas (mainly carbon monoxide (CO), carbon dioxide (CO(2)), and hydrogen (H(2))) called synthesis gas, or syngas, by thermal degradation without combustion. Syngas can be used for heat or electricity production by thermochemical processes. This project aims at developing an alternative way to bioupgrade syngas into biogas (mainly methane), via anaerobic fermentation. Nonacclimated industrial granular sludge to be used as reactor inoculum was initially evaluated for mesophilic carboxydotrophic methanogenesis potential in batch tests at 4 and 8 mmol CO/g VSS.d, in the absence and presence of H(2) and CO(2), respectively. Granular sludge was then introduced into a 30 L gas-lift reactor and supplied with CO, to study the production of methane and other metabolites, at different gas dilutions as well as feeding and recirculation rates. A maximal CO conversion efficiency of 75%, which was gas-liquid mass transfer limited, occurred at a CO partial pressure of 0.6 atm combined with a gas recirculation ratio of 20:1. The anaerobic granule potential for methanogenesis from CO was likely hydrogenotrophic, combined with CO-dependent H(2) formation, either under mesophilic or thermophilic conditions. Thermophilic conditions provide the anaerobic granules with a CO-bioconversion potential significantly larger (5-fold) than under mesophilic conditions, so long as the gas-liquid transfer is alleviated.

  4. Bioconversion of coal-derived synthesis gas to liquid fuels. [Butyribacterium methylotrophicum

    SciTech Connect

    Jain, M.K.

    1991-01-01

    The use of coal-derived synthesis gas as an industrial feedstock for production of fuels and chemicals has become an increasingly attractive alternative to present petroleum-based chemicals production. However, one of the major limitations in developing such a process is the required removal of catalyst poisons such as hydrogen sulfide (H{sub 2}S), carbonyl sulfide (COS), and other trace contaminants from the synthesis gas. Purification steps necessary to remove these are energy intensive and add significantly to the production cost, particularly for coals having a high sulfur content such as Illinois coal. A two-stage, anaerobic bioconversion process requiring little or no sulfur removal is proposed, where in the first stage the carbon monoxide (CO) gas is converted to butyric and acetic acids by the CO strain of Butyribacterium methylotrophicum. In the second stage, these acids along with the hydrogen (H{sub 2}) gas are converted to butanol, ethanol, and acetone by an acid utilizing mutant of Clostridium acetobutylicum. 18 figs., 18 tabs.

  5. Biological conversion of synthesis gas. Mass transfer/kinetic studies

    SciTech Connect

    Klasson, K.T.; Basu, R.; Johnson, E.R.; Clausen, E.C.; Gaddy, J.L.

    1992-03-01

    Mass transfer and kinetic studies were carried out for the Rhodospirillum rubrum and Chlorobium thiosulfatophilum bacterial systems. R. rubrum is a photosynthetic anaerobic bacterium which catalyzes the biological water gas shift reaction: CO + H{sub 2}0 {yields} CO{sub 2} + H{sub 2}. C. thiosulfatophilum is also a H{sub 2}S and COS to elemental sulfur. The growth of R. rubrum may be satisfactorily carried out at 25{degree} and 30{degree}C, while CO uptake and thus the conversion of CO best occurs at temperatures of either 30{degree}, 32{degree} or 34{degree}C. The rate of conversion of COs and H{sub 2}O to CO{sub 2} and H{sub 2}S may be modeled by a first order rate expression. The rate constant at 30{degree}C was found to be 0.243 h{sup {minus}1}. The growth of C. thiosulfatophilum may be modeled in terms of incoming light intensity using a Monod equation: {mu} = {sub 351} + I{sub o}/{sup 0.152}I{sub o}. Comparisons of the growth of R. rubrum and C. thiosulfatophilum shows that the specific growth rate of C. thiosulfatophilum is much higher at a given light intensity.

  6. Tin dioxide nanoparticles: Reverse micellar synthesis and gas sensing properties

    SciTech Connect

    Ahmed, Jahangeer; Vaidya, Sonalika; Ahmad, Tokeer; Sujatha Devi, P.; Das, Dipankar; Ganguli, Ashok K.

    2008-02-05

    Tin dioxide (SnO{sub 2}) nanoparticles have been synthesized by reverse micellar route using cetyltrimethyl ammoniumbromide (CTAB) as the surfactant. Monophasic tin dioxide (SnO{sub 2}) was obtained using NaOH as the precipitation agent at 60 deg. C, however, when liquor NH{sub 3} was used as precipitating agent then crystalline SnO{sub 2} nanoparticles are obtained at 500 deg. C. SnO{sub 2} prepared using NaOH show crystallite size of 4 and 12 nm after heating at 60 and 500 deg. C respectively using X-ray line broadening studies. Transmission electron microscopy (TEM) studies show agglomerated particles of sizes 70 and 150 nm, respectively. The grain size was found to be 6-8 nm after heating the precursor obtained (using liquor NH{sub 3}) at 500 deg. C by X-ray line broadening and the TEM studies. Dynamic light-scattering (DLS) studies show the aggregates of SnO{sub 2} nanoparticles with uniform size distribution. Moessbauer studies show an increase of s-electron density at the Sn sites compared to bulk SnO{sub 2} and a finite quadrupole splitting indicative of lowering of symmetry around tin atoms. The gas sensing characteristics have also been investigated using n-butane which show high sensitivity and fast recovery time.

  7. Design, Synthesis, and Mechanistic Evaluation of Iron-Based Catalysis for Synthesis Gas Conversion to Fuels and Chemicals

    SciTech Connect

    Enrique Iglesia; Akio Ishikawa; Manual Ojeda; Nan Yao

    2007-09-30

    A detailed study of the catalyst composition, preparation and activation protocol of Fe-based catalysts for the Fischer-Tropsch Synthesis (FTS) have been carried out in this project. We have studied the effects of different promoters on the catalytic performance of Fe-based catalysts. Specifically, we have focused on how their sequence of addition dramatically influences the performance of these materials in the Fischer-Tropsch synthesis. The resulting procedures have been optimized to improve further upon the already unprecedented rates and C{sub 5+} selectivities of the Fe-based catalysts that we have developed as part of this project. Selectivity to C{sub 5+} hydrocarbon was close to 90 % (CO{sub 2}-free basis) and CO conversion rate was about 6.7 mol h{sup -1} g-at Fe{sup -1} at 2.14 MPa, 508 K and with substoichiometric synthesis gas; these rates were larger than any reported previously for Fe-based FTS catalysts at these conditions. We also tested the stability of Fe-based catalysts during FTS reaction (10 days); as a result, the high hydrocarbon formation rates were maintained during 10 days, though the gradual deactivation was observed. Our investigation has also focused on the evaluation of Fe-based catalysts with hydrogen-poor synthesis gas streams (H{sub 2}/CO=1). We have observed that the Fe-based catalysts prepared in this project display also a high hydrocarbon synthesis rate with substoichiometric synthesis gas (H{sub 2}/CO=1) stream, which is a less desirable reactant mixture than stoichiometric synthesis gas (H{sub 2}/CO=2). We have improved the catalyst preparation protocols and achieved the highest FTS reaction rates and selectivities so far reported at the low temperatures required for selectivity and stability. Also, we have characterized the catalyst structural change and active phases formed, and their catalytic behavior during the activation process to evaluate their influences on FTS reaction. The efforts of this project led to (i

  8. Synthesis of refractory organic matter in the ionized gas phase of the solar nebula.

    PubMed

    Kuga, Maïa; Marty, Bernard; Marrocchi, Yves; Tissandier, Laurent

    2015-06-01

    In the nascent solar system, primitive organic matter was a major contributor of volatile elements to planetary bodies, and could have played a key role in the development of the biosphere. However, the origin of primitive organics is poorly understood. Most scenarios advocate cold synthesis in the interstellar medium or in the outer solar system. Here, we report the synthesis of solid organics under ionizing conditions in a plasma setup from gas mixtures (H2(O)-CO-N2-noble gases) reminiscent of the protosolar nebula composition. Ionization of the gas phase was achieved at temperatures up to 1,000 K. Synthesized solid compounds share chemical and structural features with chondritic organics, and noble gases trapped during the experiments reproduce the elemental and isotopic fractionations observed in primitive organics. These results strongly suggest that both the formation of chondritic refractory organics and the trapping of noble gases took place simultaneously in the ionized areas of the protoplanetary disk, via photon- and/or electron-driven reactions and processing. Thus, synthesis of primitive organics might not have required a cold environment and could have occurred anywhere the disk is ionized, including in its warm regions. This scenario also supports N2 photodissociation as the cause of the large nitrogen isotopic range in the solar system.

  9. Synthesis of refractory organic matter in the ionized gas phase of the solar nebula

    PubMed Central

    Kuga, Maïa; Marty, Bernard; Marrocchi, Yves; Tissandier, Laurent

    2015-01-01

    In the nascent solar system, primitive organic matter was a major contributor of volatile elements to planetary bodies, and could have played a key role in the development of the biosphere. However, the origin of primitive organics is poorly understood. Most scenarios advocate cold synthesis in the interstellar medium or in the outer solar system. Here, we report the synthesis of solid organics under ionizing conditions in a plasma setup from gas mixtures (H2(O)−CO−N2−noble gases) reminiscent of the protosolar nebula composition. Ionization of the gas phase was achieved at temperatures up to 1,000 K. Synthesized solid compounds share chemical and structural features with chondritic organics, and noble gases trapped during the experiments reproduce the elemental and isotopic fractionations observed in primitive organics. These results strongly suggest that both the formation of chondritic refractory organics and the trapping of noble gases took place simultaneously in the ionized areas of the protoplanetary disk, via photon- and/or electron-driven reactions and processing. Thus, synthesis of primitive organics might not have required a cold environment and could have occurred anywhere the disk is ionized, including in its warm regions. This scenario also supports N2 photodissociation as the cause of the large nitrogen isotopic range in the solar system. PMID:26039983

  10. Synthesis of refractory organic matter in the ionized gas phase of the solar nebula.

    PubMed

    Kuga, Maïa; Marty, Bernard; Marrocchi, Yves; Tissandier, Laurent

    2015-06-01

    In the nascent solar system, primitive organic matter was a major contributor of volatile elements to planetary bodies, and could have played a key role in the development of the biosphere. However, the origin of primitive organics is poorly understood. Most scenarios advocate cold synthesis in the interstellar medium or in the outer solar system. Here, we report the synthesis of solid organics under ionizing conditions in a plasma setup from gas mixtures (H2(O)-CO-N2-noble gases) reminiscent of the protosolar nebula composition. Ionization of the gas phase was achieved at temperatures up to 1,000 K. Synthesized solid compounds share chemical and structural features with chondritic organics, and noble gases trapped during the experiments reproduce the elemental and isotopic fractionations observed in primitive organics. These results strongly suggest that both the formation of chondritic refractory organics and the trapping of noble gases took place simultaneously in the ionized areas of the protoplanetary disk, via photon- and/or electron-driven reactions and processing. Thus, synthesis of primitive organics might not have required a cold environment and could have occurred anywhere the disk is ionized, including in its warm regions. This scenario also supports N2 photodissociation as the cause of the large nitrogen isotopic range in the solar system. PMID:26039983

  11. Interaction of coal-derived synthesis gas impurities with solid oxide fuel cell metallic components

    NASA Astrophysics Data System (ADS)

    Marina, Olga A.; Pederson, Larry R.; Coyle, Christopher A.; Edwards, Danny J.; Chou, Yeong-Shyung; Cramer, Carolyn N.

    Oxidation-resistant alloys find use as interconnect materials, heat exchangers, and gas supply tubing in solid oxide fuel cell (SOFC) systems, especially when operated at temperatures below ∼800 °C. If fueled with synthesis gas derived from coal or biomass, such metallic components could be exposed to impurities contained in those fuel sources. In this study, coupons of ferritic stainless steels Crofer 22 APU and SS 441, austenitic nickel-chromium superalloy Inconel 600, and an alumina-forming high nickel alloy alumel were exposed to synthesis gas containing ≤2 ppm phosphorus, arsenic and antimony, and reaction products were tested. Crofer 22 APU coupons coated with a (Mn,Co) 3O 4 protective layer were also evaluated. Phosphorus was found to be the most reactive. On Crofer 22 APU, the (Mn,Cr) 3O 4 passivation layer reacted to form an Mn-P-O product, predicted to be manganese phosphate from thermochemical calculations, and Cr 2O 3. On SS 441, reaction of phosphorus with (Mn,Cr) 3O 4 led to the formation of manganese phosphate as well as an Fe-P product, predicted from thermochemical calculations to be Fe 3P. Minimal interactions with antimony or arsenic in synthesis gas were limited to Fe-Sb and Fe-As solid solution formation. Though not intended for use on the anode side, a (Mn,Co) 3O 4 spinel coating on Crofer 22 APU reacted with phosphorus in synthesis gas to produce products consistent with Mn 3(PO 4) 2 and Co 2P. A thin Cr 2O 3 passivation layer on Inconel 600 did not prevent the formation of nickel phosphides and arsenides and of iron phosphides and arsenides, though no reaction with Cr 2O 3 was apparent. On alumel, an Al 2O 3 passivation layer rich in Ni did not prevent the formation of nickel phosphides, arsenides, and antimonides, though no reaction with Al 2O 3 occurred. This work shows that unprotected metallic components of an SOFC stack and system can provide a sink for P, As and Sb impurities that may be present in fuel gases, and thus complicate

  12. Rapid pressure swing absorption cleanup of post-shift reactor synthesis gas

    SciTech Connect

    Sirkar, K.K.; Majumdar, S.; Bhaumik, S.

    1991-10-31

    This investigation is concerned with the separation of gas mixtures using a novel concept of rapid pressure swing absorption (RAPSAB) of gas in a stationary absorbent liquid through gas-liquid interfaces immobilized in the pore mouths of hydrophobic microporous membranes. The process is implemented in a module well-packed with hydrophobic microporous hollow fiber membranes. The specific objectives are (1) to fiber membranes. The specific objectives are (1) to develop a theoretical model which will provide guidelines for selecting an efficient RAPSAB process cycle which includes desorption; (2) to demonstrate the concept experimentally with a simple gas mixture (e.g., Co{sub 2}-N{sub 2}) and a simple absorbent liquid such as water, and (3) to extend the concept to reactive absorbent liquids for the separation of CO, Co{sub 2} from the post-shift reactor synthesis gas. A simplified theoretical description of the novel rapid pressure swing absorption process has been developed. The absorption part of the pressure swing absorption cycle has been predicted for CO{sub 2}-N{sub 2}-water system. Numerical simulation of the model is being carried out for different operating conditions for selecting an optimum pressure swing cycle.

  13. Conversion of Mixed Oxygenates Generated from Synthesis Gas to Fuel Range Hydrocarbon

    SciTech Connect

    Ramasamy, Karthikeyan K.; Gerber, Mark A.; Lilga, Michael A.; Flake, Matthew D.

    2012-08-19

    The growing dependence in the U.S. on foreign crude oil supplies and increased concerns regarding greenhouse gas emission has generated considerable interest in research to develop renewable and environmentally friendly liquid hydrocarbon transportation fuels. One of the strategies for achieving this is to produce intermediate compounds such as alcohols and other simple oxygenates from biomass generated synthesis gas (mixture of carbon monoxide and hydrogen) and further convert them into liquid hydrocarbons. The focus of this research is to investigate the effects of mixed oxygenates intermediate product compositions on the conversion step to produce hydrocarbon liquids. A typical mixed oxygenate stream is expected to contain water (around 50%), alcohols, such as methanol and ethanol (around 35%), and smaller quantities of oxygenates such as acetaldehyde, acetic acid and ethyl acetate. However the ratio and the composition of the mixed oxygenate stream generated from synthesis gas vary significantly depending on the catalyst used and the process conditions. Zeolite catalyzed deoxygenation of methanol accompanied by chain growth is well understood under Methanol-to-Gasoline (MTG) like reaction conditions using an H-ZSM-5 zeolite as the catalyst6-8. Research has also been conducted to a limited extent in the past with higher alcohols, but not with other oxygenates present9-11. Also there has been little experimental investigation into mixtures containing substantial amounts of water. The latter is of particular interest because water separation from the hydrocarbon product would be less energy intensive than first removing it from the oxygenate intermediate stream prior to hydrocarbon synthesis, potentially reducing overall processing costs.

  14. Biological production of liquid and gaseous fuels from coal synthesis gas

    SciTech Connect

    Antorrena, G.M.; Vega, J.L.; Clausen, E.C.; Gaddy, J.L.

    1988-01-01

    Cultures of microorganisms have been isolated that convert CO, H/sub 2/ and CO/sub 2/ in coal synthesis gas into methane or ethanol. The reactions are severely mass transfer limited and bioreactor design will be a critical factor in the application of this technology. This paper presents results of culture isolation studies and development of continuous reactors for these cultures. The results of bubble columns and stirred tank reactors are presented and discussed. Methods for defining mass transfer coefficients and intrinsic kinetics are presented. Operation of these gaseous fermentations at high pressure has enabled complete conversion in reaction times of a few minutes.

  15. Microbial conversion of synthesis gas components to useful fuels and chemicals

    SciTech Connect

    Madhukar, G.R.; Elmore, B.B.; Huckabay, H.K.

    1996-12-31

    Enriched culture techniques have been used to isolate microbial cultures exhibiting growth on synthesis gas components. Three rod-shaped, gram-positive cultures have been isolated from petroleum-contaminated soil, a cow manure-soil mixture, and sheep rumen fluid. Each culture exhibits growth on carbon monoxide as its primary carbon source, producing alcohols and acids in the fermentation medium. Quantities of up to 7.5, 0.58, and 0.25 g/L of acetate, ethanol, and methanol, respectively, have been produced in batch culture with lesser amounts of acetone, butyric, and propionic acid detected. 15 refs., 5 figs., 3 tabs.

  16. Liquid phase low temperature method for production of methanol from synthesis gas and catalyst formulations therefor

    DOEpatents

    Mahajan, Devinder

    2005-07-26

    The invention provides a homogenous catalyst for the production of methanol from purified synthesis gas at low temperature and low pressure which includes a transition metal capable of forming transition metal complexes with coordinating ligands and an alkoxide, the catalyst dissolved in a methanol solvent system, provided the transition metal complex is not transition metal carbonyl. The coordinating ligands can be selected from the group consisting of N-donor ligands, P-donor ligands, O-donor ligands, C-donor ligands, halogens and mixtures thereof.

  17. Slurry phase Fischer-Tropsch synthesis: Cobalt plus a water-gas shift catalyst

    SciTech Connect

    Yates, I.C.; Satterfield, C.N.

    1989-01-01

    The rate of synthesis gas consumption over a cobalt FischerTropsch catalyst was measured in a well-mixed, continuous-flow, slurry reactor at 220 to 240[degrees]C, 0.5 to 1.5 MPa, H[sub 2]/CO feed ratios of 1.5 to 3.5 and conversions of 7 to 68% of hydrogen and 11 to 73% of carbon monoxide. The inhibiting effect of carbon monoxide was determined quantitatively and a Langmuir-Hinshelwood-type equation of the following form was found to best represent the results: -R[sub H[sub 2+Co

  18. In situ etching WO{sub 3} nanoplates: Hydrothermal synthesis, photoluminescence and gas sensor properties

    SciTech Connect

    Su, Xintai; Li, Yani; Jian, Jikang; Wang, Jide

    2010-12-15

    A novel hydrothermal process using p-nitrobenzoic acid as structure-directing agent has been employed to synthesize plate-shaped WO{sub 3} nanostructures containing holes. The p-nitrobenzoic acid plays a critical role in the synthesis of such novel WO{sub 3} nanoplates. The morphology, structure and optical property of the WO{sub 3} nanoplates have been characterized by transmission electron microcopy (TEM), scanning electron microcopy (SEM), X-ray diffraction (XRD) and photoluminescence (PL). The lateral size of the nanoplates is 500-1000 nm, and the thickness is about 80 nm. The formation mechanism of WO{sub 3} nanoplates is discussed briefly. The gas sensitivity of WO{sub 3} nanoplates was studied to ethanol and acetone at different operation temperatures and concentrations. Furthermore, the WO{sub 3} nanoplate-based gas sensor exhibits high sensitivity for ethanol and acetone as well as quick response and recovery time at low temperature.

  19. Synthesis Methods, Microscopy Characterization and Device Integration of Nanoscale Metal Oxide Semiconductors for Gas Sensing

    PubMed Central

    Vander Wal, Randy L.; Berger, Gordon M.; Kulis, Michael J.; Hunter, Gary W.; Xu, Jennifer C.; Evans, Laura

    2009-01-01

    A comparison is made between SnO2, ZnO, and TiO2 single-crystal nanowires and SnO2 polycrystalline nanofibers for gas sensing. Both nanostructures possess a one-dimensional morphology. Different synthesis methods are used to produce these materials: thermal evaporation-condensation (TEC), controlled oxidation, and electrospinning. Advantages and limitations of each technique are listed. Practical issues associated with harvesting, purification, and integration of these materials into sensing devices are detailed. For comparison to the nascent form, these sensing materials are surface coated with Pd and Pt nanoparticles. Gas sensing tests, with respect to H2, are conducted at ambient and elevated temperatures. Comparative normalized responses and time constants for the catalyst and noncatalyst systems provide a basis for identification of the superior metal-oxide nanostructure and catalyst combination. With temperature-dependent data, Arrhenius analyses are made to determine activation energies for the catalyst-assisted systems. PMID:22408484

  20. Gas-Phase Synthesis of 1-Silacyclopenta-2,4-diene.

    PubMed

    Yang, Tao; Dangi, Beni B; Thomas, Aaron M; Sun, Bing-Jian; Chou, Tzu-Jung; Chang, Agnes H H; Kaiser, Ralf I

    2016-07-01

    Silole (1-silacyclopenta-2,4-diene) was synthesized for the first time by the bimolecular reaction of the simplest silicon-bearing radical, silylidyne (SiH), with 1,3-butadiene (C4 H6 ) in the gas phase under single-collision conditions. The absence of consecutive collisions of the primary reaction product prevents successive reactions of the silole by Diels-Alder dimerization, thus enabling the clean gas-phase synthesis of this hitherto elusive cyclic species from acyclic precursors in a single-collision event. Our method opens up a versatile and unconventional path to access a previously rather obscure class of organosilicon molecules (substituted siloles), which have been difficult to access through classical synthetic methods.

  1. Isobutanol-methanol mixtures from synthesis gas. Quarterly technical progress report, July 1--September 30, 1995

    SciTech Connect

    Eglesia, E.

    1995-10-24

    Mechanistic and kinetic studies of methanol and ethanol coupling reactions on Cs/Cu/ZnO and Cu/ZnO/MnO catalysts using isotopically-labeled compounds have confirmed that coupling reactions proceed via intermediate dehydrogenation of alcohols to aldehydes. Ethanol coupling reactions are much faster than those of methanol because ethanol forms a more thermodynamically favored intermediate (acetaldehyde), with aldol condensation pathways kinetically available for chain growth. Cs decreases the rate of formation of aldehydes in alcohol dehydrogenation reaction and inhibits the undesired conversion of methanol and ethanol to synthesis gas (CO/H{sub 2}). Construction and start-up of the Catalytic Microreactor Unit (CMRU) for high pressure isobutanol synthesis studies have been completed. Initial certification runs have reproduced catalytic CO conversion rates on a standard APCI material (Cs/Cu/ZnO/Al{sub 2}O{sub 3}). Condensation of higher alcohols in the transfer lines appears to be responsible for the observed low apparent selectivity to higher alcohols. The design and construction of the Temperature-Programmed Surface Reaction (TPSR) Unit for the study of the adsorption and reaction properties of alcohols and other oxygenates on isobutanol, synthesis catalysts and components is complete. The reduction of CuO powder and of a Cs/Cu/ZnO catalyst were used to certify the apparatus before proceeding with alcohol adsorption and reaction studies.

  2. Gas temperature measurements inside a hot wall chemical vapor synthesis reactor.

    PubMed

    Notthoff, Christian; Schilling, Carolin; Winterer, Markus

    2012-11-01

    One key but complex parameter in the chemical vapor synthesis (CVS) of nanoparticles is the time temperature profile of the gas phase, which determines particle characteristics such as size (distribution), morphology, microstructure, crystal, and local structure. Relevant for the CVS process and for the corresponding particle characteristics is, however, not the T(t)-profile generated by an external energy source such as a hot wall or microwave reactor but the temperature of the gas carrying reactants and products (particles). Due to a complex feedback of the thermodynamic and chemical processes in the reaction volume with the external energy source, it is very difficult to predict the real gas phase temperature field from the externally applied T(t)-profile. Therefore, a measurement technique capable to determine the temperature distribution of the gas phase under process conditions is needed. In this contribution, we demonstrate with three proof of principle experiments the use of laser induced fluorescence thermometry to investigate the CVS process under realistic conditions.

  3. Synthesis and application of graphene-silver nanowires composite for ammonia gas sensing

    NASA Astrophysics Data System (ADS)

    Tran, Quang Trung; Hoa Huynh, Tran My; Tong, Duc Tai; Tam Tran, Van; Dinh Nguyen, Nang

    2013-12-01

    Graphene, consisting of a single carbon layer in a two-dimensional (2D) lattice, has been a promising material for application to nanoelectrical devices in recent years. In this study we report the development of a useful ammonia (NH3) gas sensor based on graphene-silver nanowires ‘composite’ with planar electrode structure. The basic strategy involves three steps: (i) preparation of graphene oxide (GO) by modified Hummers method; (ii) synthesis of silver nanowires by polyol method; and (iii) preparation of graphene and silver nanowires on two electrodes using spin and spray-coating of precursor solutions, respectively. Exposure of this sensor to NH3 induces a reversible resistance change at room temperature that is as large as ΔR/R0 ˜ 28% and this sensitivity is eight times larger than the sensitivity of the ‘intrinsic’ graphene based NH3 gas sensor (ΔR/R0 ˜ 3,5%). Their responses and the recovery times go down to ˜200 and ˜60 s, respectively. Because graphene synthesized by chemical methods has many defects and small sheets, it cannot be perfectly used for gas sensor or for nanoelectrical devices. The silver nanowires are applied to play the role of small bridges connecting many graphene islands together to improve electrical properties of graphene/silver nanowires composite and result in higher NH3 gas sensitivity.

  4. Coated gas bubbles for the continuous synthesis of hollow inorganic particles.

    PubMed

    Wan, Jiandi; Stone, Howard A

    2012-01-10

    We present a microfluidic approach for the controlled encapsulation of individual gas bubbles in micrometer-diameter aqueous droplets with high gas volume fractions and demonstrate this approach to making a liquid shell, which serves as a template for the synthesis of hollow inorganic particles. In particular, we find that an increase in the viscosity of the aqueous phase facilitates the encapsulation of individual gas bubbles in an aqueous droplet and allows control of the thickness of a thin aqueous shell. Furthermore, because such droplets contain a finite amount of water, uncontrolled hydrolysis reactions between reactive inorganic precursors and bulk water can be avoided. We demonstrate this approach by introducing reactive inorganic precursors, such as silane and titanium butoxide, for sol-gel reactions downstream from the formation of the bubble in a droplet and consequently fabricate hollow particles of silica or titania in one continuous flow process. These approaches provide a route to controlling double-emulsion-type gas-liquid microstructures and offer a new fabrication method for thin-shell-covered microbubbles and hollow microparticles.

  5. Single-step gas phase synthesis of stable iron aluminide nanoparticles with soft magnetic properties

    SciTech Connect

    Vernieres, Jerome Benelmekki, Maria; Kim, Jeong-Hwan; Grammatikopoulos, Panagiotis; Diaz, Rosa E.; Bobo, Jean-François; Sowwan, Mukhles

    2014-11-01

    Soft magnetic alloys at the nanoscale level have long generated a vivid interest as candidate materials for technological and biomedical purposes. Consequently, controlling the structure of bimetallic nanoparticles in order to optimize their magnetic properties, such as high magnetization and low coercivity, can significantly boost their potential for related applications. However, traditional synthesis methods stumble upon the long standing challenge of developing true nanoalloys with effective control over morphology and stability against oxidation. Herein, we report on a single-step approach to the gas phase synthesis of soft magnetic bimetallic iron aluminide nanoparticles, using a versatile co-sputter inert gas condensation technique. This method allowed for precise morphological control of the particles; they consisted of an alloy iron aluminide crystalline core (DO{sub 3} phase) and an alumina shell, which reduced inter-particle interactions and also prevented further oxidation and segregation of the bimetallic core. Remarkably, the as-deposited alloy nanoparticles show interesting soft magnetic properties, in that they combine a high saturation magnetization (170 emu/g) and low coercivity (less than 20 Oe) at room temperature. Additional functionality is tenable by modifying the surface of the particles with a polymer, to ensure their good colloidal dispersion in aqueous environments.

  6. Single-step gas phase synthesis of stable iron aluminide nanoparticles with soft magnetic properties

    NASA Astrophysics Data System (ADS)

    Vernieres, Jerome; Benelmekki, Maria; Kim, Jeong-Hwan; Grammatikopoulos, Panagiotis; Bobo, Jean-François; Diaz, Rosa E.; Sowwan, Mukhles

    2014-11-01

    Soft magnetic alloys at the nanoscale level have long generated a vivid interest as candidate materials for technological and biomedical purposes. Consequently, controlling the structure of bimetallic nanoparticles in order to optimize their magnetic properties, such as high magnetization and low coercivity, can significantly boost their potential for related applications. However, traditional synthesis methods stumble upon the long standing challenge of developing true nanoalloys with effective control over morphology and stability against oxidation. Herein, we report on a single-step approach to the gas phase synthesis of soft magnetic bimetallic iron aluminide nanoparticles, using a versatile co-sputter inert gas condensation technique. This method allowed for precise morphological control of the particles; they consisted of an alloy iron aluminide crystalline core (DO3 phase) and an alumina shell, which reduced inter-particle interactions and also prevented further oxidation and segregation of the bimetallic core. Remarkably, the as-deposited alloy nanoparticles show interesting soft magnetic properties, in that they combine a high saturation magnetization (170 emu/g) and low coercivity (less than 20 Oe) at room temperature. Additional functionality is tenable by modifying the surface of the particles with a polymer, to ensure their good colloidal dispersion in aqueous environments.

  7. Iron particle size effects for direct production of lower olefins from synthesis gas.

    PubMed

    Torres Galvis, Hirsa M; Bitter, Johannes H; Davidian, Thomas; Ruitenbeek, Matthijs; Dugulan, A Iulian; de Jong, Krijn P

    2012-10-01

    The Fischer-Tropsch synthesis of lower olefins (FTO) is an alternative process for the production of key chemical building blocks from non-petroleum-based sources such as natural gas, coal, or biomass. The influence of the iron carbide particle size of promoted and unpromoted carbon nanofiber supported catalysts on the conversion of synthesis gas has been investigated at 340-350 °C, H(2)/CO = 1, and pressures of 1 and 20 bar. The surface-specific activity (apparent TOF) based on the initial activity of unpromoted catalysts at 1 bar increased 6-8-fold when the average iron carbide size decreased from 7 to 2 nm, while methane and lower olefins selectivity were not affected. The same decrease in particle size for catalysts promoted by Na plus S resulted at 20 bar in a 2-fold increase of the apparent TOF based on initial activity which was mainly caused by a higher yield of methane for the smallest particles. Presumably, methane formation takes place at highly active low coordination sites residing at corners and edges, which are more abundant on small iron carbide particles. Lower olefins are produced at promoted (stepped) terrace sites that are available and active, quite independent of size. These results demonstrate that the iron carbide particle size plays a crucial role in the design of active and selective FTO catalysts. PMID:22953753

  8. Pressurised gasification of wet ethanol fermentation residue for synthesis gas production.

    PubMed

    Koido, Kenji; Hanaoka, Toshiaki; Sakanishi, Kinya

    2013-03-01

    Pressurised steam gasification of wet biomass in a fixed-bed downdraft gasifier was implemented to identify reaction conditions yielding the highest synthesis gas concentration and efficiency, and to examine the generation of sulphur compounds. The gasification of lignin-rich fermentation residue derived from a bench-plant for bioethanol production from woody biomass was investigated at p=0.99MPa and T=750-900°C for steam to biomass ratios (S/B) of 3.4-17 and equivalence ratios (φ) of 3.3-∞. The results showed that the highest concentration of around 70mol% was obtained at T⩾850°C, φ=13 and S/B=3.4, the highest efficiency of 0.26 was obtained at T=900°C, φ=3.3 and S/B=3.4, and sulphur compounds were H2S and COS. For the production of BTL synthesis gas, pressurised gasification has the potential to convert the wet residue below 77.3wt.% moisture contents.

  9. Biological conversion of synthesis gas. [Quarterly] project status report, July 1, 1992--September 30, 1992

    SciTech Connect

    Not Available

    1992-10-01

    The anaerobic, photosynthetic bacterium Chlorobium thiosulfatophilum is able to convert H{sub 2}S and COS in synthesis gas to elemental sulfur. The bacterium grows on CO{sub 2} as its carbon source at 30{degrees}C. In the absence of sulfide, the formed elemental sulfur is converted to sulfate. Thus, bioreactor designs must incorporate sulfur removal as an integral part of the bioprocess. In this initial study, C. thiosulfatophilum was used to convert H{sub 2}S to elemental sulfur in a continuous stirred tank reactor with continuous gas and liquid feed. Sulfur removal was not part of this initial system design, but will be an added feature in future work. The gas used in this study contained 2.52 percent H{sub 2}S, 10.00 percent CO{sub 2}, 14.99 percent CH{sub 4} and 72.49 percent He. The liquid flow rate to the 1380 mL reactor volume ranged from 10.8--23.6 mL/min and was a variable in the study. The initial gas flow rate was 11.6 standard mL/min, although it was also changed twice during the study. The temperature was maintained at 31{degrees}C and the agitation rate was held at 200 rpm in the Bioflo reactor. Cell density was monitored by the chlorophyl method and gas composition was monitored by gas-solid chromatography. Light at 2200 lux was supplied using two 40W tungsten light bulbs on the outside of the glass reactor vessel.

  10. Layer-modulated synthesis of uniform tungsten disulfide nanosheet using gas-phase precursors

    NASA Astrophysics Data System (ADS)

    Park, Jusang; Lee, Wonseon; Choi, Taejin; Hwang, Sung-Hwan; Myoung, Jae Min; Jung, Jae-Hoon; Kim, Soo-Hyun; Kim, Hyungjun

    2015-01-01

    The synthesis of layered transition-metal-disulfide (MS2, M = Mo, W) nanosheets with layer controllability and large-area uniformity is an essential requirement for their application in electronic and optical devices. In this report, we describe a synthesis process of WS2 nanosheets with layer controllability and high uniformity using chemical vapor deposition (CVD) and WCl6 and H2S as gas-phase precursors. Through this process, we can systematically modulate the thickness of WS2 nanosheets by controlling the duration of the reaction between WCl6 and H2S. The CVD-grown WS2 nanosheets exhibit good stoichiometry as well as dependencies of a clear Raman shift and bandgap on the number of layers. These properties are confirmed by X-ray photoemission spectroscopy, Raman spectroscopy, and photoluminescence measurements. The number of layers of WS2 nanosheets is confirmed by atomic force microscopy. Finally, we demonstrate the fabrication and performance of a photodetector based on a hybrid structure consisting of graphene and a WS2 nanosheet.The synthesis of layered transition-metal-disulfide (MS2, M = Mo, W) nanosheets with layer controllability and large-area uniformity is an essential requirement for their application in electronic and optical devices. In this report, we describe a synthesis process of WS2 nanosheets with layer controllability and high uniformity using chemical vapor deposition (CVD) and WCl6 and H2S as gas-phase precursors. Through this process, we can systematically modulate the thickness of WS2 nanosheets by controlling the duration of the reaction between WCl6 and H2S. The CVD-grown WS2 nanosheets exhibit good stoichiometry as well as dependencies of a clear Raman shift and bandgap on the number of layers. These properties are confirmed by X-ray photoemission spectroscopy, Raman spectroscopy, and photoluminescence measurements. The number of layers of WS2 nanosheets is confirmed by atomic force microscopy. Finally, we demonstrate the fabrication

  11. On-line gas chromatographic analysis of higher alcohol synthesis products from syngas.

    PubMed

    Andersson, Robert; Boutonnet, Magali; Järås, Sven

    2012-07-20

    An on-line gas chromatographic (GC) system has been developed for rapid and accurate product analysis in catalytic conversion of syngas (a mixture of H₂ and CO) to alcohols, so called "higher alcohol synthesis (HAS)". Conversion of syngas to higher alcohols is an interesting second step in the route of converting coal, natural gas and possibly biomass to liquid alcohol fuel and chemicals. The presented GC system and method are developed for analysis of the products formed from syngas using alkali promoted MoS₂ catalysts, however it is not limited to these types of catalysts. During higher alcohol synthesis not only the wanted short alcohols (∼C₂-C₅) are produced, but also a great number of other products in smaller or greater amounts, they are mainly short hydrocarbons (olefins, paraffins, branched, non-branched), aldehydes, esters and ketones as well as CO₂, H₂O. Trace amounts of sulfur-containing compounds can also be found in the product effluent when sulfur-containing catalysts are used and/or sulfur-containing syngas is feed. In the presented GC system, most of them can be separated and analyzed within 60 min without the use of cryogenic cooling. Previously, product analysis in "higher alcohol synthesis" has in most cases been carried out partly on-line and partly off-line, where the light gases (gases at room temp) are analyzed on-line and liquid products (liquid at room temp) are collected in a trap for later analysis off-line. This method suffers from many drawbacks compared to a complete on-line GC system. In this paper an on-line system using an Agilent 7890 gas chromatograph equipped with two flame ionization detectors (FID) and a thermal conductivity detector (TCD), together with an Agilent 6890 with sulfur chemiluminescence dual plasma detector (SCD) is presented. A two-dimensional GC system with Deans switch (heart-cut) and two capillary columns (HP-FFAP and HP-Al₂O₃) was used for analysis of the organic products on the FIDs. Light

  12. High octane ethers from synthesis gas-derived alcohols. Final technical report, September 25, 1990--December 24, 1993

    SciTech Connect

    Klier, K.; Herman, R.G.

    1994-05-01

    The objective of the research was to develop the methodology for the catalytic synthesis of ethers, primarily methyl isobutyl ether (MIBE) and methyl tertiary butyl ether (MTBE), directly from alcohol mixtures that are rich in methanol and 2-methyl-1-propanol (isobutanol). The overall scheme involves gasification of coal, purification and shifting of the synthesis gas, higher alcohol synthesis, and direct synthesis of ethers. The last stage of the synthesis involves direct coupling of synthesis gas-derived methanol and isobutanol that has been previously demonstrated by us to occur over superacid catalysts to yield MIBE and smaller amounts of MTBE at moderate pressures and a mixture of methanol and isobutene at low pressures. A wide range of organic resin catalysts and inorganic oxide and zeolite catalysts have been investigated for activity and selectivity in directly coupling alcohols, principally methanol and isobutanol, to form ethers and in the dehydration of isobutanol to isobutene in the presence of methanol. All of these catalysts are strong acids, and it was found that the organic and inorganic catalysts operate in different, but overlapping, temperature ranges, i.e. mainly 60--120{degrees}C for the organic resins and 90--175{degrees}C for the inorganic catalysts. For both types of catalysts, the presence of strong acid centers is required for catalytic activity, as was demonstrated by lack of activity of fully K{sup +} ion exchanged Nafion resin and zirconia prior to being sulfated by treatment with sulfuric acid.

  13. Controlled synthesis of layered Sn3O4 nanobelts by carbothermal reduction method and their gas sensor properties.

    PubMed

    Suman, P H; Longo, E; Varela, J A; Orlandi, M O

    2014-09-01

    This paper reports both the controlled synthesis of Sn3O4 nanobelts by carbothermal reduction method and the gas sensor properties of these nanostructures. The synthesized material was characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy and gas sensor measurements. The results showed that the Sn3O4 nanobelts grow in a layered way and the careful control of experimental parameters is fundamental for stabilization of the correct phase. From the gas sensor measurements using oxygen as analyte gas, it was observed that the Sn3O4 nanobelts exhibit n-type behavior and both the sensitivity and the response time are dependent on the oxygen concentration. A model based on molecules adsorption was proposed to illustrate the mechanism of gas detection of these nanostructures. In summary, these results indicate that Sn3O4 nanobelts synthesized by carbothermal reduction method are promising to be applied as gas sensors.

  14. Synthesis of a further improved porous polymer for the separation of nitrogen, oxygen, argon, and carbon monoxide by gas chromatography

    NASA Technical Reports Server (NTRS)

    Pollock, G. E.

    1986-01-01

    A further improvement has been made in the synthesis of an N-type porous polymer for the separation of permanent gases. Changing the ratios of reactants and diluting the Hi-DVB with styrene led to a porous polymer gas chromatographic packing which is superior to commercial products and to the author's own previously reported custom-made polymer.

  15. Catalysts and process development for synthesis gas conversion to isobutylene.; Quarterly report, January 1--March 31, 1991

    SciTech Connect

    Anthony, R.G.; Akgerman, A.

    1991-05-22

    The objectives of this project are to develop a new catalyst, the kinetics for this catalyst, simulate the performance of fixed bed trickle flow reactors, slurry flow reactors, and fixed bed gas phase reactors for conversion of a hydrogen lean synthesis gas to isobutylene. Isobutylene is a key reactant in the synthesis of methyl tertiary butyl ether (MTBE) and of isooctanes. MTBE and isooctanes are high octane fuels used to blend with low octane gasolines to raise the octane number required for modern automobiles. The production of these two key octane boosters is limited by the supply of isobutylene. MTBE when used as an octane enhancer also decreases the amount of pollutants emitted from the exhaust of an automobile engine. Hydrogen-rich synthesis gas has been converted to isobutylene using a zirconia based catalyst. However, the productivity and yields are low, and the ability of the catalyst to convert a hydrogen-lean synthesis gas to isobutylene with high productivity and yields, and without excessive deactivation is unknown.

  16. Luminescence study of nanosized Al2O3:Tb3+ obtained by gas-dispersed synthesis

    NASA Astrophysics Data System (ADS)

    Berezovskaya, I. V.; Poletaev, N. I.; Khlebnikova, M. E.; Zatovsky, I. V.; Bychkov, K. L.; Efryushina, N. P.; Khomenko, O. V.; Dotsenko, V. P.

    2016-09-01

    Terbium-doped Al2O3 samples were obtained by gas-dispersed synthesis. It was shown that the resulting powders, with particle sizes of 10-70 nm, consist of a mixture of transition aluminas, among which the δ *-polymorph is dominant. The luminescence properties of Al2O3:Tb3+ have been studied upon excitation in the UV-visible range of the spectrum. It was found that Tb3+ ions cause several groups of inhomogeneously broadened emission bands in the range of 470-640 nm, which are characteristic for disordered materials. In addition, the emission spectra contain a broad band at about 450 nm and several narrower ones in the 680-720 nm region. These features are attributed to surface defects and impurity Cr3+ ions occupying Al3+ octahedral positions, respectively.

  17. The performance of a thermophilic microbial fuel cell fed with synthesis gas.

    PubMed

    Hussain, A; Mehta, P; Raghavan, V; Wang, H; Guiot, S R; Tartakovsky, B

    2012-08-10

    This study demonstrated electricity generation in a thermophilic microbial fuel cell (MFC) operated on synthesis gas (syngas) as the sole electron donor. At 50°C, a volumetric power output of 30-35 mWL(R)(-1) and a syngas conversion efficiency of 87-98% was achieved. The observed pathway of syngas conversion to electricity primarily consisted of a two-step process, where the carbon monoxide and hydrogen were first converted to acetate, which was then consumed by the anodophilic bacteria to produce electricity. A denaturing gradient gel electrophoresis (DGGE) analysis of the 16S rDNA revealed the presence of Geobacter species, Acetobacter, methanogens and several uncultured bacteria and archaea in the anodic chamber. PMID:22759536

  18. Luminescence study of nanosized Al2O3:Tb3+ obtained by gas-dispersed synthesis

    NASA Astrophysics Data System (ADS)

    Berezovskaya, I. V.; Poletaev, N. I.; Khlebnikova, M. E.; Zatovsky, I. V.; Bychkov, K. L.; Efryushina, N. P.; Khomenko, O. V.; Dotsenko, V. P.

    2016-09-01

    Terbium-doped Al2O3 samples were obtained by gas-dispersed synthesis. It was shown that the resulting powders, with particle sizes of 10–70 nm, consist of a mixture of transition aluminas, among which the δ *-polymorph is dominant. The luminescence properties of Al2O3:Tb3+ have been studied upon excitation in the UV–visible range of the spectrum. It was found that Tb3+ ions cause several groups of inhomogeneously broadened emission bands in the range of 470–640 nm, which are characteristic for disordered materials. In addition, the emission spectra contain a broad band at about 450 nm and several narrower ones in the 680–720 nm region. These features are attributed to surface defects and impurity Cr3+ ions occupying Al3+ octahedral positions, respectively.

  19. Carbonyl Diisocyanate CO(NCO)2: Synthesis and Structures in Solid State and Gas Phase.

    PubMed

    Klapötke, Thomas M; Krumm, Burkhard; Rest, Sebastian; Scharf, Regina; Schwabedissen, Jan; Stammler, Hans-Georg; Mitzel, Norbert W

    2016-07-01

    A modified synthesis for carbonyl diisocyanate, CO(NCO)2, starting from trichloroisocyanuric acid and diphosgene is described. In addition to the previously reported (13)C NMR resonances, the (15)N NMR shift is determined for the first time. The structure in the solid state was determined by X-ray diffraction (XRD) on in situ grown crystals, that in the gas phase was experimentally determined by electron diffraction (GED) and for single molecules theoretically by quantum-chemical calculations. The structures are compared and discussed with related systems. Quantum-chemical calculations as well as GED and XRD prove syn-syn to be the conformation of lowest energy. In quantum-chemical calculations and GED the presence of a syn-anti conformer was confirmed and the structure of this conformer was determined.

  20. Synthesis and integration of one-dimensional nanostructures for chemical gas sensing applications

    NASA Astrophysics Data System (ADS)

    Parthangal, Prahalad Madhavan

    The need for improved measurement technology for the detection and monitoring of gases has increased tremendously for maintenance of domestic and industrial health and safety, environmental surveys, national security, food-processing, medical diagnostics and various other industrial applications. Among the several varieties of gas sensors available in the market, solid-state sensors are the most popular owing to their excellent sensitivity, ruggedness, versatility and low cost. Semiconducting metal oxides such as tin oxide (SnO2), zinc oxide (ZnO), and tungsten oxide (WO3) are routinely employed as active materials in these sensors. Since their performance is directly linked to the exposed surface area of the sensing material, one-dimensional nanostructures possessing very high surface to volume ratios are attractive candidates for designing the next generation of sensors. Such nano-sensors also enable miniaturization thereby reducing power consumption. The key to achieve success in one-dimensional nanotechnologies lies in assembly. While synthesis techniques and capabilities continue to expand rapidly, progress in controlled assembly has been sluggish due to numerous technical challenges. In this doctoral thesis work, synthesis and characterization of various one-dimensional nanostructures including nanotubes of SnO2, and nanowires of WO3 and ZnO, as well as their direct integration into miniature sensor platforms called microhotplates have been demonstrated. The key highlights of this research include devising elegant strategies for growing metal oxide nanotubes using carbon nanotubes as templates, substantially reducing process temperatures to enable growth of WO3 nanowires on microhotplates, and successfully fabricating a ZnO nanowire array based sensor using a hybrid nanowire-nanoparticle assembly approach. In every process, the gas-sensing properties of one-dimensional nanostructures were observed to be far superior in comparison with thin films of the same

  1. Synthesis and performance of bismuth trioxide nanoparticles for high energy gas generator use.

    PubMed

    Martirosyan, K S; Wang, L; Vicent, A; Luss, D

    2009-10-01

    Our experiments showed that the combustion of an Al-Bi2O3 nanoparticle mixture generated the highest pressure pulse among common nanothermite reactions and can potentially be used as a nanoenergetic gas generator. The combustion front propagation velocity and rate of energy release increased by up to three orders of magnitude when the particle size was reduced to a nanosize range for both the aluminum and the oxidizer. We developed a novel one-step (metal nitrate-glycine) combustion synthesis of nanostructured amorphous-like and highly crystalline bismuth trioxide nanoparticles. The combustion synthesis was conducted using a solution of molten bismuth nitrate as an oxidizer and glycine as a fuel. The glycine was completely combusted during the thermal decomposition of the bismuth nitrate pentahydrate and generated a temperature front that propagated through the sample. Increasing the fuel concentration increased the maximum combustion temperature from 280 to 1200 degrees C and the Bi2O3 particle size from 20 to 100 nm. The oxidizer/fuel ratio had a strong impact on the bismuth trioxide particle crystallinity. At low temperature (280 degrees C), amorphous-like bismuth trioxide nanoparticles formed, while at T > or =370 degrees C the structures were crystalline. A peak pressure of approximately 12 MPa and a thermal front propagating velocity of approximately 2500 m s(-1) were achieved during the combustion of an Al-Bi2O3 mixture containing 80 wt% of the synthesized Bi2O3 crystalline nanoparticles (size: 40-50 nm).

  2. Synthesis and performance of bismuth trioxide nanoparticles for high energy gas generator use

    NASA Astrophysics Data System (ADS)

    Martirosyan, K. S.; Wang, L.; Vicent, A.; Luss, D.

    2009-10-01

    Our experiments showed that the combustion of an Al-Bi2O3 nanoparticle mixture generated the highest pressure pulse among common nanothermite reactions and can potentially be used as a nanoenergetic gas generator. The combustion front propagation velocity and rate of energy release increased by up to three orders of magnitude when the particle size was reduced to a nanosize range for both the aluminum and the oxidizer. We developed a novel one-step (metal nitrate-glycine) combustion synthesis of nanostructured amorphous-like and highly crystalline bismuth trioxide nanoparticles. The combustion synthesis was conducted using a solution of molten bismuth nitrate as an oxidizer and glycine as a fuel. The glycine was completely combusted during the thermal decomposition of the bismuth nitrate pentahydrate and generated a temperature front that propagated through the sample. Increasing the fuel concentration increased the maximum combustion temperature from 280 to 1200 °C and the Bi2O3 particle size from 20 to 100 nm. The oxidizer/fuel ratio had a strong impact on the bismuth trioxide particle crystallinity. At low temperature (280 °C), amorphous-like bismuth trioxide nanoparticles formed, while at T>=370 °C the structures were crystalline. A peak pressure of ~12 MPa and a thermal front propagating velocity of ~2500 m s-1 were achieved during the combustion of an Al-Bi2O3 mixture containing 80 wt% of the synthesized Bi2O3 crystalline nanoparticles (size: 40-50 nm).

  3. Layer-modulated synthesis of uniform tungsten disulfide nanosheet using gas-phase precursors.

    PubMed

    Park, Jusang; Lee, Wonseon; Choi, Taejin; Hwang, Sung-Hwan; Myoung, Jae Min; Jung, Jae-Hoon; Kim, Soo-Hyun; Kim, Hyungjun

    2015-01-28

    The synthesis of layered transition-metal-disulfide (MS2, M = Mo, W) nanosheets with layer controllability and large-area uniformity is an essential requirement for their application in electronic and optical devices. In this report, we describe a synthesis process of WS2 nanosheets with layer controllability and high uniformity using chemical vapor deposition (CVD) and WCl6 and H2S as gas-phase precursors. Through this process, we can systematically modulate the thickness of WS2 nanosheets by controlling the duration of the reaction between WCl6 and H2S. The CVD-grown WS2 nanosheets exhibit good stoichiometry as well as dependencies of a clear Raman shift and bandgap on the number of layers. These properties are confirmed by X-ray photoemission spectroscopy, Raman spectroscopy, and photoluminescence measurements. The number of layers of WS2 nanosheets is confirmed by atomic force microscopy. Finally, we demonstrate the fabrication and performance of a photodetector based on a hybrid structure consisting of graphene and a WS2 nanosheet.

  4. Design and Operation of the Synthesis Gas Generator System for Reformed Propane and Glycerin Combustion

    NASA Astrophysics Data System (ADS)

    Pickett, Derek Kyle

    Due to an increased interest in sustainable energy, biodiesel has become much more widely used in the last several years. Glycerin, one major waste component in biodiesel production, can be converted into a hydrogen rich synthesis gas to be used in an engine generator to recover energy from the biodiesel production process. This thesis contains information detailing the production, testing, and analysis of a unique synthesis generator rig at the University of Kansas. Chapter 2 gives a complete background of all major components, as well as how they are operated. In addition to component descriptions, methods for operating the system on pure propane, reformed propane, reformed glycerin along with the methodology of data acquisition is described. This chapter will serve as a complete operating manual for future students to continue research on the project. Chapter 3 details the literature review that was completed to better understand fuel reforming of propane and glycerin. This chapter also describes the numerical model produced to estimate the species produced during reformation activities. The model was applied to propane reformation in a proof of concept and calibration test before moving to glycerin reformation and its subsequent combustion. Chapter 4 first describes the efforts to apply the numerical model to glycerin using the calibration tools from propane reformation. It then discusses catalytic material preparation and glycerin reformation tests. Gas chromatography analysis of the reformer effluent was completed to compare to theoretical values from the numerical model. Finally, combustion of reformed glycerin was completed for power generation. Tests were completed to compare emissions from syngas combustion and propane combustion.

  5. High Temperature Polybenzimidazole Hollow Fiber Membranes for Hydrogen Separation and Carbon Dioxide Capture from Synthesis Gas

    SciTech Connect

    Singh, Rajinder P.; Dahe, Ganpat J.; Dudeck, Kevin W.; Welch, Cynthia F.; Berchtold, Kathryn A.

    2014-12-31

    Sustainable reliance on hydrocarbon feedstocks for energy generation requires CO₂ separation technology development for energy efficient carbon capture from industrial mixed gas streams. High temperature H₂ selective glassy polymer membranes are an attractive option for energy efficient H₂/CO₂ separations in advanced power production schemes with integrated carbon capture. They enable high overall process efficiencies by providing energy efficient CO₂ separations at process relevant operating conditions and correspondingly, minimized parasitic energy losses. Polybenzimidazole (PBI)-based materials have demonstrated commercially attractive H₂/CO₂ separation characteristics and exceptional tolerance to hydrocarbon fuel derived synthesis (syngas) gas operating conditions and chemical environments. To realize a commercially attractive carbon capture technology based on these PBI materials, development of high performance, robust PBI hollow fiber membranes (HFMs) is required. In this work, we discuss outcomes of our recent efforts to demonstrate and optimize the fabrication and performance of PBI HFMs for use in pre-combustion carbon capture schemes. These efforts have resulted in PBI HFMs with commercially attractive fabrication protocols, defect minimized structures, and commercially attractive permselectivity characteristics at IGCC syngas process relevant conditions. The H₂/CO₂ separation performance of these PBI HFMs presented in this document regarding realistic process conditions is greater than that of any other polymeric system reported to-date.

  6. High Temperature Polybenzimidazole Hollow Fiber Membranes for Hydrogen Separation and Carbon Dioxide Capture from Synthesis Gas

    DOE PAGES

    Singh, Rajinder P.; Dahe, Ganpat J.; Dudeck, Kevin W.; Welch, Cynthia F.; Berchtold, Kathryn A.

    2014-12-31

    Sustainable reliance on hydrocarbon feedstocks for energy generation requires CO₂ separation technology development for energy efficient carbon capture from industrial mixed gas streams. High temperature H₂ selective glassy polymer membranes are an attractive option for energy efficient H₂/CO₂ separations in advanced power production schemes with integrated carbon capture. They enable high overall process efficiencies by providing energy efficient CO₂ separations at process relevant operating conditions and correspondingly, minimized parasitic energy losses. Polybenzimidazole (PBI)-based materials have demonstrated commercially attractive H₂/CO₂ separation characteristics and exceptional tolerance to hydrocarbon fuel derived synthesis (syngas) gas operating conditions and chemical environments. To realize a commerciallymore » attractive carbon capture technology based on these PBI materials, development of high performance, robust PBI hollow fiber membranes (HFMs) is required. In this work, we discuss outcomes of our recent efforts to demonstrate and optimize the fabrication and performance of PBI HFMs for use in pre-combustion carbon capture schemes. These efforts have resulted in PBI HFMs with commercially attractive fabrication protocols, defect minimized structures, and commercially attractive permselectivity characteristics at IGCC syngas process relevant conditions. The H₂/CO₂ separation performance of these PBI HFMs presented in this document regarding realistic process conditions is greater than that of any other polymeric system reported to-date.« less

  7. An alternative gas sensor material: Synthesis and electrical characterization of SmCoO{sub 3}

    SciTech Connect

    Michel, Carlos Rafael . E-mail: michelucr@yahoo.es; Delgado, Emilio; Santillan, Gloria; Martinez, Alma H.; Chavez-Chavez, Arturo

    2007-01-18

    Single-phase perovskite SmCoO{sub 3} was prepared by a wet-chemical synthesis technique using metal-nitrates and citric acid; after its characterization by thermal analyses and X-ray diffraction, sintering at 900 deg. C in air, gave single phase and well crystallized powders. The powders were mixed with an organic solvent to prepare a slurry, which was deposited on alumina substrates as thick films, using the screen-printing technique. Electrical and gas sensing properties of sintered SmCoO{sub 3} films were investigated in air, O{sub 2} and CO{sub 2}, the results show that sensitivity reached a maximum value at 420 deg. C, for both gases. Dynamic tests revealed a better behavior of SmCoO{sub 3} in CO{sub 2} than O{sub 2}, due to a fast response and a larger electrical resistance change to this gas. X-ray diffraction made on powders after electrical characterization in gases, showed that perovskite-type structure was preserved.

  8. Synthesis and gas adsorption study of porous metal-organic framework materials

    NASA Astrophysics Data System (ADS)

    Mu, Bin

    Metal-organic frameworks (MOFs) or porous coordination polymers (PCPs) have become the focus of intense study over the past decade due to their potential for advancing a variety of applications including air purification, gas storage, adsorption separations, catalysis, gas sensing, drug delivery, and so on. These materials have some distinct advantages over traditional porous materials such as the well-defined structures, uniform pore sizes, chemically functionalized sorption sites, and potential for postsynthetic modification, etc. Thus, synthesis and adsorption studies of porous MOFs have increased substantially in recent years. Among various prospective applications, air purification is one of the most immediate concerns, which has urgent requirements to improve current nuclear, biological, and chemical (NBC) filters involving commercial and military purposes. Thus, the major goal of this funded project is to search, synthesize, and test these novel hybrid porous materials for adsorptive removal of toxic industrial chemicals (TICs) and chemical warfare agents (CWAs), and to install the benchmark for new-generation NBC filters. The objective of this study is three-fold: (i) Advance our understanding of coordination chemistry by synthesizing novel MOFs and characterizing these porous coordination polymers; (ii) Evaluate porous MOF materials for gasadsorption applications including CO2 capture, CH4 storage, other light gas adsorption and separations, and examine the chemical and physical properties of these solid adsorbents including thermal stability and heat capacity of MOFs; (iii) Evaluate porous MOF materials for next-generation NBC filter media by adsorption breakthrough measurements of TICs on MOFs, and advance our understanding about structureproperty relationships of these novel adsorbents.

  9. Effects of feed gas composition and catalyst thickness on carbon nanotube and nanofiber synthesis by plasma enhanced chemical vapor deposition.

    PubMed

    Garg, R K; Kim, S S; Hash, D B; Gore, J P; Fisher, T S

    2008-06-01

    Many engineering applications require carbon nanotubes with specific characteristics such as wall structure, chirality and alignment. However, precise control of nanotube properties grown to application specifications remains a significant challenge. Plasma-enhanced chemical vapor deposition (PECVD) offers a variety of advantages in the synthesis of carbon nanotubes in that several important synthesis parameters can be controlled independently. This paper reports an experimental study of the effects of reacting gas composition (percentage methane in hydrogen) and catalyst film thickness on carbon nanotube (CNT) growth and a computational study of gas-phase composition for the inlet conditions of experimentally observed carbon nanotube growth using different chemical reaction mechanisms. The simulations seek to explain the observed effects of reacting gas composition and to identify the precursors for CNT formation. The experimental results indicate that gas-phase composition significantly affects the synthesized material, which is shown to be randomly aligned nanotube and nanofiber mats for relatively methane-rich inlet gas mixtures and non-tubular carbon for methane-lean incoming mixtures. The simulation results suggest that inlet methane-hydrogen mixture coverts to an acetylene-methane-hydrogen mixture with minor amounts of ethylene, hydrogen atom, and methyl radical. Acetylene appears to be the indicator species for solid carbon formation. The simulations also show that inlet methane-hydrogen mixture does not produce enough gas-phase precursors needed to form quality CNTs below 5% CH4 concentrations in the inlet stream. PMID:18681048

  10. Simulation of a process for the two-stage thermal conversion of biomass into the synthesis gas

    NASA Astrophysics Data System (ADS)

    Kosov, V. F.; Lavrenov, V. A.; Zaichenko, V. M.

    2015-11-01

    The paper presents results of simulation of a process for the two-stage thermal conversion of wood biomass into the synthesis gas. The first stage of process is pyrolysis of raw materials, the second stage is cracking of volatile pyrolysis products which blown through the char at a temperature of about 1000° C. Char is a porous biomass residue with carbon content about 90%. The simulation based on the results of experimental investigations of a pilot plant with capacity up to 50 kg of raw material per hour. The main result of simulation is estimation of an energy conversion efficiency of wood biomass into synthesis gas for three different operation modes. The first mode is conversion of biomass into fuel gas and char, and the char is not further used. The second mode is the same, but char used as fuel for producing heat for own demand of the process. The third mode includes gasification of char by means of water steam, aimed to obtaining an additional yield of synthesis gas. The simulation shown, that total efficiency of power plant was 17.1% in the first mode, 22.4% in the second mode and 22.6% in the third mode.

  11. Solar Thermal Conversion of Biomass to Synthesis Gas: Cooperative Research and Development Final Report, CRADA Number CRD-09-00335

    SciTech Connect

    Netter, J.

    2013-08-01

    The CRADA is established to facilitate the development of solar thermal technology to efficiently and economically convert biomass into useful products (synthesis gas and derivatives) that can replace fossil fuels. NREL's High Flux Solar Furnace will be utilized to validate system modeling, evaluate candidate reactor materials, conduct on-sun testing of the process, and assist in the development of solar process control system. This work is part of a DOE-USDA 3-year, $1M grant.

  12. Bioconversion of coal-derived synthesis gas to liquid fuels. Final report, September 29, 1992--December 27, 1994

    SciTech Connect

    Jain, M.K.; Worden, R.M.; Grethlein, H.E.

    1995-01-15

    The proposed research project consists of an integrated, two-stage fermentation and a highly energy-efficient product separation scheme. In the first fermentation, Butyribacterium methylotrophicum converts carbon monoxide (CO) into butyric acid and acetic acids which are then converted into butanol, ethanol, and a small amount of acetone in the second stage fermentation by Clostridium acetobutylicum. An advanced separation system process, based on pervaporation, removes the alcohols from the fermentation broth as they are formed, along with some of the hydrogen sulfide (H{sub 2}S), to minimize possible inhibition of the fermentations. This bioconversion process offers a critical advantage over conventional, catalytic processes for synthesis gas conversion: the microorganisms are several orders of magnitude more sulfur tolerant than metallic catalysts. The catalysts require sulfur removal to the parts per million level, while the microorganisms are unaffected by H{sub 2}S and carbonyl sulfide (COS) at one part per hundred--roughly the composition of sulfur in raw synthesis gas. During the two-year course of this project, the following major objectives have been accomplished: demonstrated long-term cell recycle of continuous fermentation of synthesis gas; demonstrated cell immobilization of Butyribacterium methylotrophicum; identified trickle-bed reactor as a viable alternative fermentation method; modulated metabolic pathways to increase C4 formation during synthesis gas fermentation; recovered carbon and electrons from H{sub 2} and CO{sub 2} with pathway modulation for increased C4 production; developed bacterial strains with improved selectivity for butyrate fermentation; demonstrated two-stage CO to alcohol fermentation; and concentrated alcohol from solventogenic fermentation by pervaporation.

  13. Hydrocarbon selectivity model for gas-solid Fischer-Tropsch synthesis on precipitated iron catalysts

    SciTech Connect

    Laan, G.P. van der; Beenackers, A.A.C.M.

    1999-04-01

    The kinetics of the gas-solid Fischer-Tropsch (FT) synthesis over a commercial Fe-Cu-K-SiO{sub 2} catalyst was studied in a continuous spinning basket reactor. Experimental conditions were varied as follows: reactor pressure of 0.8--3.2 MPa, H{sub 2}/CO feed ratio = 0.5--2.0, and a space velocity of 0.5--2.0 {times} 10{sup {minus}3} Nm{sup 3}/kg{sub cat} s at a constant temperature of 523 K. A new product distribution model for linear hydrocarbons is proposed. Deviations from conventional Anderson-Schulz-Flory distribution can be quantitatively described with an {alpha}-olefin readsorption product distribution model. The experimentally observed relatively high yield of methane, relatively low yield of ethene, and both the exponential decrease of the olefin-to-paraffin ratio and the change of the chain growth parameter with chain length can all be predicted from this new model. It combines a mechanistic model of olefin readsorption with kinetics of chain growth and termination on the same catalytic sites. The hydrocarbon formation is based on the surface carbide mechanism by CH{sub 2} insertion. The olefin readsorption rate depends on the chain length because of increasing physisorption strength on the catalyst surface and increasing solubility in FT wax with increasing chain length. Interfacial concentrations of reactive olefins near the gas-wax and wax-catalyst surface are used in the kinetic model. With optimization of three parameters per experimental product distribution, the olefin readsorption product distribution model proved to predict product selectivities accurately over the entire range of experimental conditions. The relative deviations are 10.1% and 9.1% for the selectivity to paraffins and olefins with n < 11, respectively.

  14. Germanium-silicon alloy and core-shell nanocrystals by gas phase synthesis.

    PubMed

    Mehringer, Christian; Kloner, Christian; Butz, Benjamin; Winter, Benjamin; Spiecker, Erdmann; Peukert, Wolfgang

    2015-03-12

    In this work we present a novel route to synthesize well defined germanium-silicon alloy (GexSi1-x) and core-shell nanocrystals (NCs) employing monosilane (SiH4) and monogermane (GeH4) as precursors in a continuously operated two-stage hot-wall aerosol reactor setup. The first hot-wall reactor stage (HWR I) is used to produce silicon (Si) seed particles from SiH4 pyrolysis in Argon (Ar). The resulting seeding aerosol is fed into the second reactor stage (HWR II) and a mixture of SiH4 and GeH4 is added. The ratio of the precursors in the feed, their partial pressures, the synthesis temperature in HWR II and the overall pressure are varied depending on the desired morphology and composition. Alloy particle production is achieved in the heterogeneous surface reaction regime, meaning that germanium (Ge) and Si are deposited on the seed surface simultaneously. The NCs can be synthesized with any desired composition, whilst maintaining a mean diameter around 30 nm with a geometric standard deviation (GSD) around 1.25. The absorption behavior and the related fundamental optical band gap energy in dependence on the alloy composition are exemplarily presented. They prove the possibility to tailor NC properties for electronical and opto-electronical applications. In the homogeneous gas phase reaction regime facetted Ge-Si core-shell structures are accessible. The Ge deposition on the seeds precedes the Si deposition due to different gas phase reaction kinetics of the precursors. The Si layer grows epitaxially on the Ge core and is around 5 nm thick. PMID:25700152

  15. Germanium-silicon alloy and core-shell nanocrystals by gas phase synthesis.

    PubMed

    Mehringer, Christian; Kloner, Christian; Butz, Benjamin; Winter, Benjamin; Spiecker, Erdmann; Peukert, Wolfgang

    2015-03-12

    In this work we present a novel route to synthesize well defined germanium-silicon alloy (GexSi1-x) and core-shell nanocrystals (NCs) employing monosilane (SiH4) and monogermane (GeH4) as precursors in a continuously operated two-stage hot-wall aerosol reactor setup. The first hot-wall reactor stage (HWR I) is used to produce silicon (Si) seed particles from SiH4 pyrolysis in Argon (Ar). The resulting seeding aerosol is fed into the second reactor stage (HWR II) and a mixture of SiH4 and GeH4 is added. The ratio of the precursors in the feed, their partial pressures, the synthesis temperature in HWR II and the overall pressure are varied depending on the desired morphology and composition. Alloy particle production is achieved in the heterogeneous surface reaction regime, meaning that germanium (Ge) and Si are deposited on the seed surface simultaneously. The NCs can be synthesized with any desired composition, whilst maintaining a mean diameter around 30 nm with a geometric standard deviation (GSD) around 1.25. The absorption behavior and the related fundamental optical band gap energy in dependence on the alloy composition are exemplarily presented. They prove the possibility to tailor NC properties for electronical and opto-electronical applications. In the homogeneous gas phase reaction regime facetted Ge-Si core-shell structures are accessible. The Ge deposition on the seeds precedes the Si deposition due to different gas phase reaction kinetics of the precursors. The Si layer grows epitaxially on the Ge core and is around 5 nm thick.

  16. Bioconversion of coal-derived synthesis gas to liquid fuels. Annual report, September 29, 1992--September 28, 1993

    SciTech Connect

    Jain, M.K.; Worden, R.M.; Grethlein, H.E.

    1993-10-21

    The overall objective of the project is to develop and optimize a two-stage fermentation process for the conversion of coal derived synthesis gas in an mixture of alcohols. The goals include the development of superior strains with high product tolerance and productivity, optimization of process conditions for high volumetric productivity and product concentrations, integration and optimization of two stage syngas fermentation, evaluation of bioreactor configurations for enhanced mass transfer, evaluation of syngas conversion by a culture of Butyribacterium methyltrophicum and Clostridium acetobutylicum, development of a membrane based pervaporation system for in situ removal of alcohols, and development of a process for reduction of carbon and electron loss. The specific goals for year one (September 1992 - September 1993) were (1) development of a project work plan, (2) development of superior CO-utilizing strains, (3) optimization of process conditions for conversion of synthesis gas to a mixture of acids in a continuously stirred reactor (CSTR), (4) evaluation of different bioreactor configurations for maximization of mass transfer of synthesis gas, (5) development of a membrane based pervaporation system, and (6) reduction of carbon and electron loss via H{sub 2}CO{sub 2} fermentation. Experimentation and progress toward these goals are described in this report.

  17. Catalyst and process development for synthesis gas conversion to isobutylene. Quarterly report, October 1, 1993--December 31, 1993

    SciTech Connect

    Anthony, R.G.; Akgerman, A.

    1994-05-01

    The objectives of this project are to develop a new catalyst; the kinetics for this catalyst; reactor models for trickle bed, slurry and fixed bed reactors; and to simulate the performance of fixed bed trickle flow reactors, slurry flow reactors, and fixed bed gas phase reactors for conversion of a hydrogen lean synthesis gas to isobutylene. A hydrogen-lean synthesis gas with a ratio of H{sub 2}/CO of 0.5 to 1.0 is produced from the gasification of coal, lignite, or biomass. Isobutylene is a key reactant in the synthesis of methyl tertiary butyl ether (MTBE) and of isooctanes. MTBE and isooctanes are high octane fuels used to blend with low octane gasolines to raise the octane number required for modern automobiles. The production of these two key octane boosters is limited by the supply of isobutylene. MTBE, when used as an octane enhancer, also decreases the amount of pollutants emitted from the exhaust of an automobile engine.

  18. Simultaneous assessment of cholesterol absorption and synthesis in humans using on-line gas chromatography/ combustion and gas chromatography/pyrolysis/isotope-ratio mass spectrometry.

    PubMed

    Gremaud, G; Piguet, C; Baumgartner, M; Pouteau, E; Decarli, B; Berger, A; Fay, L B

    2001-01-01

    A number of dietary components and drugs are known to inhibit the absorption of dietary and biliary cholesterol, but at the same time can compensate by increasing cholesterol synthesis. It is, therefore, necessary to have a convenient and accurate method to assess both parameters simultaneously. Hence, we validated such a method in humans using on-line gas chromatography(GC)/combustion and GC/pyrolysis/isotope-ratio mass spectrometry (IRMS). Cholesterol absorption was measured using the ratio of [(13)C]cholesterol (injected intravenously) to [(18)O]cholesterol (administered orally). Simultaneously, cholesterol synthesis was measured using the deuterium incorporation method. Our methodology was applied to 12 mildly hypercholesterolemic men that were given a diet providing 2685 +/- 178 Kcal/day (mean +/- SD) and 255 +/- 8 mg cholesterol per day. Cholesterol fractional synthesis rates ranged from 5.0 to 10.5% pool/day and averaged 7.36% +/- 1.78% pool/day (668 +/- 133 mg/day). Cholesterol absorption ranged from 36.5-79.9% with an average value of 50.8 +/- 15.4%. These values are in agreement with already known data obtained with mildly hypercholesterolemic Caucasian males placed on a diet similar to the one used for this study. However, our combined IRMS method has the advantage over existing methods that it enables simultaneous measurement of cholesterol absorption and synthesis in humans, and is therefore an important research tool for studying the impact of dietary treatments on cholesterol parameters.

  19. Gas-phase synthesis of the benzyl radical (C(6)H(5)CH(2)).

    PubMed

    Dangi, Beni B; Parker, Dorian S N; Yang, Tao; Kaiser, Ralf I; Mebel, Alexander M

    2014-04-25

    Dicarbon (C2 ), the simplest bare carbon molecule, is ubiquitous in the interstellar medium and in combustion flames. A gas-phase synthesis is presented of the benzyl radical (C6 H5 CH2 ) by the crossed molecular beam reaction of dicarbon, C2 (X(1) Σg (+) , a(3) Πu ), with 2-methyl-1,3-butadiene (isoprene; C5 H8 ; X(1) A') accessing the triplet and singlet C7 H8 potential energy surfaces (PESs) under single collision conditions. The experimental data combined with ab initio and statistical calculations reveal the underlying reaction mechanism and chemical dynamics. On the singlet and triplet surfaces, the reactions involve indirect scattering dynamics and are initiated by the barrierless addition of dicarbon to the carbon-carbon double bond of the 2-methyl-1,3-butadiene molecule. These initial addition complexes rearrange via multiple isomerization steps, leading eventually to the formation of C7 H7 radical species through atomic hydrogen elimination. The benzyl radical (C6 H5 CH2 ), the thermodynamically most stable C7 H7 isomer, is determined as the major product.

  20. Kinetic Studies on Fermentative Production of Biofuel from Synthesis Gas Using Clostridium ljungdahlii

    PubMed Central

    Mohamed, Abdul Rahman; Najafpour, Ghasem D.; Younesi, Habibollah; Uzir, Mohamad Hekarl

    2014-01-01

    The intrinsic growth, substrate uptake, and product formation biokinetic parameters were obtained for the anaerobic bacterium, Clostridium ljungdahlii, grown on synthesis gas in various pressurized batch bioreactors. A dual-substrate growth kinetic model using Luong for CO and Monod for H2 was used to describe the growth kinetics of the bacterium on these substrates. The maximum specific growth rate (μmax = 0.195 h−1) and Monod constants for CO (Ks,CO = 0.855 atm) and H2 (Ks,H2 = 0.412 atm) were obtained. This model also accommodated the CO inhibitory effects on cell growth at high CO partial pressures, where no growth was apparent at high dissolved CO tensions (PCO∗ > 0.743 atm). The Volterra model, Andrews, and modified Gompertz were, respectively, adopted to describe the cell growth, substrate uptake rate, and product formation. The maximum specific CO uptake rate (qmax = 34.364 mmol/gcell/h), CO inhibition constant (KI = 0.601 atm), and maximum rate of ethanol (Rmax = 0.172 mmol/L/h at PCO = 0.598 atm) and acetate (Rmax = 0.096 mmol/L/h at PCO = 0.539 atm) production were determined from the applied models. PMID:24672390

  1. The economic production of alcohol fuels from coal-derived synthesis gas

    SciTech Connect

    Kugler, E.L.; Dadyburjor, D.B.; Yang, R.Y.K.

    1995-12-31

    The objectives of this project are to discover, (1) study and evaluate novel heterogeneous catalytic systems for the production of oxygenated fuel enhancers from synthesis gas. Specifically, alternative methods of preparing catalysts are to be investigated, and novel catalysts, including sulfur-tolerant ones, are to be pursued. (Task 1); (2) explore, analytically and on the bench scale, novel reactor and process concepts for use in converting syngas to liquid fuel products. (Task 1); (3) simulate by computer the most energy efficient and economically efficient process for converting coal to energy, with primary focus on converting syngas to fuel alcohols. (Task 2); (4) develop on the bench scale the best holistic combination of chemistry, catalyst, reactor and total process configuration integrated with the overall coal conversion process to achieve economic optimization for the conversion of syngas to liquid products within the framework of achieving the maximum cost effective transformation of coal to energy equivalents. (Tasks 1 and 2); and (5) evaluate the combustion, emission and performance characteristics of fuel alcohols and blends of alcohols with petroleum-based fuels. (Task 2)

  2. Hydrothermal synthesis of highly nitrogen-doped few-layer graphene via solid–gas reaction

    SciTech Connect

    Liang, Xianqing; Zhong, Jun; Shi, Yalin; Guo, Jin; Huang, Guolong; Hong, Caihao; Zhao, Yidong

    2015-01-15

    Highlights: • A novel approach to synthesis of N-doped few-layer graphene has been developed. • The high doping levels of N in products are achieved. • XPS and XANES results reveal a thermal transformation of N bonding configurations. • The developed method is cost-effective and eco-friendly. - Abstract: Nitrogen-doped (N-doped) graphene sheets with high doping concentration were facilely synthesized through solid–gas reaction of graphene oxide (GO) with ammonia vapor in a self-designed hydrothermal system. The morphology, surface chemistry and electronic structure of N-doped graphene sheets were investigated by TEM, AFM, XRD, XPS, XANES and Raman characterizations. Upon hydrothermal treatment, up to 13.22 at% of nitrogen could be introduced into the crumpled few-layer graphene sheets. Both XPS and XANES analysis reveal that the reaction between oxygen functional groups in GO and ammonia vapor produces amide and amine species in hydrothermally treated GO (HTGO). Subsequent thermal annealing of the resultant HTGO introduces a gradual transformation of nitrogen bonding configurations in graphene sheets from amine N to pyridinic and graphitic N with the increase of annealing temperature. This study provides a simple but cost-effective and eco-friendly method to prepare N-doped graphene materials in large-scale for potential applications.

  3. High pressure synthesis gas conversion. Task 2: Determination of maximum operating pressure

    SciTech Connect

    Not Available

    1993-05-01

    The purpose of this research project was to build and test a high pressure fermentation system for the production of ethanol from synthesis gas. The fermenters, pumps, controls, and analytical system were procured or fabricated and assembled in our laboratory. This system was then used to determine the effects of high pressure on growth and ethanol production by C. ljungdahlil. The limits of cell concentration and mass transport relationships were found in CSTR and immobilized cell reactors (ICR). The minimum retention times and reactor volumes were found for ethanol production in these reactors. The purpose of this report was to present the results of high pressure experiments aimed at determining the maximum operating pressure of C. ljungdahlil. Preliminary experiments carried out in approaching the pressure maximum are presented, as well as experimental results at the maximum pressure of 150 psig. This latter pressure was the maximum operating pressure when using the defined medium of Phillips et al., and is expected to change if alternative media are employed.

  4. Reforming of biogas to synthesis gas by a rotating arc plasma at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Chung, Woo-Jae; Park, Hyun-Woo; Liu, Jing-Lin; Park, Dong-Wha

    2015-09-01

    In order to produce synthesis gas, reforming of biogas composed with 60 percent for CH4 and 40 percent for CO2 was performed by a novel rotating arc plasma process. The effect of O2/CH4 ratio on the conversion, syngas composition and energy cost was investigated to evaluate the performance of proposed system compared with conventional gliding arc plasma process. When the O2/CH4 ratio was increased from 0.4 to 0.9, the conversions of CH4 and O2 increased up to 97.5 percent and 98.8 percent, respectively, while CO2 conversion was almost constant to be 38.6 percent. This is due to more enhance the partial oxidation of CH4 to CO and H2 than that of dry reforming by increasing the O2/CH4 ratio. In this work, energy cost of 32 kJ/mol was achieved with high syngas composition of 71 percent using pure O2 as oxidant reactant. These are lower than those of different arc plasma processes (energy cost of 122 - 1870 kJ/mol) such as spark, spark-shade and gliding arc plasma. Because, this rotating arc plasma can remain in a long arc length and a large volume of plasma with constant arc length mode.

  5. [Determination of low-carbon alcohols, aldehydes and ketones in aqueous products of Fischer-Tropsch synthesis by gas chromatography].

    PubMed

    Gai, Qingqing; Wu, Peng; Shi, Yulin; Bai, Yu; Long, Yinhua

    2015-01-01

    A method for the determination of low-carbon (C1-C8) alcohols, aldehydes and ketones in aqueous products of Fischer-Tropsch synthesis was developed by gas chromatography. It included the optimization of separation conditions, the precision and accuracy of determination, and the use of correction factors of the analytes to ethanol for quantification. The aqueous products showed that the correlation coefficients for ethanol in different content ranges were above 0.99, which means it had good linear correlations. The spiked recoveries in the aqueous samples of Fischer-Tropsch synthesis were from 93.4% to 109.6%. The accuracy of the method can satisfy the requirement for the analysis of the aqueous samples of Fischer-Tropsch synthesis. The results showed that the total mass fractions of the major low-carbon alcohols, aldehydes, ketones in aqueous products of Fischer-Tropsch synthesis were about 3%-12%, and the contents of ethanol were the highest (about 1.7%-7.3%). The largest share of the total proportion was n-alcohols, followed by isomeric alcohols, aldehydes and ketones were the lowest. This method is simple, fast, and has great significance for the analysis of important components in aqueous products of Fischer-Tropsch synthesis.

  6. Bioconversion of coal-derived synthesis gas to liquid fuels. Final technical report, September 1, 1990--August 31, 1991

    SciTech Connect

    Jain, M.K.

    1991-12-31

    The use of coal-derived synthesis gas as an industrial feedstock for production of fuels and chemicals has become an increasingly attractive alternative to present petroleum-based chemicals production. However, one of the major limitations in developing such a process is the required removal of catalyst poisons such as hydrogen sulfide (H{sub 2}S), carbonyl sulfide (COS), and other trace contaminants from the synthesis gas. Purification steps necessary to remove these are energy intensive and add significantly to the production cost, particularly for coals having a high sulfur content such as Illinois coal. A two-stage, anaerobic bioconversion process requiring little or no sulfur removal is proposed, where in the first stage the carbon monoxide (CO) gas is converted to butyric and acetic acids by the CO strain of Butyribacterium methylotrophicum. In the second stage, these acids along with the hydrogen (H{sub 2}) gas are converted to butanol, ethanol, and acetone by an acid utilizing mutant of Clostridium acetobutylicum. 18 figs., 18 tabs.

  7. Equipment Design and Cost Estimation for Small Modular Biomass Systems, Synthesis Gas Cleanup, and Oxygen Separation Equipment; Task 2: Gas Cleanup Design and Cost Estimates -- Wood Feedstock

    SciTech Connect

    Nexant Inc.

    2006-05-01

    As part of Task 2, Gas Cleanup and Cost Estimates, Nexant investigated the appropriate process scheme for treatment of wood-derived syngas for use in the synthesis of liquid fuels. Two different 2,000 metric tonne per day gasification schemes, a low-pressure, indirect system using the gasifier, and a high-pressure, direct system using gasification technology were evaluated. Initial syngas conditions from each of the gasifiers was provided to the team by the National Renewable Energy Laboratory. Nexant was the prime contractor and principal investigator during this task; technical assistance was provided by both GTI and Emery Energy.

  8. Status and future opportunities for conversion of synthesis gas to liquid energy fuels: Final report

    SciTech Connect

    Mills, G. . Center for Catalytic Science and Technology)

    1993-05-01

    The manufacture of liquid energy fuels from syngas (a mixture of H[sub 2] and CO, usually containing CO[sub 2]) is of growing importance and enormous potential because: (1) Abundant US supplies of coal, gas, and biomass can be used to provide the needed syngas. (2) The liquid fuels produced, oxygenates or hydrocarbons, can help lessen environmental pollution. Indeed, oxygenates are required to a significant extent by the Clean Air Act Amendments (CAAA) of 1990. (3) Such liquid synfuels make possible high engine efficiencies because they have high octane or cetane ratings. (4) There is new, significantly improved technology for converting syngas to liquid fuels and promising opportunities for further improvements. This is the subject of this report. The purpose of this report is to provide an account and evaluative assessment of advances in the technology for producing liquid energy fuels from syngas and to suggest opportunities for future research deemed promising for practical processes. Much of the improved technology for selective synthesis of desired fuels from syngas has resulted from advances in catalytic chemistry. However, novel process engineering has been particularly important recently, utilizing known catalysts in new configurations to create new catalytic processes. This report is an update of the 1988 study Catalysts for Fuels from Syngas: New Directions for Research (Mills 1988), which is included as Appendix A. Technology for manufacture of syngas is not part of this study. The manufacture of liquid synfuels is capital intensive. Thus, in evaluating advances in fuels technology, focus is on the potential for improved economics, particularly on lowering plant investment costs. A second important criteria is the potential for environmental benefits. The discussion is concerned with two types of hydrocarbon fuels and three types of oxygenate fuels that can be synthesized from syngas. Seven alternative reaction pathways are involved.

  9. Status and future opportunities for conversion of synthesis gas to liquid energy fuels: Final report

    SciTech Connect

    Mills, G

    1993-05-01

    The manufacture of liquid energy fuels from syngas (a mixture of H{sub 2} and CO, usually containing CO{sub 2}) is of growing importance and enormous potential because: (1) Abundant US supplies of coal, gas, and biomass can be used to provide the needed syngas. (2) The liquid fuels produced, oxygenates or hydrocarbons, can help lessen environmental pollution. Indeed, oxygenates are required to a significant extent by the Clean Air Act Amendments (CAAA) of 1990. (3) Such liquid synfuels make possible high engine efficiencies because they have high octane or cetane ratings. (4) There is new, significantly improved technology for converting syngas to liquid fuels and promising opportunities for further improvements. This is the subject of this report. The purpose of this report is to provide an account and evaluative assessment of advances in the technology for producing liquid energy fuels from syngas and to suggest opportunities for future research deemed promising for practical processes. Much of the improved technology for selective synthesis of desired fuels from syngas has resulted from advances in catalytic chemistry. However, novel process engineering has been particularly important recently, utilizing known catalysts in new configurations to create new catalytic processes. This report is an update of the 1988 study Catalysts for Fuels from Syngas: New Directions for Research (Mills 1988), which is included as Appendix A. Technology for manufacture of syngas is not part of this study. The manufacture of liquid synfuels is capital intensive. Thus, in evaluating advances in fuels technology, focus is on the potential for improved economics, particularly on lowering plant investment costs. A second important criteria is the potential for environmental benefits. The discussion is concerned with two types of hydrocarbon fuels and three types of oxygenate fuels that can be synthesized from syngas. Seven alternative reaction pathways are involved.

  10. Synthesis gas production with an adjustable H{sub 2}/CO ratio through the coal gasification process: effects of coal ranks and methane addition

    SciTech Connect

    Yan Cao; Zhengyang Gao; Jing Jin; Hongchang Zhou; Marten Cohron; Houying Zhao; Hongying Liu; Weiping Pan

    2008-05-15

    Direct production of synthesis gas using coal as a cheap feedstock is attractive but challenging due to its low H{sub 2}/CO ratio of generated synthesis gas. Three typical U.S. coals of different ranks were tested in a 2.5 in. coal gasifier to investigate their gasification reactivity and adjustability on H{sub 2}/CO ratio of generated synthesis gas with or without the addition of methane. Tests indicated that lower-rank coals (lignite and sub-bituminous) have higher gasification reactivity than bituminous coals. The coal gasification reactivity is correlated to its synthesis-gas yield and the total percentage of H{sub 2} and CO in the synthesis gas, but not to the H{sub 2}/CO ratio. The H{sub 2}/CO ratio of coal gasification was found to be correlated to the rank of coals, especially the H/C ratio of coals. Methane addition into the dense phase of the pyrolysis and gasification zone of the cogasification reactor could make the best use of methane in adjusting the H{sub 2}/CO ratio of the generated synthesis gas. The maximum methane conversion efficiency, which was likely correlated to its gasification reactivity, could be achieved by 70% on average for all tested coals. The actual catalytic effect of generated coal chars on methane conversion seemed coal-dependent. The coal-gasification process benefits from methane addition and subsequent conversion on the adjustment of the H{sub 2}/CO ratio of synthesis gas. The methane conversion process benefits from the use of coal chars due to their catalytic effects. This implies that there were likely synergistic effects on both. 25 refs., 3 figs., 3

  11. The economical production of alcohol fuels from coal-derived synthesis gas. Quarterly technical progress report No. 5, October 1, 1992--December 31, 1992

    SciTech Connect

    Not Available

    1993-01-01

    Two base case flow sheets have now been prepared. In the first, which was originally presented in TPR4, a Texaco gasifier is used. Natural gas is also burned in sufficient quantity to increase the hydrogen to carbon monoxide ratio of the synthesis gas to the required value of 1. 1 for alcohol synthesis. Acid gas clean up and sulfur removal are accomplished using the Rectisol process followed by the Claus and Beavon processes. About 10% of the synthesis gas is sent to a power generation unit in order to produce electric power, with the remaining 90% used for alcohol synthesis. For this process, the estimated installed cost is $474.2 mm. The estimated annual operating costs are $64.5 MM. At a price of alcohol fuels in the vicinity of $1. 00/gal, the pay back period for construction of this plant is about four years. The details of this case, called Base Case 1, are presented in Appendix 1. The second base case, called Base Case 2, also has a detailed description and explanation in Appendix 1. In Base Case 2, a Lurgi Gasifier is used. The motivation for using a Lurgi Gasifier is that it runs at a lower temperature and pressure and, therefore, produces by-products such as coal liquids which can be sold. Based upon the economics of joint production, discussed in Technical Progress Report 4, this is a necessity. Since synthesis gas from natural gas is always less expensive to produce than from coal, then alcohol fuels will always be less expensive to produce from natural gas than from coal. Therefore, the only way to make coal- derived alcohol fuels economically competitive is to decrease the cost of production of coal-derived synthesis gas. one method for accomplishing this is to sell the by-products from the gasification step. The details of this strategy are discussed in Appendix 3.

  12. Ultra-fast Microwave Synthesis of ZnO Nanowires and their Dynamic Response Toward Hydrogen Gas.

    PubMed

    Qurashi, Ahsanulhaq; Tabet, N; Faiz, M; Yamzaki, Toshinari

    2009-04-25

    Ultra-fast and large-quantity (grams) synthesis of one-dimensional ZnO nanowires has been carried out by a novel microwave-assisted method. High purity Zinc (Zn) metal was used as source material and placed on microwave absorber. The evaporation/oxidation process occurs under exposure to microwave in less than 100 s. Field effect scanning electron microscopy analysis reveals the formation of high aspect-ratio and high density ZnO nanowires with diameter ranging from 70 to 80 nm. Comprehensive structural analysis showed that these ZnO nanowires are single crystal in nature with excellent crystal quality. The gas sensor made of these ZnO nanowires exhibited excellent sensitivity, fast response, and good reproducibility. Furthermore, the method can be extended for the synthesis of other oxide nanowires that will be the building block of future nanoscale devices.

  13. Biological conversion of synthesis gas: Quarterly report [No. 3-4, July 1, 1993--September 3, 1993

    SciTech Connect

    Ackerson, M.D.; Clausen, E.C.; Gaddy, J.L.

    1993-10-01

    This report details the status of the Biological Conversion of Synthesis Gas Project. The following tasks are described as being completed: (1) the test plan, (2) culture development, and (3) the mass transfer/kinetic studies. The bioreactor studies (Task 4) are underway. The continuous stirred tank reactor system for the conversion of H{sub 2}S to elemental sulfur using Chlorobium thiosulfatophilum has been studied for varying light intensities. The system was also modified to include both sulfur recovery and cell recycle using ceramic membranes. Studies were also performed to observe the effects of cell recycle using a polysulfone hollow filter membrane module. Work on Task 5, limiting conditions/scale-up, includes a scale-up study with three different size reactors to establish the optimum operating conditions for hydrogen production from synthesis gas by the biological water-gas shift reaction using the photosynthetic bacterium Rhodospirillum rubrum. Finally, Task 6, an economic analysis, was performed for the H{sub 2} production system using R. rubrum. The analyses show that biological H{sub 2} production from syngas can be very economical if the light requirements for R. rubrum can be neglected.

  14. One-step large scale gas phase synthesis of Mn(2 + ) doped ZnS nanoparticles in reducing flames.

    PubMed

    Athanassiou, E K; Grass, R N; Stark, W J

    2010-05-28

    Metal sulfide nanoparticles have attracted considerable interest because of their unique semiconducting and electronic properties. In order to prepare these fascinating materials at an industrial scale, however, solvent-free, dry processes would be most advantageous. In the present work, we demonstrate how traditional oxide nanoparticle synthesis in flames can be extended to sulfides if we apply a careful control on flame gas composition and sulfur content. The ultra-fast (<1 ms) gas phase kinetics at elevated temperatures allow direct sulfidization of metals in flames ([Formula: see text]). As a representative example, we prepared air-stable Mn(2 + ) doped zinc sulfide nanoparticles. Post-sintering of the initially polycrystalline nanopowder resulted in a material of high crystallinity and improved photoluminescence. An analysis of the thermodynamics, gas composition, and kinetics in these reducing flames indicates that the here-presented extension of flame synthesis provides access to a broad range of metal sulfide nanoparticles and offers an alternative to non-oxide phosphor preparation. PMID:20431199

  15. One-step large scale gas phase synthesis of Mn2 + doped ZnS nanoparticles in reducing flames

    NASA Astrophysics Data System (ADS)

    Athanassiou, E. K.; Grass, R. N.; Stark, W. J.

    2010-05-01

    Metal sulfide nanoparticles have attracted considerable interest because of their unique semiconducting and electronic properties. In order to prepare these fascinating materials at an industrial scale, however, solvent-free, dry processes would be most advantageous. In the present work, we demonstrate how traditional oxide nanoparticle synthesis in flames can be extended to sulfides if we apply a careful control on flame gas composition and sulfur content. The ultra-fast (<1 ms) gas phase kinetics at elevated temperatures allow direct sulfidization of metals in flames (\\mathrm {MO}_{x} \\Rightarrow \\mathrm {MS}_{x} ). As a representative example, we prepared air-stable Mn2 + doped zinc sulfide nanoparticles. Post-sintering of the initially polycrystalline nanopowder resulted in a material of high crystallinity and improved photoluminescence. An analysis of the thermodynamics, gas composition, and kinetics in these reducing flames indicates that the here-presented extension of flame synthesis provides access to a broad range of metal sulfide nanoparticles and offers an alternative to non-oxide phosphor preparation.

  16. Interaction of iron-copper mixed metal oxide oxygen carriers with simulated synthesis gas derived from steam gasification of coal

    SciTech Connect

    Siriwardane, Ranjani V.; Ksepko, Ewelina; Tian, Hanging

    2013-01-01

    The objective of this work was to prepare supported bimetallic Fe–Cu oxygen carriers and to evaluate their performance for the chemical-looping combustion (CLC) process with simulated synthesis gas derived from steam gasification of coal/air. Ten-cycle CLC tests were conducted with Fe–Cu oxygen carriers in an atmospheric thermogravimetric analyzer utilizing simulated synthesis gas derived from the steam gasification of Polish Janina coal and Illinois #6 coal as fuel. The effect of temperature on reaction rates, chemical stability, and oxygen transport capacity were determined. Fractional reduction, fractional oxidation, and global rates of reactions were calculated from the thermogravimetric analysis (TGA) data. The supports greatly affected reaction performance. Data showed that reaction rates and oxygen capacities were stable during the 10-cycle TGA tests for most Fe–Cu/support oxygen carriers. Bimetallic Fe–Cu/support oxygen carriers showed higher reduction rates than Fe-support oxygen carriers. The carriers containing higher Cu content showed better stabilities and better reduction rates. An increase in temperature from 800 °C to 900 °C did not have a significant effect on either the oxygen capacity or the reduction rates with synthesis gas derived from Janina coal. Oxidation reaction was significantly faster than reduction reaction for all supported Fe–Cu oxygen carriers. Carriers with higher Cu content had lower oxidation rates. Ten-cycle TGA data indicated that these oxygen carriers had stable performances at 800–900 °C and might be successfully used up to 900 °C for coal CLC reaction in the presence of steam.

  17. Synthesis Methods, Microscopy Characterization and Device Integration of Nanoscale Metal Oxide Semiconductors for Gas Sensing in Aerospace Applications

    NASA Technical Reports Server (NTRS)

    VanderWal, Randy L.; Berger, Gordon M.; Kulis, Michael J.; Hunter, Gary W.; Xu, Jennifer C.; Evans, Laura J.

    2009-01-01

    A comparison is made between SnO2, ZnO, and TiO2 single-crystal nanowires and SnO2 polycrystalline nanofibers for gas sensing. Both nanostructures possess a one-dimensional morphology. Different synthesis methods are used to produce these materials: thermal evaporation-condensation (TEC), controlled oxidation, and electrospinning. Advantages and limitations of each technique are listed. Practical issues associated with harvesting, purification, and integration of these materials into sensing devices are detailed. For comparison to the nascent form, these sensing materials are surface coated with Pd and Pt nanoparticles. Gas sensing tests, with respect to H2, are conducted at ambient and elevated temperatures. Comparative normalized responses and time constants for the catalyst and noncatalyst systems provide a basis for identification of the superior metal-oxide nanostructure and catalyst combination. With temperature-dependent data, Arrhenius analyses are made to determine an activation energy for the catalyst-assisted systems.

  18. Gas atomization synthesis of refractory or intermetallic compounds and supersaturated solid solutions

    DOEpatents

    Anderson, Iver E.; Lograsso, Barbara K.; Ellis, Timothy W.

    1994-01-01

    A metallic melt is atomized using a high pressure atomizing gas wherein the temperature of the melt and the composition of the atomizing gas are selected such that the gas and melt react in the atomization spray zone to form a refractory or intermetallic compound in the as-atomized powder particles. A metallic melt is also atomized using a high pressure atomizing gas mixture gas wherein the temperature of the melt and the ratio of a reactive gas to a carrier gas are selected to form powder particles comprising a supersaturated solid solution of the atomic species of the reactive gas in the particles. The powder particles are then heat treated to precipitate dispersoids in-situ therein to form a dispersion strengthened material.

  19. Gas atomization synthesis of refractory or intermetallic compounds and supersaturated solid solutions

    DOEpatents

    Anderson, I.E.; Lograsso, B.K.; Ellis, T.W.

    1994-11-29

    A metallic melt is atomized using a high pressure atomizing gas wherein the temperature of the melt and the composition of the atomizing gas are selected such that the gas and melt react in the atomization spray zone to form a refractory or intermetallic compound in the as-atomized powder particles. A metallic melt is also atomized using a high pressure atomizing gas mixture gas wherein the temperature of the melt and the ratio of a reactive gas to a carrier gas are selected to form powder particles comprising a supersaturated solid solution of the atomic species of the reactive gas in the particles. The powder particles are then heat treated to precipitate dispersoids in-situ therein to form a dispersion strengthened material. 9 figures.

  20. Preparation of olefins from synthesis gas using ruthenium supported on ceric oxide

    DOEpatents

    Pierantozzi, R.

    1985-04-09

    A catalyst comprising a ruthenium carbonyl compound deposited on a cerium oxide-containing support material provides for the selective synthesis of low molecular weight olefinic hydrocarbons from mixtures of hydrogen and carbon monoxide.

  1. Ruthenium carbonyl catalyst supported on ceric oxide for preparation of olefins from synthesis gas

    DOEpatents

    Pierantozzi, R.

    1985-04-02

    A catalyst comprising a ruthenium carbonyl compound deposited on a cerium oxide-containing support material provides for the selective synthesis of low molecular weight olefinic hydrocarbons from mixtures of hydrogen and carbon monoxide.

  2. Ruthenium carbonyl catalyst supported on ceric oxide for preparation of olefins from synthesis gas

    DOEpatents

    Pierantozzi, Ronald

    1985-01-01

    A catalyst comprising a ruthenium carbonyl compound deposited on a cerium oxide-containing support material provides for the selective synthesis of low molecular weight olefinic hydrocarbons from mixtures of hydrogen and carbon monoxide.

  3. Preparation of olefins from synthesis gas using ruthenium supported on ceric oxide

    DOEpatents

    Pierantozzi, Ronald

    1985-01-01

    A catalyst comprising a ruthenium carbonyl compound deposited on a cerium oxide-containing support material provides for the selective synthesis of low molecular weight olefinic hydrocarbons from mixtures of hydrogen and carbon monoxide.

  4. Synthesis of dimethyl ether and alternative fuels in the liquid phase from coal-derived synthesis gas

    SciTech Connect

    Bhatt, B.L.

    1992-09-01

    As part of the DOE-sponsored contract for the Synthesis of Dimethyl Ether (DME) and Alternative Fuels in the Liquid Phase from Coal- Derived Syngas, the single-step, slurry phase DME synthesis process was developed. The development involved screening of catalyst systems, process variable studies, and catalyst life studies in two 300 ml stirred autoclaves. As a spin-off of the Liquid Phase Methanol (LPMEOH*) process, the new process significantly improves the syngas conversion efficiency of the LPMEOH process. This improvement can be achieved by replacing a portion of methanol catalyst with a dehydration catalyst in the reactor, resulting in the product methanol being converted to DME, thus avoiding the thermodynamic equilibrium constraint of the methanol reaction. Overall, this increases syngas conversion per-pass. The selectivity and productivity of DME and methanol are affected by the catalyst system employed as well as operating conditions. A preferred catalyst system, consisting of a physical mixture of a methanol catalyst and a gamma alumina, was identified. An improvement of about 50% in methanol equivalent productivity was achieved compared to the LPMEOH process. Results from the process variable study indicate that higher pressure and CO[sub 2] removal benefit the process significantly. Limited life studies performed on the preferred catalyst system suggest somewhat higher than expected deactivation rate for the methanol catalyst. Several DME/methanol mixtures were measured for their key properties as transportation fuels. With small amounts of DME added, significant improvements in both flash points and Reid Vapor Pressure (RVP) were observed over the corresponding values of methanol alone.

  5. Catalyst and process development for synthesis gas conversion to isobutylene. Final report, September 1, 1990--January 31, 1994

    SciTech Connect

    Anthony, R.G.; Akgerman, A.; Philip, C.V.; Erkey, C.; Feng, Z.; Postula, W.S.; Wang, J.

    1995-03-01

    This project was initiated because the supply of isobutylene had been identified as a limitation on the production of methyl-t-butyl ether, a gasoline additive. Prior research on isobutylene synthesis had been at low conversion (less than 5%) or extremely high pressures (greater than 300 bars). The purpose of this research was to optimize the synthesis of a zirconia based catalyst, determine process conditions for producing isobutylene at pressures less than 100 bars, develop kinetic and reactor models, and simulate the performance of fixed bed, trickle bed and slurry flow reactors. A catalyst, reactor models and optimum operating conditions have been developed for producing isobutylene from coal derived synthesis gas. The operating conditions are much less severe than the reaction conditions developed by the Germans during and prior to WWII. The low conversion, i.e. CO conversion less than 15%, have been perceived to be undesirable for a commercial process. However, the exothermic nature of the reaction and the ability to remove heat from the reactor could limit the extent of conversion for a fixed bed reactor. Long residence times for trickle or slurry (bubble column) reactors could result in high CO conversion at the expense of reduced selectivities to iso C{sub 4} compounds. Economic studies based on a preliminary design, and a specific location will be required to determine the commercial feasibility of the process.

  6. Synthesis and Characterization of Cobalt Containing Nanoparticles on Alumina A Potential Catalyst for Gas to Liquid Fuels Production

    NASA Technical Reports Server (NTRS)

    Cowen, Jonathan; Hepp, Aloysius F.

    2016-01-01

    Fisher-Tröpsch synthesis (FTS) is a century-old gas-to-liquid (GTL) technology that commonly employs cobalt (Co, on an oxide support) or iron (supported or not) species catalysts. It has been well established that the activity of the Co catalyst depends directly upon the number of surface Co atoms. The addition of promoter (mainly noble) metals has been widely utilized to increase the fraction of Co that is available for surface catalysis. Direct synthesis of Co nanoparticles is a possible alternative approach; our preliminary synthesis and characterization efforts are described. Materials were characterized by various transmission microscopies and energy dispersive spectroscopy. Tri-n-octylphosphine oxide (TOPO) and dicobalt octacarbonyl were heated under argon to a temperature of 180 deg with constant stirring for 1 hr. Quenching the reaction in toluene produced Co-containing nanoparticles with a diameter of 5 to 10 nm. Alternatively, an alumina support (SBA-200 Al2O3) was added; the reaction was further stirred and the temperature was decreased to 140 deg to reduce the rate of further growth/ripening of the nucleated Co nanoparticles. A typical size of Co-containing NPs was also found to be in the range of 5 to 10 nm. This can be contrasted with a range of 50 to 200 nm for conventionally-produced Co-Al2O3 Fischer-Tröpsch catalysts. This method shows great potential for production of highly dispersed catalysts that are either supported or unsupported.

  7. Biohydrogen production in a continuous stirred tank bioreactor from synthesis gas by anaerobic photosynthetic bacterium: Rhodopirillum rubrum.

    PubMed

    Younesi, Habibollah; Najafpour, Ghasem; Ku Ismail, Ku Syahidah; Mohamed, Abdul Rahman; Kamaruddin, Azlina Harun

    2008-05-01

    Hydrogen may be considered a potential fuel for the future since it is carbon-free and oxidized to water as a combustion product. Bioconversion of synthesis gas (syngas) to hydrogen was demonstrated in continuous stirred tank bioreactor (CSTBR) utilizing acetate as a carbon source. An anaerobic photosynthetic bacterium, Rhodospirillum rubrum catalyzed water-gas shift reaction which was applied for the bioconversion of syngas to hydrogen. The continuous fermentation of syngas in the bioreactor was continuously operated at various gas flow rates and agitation speeds, for the period of two months. The gas flow rates were varied from 5 to 14 ml/min. The agitation speeds were increasingly altered in the range of 150-500 rpm. The pH and temperature of the bioreactor was set at 6.5 and 30 degrees C. The liquid flow rate was kept constant at 0.65 ml/min for the duration of 60 days. The inlet acetate concentration was fed at 4 g/l into the bioreactor. The hydrogen production rate and yield were 16+/-1.1 mmol g(-1)cell h(-1) and 87+/-2.4% at fixed agitation speed of 500 rpm and syngas flow rate of 14 ml/min, respectively. The mass transfer coefficient (KLa) at this condition was approximately 72.8h(-1). This new approach, using a biocatalyst was considered as an alternative method of conventional Fischer-Tropsch synthetic reactions, which were able to convert syngas into hydrogen.

  8. Synthesis, Characterization, and Gas Sensing Properties of Pure and Mn-doped ZnO Nanocrystalline Particles

    NASA Astrophysics Data System (ADS)

    Saydi, J.; Karimi, M.; Mazhdi, M.; Seidi, J.; Mazhdi, F.

    2014-10-01

    Nanocrystalline ZnO and Mn (1 wt.%)-doped ZnO particles have been synthesized via reverse micelle method. The structural, particulate, and optical properties of the synthesized nanoparticles have been studied by XRD, TEM, UV-Vis, and PL spectroscopy. The obtained data indicate the synthesis of the pure nanoparticles structure with wurtzite structure, average particle size of 18-21 nm, and high optical quality. Gas sensing properties of the nanocrystalline ZnO and Mn-doped ZnO particles toward gasoline and ethanol vapors have been investigated at different temperatures and concentrations. The results show that the optimum working temperature of the gas sensors based on ZnO and Mn-doped ZnO particles are about 633 and 620 K toward ethanol vapor and about 560 and 608 K toward gasoline vapor, respectively. Based on the results, although Mn impurities reduce the sensitivity of the ZnO gas sensor, they cause sensor to saturate at much higher gas concentration.

  9. Mechanochemical synthesis in the Li-Mg-N-D system under deuterium gas: a neutron diffraction study.

    PubMed

    Li, Z; Zhang, J; Latroche, M; Wang, S; Jiang, L; Du, J; Cuevas, F

    2016-09-14

    The Mg(NH2)2/2LiH mixture is considered as one of the most valuable reversible hydrogen storage systems for feeding PEM fuel cells. In this paper, we investigate the mechanochemical synthesis in the Li-Mg-N-H system under deuterium gas, using Li3N and Mg as reactants, and the structural and sorption properties of the intermediate and final products mainly by means of neutron powder diffraction. Mechanochemistry leads to the end formation of amorphous Mg(ND2)2, which crystallizes upon heating above 425 K. During synthesis, a novel cation-mixed nitride/imide phase of simplified composition Li3MgN2D has been unveiled as the intermediate phase. It crystallizes in the cubic disordered anti-fluorite type structure (S.G. Fm3[combining macron]m) with a lattice parameter of 4.996 Å at room temperature. Deuterium absorption in this compound occurs through an original solid solution type mechanism ending with the imide compound β-Li2MgN2D2. The conjoint use of mechanochemistry under deuterium gas and in situ neutron diffraction techniques offers new avenues for better characterization of the efficient hydrogen storage materials. In particular, this work highlights the unexpected role of intermediate nitride/imide phases in the Li-Mg-N-H system. PMID:27523164

  10. Mechanochemical synthesis in the Li-Mg-N-D system under deuterium gas: a neutron diffraction study.

    PubMed

    Li, Z; Zhang, J; Latroche, M; Wang, S; Jiang, L; Du, J; Cuevas, F

    2016-09-14

    The Mg(NH2)2/2LiH mixture is considered as one of the most valuable reversible hydrogen storage systems for feeding PEM fuel cells. In this paper, we investigate the mechanochemical synthesis in the Li-Mg-N-H system under deuterium gas, using Li3N and Mg as reactants, and the structural and sorption properties of the intermediate and final products mainly by means of neutron powder diffraction. Mechanochemistry leads to the end formation of amorphous Mg(ND2)2, which crystallizes upon heating above 425 K. During synthesis, a novel cation-mixed nitride/imide phase of simplified composition Li3MgN2D has been unveiled as the intermediate phase. It crystallizes in the cubic disordered anti-fluorite type structure (S.G. Fm3[combining macron]m) with a lattice parameter of 4.996 Å at room temperature. Deuterium absorption in this compound occurs through an original solid solution type mechanism ending with the imide compound β-Li2MgN2D2. The conjoint use of mechanochemistry under deuterium gas and in situ neutron diffraction techniques offers new avenues for better characterization of the efficient hydrogen storage materials. In particular, this work highlights the unexpected role of intermediate nitride/imide phases in the Li-Mg-N-H system.

  11. Equipment Design and Cost Estimation for Small Modular Biomass Systems, Synthesis Gas Cleanup, and Oxygen Separation Equipment; Task 9: Mixed Alcohols From Syngas -- State of Technology

    SciTech Connect

    Nexant Inc.

    2006-05-01

    This deliverable is for Task 9, Mixed Alcohols from Syngas: State of Technology, as part of National Renewable Energy Laboratory (NREL) Award ACO-5-44027, ''Equipment Design and Cost Estimation for Small Modular Biomass Systems, Synthesis Gas Cleanup and Oxygen Separation Equipment''. Task 9 supplements the work previously done by NREL in the mixed alcohols section of the 2003 technical report Preliminary Screening--Technical and Economic Assessment of Synthesis Gas to Fuels and Chemicals with Emphasis on the Potential for Biomass-Derived Syngas.

  12. Engineering high-performance Pd core-MgO porous shell nanocatalysts via heterogeneous gas-phase synthesis

    NASA Astrophysics Data System (ADS)

    Singh, Vidyadhar; Cassidy, Cathal; Abild-Pedersen, Frank; Kim, Jeong-Hwan; Aranishi, Kengo; Kumar, Sushant; Lal, Chhagan; Gspan, Christian; Grogger, Werner; Sowwan, Mukhles

    2015-08-01

    We report on the design and synthesis of high performance catalytic nanoparticles with a robust geometry via magnetron-sputter inert-gas condensation. Sputtering of Pd and Mg from two independent neighbouring targets enabled heterogeneous condensation and growth of nanoparticles with controlled Pd core-MgO porous shell structure. The thickness of the shell and the number of cores within each nanoparticle could be tailored by adjusting the respective sputtering powers. The nanoparticles were directly deposited on glassy carbon electrodes, and their catalytic activity towards methanol oxidation was examined by cyclic voltammetry. The measurements indicated that the catalytic activity was superior to conventional bare Pd nanoparticles. As confirmed by electron microscopy imaging and supported by density-functional theory (DFT) calculations, we attribute the improved catalytic performance primarily to inhibition of Pd core sintering during the catalytic process by the metal-oxide shell.We report on the design and synthesis of high performance catalytic nanoparticles with a robust geometry via magnetron-sputter inert-gas condensation. Sputtering of Pd and Mg from two independent neighbouring targets enabled heterogeneous condensation and growth of nanoparticles with controlled Pd core-MgO porous shell structure. The thickness of the shell and the number of cores within each nanoparticle could be tailored by adjusting the respective sputtering powers. The nanoparticles were directly deposited on glassy carbon electrodes, and their catalytic activity towards methanol oxidation was examined by cyclic voltammetry. The measurements indicated that the catalytic activity was superior to conventional bare Pd nanoparticles. As confirmed by electron microscopy imaging and supported by density-functional theory (DFT) calculations, we attribute the improved catalytic performance primarily to inhibition of Pd core sintering during the catalytic process by the metal-oxide shell

  13. Equipment Design and Cost Estimation for Small Modular Biomass Systems, Synthesis Gas Cleanup, and Oxygen Separation Equipment; Task 2: Gas Cleanup Design and Cost Estimates -- Black Liquor Gasification

    SciTech Connect

    Nexant Inc.

    2006-05-01

    As part of Task 2, Gas Cleanup and Cost Estimates, Nexant investigated the appropriate process scheme for removal of acid gases from black liquor-derived syngas for use in both power and liquid fuels synthesis. Two 3,200 metric tonne per day gasification schemes, both low-temperature/low-pressure (1100 deg F, 40 psi) and high-temperature/high-pressure (1800 deg F, 500 psi) were used for syngas production. Initial syngas conditions from each of the gasifiers was provided to the team by the National Renewable Energy Laboratory and Princeton University. Nexant was the prime contractor and principal investigator during this task; technical assistance was provided by both GTI and Emery Energy.

  14. Engineering Development of Ceramic Membrane Reactor System for Converting Natural Gas to Hydrogen and Synthesis Gas for Liquid Transportation Fuels

    SciTech Connect

    Air Products and Chemicals

    2008-09-30

    An Air Products-led team successfully developed ITM Syngas technology from the concept stage to a stage where a small-scale engineering prototype was about to be built. This technology produces syngas, a gas containing carbon monoxide and hydrogen, by reacting feed gas, primarily methane and steam, with oxygen that is supplied through an ion transport membrane. An ion transport membrane operates at high temperature and oxygen ions are transported through the dense membrane's crystal lattice when an oxygen partial pressure driving force is applied. This development effort solved many significant technical challenges and successfully scaled-up key aspects of the technology to prototype scale. Throughout the project life, the technology showed significant economic benefits over conventional technologies. While there are still on-going technical challenges to overcome, the progress made under the DOE-funded development project proved that the technology was viable and continued development post the DOE agreement would be warranted.

  15. Effects of aluminum additions to gas atomized reaction synthesis produced oxide dispersion strengthened alloys

    NASA Astrophysics Data System (ADS)

    Spicher, Alexander Lee

    The production of an aluminum containing ferritic oxide dispersion strengthened (ODS) alloy was investigated. The production method used in this study was gas atomization reaction synthesis (GARS). GARS was chosen over the previously commercial method of mechanical alloying (MA) process due to complications from this process. The alloy compositions was determined from three main components; corrosion resistance, dispersoid formation, and additional elements. A combination of Cr and Al were necessary in order to create a protective oxide in the steam atmosphere that the boiler tubing in the next generation of coal-fired power plants would be exposed to. Hf and Y were chosen as dispersoid forming elements due to their increased thermal stability and potential to avoid decreased strength caused by additions of Al to traditional ODS materials. W was used as an additive due to benefits as a strengthener as well as its benefits for creep rupture time. The final composition chosen for the alloy was Fe-16Cr-12Al-0.9W-0.25Hf-0.2Y at%. The aforementioned alloy, GA-1-198, was created through gas atomization with atomization gas of Ar-300ppm O2. The actual composition created was found to be Fe-15Cr-12.3Al-0.9W-0.24Hf-0.19Y at%. An additional alloy that was nominally the same without the inclusion of aluminum was created as a comparison for the effects on mechanical and corrosion properties. The actual composition of the comparison alloy, GA-1-204, was Fe-16Cr-0Al-0.9W-0.25Hf-0.24Y at%. An investigation on the processing parameters for these alloys was conducted on the GA-1-198 alloy. In order to predict the necessary amount of time for heat treatment, a diffusion study was used to find the diffusion rate of oxygen in cast alloys with similar composition. The diffusion rate was found to be similar to that of other GARS compositions that have been created without the inclusion of aluminum. The effect of heat treatment time was investigated with temperatures of 950°C, 1000

  16. The synthesis of methanol and the reverse water-gas shift reaction over Zn-deposited Cu(100) and Cu(110) surfaces: comparison with Zn/Cu(111)

    NASA Astrophysics Data System (ADS)

    Nakamura, I.; Fujitani, T.; Uchijima, T.; Nakamura, J.

    1998-03-01

    The catalytic activity of Zn vapor-deposited Cu(100) and Cu(110) surfaces for methanol synthesis by the hydrogenation of CO 2 and the reverse water-gas shift reaction were studied using an XPS apparatus combined with a high-pressure flow reactor (18 atm). At a reaction temperature of 523 K, no promotional effect of Zn was observed for the methanol synthesis on both Zn/Cu(100) and Zn/Cu(110). The results were quite different from those for Zn/Cu(111), on which a significant promotion of methanol synthesis activity appeared to be due to the deposition of Zn, indicating that the promotional effect of Zn was sensitive to the surface structure of Cu. However, hysteresis was observed in the catalytic activity for methanol synthesis over the Zn/Cu(110) surface upon heating above 543 K in the reaction mixture. The activity became twice that measured before heating, which was close to the methanol synthesis activity of Zn/Cu(111) at the same Zn coverage. On the other hand, no such hysteresis was observed for the reverse water-gas shift reaction on Zn/Cu(110), indicating that the active site for methanol synthesis was not identical to that for the reverse water-gas shift reaction. In the post-reaction surface analysis, formate species was detected on both Zn/Cu(100) and Zn/Cu(110), whose coverage increased with increasing Zn coverage at 0< ΘZn<0.2. No correlation between the formate coverage and the methanol synthesis activity was obtained, which was in contrast to the results for Zn/Cu(111). Thus, the structure sensitivity observed in the catalytic activity of methanol synthesis over Zn-deposited Cu surfaces is ascribed to the significant difference in the reactivity of the formate intermediate.

  17. High pressure synthesis gas fermentation. [Quarterly status] report, July 15, 1991--October 14, 1991

    SciTech Connect

    Not Available

    1991-12-31

    Construction of the high pressure gas phase fermentation system is nearing completion. All non-explosion proof components will be housed separately in a gas-monitored plexiglas cabinet. A gas-monitoring system has been designed to ensure the safety of the operations in case of small or large accidental gas releases. Preliminary experiments investigating the effects of high pressure on Clostridium 1jungdahlii have shown that growth and CO uptake are not negatively affected and CO uptake by an increased total pressure of 100 psig at a syngas partial pressure of 10 psig.

  18. The economical production of alcohol fuels from coal-derived synthesis gas: Case studies, design, and economics

    SciTech Connect

    1995-10-01

    This project is a combination of process simulation and catalyst development aimed at identifying the most economical method for converting coal to syngas to linear higher alcohols to be used as oxygenated fuel additives. There are two tasks. The goal of Task 1 is to discover, study, and evaluate novel heterogeneous catalytic systems for the production of oxygenated fuel enhancers from synthesis gas, and to explore, analytically and on the bench scale, novel reactor and process concepts for use in converting syngas to liquid fuel products. The goal of Task 2 is to simulate, by computer, energy efficient and economically efficient processes for converting coal to energy (fuel alcohols and/or power). The primary focus is to convert syngas to fuel alcohols. This report contains results from Task 2. The first step for Task 2 was to develop computer simulations of alternative coal to syngas to linear higher alcohol processes, to evaluate and compare the economics and energy efficiency of these alternative processes, and to make a preliminary determination as to the most attractive process configuration. A benefit of this approach is that simulations will be debugged and available for use when Task 1 results are available. Seven cases were developed using different gasifier technologies, different methods for altering the H{sub 2}/CO ratio of the syngas to the desired 1.1/1, and with the higher alcohol fuel additives as primary products and as by-products of a power generation facility. Texaco, Shell, and Lurgi gasifier designs were used to test gasifying coal. Steam reforming of natural gas, sour gas shift conversion, or pressure swing adsorption were used to alter the H{sub 2}/CO ratio of the syngas. In addition, a case using only natural gas was prepared to compare coal and natural gas as a source of syngas.

  19. Influence of the gas mixture temperature on the efficiency of synthesis gas production from ethanol in a nonequilibrium plasma

    NASA Astrophysics Data System (ADS)

    Tsymbalyuk, A. N.; Levko, D. S.; Chernyak, V. Ya.; Martysh, E. V.; Nedybalyuk, O. A.; Solomenko, E. V.

    2013-08-01

    The mechanism behind the plasma conversion of a mixture of ethanol vapor, water vapor, air, and carbon dioxide CO2 in the nonequilibrium plasma of a tornado discharge is studied. The influence of the CO2 flow rate, the current through the discharge, and the gas temperature in the discharge on the concentrations of molecular hydrogen and carbon monoxide CO is studied. Comparison between the concentrations of the gaseous mixture's main components at the output from the reactor obtained experimentally and by numerical simulation shows that the adopted kinetic mechanism adequately describes the plasma kinetics in the mixture.

  20. Synthesis of Fe Doped ZnO Nanowire Arrays that Detect Formaldehyde Gas.

    PubMed

    Jeon, Yoo Sang; Seo, Hyo Won; Kim, Su Hyo; Kim, Young Keun

    2016-05-01

    Owing to their chemical and thermal stability and doping effects on providing electrons to the conduction band, doped ZnO nanowires have generated interest for use in electronic devices. Here we report hydrothermally grown Fe-doped ZnO nanowires and their gas-sensing properties. The synthesized nanowires have a high crystallinity and are 60 nm in diameter and 1.7 μm in length. Field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) are employed to understand the doping effects on the microstructures and gas sensing properties. When the Fe-doped ZnO nanowire arrays were evaluated for gas sensing, responses were recorded through changes in temperature and gas concentration. Gas sensors consisting of ZnO nanowires doped with 3-5 at.% Fe showed optimum formaldehyde (HCHO) sensing performance at each working temperature.

  1. Synthesis of Fe Doped ZnO Nanowire Arrays that Detect Formaldehyde Gas.

    PubMed

    Jeon, Yoo Sang; Seo, Hyo Won; Kim, Su Hyo; Kim, Young Keun

    2016-05-01

    Owing to their chemical and thermal stability and doping effects on providing electrons to the conduction band, doped ZnO nanowires have generated interest for use in electronic devices. Here we report hydrothermally grown Fe-doped ZnO nanowires and their gas-sensing properties. The synthesized nanowires have a high crystallinity and are 60 nm in diameter and 1.7 μm in length. Field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) are employed to understand the doping effects on the microstructures and gas sensing properties. When the Fe-doped ZnO nanowire arrays were evaluated for gas sensing, responses were recorded through changes in temperature and gas concentration. Gas sensors consisting of ZnO nanowires doped with 3-5 at.% Fe showed optimum formaldehyde (HCHO) sensing performance at each working temperature. PMID:27483827

  2. Bench-scale demonstration of biological production of ethanol from coal synthesis gas. Quarterly report, January 1, 1993--March 31, 1993

    SciTech Connect

    Not Available

    1993-11-01

    Several batch experiments have been performed in developing the ethanol-producing isolates ER12 and ER18 for ethanol production from synthesis gas. In addition, Clostridium ljungdahlii, strain PETC, has been used in a two-stage continuous stirred tank reactor system. Ethanol concentrations from the CSTR system have reached 12 g/L.

  3. Effect of Varying Inert Gas and Acetylene Concentration on the Synthesis of Carbon Nanotubes.

    PubMed

    Afrin, Rahat; Abbas, Syed Mustansar; Shah, Nazar Abbas; Mustafa, Muhammad Farooq; Ali, Zulfiqar; Ahmad, Nisar

    2016-03-01

    The multiwalled carbon nanotubes (MWCNTs) with small diameter and high purity were achieved by chemical vapor deposition technique using silicon substrate. The introduction of specific concentration of inert gas with hydrocarbon played a key role in controlling morphology and diameter of MWCNTs. Nickel mixed ferrite nanoparticles were used as a catalyst for the growth of MWCNTs. Growth parameters like concentration of hydrocarbon source and inert gas flow, composition of catalyst particles and growth temperature were studied. In this work smaller diameter and twisted MWCNTs were formed by dilution of acetylene with argon gas. Electrical properties suggest a semimetallic behavior of synthesized MWCNTs. PMID:27455741

  4. Effect of Varying Inert Gas and Acetylene Concentration on the Synthesis of Carbon Nanotubes.

    PubMed

    Afrin, Rahat; Abbas, Syed Mustansar; Shah, Nazar Abbas; Mustafa, Muhammad Farooq; Ali, Zulfiqar; Ahmad, Nisar

    2016-03-01

    The multiwalled carbon nanotubes (MWCNTs) with small diameter and high purity were achieved by chemical vapor deposition technique using silicon substrate. The introduction of specific concentration of inert gas with hydrocarbon played a key role in controlling morphology and diameter of MWCNTs. Nickel mixed ferrite nanoparticles were used as a catalyst for the growth of MWCNTs. Growth parameters like concentration of hydrocarbon source and inert gas flow, composition of catalyst particles and growth temperature were studied. In this work smaller diameter and twisted MWCNTs were formed by dilution of acetylene with argon gas. Electrical properties suggest a semimetallic behavior of synthesized MWCNTs.

  5. Engineering high-performance Pd core-MgO porous shell nanocatalysts via heterogeneous gas-phase synthesis.

    PubMed

    Singh, Vidyadhar; Cassidy, Cathal; Abild-Pedersen, Frank; Kim, Jeong-Hwan; Aranishi, Kengo; Kumar, Sushant; Lal, Chhagan; Gspan, Christian; Grogger, Werner; Sowwan, Mukhles

    2015-08-28

    We report on the design and synthesis of high performance catalytic nanoparticles with a robust geometry via magnetron-sputter inert-gas condensation. Sputtering of Pd and Mg from two independent neighbouring targets enabled heterogeneous condensation and growth of nanoparticles with controlled Pd core-MgO porous shell structure. The thickness of the shell and the number of cores within each nanoparticle could be tailored by adjusting the respective sputtering powers. The nanoparticles were directly deposited on glassy carbon electrodes, and their catalytic activity towards methanol oxidation was examined by cyclic voltammetry. The measurements indicated that the catalytic activity was superior to conventional bare Pd nanoparticles. As confirmed by electron microscopy imaging and supported by density-functional theory (DFT) calculations, we attribute the improved catalytic performance primarily to inhibition of Pd core sintering during the catalytic process by the metal-oxide shell.

  6. Engineering high-performance Pd core-MgO porous shell nanocatalysts via heterogeneous gas-phase synthesis.

    PubMed

    Singh, Vidyadhar; Cassidy, Cathal; Abild-Pedersen, Frank; Kim, Jeong-Hwan; Aranishi, Kengo; Kumar, Sushant; Lal, Chhagan; Gspan, Christian; Grogger, Werner; Sowwan, Mukhles

    2015-08-28

    We report on the design and synthesis of high performance catalytic nanoparticles with a robust geometry via magnetron-sputter inert-gas condensation. Sputtering of Pd and Mg from two independent neighbouring targets enabled heterogeneous condensation and growth of nanoparticles with controlled Pd core-MgO porous shell structure. The thickness of the shell and the number of cores within each nanoparticle could be tailored by adjusting the respective sputtering powers. The nanoparticles were directly deposited on glassy carbon electrodes, and their catalytic activity towards methanol oxidation was examined by cyclic voltammetry. The measurements indicated that the catalytic activity was superior to conventional bare Pd nanoparticles. As confirmed by electron microscopy imaging and supported by density-functional theory (DFT) calculations, we attribute the improved catalytic performance primarily to inhibition of Pd core sintering during the catalytic process by the metal-oxide shell. PMID:26203627

  7. High pressure synthesis gas fermentation. [Quarterly status] report, October 15, 1991--January 14, 1992

    SciTech Connect

    Not Available

    1992-09-01

    The construction of the high pressure gas phase fermentation system has been completed. Photographs of the various components of the system are presented, along with an operating procedure for the equipment.

  8. Controllable Synthesis of Formaldehyde Modified Manganese Oxide Based on Gas-Liquid Interfacial Reaction and Its Application of Electrochemical Sensing.

    PubMed

    Bai, Wushuang; Sheng, Qinglin; Nie, Fei; Zheng, Jianbin

    2015-12-30

    Controllable synthesis of manganese oxides was performed via a simple one-step synthetic method. Then obtained manganese oxides which exhibit flower-like, cloud-like, hexagon-like, and rod-like morphologies were modified by formaldehyde based on a simple self-made gas-liquid reaction device respectively and the modified manganese oxides with coral-like, scallop-like and rod-like morphology were synthesized accordingly. The obtained materials were characterized and the formation mechanism was also researched. Then the modified manganese oxides were used to fabricate electrochemical sensors to detect H2O2. Comparison of electrochemical properties between three kinds of modified manganese oxides was investigated and the best one has been successfully employed as H2O2 sensor which shows a low detection limit of 0.01 μM, high sensitivity of 162.69 μA mM(-1) cm(-2), and wide linear range of 0.05 μM-12.78 mM. The study provides a new method for controllable synthesis of metal oxides, and electrochemical application of formaldehyde modified manganese oxides will provides a new strategy for electrochemical sensing with high performance, low cost, and simple fabrication. PMID:26647786

  9. Controllable Synthesis of Formaldehyde Modified Manganese Oxide Based on Gas-Liquid Interfacial Reaction and Its Application of Electrochemical Sensing.

    PubMed

    Bai, Wushuang; Sheng, Qinglin; Nie, Fei; Zheng, Jianbin

    2015-12-30

    Controllable synthesis of manganese oxides was performed via a simple one-step synthetic method. Then obtained manganese oxides which exhibit flower-like, cloud-like, hexagon-like, and rod-like morphologies were modified by formaldehyde based on a simple self-made gas-liquid reaction device respectively and the modified manganese oxides with coral-like, scallop-like and rod-like morphology were synthesized accordingly. The obtained materials were characterized and the formation mechanism was also researched. Then the modified manganese oxides were used to fabricate electrochemical sensors to detect H2O2. Comparison of electrochemical properties between three kinds of modified manganese oxides was investigated and the best one has been successfully employed as H2O2 sensor which shows a low detection limit of 0.01 μM, high sensitivity of 162.69 μA mM(-1) cm(-2), and wide linear range of 0.05 μM-12.78 mM. The study provides a new method for controllable synthesis of metal oxides, and electrochemical application of formaldehyde modified manganese oxides will provides a new strategy for electrochemical sensing with high performance, low cost, and simple fabrication.

  10. Magnesium carbide synthesis from methane and magnesium oxide - a potential methodology for natural gas conversion to premium fuels and chemicals

    SciTech Connect

    Diaz, A.F.; Modestino, A.J.; Howard, J.B.

    1995-12-31

    Diversification of the raw materials base for manufacturing premium fuels and chemicals offers U.S. and international consumers economic and strategic benefits. Extensive reserves of natural gas in the world provide a valuable source of clean gaseous fuel and chemical feedstock. Assuming the availability of suitable conversion processes, natural gas offers the prospect of improving flexibility in liquid fuels and chemicals manufacture, and thus, the opportunity to complement, supplement, or displace petroleum-based production as economic and strategic considerations require. The composition of natural gas varies from reservoir to reservoir but the principal hydrocarbon constituent is always methane (CH{sub 4}). With its high hydrogen-to-carbon ratio, methane has the potential to produce hydrogen or hydrogen-rich products. However, methane is a very chemically stable molecule and, thus, is not readily transformed to other molecules or easily reformed to its elements (H{sub 2} and carbon). In many cases, further research is needed to augment selectivity to desired product(s), increase single-pass conversions, or improve economics (e.g. there have been estimates of $50/bbl or more for liquid products) before the full potential of these methodologies can be realized on a commercial scale. With the trade-off between gas conversion and product selectivity, a major challenge common to many of these technologies is to simultaneously achieve high methane single-pass conversions and high selectivity to desired products. Based on the results of the scoping runs, there appears to be strong indications that a breakthrough has finally been achieved in that synthesis of magnesium carbides from MgO and methane in the arc discharge reactor has been demonstrated.

  11. Optimization of a corn steep medium for production of ethanol from synthesis gas fermentation by Clostridium ragsdalei.

    PubMed

    Saxena, Jyotisna; Tanner, Ralph S

    2012-04-01

    Fermentation of biomass derived synthesis gas to ethanol is a sustainable approach that can provide more usable energy and environmental benefits than food-based biofuels. The effects of various medium components on ethanol production by Clostridium ragsdalei utilizing syngas components (CO:CO(2)) were investigated, and corn steep liquor (CSL) was used as an inexpensive nutrient source for ethanol production by C. ragsdalei. Elimination of Mg(2+), NH(4) (+) and PO(4) (3-) decreased ethanol production from 38 to 3.7, 23 and 5.93 mM, respectively. Eliminating Na(+), Ca(2+), and K(+) or increasing Ca(2+), Mg(2+), K(+), NH(4) (+) and PO(4) (3-) concentrations had no effect on ethanol production. However, increased Na(+) concentration (171 mM) inhibited growth and ethanol production. Yeast extract (0.5 g l(-1)) and trace metals were necessary for growth of C. ragsdalei. CSL alone did not support growth and ethanol production. Nutrients limiting in CSL were trace metals, NH(4) (+) and reducing agent (Cys: cysteine sulfide). Supplementation of trace metals, NH(4) (+) and CyS to CSL (20 g l(-1), wet weight basis) yielded better growth and similar ethanol production as compared to control medium. Using 10 g l(-1), the nutritional limitation led to reduced ethanol production. Higher concentrations of CSL (50 and 100 g l(-1)) were inhibitory for cell growth and ethanol production. The CSL could replace yeast extract, vitamins and minerals (excluding NH(4) (+)). The optimized CSL medium produced 120 and 50 mM of ethanol and acetate, respectively. The CSL could provide as an inexpensive source of most of the nutrients required for the syngas fermentation, and thus could improve the economics of ethanol production from biomass derived synthesis gas by C. ragsdalei.

  12. Optimization of a corn steep medium for production of ethanol from synthesis gas fermentation by Clostridium ragsdalei.

    PubMed

    Saxena, Jyotisna; Tanner, Ralph S

    2012-04-01

    Fermentation of biomass derived synthesis gas to ethanol is a sustainable approach that can provide more usable energy and environmental benefits than food-based biofuels. The effects of various medium components on ethanol production by Clostridium ragsdalei utilizing syngas components (CO:CO(2)) were investigated, and corn steep liquor (CSL) was used as an inexpensive nutrient source for ethanol production by C. ragsdalei. Elimination of Mg(2+), NH(4) (+) and PO(4) (3-) decreased ethanol production from 38 to 3.7, 23 and 5.93 mM, respectively. Eliminating Na(+), Ca(2+), and K(+) or increasing Ca(2+), Mg(2+), K(+), NH(4) (+) and PO(4) (3-) concentrations had no effect on ethanol production. However, increased Na(+) concentration (171 mM) inhibited growth and ethanol production. Yeast extract (0.5 g l(-1)) and trace metals were necessary for growth of C. ragsdalei. CSL alone did not support growth and ethanol production. Nutrients limiting in CSL were trace metals, NH(4) (+) and reducing agent (Cys: cysteine sulfide). Supplementation of trace metals, NH(4) (+) and CyS to CSL (20 g l(-1), wet weight basis) yielded better growth and similar ethanol production as compared to control medium. Using 10 g l(-1), the nutritional limitation led to reduced ethanol production. Higher concentrations of CSL (50 and 100 g l(-1)) were inhibitory for cell growth and ethanol production. The CSL could replace yeast extract, vitamins and minerals (excluding NH(4) (+)). The optimized CSL medium produced 120 and 50 mM of ethanol and acetate, respectively. The CSL could provide as an inexpensive source of most of the nutrients required for the syngas fermentation, and thus could improve the economics of ethanol production from biomass derived synthesis gas by C. ragsdalei. PMID:22805937

  13. Equipment Design and Cost Estimation for Small Modular Biomass Systems, Synthesis Gas Cleanup, and Oxygen Separation Equipment; Task 2.3: Sulfur Primer

    SciTech Connect

    Nexant Inc.

    2006-05-01

    This deliverable is Subtask 2.3 of Task 2, Gas Cleanup Design and Cost Estimates, of NREL Award ACO-5-44027, ''Equipment Design and Cost Estimation for Small Modular Biomass Systems, Synthesis Gas Cleanup and Oxygen Separation Equipment''. Subtask 2.3 builds upon the sulfur removal information first presented in Subtask 2.1, Gas Cleanup Technologies for Biomass Gasification by adding additional information on the commercial applications, manufacturers, environmental footprint, and technical specifications for sulfur removal technologies. The data was obtained from Nexant's experience, input from GTI and other vendors, past and current facility data, and existing literature.

  14. TiO2 Nanotubes: Recent Advances in Synthesis and Gas Sensing Properties

    PubMed Central

    Galstyan, Vardan; Comini, Elisabetta; Faglia, Guido; Sberveglieri, Giorgio

    2013-01-01

    Synthesis—particularly by electrochemical anodization-, growth mechanism and chemical sensing properties of pure, doped and mixed titania tubular arrays are reviewed. The first part deals on how anodization parameters affect the size, shape and morphology of titania nanotubes. In the second part fabrication of sensing devices based on titania nanotubes is presented, together with their most notable gas sensing performances. Doping largely improves conductivity and enhances gas sensing performances of TiO2 nanotubes. PMID:24184919

  15. Synthesis and characterization of nano crystalline nickel zinc ferrite for chlorine gas sensor at room temperature

    SciTech Connect

    Pawar, C. S.; Gujar, M. P.; Mathe, V. L.

    2015-06-24

    Nano crystalline Nickel Zinc ferrite (Ni{sub 0.25}Zn{sub 0.75}Fe{sub 2}O{sub 4}) thin films were synthesized by Sol Gel method for gas response. The phase and microstructure of the obtained Ni{sub 0.25}Zn{sub 0.75}Fe{sub 2}O{sub 4} thin films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM). The nanostructured Ni{sub 0.25}Zn{sub 0.75}Fe{sub 2}O{sub 4} thin film shows single spinel phase. Magnetic study was obtained with the help of VSM. The effects of working temperature on the gas response were studied. The results reveal that the Ni{sub 0.25}Zn{sub 0.75}Fe{sub 2}O{sub 4} thin film gas sensor shows good selectivity to chlorine gas at room temperature. The sensor shows highest sensitivity (∼50%) at room temperature, indicating its application in detecting chlorine gas at room temperature in the future.

  16. Synthesis of nestlike ZnO hierarchically porous structures and analysis of their gas sensing properties.

    PubMed

    Wang, Xinzhen; Liu, Wei; Liu, Jiurong; Wang, Fenglong; Kong, Jing; Qiu, Song; He, Cuizhu; Luan, Liqiang

    2012-02-01

    Nestlike 3D ZnO porous structures with size of 1.0-3.0 μm have been synthesized through annealing the zinc hydroxide carbonate precursor, which was obtained by a one-pot hydrothermal process with the assistance of glycine, Na(2)SO(4), and polyvinyl pyrrolidone (PVP). The nestlike 3D ZnO structures are built of 2D nanoflakes with the thickness of ca. 20 nm, which exhibit the nanoporous wormhole-like characteristic. The measured surface area is 36.4 m(2)g(-1) and the pore size is ca. 3-40 nm. The unique nestlike 3D ZnO porous structures provided large contacting surface area for electrons, oxygen and target gas molecules, and abundant channels for gas diffusion and mass transport. Gas sensing tests showed that the nestlike 3D ZnO porous structures exhibit excellent gas sensing performances such as high sensitivity and fast response and recovery speed, suggesting the potential applications as advanced gas sensing materials.

  17. Economics of Undiscovered Oil and Gas in the North Slope of Alaska: Economic Update and Synthesis

    USGS Publications Warehouse

    Attanasi, E.D.; Freeman, P.A.

    2009-01-01

    The U.S. Geological Survey (USGS) has published assessments by geologists of undiscovered conventional oil and gas accumulations in the North Slope of Alaska; these assessments contain a set of scientifically based estimates of undiscovered, technically recoverable quantities of oil and gas in discrete oil and gas accumulations that can be produced with conventional recovery technology. The assessments do not incorporate economic factors such as recovery costs and product prices. The assessors considered undiscovered conventional oil and gas resources in four areas of the North Slope: (1) the central North Slope, (2) the National Petroleum Reserve in Alaska (NPRA), (3) the 1002 Area of the Arctic National Wildlife Refuge (ANWR), and (4) the area west of the NPRA, called in this report the 'western North Slope'. These analyses were prepared at different times with various minimum assessed oil and gas accumulation sizes and with slightly different assumptions. Results of these past studies were recently supplemented with information by the assessment geologists that allowed adjustments for uniform minimum assessed accumulation sizes and a consistent set of assumptions. The effort permitted the statistical aggregation of the assessments of the four areas composing the study area. This economic analysis is based on undiscovered assessed accumulation distributions represented by the four-area aggregation and incorporates updates of costs and technological and fiscal assumptions used in the initial economic analysis that accompanied the geologic assessment of each study area.

  18. Novel nano coordination polymer based synthesis of porous ZnO hexagonal nanodisk for higher gas sorption and photocatalytic activities

    NASA Astrophysics Data System (ADS)

    Rakibuddin, M.; Ananthakrishnan, Rajakumar

    2016-01-01

    Zinc(II)-based nano co-ordination polymers (NCPs) are first prepared at room temperature from three different isomers of dihydroxysalophen (DHS) ligand with Zn(OAc)2·2H2O and 1,4-benzenedicarboxylic acid (BDC) in DMF solvent. Facile calcinations of [Zn (DHS) (BDC)]·nH2O (shortly denoted as Zn(II)-based NCP) at ambient conditions produces porous ZnO hexagonal nanodisks. Moreover, a novel approach has been introduced to observe the effect of ligand of the NCP on the physico-chemical properties of the as-synthesized ZnO. The porous ZnO nanodisks are characterized by FT-IR, PXRD, TEM, FESEM, EDX and BET analysis, and the results exhibit that they possess different sizes, surface areas and porosities. Nitrogen gas sorption capacity and photocatalytic activities of the as-prepared ZnO nanodisks are also checked, and it is noticed that they differ in these physico-chemical properties due to having different porosities and surface areas. A comparative study is also done with commercially available ZnO; interestingly, the commercial ZnO exhibited lower surface area, gas sorption and photocatalytic activity compared to the ZnO nanodisks. Hence, preparation of the ZnO through the NCP route and tuning their physico-chemical properties would offer new directions in synthesis of various nano metal oxides of unique properties.

  19. Catalyst and process development for synthesis gas conversion to isobutylene. Quarterly report, January 1, 1993--March 31, 1993

    SciTech Connect

    Anthony, R.G.; Akgerman, A.

    1993-04-17

    The objectives of this project are to develop a new catalyst, the kinetics for this catalyst, reactor models for trickle bed, slurry and fixed bed reactors, and simulate the performance of fixed bed trickle flow reactors, slurry flow reactors, and fixed bed gas phase reactors for conversion of a hydrogen lean synthesis gas to isobutylene. The six main accomplishments for the quarter are the following: (1) activity testing with the 7% (wt) Ce-ZrO{sub 2}, (2) activity testing the same catalyst with CO from an aluminum cylinder, (3) preparation of ZrO{sub 2} by heating zirconyl nitrate, (4) preparation of an active zirconia prepared by a modified sol gel procedure and evaluation of the catalytic activity of a commercial zirconia and the catalysts prepared by the sol gel procedure, (5) determining the effect of separator temperatures and oil flow rate on the performance of a trickle bed reactor, and (6) calculation of the equilibrium composition of the C{sub 2} to C{sub 5} olefins, and initiation of the development of a macrokinetic model. The details of each of these accomplishments are discussed.

  20. Toward industrial scale synthesis of ultrapure singlet nanoparticles with controllable sizes in a continuous gas-phase process

    NASA Astrophysics Data System (ADS)

    Feng, Jicheng; Biskos, George; Schmidt-Ott, Andreas

    2015-10-01

    Continuous gas-phase synthesis of nanoparticles is associated with rapid agglomeration, which can be a limiting factor for numerous applications. In this report, we challenge this paradigm by providing experimental evidence to support that gas-phase methods can be used to produce ultrapure non-agglomerated “singlet” nanoparticles having tunable sizes at room temperature. By controlling the temperature in the particle growth zone to guarantee complete coalescence of colliding entities, the size of singlets in principle can be regulated from that of single atoms to any desired value. We assess our results in the context of a simple analytical model to explore the dependence of singlet size on the operating conditions. Agreement of the model with experimental measurements shows that these methods can be effectively used for producing singlets that can be processed further by many alternative approaches. Combined with the capabilities of up-scaling and unlimited mixing that spark ablation enables, this study provides an easy-to-use concept for producing the key building blocks for low-cost industrial-scale nanofabrication of advanced materials.

  1. Toward industrial scale synthesis of ultrapure singlet nanoparticles with controllable sizes in a continuous gas-phase process

    PubMed Central

    Feng, Jicheng; Biskos, George; Schmidt-Ott, Andreas

    2015-01-01

    Continuous gas-phase synthesis of nanoparticles is associated with rapid agglomeration, which can be a limiting factor for numerous applications. In this report, we challenge this paradigm by providing experimental evidence to support that gas-phase methods can be used to produce ultrapure non-agglomerated “singlet” nanoparticles having tunable sizes at room temperature. By controlling the temperature in the particle growth zone to guarantee complete coalescence of colliding entities, the size of singlets in principle can be regulated from that of single atoms to any desired value. We assess our results in the context of a simple analytical model to explore the dependence of singlet size on the operating conditions. Agreement of the model with experimental measurements shows that these methods can be effectively used for producing singlets that can be processed further by many alternative approaches. Combined with the capabilities of up-scaling and unlimited mixing that spark ablation enables, this study provides an easy-to-use concept for producing the key building blocks for low-cost industrial-scale nanofabrication of advanced materials. PMID:26511290

  2. Toward industrial scale synthesis of ultrapure singlet nanoparticles with controllable sizes in a continuous gas-phase process.

    PubMed

    Feng, Jicheng; Biskos, George; Schmidt-Ott, Andreas

    2015-01-01

    Continuous gas-phase synthesis of nanoparticles is associated with rapid agglomeration, which can be a limiting factor for numerous applications. In this report, we challenge this paradigm by providing experimental evidence to support that gas-phase methods can be used to produce ultrapure non-agglomerated "singlet" nanoparticles having tunable sizes at room temperature. By controlling the temperature in the particle growth zone to guarantee complete coalescence of colliding entities, the size of singlets in principle can be regulated from that of single atoms to any desired value. We assess our results in the context of a simple analytical model to explore the dependence of singlet size on the operating conditions. Agreement of the model with experimental measurements shows that these methods can be effectively used for producing singlets that can be processed further by many alternative approaches. Combined with the capabilities of up-scaling and unlimited mixing that spark ablation enables, this study provides an easy-to-use concept for producing the key building blocks for low-cost industrial-scale nanofabrication of advanced materials. PMID:26511290

  3. Toward industrial scale synthesis of ultrapure singlet nanoparticles with controllable sizes in a continuous gas-phase process.

    PubMed

    Feng, Jicheng; Biskos, George; Schmidt-Ott, Andreas

    2015-10-29

    Continuous gas-phase synthesis of nanoparticles is associated with rapid agglomeration, which can be a limiting factor for numerous applications. In this report, we challenge this paradigm by providing experimental evidence to support that gas-phase methods can be used to produce ultrapure non-agglomerated "singlet" nanoparticles having tunable sizes at room temperature. By controlling the temperature in the particle growth zone to guarantee complete coalescence of colliding entities, the size of singlets in principle can be regulated from that of single atoms to any desired value. We assess our results in the context of a simple analytical model to explore the dependence of singlet size on the operating conditions. Agreement of the model with experimental measurements shows that these methods can be effectively used for producing singlets that can be processed further by many alternative approaches. Combined with the capabilities of up-scaling and unlimited mixing that spark ablation enables, this study provides an easy-to-use concept for producing the key building blocks for low-cost industrial-scale nanofabrication of advanced materials.

  4. Catalyst-Free Synthesis of ZnO Nanowires on Oxidized Silicon Substrate for Gas Sensing Applications.

    PubMed

    Behera, B; Chandra, S

    2015-06-01

    In the present work, we report the synthesis of nanostructured ZnO by oxidation of zinc film without using a seed or catalyst layer. The zinc films were deposited on oxidized Si substrates by RF magnetron sputtering process. These were oxidized in dry and wet air/oxygen ambient. The optimized process yielded long nanowires of ZnO having diameter of around 60-70 nm and spread uniformly over the surface. The effect of oxidation temperature, time, Zn film thickness and the ambient has strong influence on the morphology of resulting nanostruxctured ZnO film. The films were characterized by scanning electron microscopy for morphological studies and X-ray diffraction (XRD) analysis to study the phase of the nanostructured ZnO. Room temperature photoluminescence (PL) measurements of the nanowires show UV and green emission. A sensor was designed and fabricated using nanostructured ZnO film, incorporating inter-digital-electrode (IDE) for the measurement of resistance of the sensing layer. The gas sensing properties were investigated from the measurement of change in resistance when exposed to vapours of different volatile organic compound (VOC) such as acetone, ethanol, methanol and 2-propanol. The results suggest that ZnO nanowires fabricated by this method have potential application in gas sensors.

  5. Synthesis of ZnO nanosheet arrays with exposed (100) facets for gas sensing applications.

    PubMed

    Xiao, Chuanhai; Yang, Tianye; Chuai, Mingyan; Xiao, Bingxin; Zhang, Mingzhe

    2016-01-01

    ZnO nanosheet (NS) arrays have been synthesized by a facile ultrathin liquid layer electrodeposition method. The ion concentration and electrode potential play important roles in the formation of ZnO NS arrays. Studies on the structural information indicate that the NSs are exposed with (100) facets. The results of Raman and PL spectra indicate that there existed a large amount of oxygen vacancies in the NSs. The gas sensing performances of the ZnO NS arrays are investigated: the ZnO NS arrays exhibited high gas selectivity and quick response/recovery for detecting NO2 at a low working temperature. High binding energies between NO2 molecules and exposed ZnO(100) facets lead to large surface reconstructions, which is responsible for the intrinsic NO2 sensing properties. In addition, the highly exposed surface and a large amount of oxygen vacancies existing in the NSs also make a great contribution to the gas sensing performance.

  6. Biological conversion of synthesis gas. Project status report, January 1, 1993--March 31, 1993

    SciTech Connect

    Clausen, E.C.

    1993-04-10

    A continuous stirred tank reactor with and without sulfur recovery has been operated using Chlorobium thiosulfatophilum for the conversion of H{sub 2}S to elemental sulfur. In operating the reactor system with sulfur recovery, a gas retention time of 40 min was required to obtain a 100 percent conversion of H{sub 2}S to elemental sulfur. Essentially no SO{sub 4}{sup 2{minus}}, an undesirable product, was produced under these conditions. Significant reductions in the gas retention time are expected by employing cell recycle after sulfur recovery, and by using increased pressure.

  7. Design of generic coal conversion facilities: Production of oxygenates from synthesis gas---A technology review

    SciTech Connect

    Not Available

    1991-10-01

    This report concentrates on the production of oxygenates from coal via gasification and indirect liquefaction. At the present the majority of oxygenate synthesis programs are at laboratory scale. Exceptions include commercial and demonstration scale plants for methanol and higher alcohols production, and ethers such as MTBE. Research and development work has concentrated on elucidating the fundamental transport and kinetic limitations governing various reactor configurations. But of equal or greater importance has been investigations into the optimal catalyst composition and process conditions for the production of various oxygenates.

  8. Water and methanol in low-mass protostellar outflows: gas-phase synthesis, ice sputtering and destruction

    NASA Astrophysics Data System (ADS)

    Suutarinen, A. N.; Kristensen, L. E.; Mottram, J. C.; Fraser, H. J.; van Dishoeck, E. F.

    2014-05-01

    Water in outflows from protostars originates either as a result of gas-phase synthesis from atomic oxygen at T ≳ 200 K, or from sputtered ice mantles containing water ice. We aim to quantify the contribution of the two mechanisms that lead to water in outflows, by comparing observations of gas-phase water to methanol (a grain surface product) towards three low-mass protostars in NGC 1333. In doing so, we also quantify the amount of methanol destroyed in outflows. To do this, we make use of James Clerk Maxwell Telescope and Herschel-Heterodyne Instrument for the Far-Infrared data of H2O, CH3OH and CO emission lines and compare them to RADEX non-local thermodynamic equilibrium excitation simulations. We find up to one order of magnitude decrease in the column density ratio of CH3OH over H2O as the velocity increases in the line wings up to ˜15 km s-1. An independent decrease in X(CH3OH) with respect to CO of up to one order of magnitude is also found in these objects. We conclude that gas-phase formation of H2O must be active at high velocities (above 10 km s-1 relative to the source velocity) to re-form the water destroyed during sputtering. In addition, the transition from sputtered water at low velocities to form water at high velocities must be gradual. We place an upper limit of two orders of magnitude on the destruction of methanol by sputtering effects.

  9. Gas-phase synthesis and reactivity of Cu(+)-benzyne complexes.

    PubMed

    Chai, Yunfeng; Shen, Shanshan; Weng, Guofeng; Pan, Yuanjiang

    2014-10-11

    Cu(+)-benzyne complexes bearing bidentate nitrogen ligands were synthesized in the gas phase for the first time using electrospray ionization mass spectrometry. The addition reactivity of copper-stabilized benzyne with amines was studied in the ion trap analyzer. The structures of products were identified by comparing their MS(n) data with authentic compounds obtained from another generation route.

  10. Isobutanol-methanol mixtures from synthesis gas. Quarterly technical progress report, 1 January--31 March 1996

    SciTech Connect

    1996-04-20

    A series of CuMgCeO{sub x} catalysts have been prepared. Range of Cu dispersion, determined by N{sub 2}O titration, was 19-48% and are among the highest reported in the literature for Cu-based methanol and higher alcohol synthesis catalysts. Kinetics of MeOH and EtOH coupling reactions on Cu/ZnO and K-Cu/MgO/CeO{sub 2} catalysts indicate that Cu promotes alcohol dehydrogenation. Acetaldehyde is a reactive intermediate. High-pressure isobutanol synthesis studies have been carried out on K- and Cs-promoted Cu/MgO/CeO{sub 2} catalysts. The K promoter is more active than Cs for CO conversion, but the Cs promoter activates the C{sub 1} to C{sub 2} step more effectively. Catalysts with high alkali loading resulted in low conversions. Temperature programmed surface reaction studies of MeOH, EtOH, and acetaldehyde on MgO/CeO{sub 2}-based Cu catalysts show evolution of acetone, crotonaldehyde, methyl ethyl ketone, H2, carbon oxides. Neither EtOH nor acetaldehyde produces propionaldehyde or 1- propanol, suggesting that these C{sub 3} species can only form via reactions involving C{sub 1} and C{sub 2} oxygenate species.

  11. Aperture synthesis mapping of molecular gas in high-luminosity IRAS galaxies

    NASA Technical Reports Server (NTRS)

    Sanders, D. B.; Soifer, B. T.; Scoville, N. Z.; Sargent, A. I.

    1988-01-01

    The Owens Valley millimeter-wave interferometer has been used for high-resolution mapping of the 2.6 mm CO emission from the high-luminosity infrared galaxies NGC 520 (Arp 157), NGC 7469 (Arp 298), and Arp 55. Assuming the same empirical relationship between CO brightness and molecular hydrogen surface mass density as has been found for giant molecular clouds in the Milky Way, it is found that the masses of H2 gas in these concentrations are 10 to the 9th - 10 to the 10th solar masses, typically one-third of the total molecular gas content of these galaxies. The interferometric sizes correspond to radii of 0.8 kpc (NGC 520), 1.4 kpc (NGC 7469), and less than 2.8 kpc (Arp 55). For the same regions the dynamical masses estimated from the CO line width and size of the emission region are only a factor of 3-5 higher. The mean molecular gas surface densities averaged over these regions are in the range 610-825 solar masses/sq pc, a factor of 10 brighter than those obtained for corresponding regions in the nucleus of the Milky Way. The high mass fractions obtained for the interstellar medium in the central regions of these three galaxies strongly suggest that large-scale gravitational instability in the gas may play an important role in the further concentration of the gas in the nucleus and in possibly precipitating a large-scale burst of star formation.

  12. Synthesis, fractionation, and thin film processing of nanoparticles using the tunable solvent properties of carbon dioxide gas expanded liquids

    NASA Astrophysics Data System (ADS)

    Anand, Madhu

    Nanoparticles have received significant attention because of their unusual characteristics including high surface area to volume ratios. Materials built from nanoparticles possess unique chemical, physical, mechanical and optical properties. Due to these properties, they hold potential in application areas such as catalysts, sensors, semiconductors and optics. At the same time, CO 2 in the form of supercritical fluid or CO2 gas-expanded liquid mixtures has gained significant attention in the area of processing nanostructures. This dissertation focuses on the synthesis and processing of nanoparticles using CO2 tunable solvent systems. Nanoparticle properties depend heavily on their size and, as such, the ability to finely control the size and uniformity of nanoparticles is of utmost importance. Solution based nanoparticle formation techniques are attractive due to their simplicity, but they often result in the synthesis of particles with a wide size range. To address this limitation, a post-synthesis technique has been developed in this dissertation to fractionate polydisperse nanoparticles ( s . = 30%) into monodisperse fractions ( s . = 8%) using tunable physicochemical properties of CO 2 expanded liquids, where CO2 is employed as an antisolvent. This work demonstrates that by controlling the addition of CO2 (pressurization) to an organic dispersion of nanoparticles, the ligand stabilized nanoparticles can be size selectively precipitated within a novel high pressure apparatus that confines the particle precipitation to a specified location on a surface. Unlike current techniques, this CO2 expanded liquid approach provides faster and more efficient particle size separation, reduction in organic solvent usage, and pressure tunable size selection in a single process. To improve our fundamental understanding and to further refine the size separation process, a detailed study has been performed to identify the key parameters enabling size separation of various

  13. Synthesis and analysis of novel polymers with high permselectivity and permeability in gas separation applications

    SciTech Connect

    Koros, W.J.; Paul, D.R.

    1991-12-31

    Significant progress was made toward developing advanced materials for gas separation membrane applications and rationalizing molecular structure and efficacy: Synthesized and tested polyarylates based on terephthalic or isophthalic acid or a tertiary butyl derivative of the isophthalic acid with different diols to illustrate the effects of: opening'' the matrix by incorporation of bulky packing inhibiting groups such as the tertiary butyl moiety inhibition of backbone motion via meta connected backbone connections and tightening'' of the matrix by incorporation of polar halogens. Completed high temperature characterization of sorption and transport properties for novel materials. Continued studies of the phenyl-substituted polymers aimed at producing super stable high temperature useful polymers for gas separations. Synthesized a polyarylate based on the spirobiindane diol and bibenzoyl acid chloride to incorporate long flat packable bibenzoyl units between packing disruptive spirobiindane units in an attempt to control the segmental level morphology to produce highly selective bottleneck'' regions between highly open regions.

  14. Hydrothermal synthesis of h-MoO3 microrods and their gas sensing properties to ethanol

    NASA Astrophysics Data System (ADS)

    Liu, Yueli; Yang, Shuang; Lu, Yu; Podval'naya, Natal'ya V.; Chen, Wen; Zakharova, Galina S.

    2015-12-01

    Hexagonal molybdenum trioxide (h-MoO3) microrods were successfully synthesized via a novel and facile hydrothermal route from peroxomolybdate solution with the presence of NH4Cl as the mineralizer. A variety of the techniques including X-ray diffraction (XRD), scanning electron microscopy (SEM), differential scanning calorimetry combined with the thermal gravimetric analysis (DSC-TG) were used to characterize the product. The gas sensing test indicates that h-MoO3 microrods have a good response to 5-500 ppm ethanol in the range of 273-380 °C, and the optimum operating temperature is 332 °C with a high sensitivity of 8.24 to 500 ppm ethanol. Moreover, it also has a good selectivity toward ethanol gas if compared with other gases, such as ammonia, methanol and toluene. The sensing mechanism of h-MoO3 microrods to ethanol was also discussed.

  15. Microporous Polymers from a Carbazole-Based Triptycene Monomer: Synthesis and Their Applications for Gas Uptake.

    PubMed

    Zhai, Tian-Long; Tan, Liangxiao; Luo, Yi; Liu, Jun-Min; Tan, Bien; Yang, Xiang-Liang; Xu, Hui-Bi; Zhang, Chun

    2016-01-01

    Two kinds of novel organic microporous polymers TCPs (TCP-A and TCP-B) were prepared by two cost-effective synthetic strategies from the monomer of tricarbazolyltriptycene (TCT). Their structure and properties were characterized by FT-IR, solid (13) C NMR, powder XRD, SEM, TEM, and gas absorption measurements. TCP-B displayed a high surface area (1469 m(2)  g(-1) ) and excellent H2 storage (1.70 wt % at 1 bar/77 K) and CO2 uptake abilities (16.1 wt % at 1 bar/273 K), which makes it a promising material for potential application in gas storage.

  16. Synthesis and analysis of novel polymers with high permselectivity and permeability in gas separation applications

    SciTech Connect

    Koros, W.J.; Paul, D.R.

    1991-11-15

    We have synthesized and completed characterization of permeability and selectivity properties of a group of polysulfones and polyether ketones with the potential for higher use temperatures, as well as members of a series of polyesters derived from spirobiindane bisphenol monomer in conjunction with meta and para substituted diacid chlorides. We have also synthesized and characterized the gas transport and thermal properties of diphenyl substituted polyphenylene oxide. The diphenyl substituted material has a potential for higher temperature applications than the standard dimethyl substituted polymer. The temperature dependence of the gas transport properties for the oxygen/nitrogen system was characterized over the range from 35 to 65{degree}C for both of these analog materials.

  17. Gas phase synthesis of non-bundled, small diameter single-walled carbon nanotubes with near-armchair chiralities

    SciTech Connect

    Mustonen, K.; Laiho, P.; Kaskela, A.; Zhu, Z.; Reynaud, O.; Houbenov, N.; Tian, Y.; Jiang, H.; Kauppinen, E. I.; Susi, T.; Nasibulin, A. G.

    2015-07-06

    We present a floating catalyst synthesis route for individual, i.e., non-bundled, small diameter single-walled carbon nanotubes (SWCNTs) with a narrow chiral angle distribution peaking at high chiralities near the armchair species. An ex situ spark discharge generator was used to form iron particles with geometric number mean diameters of 3–4 nm and fed into a laminar flow chemical vapour deposition reactor for the continuous synthesis of long and high-quality SWCNTs from ambient pressure carbon monoxide. The intensity ratio of G/D peaks in Raman spectra up to 48 and mean tube lengths up to 4 μm were observed. The chiral distributions, as directly determined by electron diffraction in the transmission electron microscope, clustered around the (n,m) indices (7,6), (8,6), (8,7), and (9,6), with up to 70% of tubes having chiral angles over 20°. The mean diameter of SWCNTs was reduced from 1.10 to 1.04 nm by decreasing the growth temperature from 880 to 750 °C, which simultaneously increased the fraction of semiconducting tubes from 67% to 80%. Limiting the nanotube gas phase number concentration to ∼10{sup 5 }cm{sup −3} prevented nanotube bundle formation that is due to collisions induced by Brownian diffusion. Up to 80% of 500 as-deposited tubes observed by atomic force and transmission electron microscopy were individual. Transparent conducting films deposited from these SWCNTs exhibited record low sheet resistances of 63 Ω/□ at 90% transparency for 550 nm light.

  18. Gas phase synthesis of non-bundled, small diameter single-walled carbon nanotubes with near-armchair chiralities

    NASA Astrophysics Data System (ADS)

    Mustonen, K.; Laiho, P.; Kaskela, A.; Zhu, Z.; Reynaud, O.; Houbenov, N.; Tian, Y.; Susi, T.; Jiang, H.; Nasibulin, A. G.; Kauppinen, E. I.

    2015-07-01

    We present a floating catalyst synthesis route for individual, i.e., non-bundled, small diameter single-walled carbon nanotubes (SWCNTs) with a narrow chiral angle distribution peaking at high chiralities near the armchair species. An ex situ spark discharge generator was used to form iron particles with geometric number mean diameters of 3-4 nm and fed into a laminar flow chemical vapour deposition reactor for the continuous synthesis of long and high-quality SWCNTs from ambient pressure carbon monoxide. The intensity ratio of G/D peaks in Raman spectra up to 48 and mean tube lengths up to 4 μm were observed. The chiral distributions, as directly determined by electron diffraction in the transmission electron microscope, clustered around the (n,m) indices (7,6), (8,6), (8,7), and (9,6), with up to 70% of tubes having chiral angles over 20°. The mean diameter of SWCNTs was reduced from 1.10 to 1.04 nm by decreasing the growth temperature from 880 to 750 °C, which simultaneously increased the fraction of semiconducting tubes from 67% to 80%. Limiting the nanotube gas phase number concentration to ˜105 cm-3 prevented nanotube bundle formation that is due to collisions induced by Brownian diffusion. Up to 80% of 500 as-deposited tubes observed by atomic force and transmission electron microscopy were individual. Transparent conducting films deposited from these SWCNTs exhibited record low sheet resistances of 63 Ω/□ at 90% transparency for 550 nm light.

  19. Synthesis of formamide and isocyanic acid after ion irradiation of frozen gas mixtures

    NASA Astrophysics Data System (ADS)

    Kaňuchová, Z.; Urso, R. G.; Baratta, G. A.; Brucato, J. R.; Palumbo, M. E.; Strazzulla, G.

    2016-01-01

    Context. Formamide (NH2HCO) and isocyanic acid (HNCO) have been observed as gaseous species in several astronomical environments such as cometary comae and pre- and proto-stellar objects. A debate is open on the formation route of those molecules, in particular if they are formed by chemical reactions in the gas phase and/or on grains. In this latter case it is relevant to understand if the formation occurs through surface reactions or is induced by energetic processing. Aims: We present arguments that support the formation of formamide in the solid phase by cosmic-ion-induced energetic processing of ices present as mantles of interstellar grains and on comets. Formamides, along with other molecules, are expelled in the gas phase when the physical parameters are appropriate to induce the desorption of ices. Methods: We have performed several laboratory experiments in which ice mixtures (H2O:CH4:N2, H2O:CH4:NH3, and CH3OH:N2) were bombarded with energetic (30-200 keV) ions (H+ or He+). FTIR spectroscopy was performed before, during, and after ion bombardment. In particular, the formation of HNCO and NH2HCO was measured quantiatively. Results: Energetic processing of ice can quantitatively reproduce the amount of NH2HCO observed in cometary comae and in many circumstellar regions. HNCO is also formed, but additional formation mechanisms are requested to quantitatively account for the astronomical observations. Conclusions: We suggest that energetic processing of ices in the pre- and proto-stellar regions and in comets is the main mechanism to produce formamide, which, once it is released in the gas phase because of desorption of ices, is observed in the gas phase in these astrophysical environments.

  20. A simple large-scale synthesis of mesoporous In2O3 for gas sensing applications

    NASA Astrophysics Data System (ADS)

    Zhang, Su; Song, Peng; Yan, Huihui; Yang, Zhongxi; Wang, Qi

    2016-08-01

    In this paper, large-scale mesoporous In2O3 nanostructures were synthesized by a facile Lewis acid catalytic the furfural alcohol resin (FAR) template route for the high-yield. Their morphology and structure were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), differential thermal and thermogravimetry analysis (DSC-TG) and the Brunauer-Emmett-Teller (BET) approach. The as-obtained mesoporous In2O3 nanostructures possess excellent mesoporous and network structure, which increases the contact area with the gases, it is conducive for adsorption-desorption of gas on the surface of In2O3. The In2O3 particles and pores were both about 15 nm and very uniform. In gas-sensing measurements with target gases, the gas sensor based on mesoporous In2O3 nanostructures showed a good response, short response-recovery time, good selectivity and stability to ethanol. These properties are due to the large specific surface area of mesoporous structure. This synthetic method could use as a new design concept for functional mesoporous nanomaterials and for mass production.

  1. Synthesis and properties of ZnO nanorods as ethanol gas sensors

    NASA Astrophysics Data System (ADS)

    Mirabbaszadeh, K.; Mehrabian, M.

    2012-03-01

    Uniform ZnO nanorods were synthesized via the sol-gel process under mild conditions in which different ZnO nanostructures have been prepared by changing the pH of growth solution. It was seen that the optimum nanorods were grown at pH 11.33. The prepared ZnO nanostructures and morphologies were characterized by x-ray diffraction and scanning electron microscopy measurements. The ZnO one-dimensional nanostructures were found to have a wurtzite hexagonal crystalline structure and grow along the [001] direction. The optimum nanorods were about 1 μm in length and less than 100 nm in diameter. The ZnO nanostructures have been tested for different concentrations and different operating temperatures for ethanol vapor in air and the surface resistance of the sensors has been evaluated as a function of different parameters. The gas sensor fabricated from ZnO nanorods grown in solution with a special pH exhibited good performance. The sensor response to 5000 ppm ethanol was up to about 2.5 at the operating temperature of 300 °C. The differences in gas-sensing performance between the sensors were analyzed based on the defects created in the nanorods during their fast growth. The correlations between material structures and the properties of the gas sensors are discussed.

  2. Synthesis of hierarchical SnO2 nanoflowers with enhanced acetic acid gas sensing properties

    NASA Astrophysics Data System (ADS)

    Jin, W. X.; Ma, S. Y.; Tie, Z. Z.; Li, W. Q.; Luo, J.; Cheng, L.; Xu, X. L.; Wang, T. T.; Jiang, X. H.; Mao, Y. Z.

    2015-10-01

    Different morphologies hierarchical flower-like tin dioxide (SnO2) nanostructures were fabricated by changing the volume ratio of glycol and de-ionized water (Vg:Vw = 0, 1:2, 1:1 and 2:1) under a template-free and low-cost hydrothermal method and subsequent calcinations. The architectures, morphologies and gas sensing performances of the products were characterized by X-ray diffraction patterns (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET) and gas-sensing measurement device. It can be observed that all the nanoflowers were composed of two-dimensional (2D) nanosheets, and the thickness of nanosheets is only about 9 nm when Vg:Vw = 1:1. The sensor based on the product of Vg:Vw = 1:1 exhibited excellent gas sensing performance toward 500 ppm acetic acid at 260 °C, and the response value of this sensor was about 153.6, which was above 7.5 times higher than that of ammonia (about 20.3). In addition, the 3D flower-like SnO2 nanostructures exhibited not only high response and selectivity to ppm level acetone, but also fast response and recovery time within 10 s, demonstrating it can be used as a potential candidate for detecting acetic acid. Finally, the possible formation mechanism was proposed, too.

  3. Biological conversion of synthesis gas. [Chlorobium thiosulfatophilum, chlorobium phaeobacteroides, and Rhodospirillum rubrum

    SciTech Connect

    Not Available

    1992-01-06

    The anaerobic bacterium Rhodospirillum rubrum has been chosen for catalysis of the biological water gas shift reaction. Two bacteria, Chlorobium thiosulfatophilum and Chlorobium phaeobacteroides, are being evaluated as candidates for H{sub 2}S conversion to elemental sulfur. Since these latter two organisms both grow and convert H{sub 2}S in batch culture using standard basal medium, the choice of a suitable bacterium must be made in consideration of specific growth and uptake rates. Produced elemental sulfur stability against further oxidation to sulfate, and minimal use of H{sub 2} as a producing agent must also be considered. The effects of temperature on the performance of R. rubrum were evaluated. It was found that the cell concentration was highest at temperatures of 25 and 30{degree}C, and that the specific uptake rate was highest at temperatures of 30, 32 and 34{degree}C. No growth was observed at 37{degree}C. Also, temperature did not affect the yield of H{sub 2} from CO. Thus, R. rubrum may be used for biological rates gas shift at any temperature between 30 and 34{degree}C, although growth is maximized at lower temperatures. Preliminary studies with C. thiosulfatophilum showed rapid utilization of H{sub 2}S from the gas and liquid phases with subsequent production of elemental sulfur. Elemental sulfur production interfered with cell concentrations measurements, although a technique has been developed to rectify this problem.

  4. Synthesis of Diacid-Assisted Indium Oxide Nanoparticles and Its CO Gas Sensing Activity.

    PubMed

    Lee, Soo-Keun; Chang, Daeic; Yang, Seung Dae; Kim, Sang Wook

    2015-12-01

    Indium oxide (In2O3) is an extreme wide band-gap oxide material with unique electronic and optical properties that is used widely in solar cells, gas sensors and optoelectronic devices. In this study, two types of In2O3 nanostructures were prepared by a simple hydrothermal method using succinic acid (SA) or malonic acid (MA) as the assistant agents. The products were characterized by powder X-ray diffractions and scanning electron microscopy (SEM). SEM of the products showed that the In2O3 nanostructures prepared in the presence of SA have a typical cubic morphology with a length and height of -30 nm, whereas the In2O3 nanostructures synthesized in the presence of MA has an atypical rock shape, length and height of 30 -300 nm. Gas sensitivity measurements suggested that both In2O3 sensors (operated at 350 degrees C) have a good response to carbon monoxide (CO) compared to the commercial In2O3 nanoparticles. The SA-In2O3 sensor showed a shorter response time and stronger response than the MA-In2O3 sensor, suggesting that the improved gas sensing performance can be attributed mainly to the surface area. PMID:26682433

  5. Synthesis of Diacid-Assisted Indium Oxide Nanoparticles and Its CO Gas Sensing Activity.

    PubMed

    Lee, Soo-Keun; Chang, Daeic; Yang, Seung Dae; Kim, Sang Wook

    2015-12-01

    Indium oxide (In2O3) is an extreme wide band-gap oxide material with unique electronic and optical properties that is used widely in solar cells, gas sensors and optoelectronic devices. In this study, two types of In2O3 nanostructures were prepared by a simple hydrothermal method using succinic acid (SA) or malonic acid (MA) as the assistant agents. The products were characterized by powder X-ray diffractions and scanning electron microscopy (SEM). SEM of the products showed that the In2O3 nanostructures prepared in the presence of SA have a typical cubic morphology with a length and height of -30 nm, whereas the In2O3 nanostructures synthesized in the presence of MA has an atypical rock shape, length and height of 30 -300 nm. Gas sensitivity measurements suggested that both In2O3 sensors (operated at 350 degrees C) have a good response to carbon monoxide (CO) compared to the commercial In2O3 nanoparticles. The SA-In2O3 sensor showed a shorter response time and stronger response than the MA-In2O3 sensor, suggesting that the improved gas sensing performance can be attributed mainly to the surface area.

  6. Study of synthesis gas conversion over metal oxides. Progress report, August 1, 1983-July 31, 1984

    SciTech Connect

    Ekerdt, J.G.

    1984-01-01

    The primary objectives of the research are identification of the reaction intermediates present during CO hydrogenation reactions, determination of the reaction pathways whereby the intermediates are converted into products, identification of the active sites for the various steps in CO hydrogenation and the development of an understanding of the causes for catalytic activity and selectivity. Iron oxide and zirconium dioxide catalysts were used to study the Fischer-Tropsch and isosynthesis processes, respectively. Both involve CO hydrogenation but display very different selectivity and catalytic chemistry. The presence of acyl intermediates and their role, if any, in the Fischer-Tropsch process over iron-based catalysts was studied at one to ten atm total pressure and 225/sup 0/C. The studies involved introducing a scavenger into the CO/H/sub 2/ feed mixture which would selectively react with acyl species and form a compound which was easily identified. The significance of our experiments and their interpretation is difficult to assess at present. We were unable to correlate the concentration of hydrocarbon or oxygenated synthesis products, chiefly methanol and ethanol, with the concentrations of trialkyl amines. A correlation may have suggested if acyl species are formed during the propagation reaction or if they are formed as precursors to aldehyde and alcohol products. The diethyl amine studies do provide consistent evidence that CO insertion does occur over a heterogeneous surface during Fischer-Tropsch synthesis. The isosynthesis studies have included work at 35 atm and at 1 atm. The high pressure work is examining the branching reaction and the C/sub 2/-C/sub 4/ isosynthesis products. The 1 atm studies are examining the C/sub 1/ surface species which may initiate the reaction as well as participate in the formation of C/sub 2/+ products and are examining the role of surface sites in CO/H/sub 2/ reactions over ZrO/sub 2/. 20 references, 2 figures.

  7. DDR-type zeolite membrane synthesis, modification and gas permeation studies

    DOE PAGES

    Yang, Shaowei; Cao, Zishu; Arvanitis, Antonios; Sun, Xinhui; Xu, Zhi; Dong, Junhang

    2016-01-22

    DDR-type zeolite membrane was synthesized on porous α-alumina substrate by hydrothermal treatment of a ball-milled Sigmal-1 crystal seed layer in an aluminum-free precursor solution containing 1-Adamantylamine as the structure directing agent (SDA). The as-synthesized DDR zeolite membranes were defect-free but the supported zeolite layers were susceptible to crack development during the subsequent high-temperature SDA removal process. The cracks were effectively eliminated by the liquid phase chemical deposition method using tetramethoxysilane as the precursor for silica deposits. The modified membrane was extensively studied for H2, He, O2, N2, CO2, CH4, and i-C4H10 pure gas permeation and CO2/CH4 mixture separation. At 297more » K and 2-bar feed gas pressure, the membrane achieved a CO2/CH4 separation factor of ~92 for a feed containing 90% CO2, which decreased to 62 for a feed containing 10% CO2 with the CO2 permeance virtually unchanged at ~1.8×10–7 mol/m• sup>2 s • Pa regardless of the feed composition. It also exhibited an O2/N2 permselectivity of 1.8 at 297 K. Furthermore, the gas permeation behaviors of the current aluminum-containing DDR type zeolite membrane are generally in good agreement with the findings in both experimental and theoretical studies on the pure-silica DDR membranes in recent literature.« less

  8. Improved sensitivity and selectivity of pristine zinc oxide nanostructures to H2S gas: Detailed study on the synthesis reaction time

    NASA Astrophysics Data System (ADS)

    Motaung, David E.; Mhlongo, Gugu H.; Bolokang, Amogelang S.; Dhonge, Baban P.; Swart, Hendrik C.; Sinha Ray, Suprakas

    2016-11-01

    The gas sensing properties of ZnO nanostructures synthesized at various reaction times are reported in this study. The response of ZnO nanostructures to H2, NH3, H2S and NO2 gases was investigated at different operating temperatures and gas concentrations. Surface morphology analyses showed that the geometry of the nanostructures transforms with the synthesis reaction time. Topography analyses demonstrated a surface roughness of approximately 68.25, 70.31, 74.75 nm for the samples synthesized for 24, 48 and 72 h, respectively. The dependence of the morphology on the H2, NH3, NO2 and H2S gas sensing performance was observed. The alteration of the nanostructures diameter/geometry demonstrated a change in both the magnitude and temperature of the maximum sensor response. The 72 h ZnO sensing material revealed improved response and higher sensitivity and selectivity to H2S gas, while the 24 h sensing material revealed enhanced response and selectivity to NO2 gas at 300 °C. Moreover, the 72 h sensing material exhibited a higher sensitivity of 144.22 ppm-1 at 300 °C. These findings disclosed that by varying the synthesis reaction time, the sensing properties, such as the response, sensitivity and selectivity of the ZnO nanostructures could be tuned.

  9. Efficient utilization of greenhouse gases in a gas-to-liquids process combined with CO2/steam-mixed reforming and Fe-based Fischer-Tropsch synthesis.

    PubMed

    Zhang, Chundong; Jun, Ki-Won; Ha, Kyoung-Su; Lee, Yun-Jo; Kang, Seok Chang

    2014-07-15

    Two process models for carbon dioxide utilized gas-to-liquids (GTL) process (CUGP) mainly producing light olefins and Fischer-Tropsch (F-T) synthetic oils were developed by Aspen Plus software. Both models are mainly composed of a reforming unit, an F-T synthesis unit and a recycle unit, while the main difference is the feeding point of fresh CO2. In the reforming unit, CO2 reforming and steam reforming of methane are combined together to produce syngas in flexible composition. Meanwhile, CO2 hydrogenation is conducted via reverse water gas shift on the Fe-based catalysts in the F-T synthesis unit to produce hydrocarbons. After F-T synthesis, the unreacted syngas is recycled to F-T synthesis and reforming units to enhance process efficiency. From the simulation results, it was found that the carbon efficiencies of both CUGP options were successfully improved, and total CO2 emissions were significantly reduced, compared with the conventional GTL processes. The process efficiency was sensitive to recycle ratio and more recycle seemed to be beneficial for improving process efficiency and reducing CO2 emission. However, the process efficiency was rather insensitive to split ratio (recycle to reforming unit/total recycle), and the optimum split ratio was determined to be zero.

  10. Gas-phase synthesis of morpholine from diethylene glycol and ammonia

    SciTech Connect

    Kronich, I.G.; Dobrovol'skii, S.V.; Nikolaev, Y.T.; Shikunov, B.I.; Dyumaev, K.M.

    1982-11-01

    The theory and practice of catalysis in the process of amination of compounds which contain two or more hydroxyl groups has generated much interest. Specifically, there is particular interest in the reaction of diethylene glycol and ammonia; the amination process in this case is accompanied by cyclization with formation of morpholine - a very important product which is needed in growing amounts in the production of rubber vulcanization accelerators, optical bleaches and a number of other products. The possibility of producing morpholine from diethylene glycol and ammonia in gas phase in the presence of hydrogenating-dehydrogenating catalysts was demonstrated earlier. This report presents the results of further research in this area.

  11. Iron catalyst for preparation of polymethylene from synthesis gas and method for producing the catalyst

    DOEpatents

    Sapienza, R.S.; Slegeir, W.A.

    1990-05-15

    This invention relates to a process for synthesizing hydrocarbons; more particularly, the invention relates to a process for synthesizing long-chain hydrocarbons known as polymethylene from carbon monoxide and hydrogen or from carbon monoxide and water or mixtures thereof in the presence of a catalyst comprising iron and platinum or palladium or mixtures thereof which may be supported on a solid material, preferably an inorganic refractory oxide. This process may be used to convert a carbon monoxide containing gas to a product which could substitute for high density polyethylene.

  12. Iron catalyst for preparation of polymethylene from synthesis gas and method for producing the catalyst

    DOEpatents

    Sapienza, Richard S.; Slegeir, William A.

    1990-01-01

    This invention relates to a process for synthesizing hydrocarbons; more particularly, the invention relates to a process for synthesizing long-chain hydrocarbons known as polymethylene from carbon monoxide and hydrogen or from carbon monoxide and water or mixtures thereof in the presence of a catalyst comprising iron and platinum or palladium or mixtures thereof which may be supported on a solid material, preferably an inorganic refractory oxide. This process may be used to convert a carbon monoxide containing gas to a product which could substitute for high density polyethylene.

  13. NEBULAR: Spectrum synthesis for mixed hydrogen-helium gas in ionization equilibrium

    NASA Astrophysics Data System (ADS)

    Schirmer, Mischa

    2016-08-01

    NEBULAR synthesizes the spectrum of a mixed hydrogen helium gas in collisional ionization equilibrium. It is not a spectral fitting code, but it can be used to resample a model spectrum onto the wavelength grid of a real observation. It supports a wide range of temperatures and densities. NEBULAR includes free-free, free-bound, two-photon and line emission from HI, HeI and HeII. The code will either return the composite model spectrum, or, if desired, the unrescaled atomic emission coefficients. It is written in C++ and depends on the GNU Scientific Library (GSL).

  14. The mathematical description of the gasification process of woody biomass in installations with a plasma heat source for producing synthesis gas

    NASA Astrophysics Data System (ADS)

    Sadrtdinov, A. R.; Safin, R. G.; Gerasimov, M. K.; Petrov, V. I.; Gilfanov, K. K.

    2016-04-01

    The article presents the scheme of processing of plant biomass in the gasification installation with a plasma heat source to produce synthesis gas suitable for chemical industry. The analyzed physical picture of raw materials' recycling process underlies a mathematical description of the process set out in the form of the basic differential equations with boundary conditions. The received mathematical description allows calculating of the main parameters of equipment for biomass recycling and to determine the optimal modes of its operation.

  15. Catalyst and process development for synthesis gas conversion to isobutylene. Final report, September 1, 1990--January 31, 1994

    SciTech Connect

    Anthony, R.G.; Akgerman, A.

    1994-05-06

    Previous work on isosynthesis (conversion of synthesis gas to isobutane and isobutylene) was performed at very low conversions or extreme process conditions. The objectives of this research were (1) determine the optimum process conditions for isosynthesis; (2) determine the optimum catalyst preparation method and catalyst composition/properties for isosynthesis; (3) determine the kinetics for the best catalyst; (4) develop reactor models for trickle bed, slurry, and fixed bed reactors; and (5) simulate the performance of fixed bed trickle flow reactors, slurry flow reactors, and fixed bed gas phase reactors for isosynthesis. More improvement in catalyst activity and selectivity is needed before isosynthesis can become a commercially feasible (stand-alone) process. Catalysts prepared by the precipitation method show the most promise for future development as compared with those prepared hydrothermally, by calcining zirconyl nitrate, or by a modified sol-gel method. For current catalysts the high temperatures (>673 K) required for activity also cause the production of methane (because of thermodynamics). A catalyst with higher activity at lower temperatures would magnify the unique selectivity of zirconia for isobutylene. Perhaps with a more active catalyst and acidification, oxygenate production could be limited at lower temperatures. Pressures above 50 atm cause an undesirable shift in product distribution toward heavier hydrocarbons. A model was developed that can predict carbon monoxide conversion an product distribution. The rate equation for carbon monoxide conversion contains only a rate constant and an adsorption equilibrium constant. The product distribution was predicted using a simple ratio of the rate of CO conversion. This report is divided into Introduction, Experimental, and Results and Discussion sections.

  16. Dual gas-bubble-assisted solvothermal synthesis of magnetite with tunable size and structure.

    PubMed

    He, Quanguo; Wu, Zhaohui; Huang, Chunyan

    2011-10-01

    We present a facile solvothermal approach by employing ammonium bicarbonate (NH4HCO3) and ammonium acetate (NH4Ac) as dual gas-bubble-generating structure-directing agent to produce of magnetite (Fe3O4) particles with tunable size ranging from 90 nm to 400 nm and controllable structures including porous and hollow construction. The size, morphology and structure of the final products are achieved by simple adjustment of the molar ratio of NH4HCO3 and NH4Ac, ammonium ion concentration and the reaction time. The results reveal that the molar ratio of NH4HCO3 and NH4Ac strongly influenced the morphology and size of magnetite particles, even could decide the kind of architecture including solid, hollow and porous to form. Particularly, ammonium ion molar concentration plays a significant role in controlling size and magnetic property for magnetite particles. Simultaneously, prolonging the reaction time is beneficial to the magnetite particles growth and inner space escalation with altered reaction time at a certain concentration of ammonium and molar ratio of NH4HCO3 and NH4Ac. Such a design conception of dual gas-bubble-assistance used here is promisingly positive and significant for hollow magnetic particles fabrication and may be extended to other nano-scale hollow construction. PMID:22400226

  17. Nickel oxide nanowires: vapor liquid solid synthesis and integration into a gas sensing device

    NASA Astrophysics Data System (ADS)

    Kaur, N.; Comini, E.; Zappa, D.; Poli, N.; Sberveglieri, G.

    2016-05-01

    In the field of advanced sensor technology, metal oxide nanostructures are promising materials due to their high charge carrier mobility, easy fabrication and excellent stability. Among all the metal oxide semiconductors, nickel oxide (NiO) is a p-type semiconductor with a wide band gap and excellent optical, electrical and magnetic properties, which has not been much investigated. Herein, we report the growth of NiO nanowires by using the vapor liquid solid (VLS) technique for gas sensing applications. Platinum, palladium and gold have been used as a catalyst for the growth of NiO nanowires. The surface morphology of the nanowires was investigated through scanning electron microscopy to find out which catalyst and growth conditions are best for the growth of nanowires. GI-XRD and Raman spectroscopies were used to confirm the crystalline structure of the material. Different batches of sensors have been prepared, and their sensing performances towards different gas species such as carbon monoxide, ethanol, acetone and hydrogen have been explored. NiO nanowire sensors show interesting and promising performances towards hydrogen.

  18. Biological conversion of synthesis gas. Final report, August 31, 1990--September 3, 1993

    SciTech Connect

    Basu, R.; Klasson, K.T.; Johnson, E.R.; Takriff, M.; Clausen, E.C.; Gaddy, J.L.

    1993-09-01

    Based upon the results of this culture screening study, Rhodospirillum rubrum is recommended for biocatalysis of the water gas shift reaction and Chlorobium thiosulfatophilum is recommended for H{sub 2}S conversion to elemental sulfur. Both bacteria require tungsten light for growth and can be co-cultured together if H{sub 2}S conversion is not complete (required concentration of at least 1 ppM), thereby presenting H{sub 2} uptake by Chlorobium thiosulfatophilum. COS degradation may be accomplished by utilizing various CO-utilizing bacteria or by indirectly converting COS to elemental sulfur after the COS first undergoes reaction to H{sub 2} in water. The second alternative is probably preferred due to the low expected concentration of COS relative to H{sub 2}S. Mass transfer and kinetic studies were carried out for the Rhodospirillum rubrum and Chlorobium thiosulfatophilum bacterial systems. Rhodospirillum rubrum is a photosynthetic anaerobic bacterium which catalyzes the biological water gas shift reaction: CO + H{sub 2}O {yields} CO{sub 2} + H{sub 2}. Chlorobium thiosulfatophilum is also a photosynthetic anaerobic bacteria, and converts H{sub 2}S and COS to elemental sulfur.

  19. Biological conversion of synthesis gas. Project status report, October 1, 1992--December 31, 1992

    SciTech Connect

    Ackerson, M.D.; Clausen, E.C.; Gaddy, J.L.

    1993-01-05

    Syngas is known to contain approximately 1 percent H{sub 2}S, along with CO{sub 2}, C0{sub 2}, H{sub 2} and CH{sub 4}. Similarly, the syngas may become contaminated with oxygen, particularly during reactor start-up and during maintenance. Previous studies with the water-gas shift bacterium Rhodospirillum rubrum have shown that the bacterium is tolerant of small quantities of oxygen, but the effects of oxygen on CO-consumption are unknown. Similarly, R. rubrum is known to be tolerant of H{sub 2}S, with high concentrations of H{sub 2}S negatively affecting CO-uptake. Batch experiments were thus carried out to determine the effects of H{sub 2}S and O{sub 2} on CO-uptake by R. rubrum. The results of these experiments were quantified by using Monod equations modified by adding terms for CO, H{sub 2}S and O{sub 2} inhibition. The techniques used in determining kinetic expressions previously shown for other gas-phase substrate bacterial systems including R. rubrum were utilized.

  20. Synthesis and analysis of nanostructured composite particles from gas-saturated solutions

    NASA Astrophysics Data System (ADS)

    Gil'mutdinov, I. I.; Gil'mutdinov, I. M.; Kuznetsova, I. V.; Sabirzyanov, A. N.

    2015-05-01

    Ibuprofen/polyethylene glycol 4000 and methylparaben/polyethylene glycol 4000 nanostructured composite particles are synthesized from gas-saturated solutions (PGSS, particles from gas saturated solution). The dependences of the mean size of composite particles on pressure, temperature, and the expansion channel diameter are revealed. The studies are conducted in the pressure range of 10 to 30 MPa, at temperatures ranging from 40 to 80°C, and for expansion channel diameters in the range of 200 to 500 μm. The physicochemical properties of the composite particles are investigated using a differential scanning calorimeter and phase analysis is performed by means of X-ray diffraction. The composition of composite particles is determined via mass spectrometric analysis. Chromatography-tandem mass spectrometry with electronic ionization is used for the quantitative analysis of ibuprofen, while mass spectrometry of matrix-assisted laser desorption/ionization (MALDI) is used in the analysis of polyethylene glycol 4000. The dependence of the concentration of components in composite particles on pressure is obtained.

  1. Dual gas-bubble-assisted solvothermal synthesis of magnetite with tunable size and structure.

    PubMed

    He, Quanguo; Wu, Zhaohui; Huang, Chunyan

    2011-10-01

    We present a facile solvothermal approach by employing ammonium bicarbonate (NH4HCO3) and ammonium acetate (NH4Ac) as dual gas-bubble-generating structure-directing agent to produce of magnetite (Fe3O4) particles with tunable size ranging from 90 nm to 400 nm and controllable structures including porous and hollow construction. The size, morphology and structure of the final products are achieved by simple adjustment of the molar ratio of NH4HCO3 and NH4Ac, ammonium ion concentration and the reaction time. The results reveal that the molar ratio of NH4HCO3 and NH4Ac strongly influenced the morphology and size of magnetite particles, even could decide the kind of architecture including solid, hollow and porous to form. Particularly, ammonium ion molar concentration plays a significant role in controlling size and magnetic property for magnetite particles. Simultaneously, prolonging the reaction time is beneficial to the magnetite particles growth and inner space escalation with altered reaction time at a certain concentration of ammonium and molar ratio of NH4HCO3 and NH4Ac. Such a design conception of dual gas-bubble-assistance used here is promisingly positive and significant for hollow magnetic particles fabrication and may be extended to other nano-scale hollow construction.

  2. Slurry phase Fischer-Tropsch synthesis: Cobalt plus a water-gas shift catalyst

    SciTech Connect

    Chanenchuk, C.A.; Yates, I.C.; Satterfield, C.N.

    1990-01-01

    A Co/MgO/SiO[sub 2] Fischer-Tropsch catalyst was operated simultaneously with a Cu/ZnO/Al[sub 2]O[sub 3] water-gas-shift catalyst in a slurry reactor for over 400 hours. The process conditions were held constant at a temperature of 240[degrees]C, a pressure of 0.79 MPa, and a 1.1 H[sub 2]/CO feed of 0.065 Nl/min-g.cat. The Fischer-Tropsch activity remained constant at the level predicted by the operation of the Co/MgO/SiO[sub 2] catalyst alone. The water-gas-shift reaction was near equilibrium. The hydrocarbon product distribution of the combined catalyst system was stable and matched that of the CO/MgO/SiO[sub 2] operating alone under similar conditions. The combined catalyst system exhibited a high selectivity to n-alkanes. Neither catalysts's operation appeared to have a detrimental effect on that of the other, showing promise for future option.

  3. Nickel oxide nanowires: vapor liquid solid synthesis and integration into a gas sensing device.

    PubMed

    Kaur, N; Comini, E; Zappa, D; Poli, N; Sberveglieri, G

    2016-05-20

    In the field of advanced sensor technology, metal oxide nanostructures are promising materials due to their high charge carrier mobility, easy fabrication and excellent stability. Among all the metal oxide semiconductors, nickel oxide (NiO) is a p-type semiconductor with a wide band gap and excellent optical, electrical and magnetic properties, which has not been much investigated. Herein, we report the growth of NiO nanowires by using the vapor liquid solid (VLS) technique for gas sensing applications. Platinum, palladium and gold have been used as a catalyst for the growth of NiO nanowires. The surface morphology of the nanowires was investigated through scanning electron microscopy to find out which catalyst and growth conditions are best for the growth of nanowires. GI-XRD and Raman spectroscopies were used to confirm the crystalline structure of the material. Different batches of sensors have been prepared, and their sensing performances towards different gas species such as carbon monoxide, ethanol, acetone and hydrogen have been explored. NiO nanowire sensors show interesting and promising performances towards hydrogen.

  4. Synthesis, characterization and gas sensing properties of novel homo and hetero dinuclear ball-type phthalocyanines.

    PubMed

    Kakı, Esra; Altındal, Ahmet; Salih, Bekir; Bekaroğlu, Özer

    2015-05-01

    New ball-type homodinuclear Co(ii)-Co(ii) phthalocyanine () and ball-type heterodinuclear Co(ii)-Fe(ii) phthalocyanine () were synthesized from the corresponding [2,10,16,24-tetrakis{4,4'-cyclohexylidenebis(2-cyclohexyphenoxyphthalonitrile)}phthalocyaninatocobalt(ii)] (). The novel compounds have been characterized by elemental analysis, IR, UV-Vis and MALDI-TOF mass spectroscopy. Gas sensing capability of the spin coated film of and were studied using amperometric technique at various temperatures. For a better understanding of the interaction of and films with organic compounds, two different groups of compounds (aromatics and alcohols) were selected as test analytes. It was observed that the operating temperature had a considerable effect on the gas sensing performance of the sensors investigated. The experimental results show that film offers a promising perspective as a sensing material for the detection of relatively low aromatic vapours even at room temperature. This suggests that aromatics might be distinguished from alcohols. The obtained data were analysed using two different adsorption kinetic models: the pseudo first order equation and Elovich equation to determine the best fit equation for the adsorption of toluene vapor onto and films. The first-order equation was the best of the various kinetic models studied to describe the adsorption kinetic of toluene on Pc films at higher concentrations, as evidenced by the highest correlation coefficients. In addition, it was observed that Elovich equation generates a straight line that best fit to the data of adsorption of lower concentrations of toluene.

  5. Isobutanol-methanol mixtures from synthesis gas. Quarterly report, July 1 - September 30, 1996

    SciTech Connect

    Iglesia, E.

    1996-12-01

    A series of CuMgCeO{sub x} catalysts have been prepared by coprecipitating the corresponding metal nitrates with a mixed solution of potassium carbonate and potassium hydroxide. The bulk composition of the catalyst has been measured by atomic absorption (AA) analysis and the Cu dispersion has been determined by N{sub 2}O titration at 90 {degrees}C. CeO{sub x} does not contribute to the measured copper dispersion in K-CuO{sub 0.5}Mg{sub 5}CeO{sub x} samples and the high dispersion value indeed reflects the presence of Cu metal small crystallites. Kinetic studies of methanol and propionaldehyde coupling reactions on K-Cu/MgO/CeO{sub 2} and MgO/CeO{sub 2} catalysts indicate that Cu enhances the rates of alcohol dehydrogenation. High-pressure isobutanol synthesis from CO/H{sub 2} has been studied on CuO{sub 0.5}Mg{sub 5}O{sub x} catalysts at 593 K and 4.5 MPa. CuO{sub 0.5}Mg{sub 5}O{sub x} catalysts show high hydrocarbon and low isobutanol selectivities compared to K-CuO{sub 0.5}Mg{sub 5}CeO{sub x}, suggesting the presence of residual acidity in CuO{sub 0.5}Mg{sub 5}O{sub x}.

  6. Isobutanol-methanol mixtures from synthesis gas. Quarterly technical progress report, October 1--December 31, 1995

    SciTech Connect

    Iglesia, E.

    1996-01-10

    A series of Cu{sub 0.5}CeMe(II)O{sub x} catalysts (Me refers to Group II alkali earth elements) have been prepared by coprecipitating the corresponding metal nitrates with potassium carbonate. The bulk composition of the catalyst has been determined by atomic absorption (AA) analysis. High-pressure isobutanol synthesis studies have been carried out over a standard BASF Cs-promoted Cu/ZnO/Al{sub 2}O{sub 3} catalyst. At a CO conversion level of 32%, the isobutanol carbon selectivity is about 5%; whereas that of methanol is 40.2%. A 100% selectivity sum has now been obtained as a result of using response factors measured by the laboratory. The reactions of ethanol and acetic acid over a number of catalysts have been investigated using a temperature programmed surface reaction (TPSR) technique. Ethanol and acetone are the only desorption products observed over Cs-promoted Cu/ZnO/Al{sub 2}O{sub 3} catalysts. Surface acetate ion is believed to be the precursor for acetone formation. Over calcined hydrotalcites, i.e., MgO/Al{sub 2}O{sub 3}, ethylene is formed instead of acetone. The amount of ethylene formed decreases as Mg/Al ratio increases, suggesting a role of aluminum ions in ethanol dehydration reactions.

  7. Novel Approaches to the Production of Higher Alcohols From Synthesis Gas. Quarterly report, January 1 - March 31, 1996

    SciTech Connect

    Roberts, George W

    1997-02-13

    Effort during this quarter was devoted to three areas: 1) analyzing the data from earlier runs with "zinc chromite"catalyst and three different slurry liquids: decahydronaphthalene (Decalin®, DHN), tetrahydronaphthalene (tetralin, THN) and tetrahydroquinoline (THQ); 2) analyzing newly-obtained data from earlier thermal stability tests on DHN and THN, and 3) carrying out a thermal stability test on THQ. Both the activity and selectivity of "zinc chromite" catalyst depended on the slurry liquid that was used. The catalyst activity for methanol synthesis was in the order: THQ > DHN > THN. Despite the basic nature of THQ, it exhibited the highest dimethyl ether (DME) production rates of the three liquids. Gas chromatography/mass spectroscopy (GC/MS) analyses of samples of THN and DHN were taken at the end of standard thermal stability tests at 375°C. With both liquids, the only measurable compositional change was a minor amount of isomerization. Analysis of a sample of THN after a thermal stability test at 425°C showed a small reduction in molecular weight, and a significant amount of opening of the naphthenic ring. Preliminary data from the tehrmal stability test of THQ showed that this molecule is more stable than DHN, but less stable than THN.

  8. Synthesis of nanowires via helium and neon focused ion beam induced deposition with the gas field ion microscope.

    PubMed

    Wu, H M; Stern, L A; Chen, J H; Huth, M; Schwalb, C H; Winhold, M; Porrati, F; Gonzalez, C M; Timilsina, R; Rack, P D

    2013-05-01

    The ion beam induced nanoscale synthesis of platinum nanowires using the trimethyl (methylcyclopentadienyl)platinum(IV) (MeCpPt(IV)Me3) precursor is investigated using helium and neon ion beams in the gas field ion microscope. The He(+) beam induced deposition resembles material deposited by electron beam induced deposition with very small platinum nanocrystallites suspended in a carbonaceous matrix. The He(+) deposited material composition was estimated to be 16% Pt in a matrix of amorphous carbon with a large room-temperature resistivity (∼3.5 × 10(4)-2.2 × 10(5) μΩ cm) and temperature-dependent transport behavior consistent with a granular material in the weak intergrain tunnel coupling regime. The Ne(+) deposited material has comparable composition (17%), however a much lower room-temperature resistivity (∼600-3.0 × 10(3) μΩ cm) and temperature-dependent electrical behavior representative of strong intergrain coupling. The Ne(+) deposited nanostructure has larger platinum nanoparticles and is rationalized via Monte Carlo ion-solid simulations which show that the neon energy density deposited during growth is much larger due to the smaller ion range and is dominated by nuclear stopping relative to helium which has a larger range and is dominated by electronic stopping.

  9. Solvothermal, chloroalkoxide-based synthesis of monoclinic WO(3) quantum dots and gas-sensing enhancement by surface oxygen vacancies.

    PubMed

    Epifani, Mauro; Comini, Elisabetta; Díaz, Raül; Andreu, Teresa; Genç, Aziz; Arbiol, Jordi; Siciliano, Pietro; Faglia, Guido; Morante, Joan R

    2014-10-01

    We report for the first time the synthesis of monoclinic WO3 quantum dots. A solvothermal processing at 250 °C in oleic acid of W chloroalkoxide solutions was employed. It was shown that the bulk monoclinic crystallographic phase is the stable one even for the nanosized regime (mean size 4 nm). The nanocrystals were characterized by X-ray diffraction, High resolution transmission electron microscopy, X-ray photoelectron spectroscopy, UV-vis, Fourier transform infrared and Raman spectroscopy. It was concluded that they were constituted by a core of monoclinic WO3, surface covered by unstable W(V) species, slowly oxidized upon standing in room conditions. The WO3 nanocrystals could be easily processed to prepare gas-sensing devices, without any phase transition up to at least 500 °C. The devices displayed remarkable response to both oxidizing (nitrogen dioxide) and reducing (ethanol) gases in concentrations ranging from 1 to 5 ppm and from 100 to 500 ppm, at low operating temperatures of 100 and 200 °C, respectively. The analysis of the electrical data showed that the nanocrystals were characterized by reduced surfaces, which enhanced both nitrogen dioxide adsorption and oxygen ionosorption, the latter resulting in enhanced ethanol decomposition kinetics.

  10. Nitrogen metabolism and gas exchange parameters associated with zinc stress in tobacco expressing an ipt gene for cytokinin synthesis.

    PubMed

    Pavlíková, Daniela; Pavlík, Milan; Procházková, Dagmar; Zemanová, Veronika; Hnilička, František; Wilhelmová, Naďa

    2014-04-15

    Increased endogenous plant cytokinin (CK) content through transformation with an isopentyl transferase (ipt) gene has been associated with improved plant stress tolerance. The impact of zinc (tested levels Zn1=250, Zn2=500, Zn3=750mgkg(-1)soil) on gas exchange parameters (net photosynthetic rate, transpiration rate, stomatal conductance, intercellular CO2 concentration) and nitrogen utilization by plants resulted in changes of free amino acid concentrations (glutamic acid, glutamine, asparagine, aspartate, glycine, serine, cystein) and differed for transformed and non-transformed tobacco plants. For pot experiments, tobacco plants (Nicotiana tabacum L., cv. Wisconsin 38) transformed with a construct consisting of SAG12 promoter fused with the ipt gene for cytokinin synthesis (SAG plants) and its wild type (WT plants as a control) were used. Physiological analyses confirmed that SAG plants had improved zinc tolerance compared with the WT plants. The enhanced Zn tolerance of SAG plants was associated with the maintenance of accumulation of amino acids and with lower declines of photosynthetic and transpiration rates. In comparison to WT plants, SAG plants exposed to the highest Zn concentration accumulated lower concentrations of asparagine, which is a major metabolic product during senescence.

  11. Focused ion beam induced synthesis of antimony nanowires for gas sensor applications

    NASA Astrophysics Data System (ADS)

    Schoendorfer, Christoph; Hetzel, Martin; Pongratz, Peter; Lugstein, Alois; Bertagnolli, Emmerich

    2012-11-01

    In this paper the formation of antimony (Sb) nanowires (NWs) by a focused Ga ion beam approach and their gas sensing capability is reported. The NWs with uniform diameters of only 25 nm and lengths up to several microns are synthesized at predefined positions at room temperature in an ion beam induced self-assembling process. Then individual Sb-NWs are deposited on insulating substrates and provided with gold electrodes. Subsequently sensing characteristics of individual Sb-NWs are investigated at room temperature for H2O, CO, H2, He, O2 and ethanol over a wide concentration range. The Sb-NWs exhibit selective sensing properties for ethanol and H2O with exceptional sensitivities of more than 17 000 and 60 000, respectively.

  12. GAS-PHASE FLAME SYNTHESIS AND PROPERTIES OF MAGNETIC IRON OXIDE NANOPARTICLES WITH REDUCED OXIDATION STATE

    PubMed Central

    Kumfer, Benjamin M; Shinoda, Kozo; Jeyadevan, Balachandran; Kennedy, Ian M

    2010-01-01

    Iron oxide nanoparticles of reduced oxidation state, mainly in the form of magnetite, have been synthesized utilizing a new continuous, gas-phase, nonpremixed flame method using hydrocarbon fuels. This method takes advantage of the characteristics of the inverse flame, which is produced by injection of oxidizer into a surrounding flow of fuel. Unlike traditional flame methods, this configuration allows for the iron particle formation to be maintained in a more reducing environment. The effects of flame temperature, oxygen-enrichment and fuel dilution (i.e. the stoichiometric mixture fraction), and fuel composition on particle size, Fe oxidation state, and magnetic properties are evaluated and discussed. The crystallite size, Fe(II) fraction, and saturation magnetization were all found to increase with flame temperature. Flames of methane and ethylene were used, and the use of ethylene resulted in particles containing metallic Fe(0), in addition to magnetite, while no Fe(0) was present in samples synthesized using methane. PMID:20228941

  13. Synthesis, magnetic and ethanol gas sensing properties of semiconducting magnetite nanoparticles

    NASA Astrophysics Data System (ADS)

    Al-Ghamdi, Ahmed A.; Al-Hazmi, Faten; Al-Tuwirqi, R. M.; Alnowaiser, F.; Al-Hartomy, Omar A.; El-Tantawy, Farid; Yakuphanoglu, F.

    2013-05-01

    The superparamagnetic magnetite (Fe3O4) nanoparticles with an average size of 7 nm were synthesized using a rapid and facile microwave hydrothermal technique. The structure of the magnetite nanoparticles was characterized by X-ray diffraction (X-ray), field effect scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDS), and transmission electron microscopy (TEM). The prepared Fe3O4 was shown to have a cubic phase of pure magnetite. Magnetization hysteresis loop shows that the synthesized magnetite exhibits no hysteretic features with a superparamagnetic behavior. The ethanol gas sensing properties of the synthesized magnetite were investigated, and it was found that the responsibility time is less than 10 s with good reproducibility for ethanol sensor. Accordingly, it is evaluated that the magnetite nanoparticles can be effectively used as a solid state ethanol sensor in industrial commercial product applications.

  14. Microbial synthesis gas utilization and ways to resolve kinetic and mass-transfer limitations.

    PubMed

    Yasin, Muhammad; Jeong, Yeseul; Park, Shinyoung; Jeong, Jiyeong; Lee, Eun Yeol; Lovitt, Robert W; Kim, Byung Hong; Lee, Jinwon; Chang, In Seop

    2015-02-01

    Microbial conversion of syngas to energy-dense biofuels and valuable chemicals is a potential technology for the efficient utilization of fossils (e.g., coal) and renewable resources (e.g., lignocellulosic biomass) in an environmentally friendly manner. However, gas-liquid mass transfer and kinetic limitations are still major constraints that limit the widespread adoption and successful commercialization of the technology. This review paper provides rationales for syngas bioconversion and summarizes the reaction limited conditions along with the possible strategies to overcome these challenges. Mass transfer and economic performances of various reactor configurations are compared, and an ideal case for optimum bioreactor operation is presented. Overall, the challenges with the bioprocessing steps are highlighted, and potential solutions are suggested. Future research directions are provided and a conceptual design for a membrane-based syngas biorefinery is proposed.

  15. Flame synthesis of carbon nano onions using liquefied petroleum gas without catalyst.

    PubMed

    Dhand, Vivek; Prasad, J Sarada; Rao, M Venkateswara; Bharadwaj, S; Anjaneyulu, Y; Jain, Pawan Kumar

    2013-03-01

    Densely agglomerated, high specific surface area carbon nano onions with diameter of 30-40 nm have been synthesized. Liquefied petroleum gas and air mixtures produced carbon nano onions in diffusion flames without catalyst. The optimized oxidant to fuel ratio which produces carbon nano onions has been found to be 0.1 slpm/slpm. The experiment yielded 70% pure carbon nano onions with a rate of 5 g/h. X-ray diffraction, high-resolution electron microscopy and Raman spectrum reveal the densely packed sp(2) hybridized carbon with (002) semi-crystalline hexagonal graphite reflection. The carbon nano onions are thermally stable up to 600 °C. PMID:25427484

  16. Microbial synthesis gas utilization and ways to resolve kinetic and mass-transfer limitations.

    PubMed

    Yasin, Muhammad; Jeong, Yeseul; Park, Shinyoung; Jeong, Jiyeong; Lee, Eun Yeol; Lovitt, Robert W; Kim, Byung Hong; Lee, Jinwon; Chang, In Seop

    2015-02-01

    Microbial conversion of syngas to energy-dense biofuels and valuable chemicals is a potential technology for the efficient utilization of fossils (e.g., coal) and renewable resources (e.g., lignocellulosic biomass) in an environmentally friendly manner. However, gas-liquid mass transfer and kinetic limitations are still major constraints that limit the widespread adoption and successful commercialization of the technology. This review paper provides rationales for syngas bioconversion and summarizes the reaction limited conditions along with the possible strategies to overcome these challenges. Mass transfer and economic performances of various reactor configurations are compared, and an ideal case for optimum bioreactor operation is presented. Overall, the challenges with the bioprocessing steps are highlighted, and potential solutions are suggested. Future research directions are provided and a conceptual design for a membrane-based syngas biorefinery is proposed. PMID:25443672

  17. Synthesis of one-dimentional nanostructures for gas sensing and photovoltaic applications

    NASA Astrophysics Data System (ADS)

    Karaagac, Hakan; Peksu, Elif; Islam, M. Saif

    2015-08-01

    In this work, three-dimensional (3-D) p-n junctions were formed for the fabrication of field ionization gas sensors and solar cells. P-Si micro-pillars/ZnO NWs, n-TiO2-nanorod/p-CdTe and n-Si-NW/p-CuInSe2(CIS) material combinations were preferred for the construction of p-n hetero-junction solar cells. Vertically well-aligned Si NWs were synthesized over the surface of n-type silicon wafer by using electroless etching technique. The synthesized Si-NWs embedded into a sputter deposited mono-phase chalcopyrite thin film (CIS) for the realization of nanowire array embedded in thin film type inorganic solar cell, which exhibited a 1.51% power conversion efficiency. In addition to Si nanowires, high aspect ratio vertically well- oriented p- silicon micropillars (MPs) were also synthesized using deep reactive ion Etching (DRIE) process with the BOSCH recipe of cyclical passivation and etching. Three-dimensional (3D) p-Si-MPs/n-ZnO-NWs heterostructures were constructed from hydrothermally grown dense arrays of ZnO nanowires onto these p-type silicon micropillars. The device structures were tested for both the field ionization gas sensor and photovoltaic applications, which showed very promising results. As a final part of this study, TiO2 nanorods (NRs) were grown on FTO glass substrates by using hydrothermal technique, which is sequentially coated with CdTe thin film (sputtering) and subjected to CdCl2 chemical solution treatment to fabricate a core-shell model solar cell with a power conversion efficiency over 0.4% power conversion efficiency.

  18. Gas-Phase Synthesis of Singly and Multiply Charged Polyoxovanadate Anions Employing Electrospray Ionization and Collision Induced Dissociation

    SciTech Connect

    Al Hasan, Naila M.; Johnson, Grant E.; Laskin, Julia

    2013-07-02

    complex CID spectra. These results are consistent with the formation of more stable structures of VxOyCl and VxOy anions through low-energy CID. Finally and furthermore, our results demonstrate that solution-phase synthesis of one precursor cluster anion combined with gas-phase CID is an efficient approach for the top-down synthesis of a wide range of singly and multiply charged gas-phase metal oxide cluster anions for subsequent investigations of structure and reactivity using mass spectrometry and ion spectroscopy techniques.

  19. o-, m-, and p-benzyne negative ions in the gas phase: Synthesis, authentication, and thermochemistry

    SciTech Connect

    Wenthold, P.G.; Hu, J.; Squires, R.R.

    1996-11-27

    The isomeric m- and p-benzyne anions have been generated in the gas phase in a flowing afterglow-triple quadrupole instrument from the reactions of molecular fluorine (F{sub 2}) with m- and p-(trimethylsilyl)phenyl anions. The mechanism of the F{sub 2} reaction involves electron transfer from the (trimethylsilyl)phenyl anion to F{sub 2}, followed by nucleophilic attack on the resulting (trimethylsilyl)phenyl radical by the nascent F{sup -} formed within the intermediate ion/molecule complex. The structures of o-, m-, and p-benzyne anion are unambiguously identified by a classical derivatization scheme. Estimates of the electron affinities of m- and p-benzyne have been determined by the kinetic method. Adducts of SO{sub 2} with phenide ion and each of the isomeric benzyne anions are formed that produce measurable yields of SO{sub 2}{sup .-} and the corresponding C{sub 6}H{sub n}{sup -} ion upon CID. A calibration relation is derived between the CID yield ratios obtained for the C{sub 6}H{sub 5}SO{sub 2}{sup -} and o-C{sub 6}H{sub 4}SO{sub 2}{sup .-} adducts and the known electron affinities of phenyl radical (25.3{+-}0.1 kcal/mol) and o-benzyne (12.9{+-}0.2 kcal/mol). The measured CID ratios for the m- and p-benzyne SO{sub 2} adducts are then combined with this relation to obtain EA(m-benzzyne) = 19.5{+-}0.3 kcal/mol and EA(p-benzyne) = 28.8 {+-} 0.5 kcal/mol. These data are used to derive gas-phase acidities for the different ring positions of phenyl radical and the corresponding C-H bond strengths for the phenide ion ({Delta}H{sub acid}(C{sub 6}H{sub 5}), DH{sub 298}[C{sub 6}H{sub 4}{sup -}-H], kcal/mol). 41 refs., 2 figs., 1 tab.

  20. Synthesis of functional xLayMn/KIT-6 and features in hot coal gas desulphurization.

    PubMed

    Xia, Hong; Zhang, Fengmei; Zhang, Zhaofei; Liu, Bingsi

    2015-08-28

    To enhance the stability of sorbents during continuous desulphurization-regeneration cycles, KIT-6 with 3D pore channels was used as a support for the sorbents. A series of mesoporous xLayMn/KIT-6 sorbents with different La/Mn atomic ratios were fabricated using a sol-gel method and their desulphurization properties of hot coal gas were investigated at 700-850 °C. 3La97Mn/KIT-6 performed the best at 800 °C with a breakthrough sulphur capacity of 11.56 g sulphur per 100 g sorbent. The eight successive desulphurization (800 °C)-regeneration (600 °C) cycles revealed that 3La97Mn/KIT-6 with endurable regeneration abilities could retain 80% of the initial sulphur capacity. It indicated a better desulphurization performance compared to pure 3La97Mn and 3La97Mn/MCM-41. The fresh and used xLayMn/KIT-6 sorbents were characterized by means of BET, XRD, HRTEM, XPS and H2-TPR techniques. The XRD patterns and HRTEM images of fresh and used 3La97Mn/KIT-6 verified that the utilization of KIT-6 effectively suppressed the aggregation of Mn2O3 particles and improved the stability of the sorbent.

  1. Gas-phase combustion synthesis of titanium boride (TiB{sub 2}) nanocrystallites

    SciTech Connect

    Axelbaum, R.L.; DuFaux, D.P.; Frey, C.A.; Kelton, K.F.; Lawton, S.A.; Rosen, L.J.; Sastry, S.M.

    1996-04-01

    Two techniques are described for synthesizing nanometer-sized TiB{sub 2} particles by gas-phase combustion reactions of sodium vapor with TiCl{sub 4} and BCl{sub 3}: a low-pressure, low temperature burner and a high-temperature flow reactor. Both methods produce TiB{sub 2} particles that are less than 15 nm in diameter. The combustion by-product, NaCl, is efficiently removed from the TiB{sub 2} by water washing or vacuum sublimation. Material collected from the low-temperature burner and annealed at 1000{degree}C consists of loosely agglomerated particles 20 to 100 nm in size. Washed material from the high-temperature flow reactor consists of necked agglomerates of 3 to 15 nm particles. A thermodynamic analysis of the Ti/B/Cl/Na system indicates that near 100{percent} yields of TiB{sub 2} are possible with appropriate reactant concentrations, pressures, and temperatures. {copyright} {ital 1996 Materials Research Society.}

  2. Gas phase synthesis of organophosphorus compounds and the atmosphere of the giant planets

    NASA Astrophysics Data System (ADS)

    Bossard, A. R.; Kamga, R.; Raulin, F.

    1986-08-01

    Spark discharge and UV irradiation experiments were performed to investigate the interactions of CH4 and PH3 and the chemical evolution of PH3-H2O-NH3-CH4 mixtures in the upper atmospheres of the giant planets. The spark discharges were performed with various combinations of CH4-PH3, CH-PH3-H2, C2H6-PH3, and CH3PH2-CH4. PH3 alone and CH4-PH3 were exposed to 147 nm UV light. Sparks released into the hydrocarbon-phosphine mixtures induced the formation of alkylphosphines. The main products were H2, C2H6 and CH3PH2 when the initial mole fraction of PH3 was low. If the fraction of PH3 was high, the main products were He, CH3PH2 and P2H4. A gas phase chemical reaction model was defined for the formation reaction of methylphosphine. UV irradiation of CH4-PH3 usually produced a solid deposit and the constituents H2 and P2H4. The stability of the various reaction products in the Saturn and Jupiter atmospheres is discussed.

  3. Molecular uranates - laser synthesis of uranium oxide anions in the gas phase

    SciTech Connect

    Marcalo, Joaquim; Santos, Marta; Pires de Matos, Antonio; Gibson, John K

    2009-12-14

    Laser ablation of solid UO{sub 3} or (NH{sub 4}){sub 2}U{sub 2}O{sub 7} yielded in the gas phase molecular uranium oxide anions with compositions ranging from [UO{sub n}]{sup -} (n = 2-4) to [U{sub 14}O{sub n}]{sup -} (n = 32-35), as detected by Fourier transform ion cyclotron resonance mass spectrometry. The cluster series [U{sub x}O{sub 3x}]{sup -} for x {le} 6 and various [U{sub x}O{sub 3x-y}]{sup -}, in which y increased with increasing x, could be identified. A few anions with H atoms were also present, and their abundance increased when hydrated UO{sub 3} was used in place of anhydrous UO{sub 3}. Collision-induced dissociation experiments with some of the lower m/z cluster anions supported extended structures in which neutral UO{sub 3} constitutes the building block. Cationic uranium oxide clusters [U{sub x}O{sub n}]{sup +} (x = 2-9; n = 3-24) could also be produced and are briefly discussed. Common trends in the O/U ratios for both negative and positive clusters could be unveiled.

  4. Gas-phase synthesis of Mg-Ti nanoparticles for solid-state hydrogen storage.

    PubMed

    Calizzi, M; Venturi, F; Ponthieu, M; Cuevas, F; Morandi, V; Perkisas, T; Bals, S; Pasquini, L

    2016-01-01

    Mg-Ti nanostructured samples with different Ti contents were prepared via compaction of nanoparticles grown by inert gas condensation with independent Mg and Ti vapour sources. The growth set-up offered the option to perform in situ hydrogen absorption before compaction. Structural and morphological characterisation was carried out by X-ray diffraction, energy dispersive spectroscopy and electron microscopy. The formation of an extended metastable solid solution of Ti in hcp Mg was detected up to 15 at% Ti in the as-grown nanoparticles, while after in situ hydrogen absorption, phase separation between MgH2 and TiH2 was observed. At a Ti content of 22 at%, a metastable Mg-Ti-H fcc phase was observed after in situ hydrogen absorption. The co-evaporation of Mg and Ti inhibited nanoparticle coalescence and crystallite growth in comparison with the evaporation of Mg only. In situ hydrogen absorption was beneficial to subsequent hydrogen behaviour, studied by high pressure differential scanning calorimetry and isothermal kinetics. A transformed fraction of 90% was reached within 100 s at 300 °C during both hydrogen absorption and desorption. The enthalpy of hydride formation was not observed to differ from bulk MgH2.

  5. Advanced bioreactor systems for gaseous substrates: Conversion of synthesis gas to liquid fuels and removal of SO{sub x} and NO{sub x} from coal combustion gases

    SciTech Connect

    Selvaraj, P.T.; Kaufman, E.N.

    1995-06-01

    The purpose of the proposed research program is the development and demonstration of a new generation of gaseous substrate-based bioreactors for the production of liquid fuels from coal synthesis gas and the removal of NO{sub x} and SO{sub x} species from combustion flue gas. Coal is thermochemically converted to synthesis gas consisting of carbon monoxide, hydrogen, and carbon dioxide. Conventional catalytic upgrading of coal synthesis gas into alcohols or other oxychemicals is subject to several processing problems such as interference of the other constituents in the synthesis gases, strict CO/H{sub 2} ratios required to maintain a particular product distribution and yield, and high processing cost due to the operation at high temperatures and pressures. Recently isolated and identified bacterial strains capable of utilizing CO as a carbon source and coverting CO and H{sub 2} into mixed alcohols offer the potential of performing synthesis gas conversion using biocatalysts. Biocatalytic conversion, though slower than the conventional process, has several advantages such as decreased interference of the other constituents in the synthesis gases, no requirement for strict CO/H{sub 2} ratios, and decreased capital and oeprating costs as the biocatalytic reactions occur at ambient temperatures and pressures.

  6. Green synthesis of highly reduced graphene oxide by compressed hydrogen gas towards energy storage devices

    NASA Astrophysics Data System (ADS)

    Li, Cheng Chao; Yu, Hong; Yan, Qingyu; Hng, Huey Hoon

    2015-01-01

    Herein, we present a new strategy for the mass production of high-quality reduced graphene oxide (RGO) with a surface area of 354 m2 g-1 using high pressure hydrogen as a reducing agent under hydrothermal conditions. The high pressure used is solely generated from the packing of the gas cylinder itself and a pressure meter could simply fulfil the role of monitoring pressure. The reduction process is green without chemical wastes produced. Comparing to other reported methods, the significant advancements of our strategy lie not only in the high-quality RGO with high C/O ratio, conductivity and surface area, but also in the most environment-friendliness and cost-effectiveness, which make the large scale fabrication feasible. Moreover, clean noble metal nanocrystals such as Pt could be easily in situ deposited onto the surface of RGO nanosheets when noble metal salts are introduced into the system. In particular, the prepared RGO and Pt/RGO show exceptional electrochemical performances in supercapacitors and lithium oxygen batteries because of their clean electrochemical surface, good conductivity and large surface area. Our results reveal that the obtained RGO have a specific capacitance of 884.4 F g-1 at a current density of 0.5 A g-1, and the Pt/RGO electrode can deliver discharge-charge capacities of 1000 mAh g-1 for 40 cycles with a high round-trip efficiencies of 74.9% at 50 mA g-1 when used as Li-O2 battery electrodes.

  7. Dual Layer Monolith ATR of Pyrolysis Oil for Distributed Synthesis Gas Production

    SciTech Connect

    Lawal, Adeniyi

    2012-09-29

    We have successfully demonstrated a novel reactor technology, based on BASF dual layer monolith catalyst, for miniaturizing the autothermal reforming of pyrolysis oil to syngas, the second and most critical of the three steps for thermochemically converting biomass waste to liquid transportation fuel. The technology was applied to aged as well as fresh samples of pyrolysis oil derived from five different biomass feedstocks, namely switch-grass, sawdust, hardwood/softwood, golden rod and maple. Optimization of process conditions in conjunction with innovative reactor system design enabled the minimization of carbon deposit and control of the H2/CO ratio of the product gas. A comprehensive techno-economic analysis of the integrated process using in part, experimental data from the project, indicates (1) net energy recovery of 49% accounting for all losses and external energy input, (2) weight of diesel oil produced as a percent of the biomass to be ~14%, and (3) for a demonstration size biomass to Fischer-Tropsch liquid plant of ~ 2000 daily barrels of diesel, the price of the diesel produced is ~$3.30 per gallon, ex. tax. However, the extension of catalyst life is critical to the realization of the projected economics. Catalyst deactivation was observed and the modes of deactivation, both reversible and irreversible were identified. An effective catalyst regeneration strategy was successfully demonstrated for reversible catalyst deactivation while a catalyst preservation strategy was proposed for preventing irreversible catalyst deactivation. Future work should therefore be focused on extending the catalyst life, and a successful demonstration of an extended (> 500 on-stream hours) catalyst life would affirm the commercial viability of the process.

  8. Gas phase synthesis and reactivity of Agn+ and Ag(n-1)H+ cluster cations.

    PubMed

    Khairallah, George N; O'Hair, Richard A J

    2005-08-21

    Multi-stage mass spectrometry (MSn) on [(M + Ag - H)x + Ag]+ precursor ions (where M = an amino acid such as glycine or N,N-dimethylglycine) results in the formation of stable silver (Ag3+, Ag5+ and Ag7+) and silver hydride (Ag2H+, Ag4H+ and Ag6H+) cluster cations in the gas phase. Deuterium labelling studies reveal that the source of the hydride can be either from the alpha carbon or from one of the heteroatoms. When M = glycine, the silver cyanide clusters Ag4CN+ and Ag5(H,C,N)+ are also observed. Collision induced dissociation (CID) and DFT calculations were carried out on each of these clusters to shed some light on their possible structures. CID of the Agn+ and Ag(n-1)H+ clusters generally results in the formation of the same Ag(n-2)+ product ions via the loss of Ag2 and AgH respectively. DFT calculations also reveal that the Agn+ and Ag(n-1)H+ clusters have similar structural features and that the Ag(n-1)H+ clusters are only slightly less stable than their all silver counterparts. In addition, Agn+ and Ag(n-1)H+ clusters react with 2-propanol and 2-butylamine via similar pathways, with multiple ligand addition occurring and a coupled deamination-dehydration reaction occurring upon condensation of a third (for Ag2H+) or a fourth (for all other silver clusters) 2-butylamine molecule onto the clusters. Taken together, these results suggest that the Agn+ and Ag(n-1)H+ clusters are structurally related via the replacement of a silver atom with a hydrogen atom. This replacement does not dramatically alter the cluster stability or its unimolecular or bimolecular chemistry with the 2-propanol and 2-butylamine reagents.

  9. Synthesis of tin and tin oxide nanoparticles of low size dispersity for application in gas sensing.

    PubMed

    Nayral, C; Viala, E; Fau, P; Senocq, F; Jumas, J C; Maisonnat, A; Chaudret, B

    2000-11-17

    Nanocomposite core-shell particles that consist of a Sn0 core surrounded by a thin layer of tin oxides have been prepared by thermolysis of [(Sn(NMe2)2)2] in anisole that contains small, controlled amounts of water. The particles were characterized by means of electronic microscopies (TEM, HRTEM, SEM), X-ray diffraction (XRD) studies, photoelectron spectroscopy (XPS), and Mossbauer spectroscopy. The TEM micrographs show spherical nanoparticles, the size and size distribution of which depends on the initial experimental conditions of temperature, time, water concentration, and tin precursor concentration. Nanoparticles of 19 nm median size and displaying a narrow size distribution have been obtained with excellent yield in the optimized conditions. HRTEM, XPS, XRD and Mossbauer studies indicate the composite nature of the particles that consist of a well-crystallized tin beta core of approximately equals 11 nm covered with a layer of approximately equals 4 nm of amorphous tin dioxide and which also contain quadratic tin monoxide crystallites. The thermal oxidation of this nanocomposite yields well-crystallized nanoparticles of SnO2* without coalescence or size change. XRD patterns show that the powder consists of a mixture of two phases: the tetragonal cassiterite phase, which is the most abundant, and an orthorhombic phase. In agreement with the small SnO2 particle size, the relative intensity of the adsorbed dioxygen peak observed on the XPS spectrum is remarkable, when compared with that observed in the case of larger SnO2 particles. This is consistent with electrical conductivity measurements, which demonstrate that this material is highly sensitive to the presence of a reducing gas such as carbon monoxide. PMID:11151840

  10. Regenerable Sorbent Development for Sulfur, Chloride and Ammonia Removal from Coal-Derived Synthesis Gas

    SciTech Connect

    Siriwardane, R.V.; Tian, H.; Simonyi, T.; Webster, T.

    2007-08-01

    A large number of components in coal form corrosive and toxic compounds during coal gasification processes. DOE’s NETL aims to reduce contaminants to parts per billion in order to utilize gasification gas streams in fuel cell applications. Even more stringent requirements are expected if the fuel is to be utilized in chemical production applications. Regenerable hydrogen sulfide removal sorbents have been developed at NETL. These sorbents can remove the hydrogen sulfide to ppb range at 316 °C and at 20 atmospheres. The sorbent can be regenerated with oxygen. Reactivity and physical durability of the sorbent did not change during the multi-cycle tests. The sorbent development work has been extended to include the removal of other major impurities, such as HCl and NH3. The sorbents for HCl removal that are available today are not regenerable. Regenerable HCl removal sorbents have been developed at NETL. These sorbents can remove HCl to ppb range at 300 °C to 500 °C. The sorbent can be regenerated with oxygen. Results of TGA and bench-scale flow reactor tests with both regenerable and non-regenerable HCl removal sorbents will be discussed in the paper. Bench-scale reactor tests were also conducted with NH3 removal sorbents. The results indicated that the sorbents have a high removal capacity and good regenerability during the multi-cycle tests. Future emphasis of the NETL coal gasification/cleanup program is to develop multi-functional sorbents to remove multiple impurities in order to minimize the steps involved in the cleanup systems. To accomplish this goal, a regenerable sorbent capable of removing both HCl and H2S was developed. The results of the TGA conducted with the sorbent to evaluate the feasibility of both H2S and HCl sorption will be discussed in this paper.

  11. Greenhouse gas fluxes from drained organic soils - a synthesis of a large dataset

    NASA Astrophysics Data System (ADS)

    Tiemeyer, Bärbel

    2016-04-01

    Drained peatlands are hotspots of greenhouse gas (GHG) emissions. Agriculture is the major land use type for peatlands in Germany and other European countries, but strongly varies in its intensity regarding groundwater level and agricultural management. Although the mean annual water table depth is sometimes proposed as an overall predictor for GHG emissions, there is a strong variability of its effects on different peatlands. We synthesized 164 annual GHG budgets for 65 different sites in 13 German peatlands. Land use comprised arable land with different crops (n = 17) and grassland with a management gradient from very intensive use with up to five cuts per year to partially rewetted conservation grassland (n = 48). Carbon dioxide (net ecosystem exchange and ecosystem respiration), nitrous oxide and methane fluxes were measured with transparent and opaque manual chambers. Besides the GHG fluxes, biomass yield, fertilisation, groundwater level, climatic data, vegetation composition and soil properties were measured. Overall, we found a large variability of the total GHG budget ranging from small uptakes to extremely high emissions (> 70 t CO2-equivalents/(ha yr)). At nearly all sites, carbon dioxide was the major component of the GHG budget. Site conditions, especially the nitrogen content of the unsaturated zone and the intra-annual water level distribution, dominated the GHG emissions from grassland. Although these factors are influenced by natural conditions (peat type, regional hydrology), they could be modified by an improved water management. In the case of grassland, agricultural management such as the number of cuts had only a minor influence on the GHG budgets. Given comparable site conditions, there was no significant difference between the emissions from grassland and arable land. Due to the large heterogeneity of site conditions and crop types, emissions from arable land are difficult to explain, but management decisions such as the duration of soil

  12. Agricultural peat lands; towards a greenhouse gas sink - a synthesis of a Dutch landscape study

    NASA Astrophysics Data System (ADS)

    Schrier-Uijl, A. P.; Kroon, P. S.; Hendriks, D. M. D.; Hensen, A.; Van Huissteden, J. C.; Leffelaar, P. A.; Berendse, F.; Veenendaal, E. M.

    2013-06-01

    It is generally known that managed, drained peatlands act as carbon sources. In this study we examined how mitigation through the reduction of management and through rewetting may affect the greenhouse gas (GHG) emission and the carbon balance of intensively managed, drained, agricultural peatlands. Carbon and GHG balances were determined for three peatlands in the western part of the Netherlands from 2005 to 2008 by considering spatial and temporal variability of emissions (CO2, CH4 and N2O). One area (Oukoop) is an intensively managed grass-on-peatland, including a dairy farm, with the ground water level at an average annual depth of 0.55 m below the soil surface. The second area (Stein) is an extensively managed grass-on-peatland, formerly intensively managed, with a dynamic ground water level at an average annual depth of 0.45 m below the soil surface. The third area is an (since 1998) rewetted former agricultural peatland (Horstermeer), close to Oukoop and Stein, with the average annual ground water level at a depth of 0.2 m below the soil surface. During the measurement campaigns we found that both agriculturally managed sites acted as carbon and GHG sources but the rewetted agricultural peatland acted as a carbon and GHG sink. The terrestrial GHG source strength was 1.4 kg CO2-eq m-2 yr-1 for the intensively managed area and 1.0 kg CO2-eq m-2 yr-1 for the extensively managed area; the unmanaged area acted as a GHG sink of 0.7 kg CO2-eq m-2 yr-1. Water bodies contributed significantly to the terrestrial GHG balance because of a high release of CH4 and the loss of DOC only played a minor role. Adding the farm-based CO2 and CH4 emissions increased the source strength for the managed sites to 2.7 kg CO2-eq m-2 yr-1 for Oukoop and 2.1 kg CO2-eq m-2 yr-1 for Stein. Shifting from intensively managed to extensively managed grass-on-peat reduced GHG emissions mainly because N2O emission and farm-based CH4 emissions decreased. Overall, this study suggests that managed

  13. Facile synthesis of titania nanowires via a hot filament method and conductometric measurement of their response to hydrogen sulfide gas.

    PubMed

    Munz, Martin; Langridge, Mark T; Devarepally, Kishore K; Cox, David C; Patel, Pravin; Martin, Nicholas A; Vargha, Gergely; Stolojan, Vlad; White, Sam; Curry, Richard J

    2013-02-01

    Titania nanostructures are of increasing interest for a variety of applications, including photovoltaics, water splitting, and chemical sensing. Because of the photocatalytical properties of TiO₂, chemical processes that occur at its surface can be exploited for highly efficient nanodevices. A facile and fast synthesis route has been explored that is free of catalysts or templates. An environmental scanning electron microscopy (ESEM) system was employed to grow titania nanowires (NWs) in a water vapor atmosphere (∼1 mbar) and to monitor the growth in situ. In addition, the growth process was also demonstrated using a simple vacuum chamber. In both processes, a titanium filament was heated via the Joule effect and NWs were found to grow on its surface, as a result of thermal oxidation processes. A variety of nanostructures were observed across the filament, with morphologies changing with the wire temperature from the center to the end points. The longest NWs were obtained for temperatures between ∼730 °C and 810 °C. Typically, they have an approximate thickness of ∼300 nm and lengths of up to a few micrometers. Cross sections prepared by focused-ion-beam milling revealed the presence of a porous layer beneath the NW clusters. This indicates that the growth of NWs is driven by oxidation-induced stresses in the subsurface region of the Ti filament and by enhanced diffusion along grain boundaries. To demonstrate the potential of titania NWs grown via the hot filament method, single NW devices were fabricated and used for conductometric sensing of hydrogen sulfide (H₂S) gas. The NW electric resistance was found to decrease in the presence of H₂S. Its variation can be explained in terms of the surface depletion model. PMID:23327919

  14. Agricultural peatlands: towards a greenhouse gas sink - a synthesis of a Dutch landscape study

    NASA Astrophysics Data System (ADS)

    Schrier-Uijl, A. P.; Kroon, P. S.; Hendriks, D. M. D.; Hensen, A.; Van Huissteden, J.; Berendse, F.; Veenendaal, E. M.

    2014-08-01

    It is generally known that managed, drained peatlands act as carbon (C) sources. In this study we examined how mitigation through the reduction of the intensity of land management and through rewetting may affect the greenhouse gas (GHG) emission and the C balance of intensively managed, drained, agricultural peatlands. Carbon and GHG balances were determined for three peatlands in the western part of the Netherlands from 2005 to 2008 by considering spatial and temporal variability of emissions (CO2, CH4 and N2O). One area (Oukoop) is an intensively managed grass-on-peatland area, including a dairy farm, with the ground water level at an average annual depth of 0.55 (±0.37) m below the soil surface. The second area (Stein) is an extensively managed grass-on-peatland area, formerly intensively managed, with a dynamic ground water level at an average annual depth of 0.45 (±0.35) m below the soil surface. The third area is a (since 1998) rewetted former agricultural peatland (Horstermeer), close to Oukoop and Stein, with the average annual ground water level at a depth of 0.2 (±0.20) m below the soil surface. During the measurement campaigns we found that both agriculturally managed sites acted as C and GHG sources and the rewetted former agricultural peatland acted as a C and GHG sink. The ecosystem (fields and ditches) total GHG balance, including CO2, CH4 and N2O, amounted to 3.9 (±0.4), 1.3 (±0.5) and -1.7 (±1.8) g CO2-eq m-2 d-1 for Oukoop, Stein and Horstermeer, respectively. Adding the farm-based emissions to Oukoop and Stein resulted in a total GHG emission of 8.3 (±1.0) and 6.6 (±1.3) g CO2-eq m-2 d-1, respectively. For Horstermeer the GHG balance remained the same since no farm-based emissions exist. Considering the C balance (uncertainty range 40-60%), the total C release in Oukoop and Stein is 5270 and 6258 kg C ha-1 yr-1, respectively (including ecosystem and management fluxes), and the total C uptake in Horstermeer is 3538 kg C ha-1 yr-1. Water

  15. Purge gas recovery of ammonia synthesis plant by integrated configuration of catalytic hydrogen-permselective membrane reactor and solid oxide fuel cell as a novel technology

    NASA Astrophysics Data System (ADS)

    Siavashi, Fakhteh; Saidi, Majid; Rahimpour, Mohammad Reza

    2014-12-01

    The purge gas emission of ammonia synthesis plant which contains hazardous components is one of the major sources of environmental pollution. Using integrated configuration of catalytic hydrogen-permselective membrane reactor and solid oxide fuel cell (SOFC) system is a new approach which has a great impact to reduce the pollutant emission. By application of this method, not only emission of ammonia and methane in the atmosphere is prevented, hydrogen is produced through the methane steam reforming and ammonia decomposition reactions that take place simultaneously in a catalytic membrane reactor. The pure generated hydrogen by recovery of the purge gas in the Pd-Ag membrane reactor is used as a feed of SOFC. Since water is the only byproduct of the electrochemical reaction in the SOFC, it is recycled to the reactor for providing the required water of the reforming reaction. Performance investigation of the reactor represents that the rate of hydrogen permeation increases with enhancing the reactor temperature and pressure. Also modeling results indicate that the SOFC performance improves with increasing the temperature and fuel utilization ratio. The generated power by recovery of the purging gas stream of ammonia synthesis plant in the Razi petrochemical complex is about 8 MW.

  16. Rapid pressure swing absorption cleanup of post-shift reactor synthesis gas. Technical progress report No. 4, June 1, 1991--September 31, 1991

    SciTech Connect

    Sirkar, K.K.; Majumdar, S.; Bhaumik, S.

    1991-10-31

    This investigation is concerned with the separation of gas mixtures using a novel concept of rapid pressure swing absorption (RAPSAB) of gas in a stationary absorbent liquid through gas-liquid interfaces immobilized in the pore mouths of hydrophobic microporous membranes. The process is implemented in a module well-packed with hydrophobic microporous hollow fiber membranes. The specific objectives are (1) to fiber membranes. The specific objectives are (1) to develop a theoretical model which will provide guidelines for selecting an efficient RAPSAB process cycle which includes desorption; (2) to demonstrate the concept experimentally with a simple gas mixture (e.g., Co{sub 2}-N{sub 2}) and a simple absorbent liquid such as water, and (3) to extend the concept to reactive absorbent liquids for the separation of CO, Co{sub 2} from the post-shift reactor synthesis gas. A simplified theoretical description of the novel rapid pressure swing absorption process has been developed. The absorption part of the pressure swing absorption cycle has been predicted for CO{sub 2}-N{sub 2}-water system. Numerical simulation of the model is being carried out for different operating conditions for selecting an optimum pressure swing cycle.

  17. Synthesis and evaluation of novel biochar-based and metal oxide-based catalysts for removal of model tar (toluene), ammonia, and hydrogen sulfide from simulated producer gas

    NASA Astrophysics Data System (ADS)

    Bhandari, Pushpak

    Gasification is a thermochemical conversion process in which carbonaceous feedstock is gasified in a controlled atmosphere to generate producer gas. The producer gas is used for production of heat, power, fuels and chemicals. Various contaminants such as tars, NH3, and H2S in producer gas possess many problems due to their corrosive nature and their ability to clog and deactivate catalysts. In this study, several catalysts were synthesized, characterized, and tested for removal of three contaminants (toluene (model tar), NH3, and H2S) from the biomass-generated producer gas. Biochar, a catalyst, was generated from gasification of switchgrass. Activated carbon and acidic surface activated carbon were synthesized using ultrasonication method from biochar. Acidic surface was synthesized by coating activated carbon with dilute acid. Mixed metal oxide catalysts were synthesized from hydrotalcite precursors using novel synthesis technique using microwave and ultrasonication. Surface area of activated carbon (˜900 m2/g) was significantly higher than that of its precursor biochar (˜60 m2/g). Surface area of metal oxide catalyst was approximately 180 m2/g after calcination. Biochar, activated carbon, and acidic surface activated carbon showed toluene removal efficiencies of approximately 78, 88, and 88 %, respectively, when the catalysts were tested individually with toluene in the presence of producer gas at 800 °C. The toluene removal efficiencies increased to 86, 91, and 97 % using biochar, activated carbon and acidic surface activated carbon, respectively in the presence of NH3 and H2S in the producer gas. Increase in toluene removal efficiencies in presence of NH3 and H2S indicates that NH3 and H 2S play a role in toluene reforming reactions during simultaneous removal of contaminants. Toluene removal efficiency for mixed metal oxide was approximately 83%. Ammonia adsorption capacities were 0.008 g NH3/g catalyst for biochar and 0.03g NH3/g catalyst for activated

  18. Equipment Design and Cost Estimation for Small Modular Biomass Systems, Synthesis Gas Cleanup, and Oxygen Separation Equipment; Task 1: Cost Estimates of Small Modular Systems

    SciTech Connect

    Nexant Inc.

    2006-05-01

    This deliverable is the Final Report for Task 1, Cost Estimates of Small Modular Systems, as part of NREL Award ACO-5-44027, ''Equipment Design and Cost Estimation for Small Modular Biomass Systems, Synthesis Gas Cleanup and Oxygen Separation Equipment''. Subtask 1.1 looked into processes and technologies that have been commercially built at both large and small scales, with three technologies, Fluidized Catalytic Cracking (FCC) of refinery gas oil, Steam Methane Reforming (SMR) of Natural Gas, and Natural Gas Liquids (NGL) Expanders, chosen for further investigation. These technologies were chosen due to their applicability relative to other technologies being considered by NREL for future commercial applications, such as indirect gasification and fluidized bed tar cracking. Research in this subject is driven by an interest in the impact that scaling has on the cost and major process unit designs for commercial technologies. Conclusions from the evaluations performed could be applied to other technologies being considered for modular or skid-mounted applications.

  19. Direct and Highly Selective Conversion of Synthesis Gas into Lower Olefins: Design of a Bifunctional Catalyst Combining Methanol Synthesis and Carbon-Carbon Coupling.

    PubMed

    Cheng, Kang; Gu, Bang; Liu, Xiaoliang; Kang, Jincan; Zhang, Qinghong; Wang, Ye

    2016-04-01

    The direct synthesis of lower (C2 to C4) olefins, key building-block chemicals, from syngas (H2/CO), which can be derived from various nonpetroleum carbon resources, is highly attractive, but the selectivity for lower olefins is low because of the limitation of the Anderson-Schulz-Flory distribution. We report that the coupling of methanol-synthesis and methanol-to-olefins reactions with a bifunctional catalyst can realize the direct conversion of syngas to lower olefins with exceptionally high selectivity. We demonstrate that the choice of two active components and the integration manner of the components are crucial to lower olefin selectivity. The combination of a Zr-Zn binary oxide, which alone shows higher selectivity for methanol and dimethyl ether even at 673 K, and SAPO-34 with decreased acidity offers around 70% selectivity for C2-C4 olefins at about 10% CO conversion. The micro- to nanoscale proximity of the components favors the lower olefin selectivity.

  20. Advanced bioreactor concepts for gaseous substrates: Conversion of synthesis gas to liquid fuels and removal of SO{sub x} and NO{sub x} from coal combustion gases. CRADA final report

    SciTech Connect

    Kaufman, E.N.; Selvaraj, P.T.

    1997-10-01

    The purpose of the proposed research program was the development and demonstration of a new generation of gaseous substrate-based bioreactors for the production of liquid fuels from coal synthesis gas and the removal of NO{sub x} and SO{sub x} species from coal combustion flue gas. This study addressed the further investigation of optimal bacterial strains, growth media and kinetics for the biocatalytic conversion of coal synthesis gas to liquid fuel such as ethanol and the reduction of gaseous flue gas constituents. The primary emphasis was on the development of advanced bioreactor systems coupled with innovative biocatalytic systems that will provide increased productivity under controlled conditions. It was hoped that this would result in bioprocessing options that have both technical and economic feasibility, thus, ensuring early industrial use. Predictive mathematical models were formulated to accommodate hydrodynamics, mass transport, and conversion kinetics, and provide the data base for design and scale-up. The program was separated into four tasks: (1) Optimization of Biocatalytic Kinetics; (2) Development of Well-mixed and Columnar Reactors; (3) Development of Predictive Mathematical Models; and (4) Industrial Demonstration. Research activities addressing both synthesis gas conversion and flue gas removal were conducted in parallel by BRI and ORNL respectively.

  1. Mathematical modeling of synthesis gas fueled electrochemistry and transport including H2/CO co-oxidation and surface diffusion in solid oxide fuel cell

    NASA Astrophysics Data System (ADS)

    Bao, Cheng; Jiang, Zeyi; Zhang, Xinxin

    2015-10-01

    Fuel flexibility is a significant advantage of solid oxide fuel cell (SOFC). A comprehensive macroscopic framework is proposed for synthesis gas (syngas) fueled electrochemistry and transport in SOFC anode with two main novelties, i.e. analytical H2/CO electrochemical co-oxidation, and correction of gas species concentration at triple phase boundary considering competitive absorption and surface diffusion. Staring from analytical approximation of the decoupled charge and mass transfer, we present analytical solutions of two defined variables, i.e. hydrogen current fraction and enhancement factor. Giving explicit answer (rather than case-by-case numerical calculation) on how many percent of the current output contributed by H2 or CO and on how great the water gas shift reaction plays role on, this approach establishes at the first time an adaptive superposition mechanism of H2-fuel and CO-fuel electrochemistry for syngas fuel. Based on the diffusion equivalent circuit model, assuming series-connected resistances of surface diffusion and bulk diffusion, the model predicts well at high fuel utilization by keeping fixed porosity/tortuosity ratio. The model has been validated by experimental polarization behaviors in a wide range of operation on a button cell for H2-H2O-CO-CO2-N2 fuel systems. The framework could be helpful to narrow the gap between macro-scale and meso-scale SOFC modeling.

  2. The economical production of alcohol fuels from coal-derived synthesis gas. Quarterly technical progress report number 13, October 1--December 31, 1994

    SciTech Connect

    1995-01-01

    At WVU, Mo{sub 2}S{sub 3} was produced from gas-phase reactions at 1,100 C. The gas-phase reactor was modified to increase product yields and to decrease particle size. Four Chevrel phases were synthesized for catalytic evaluation. In addition, four supported alkali-modified MoS{sub 2} materials were prepared from a single-source precursor, K{sub 2}Mo{sub 3}S{sub 13}. Screening runs have been carried out on some of these materials and others prepared earlier. At UCC and P, test runs on the reactor system have commenced. Higher alcohols up to butanol were observed and identified at high temperatures. Significant progress has been made on the Monte Carlo uncertainty analysis. Frequency distributions have been determined for all of the equipment blocks for the Texaco gasifier cases. For these cases, there is a 10% chance that the actual installed capital cost could exceed the estimated installed capital cost by $40 million dollars. This work will continue with inclusion of variable costs and prediction of the uncertainties in the return on investment. Modifications to the simulated annealing optimization program have been underway in order to increase the level of certainty that the final result is near the global optimum. Alternative design cases have been examined in efforts to enhance the economics of the production of high alcohols. One such process may be the generation of electric power using combustion turbines fueled by synthesis gas.

  3. Influence of quenching gas injection on the temperature field in pulse-modulated induction thermal plasma for large scale nanopowder synthesis

    NASA Astrophysics Data System (ADS)

    Tanaka, Yasunori; Guo, Weixuan; Kodama, Naoto; Kita, Kentaro; Uesugi, Yoshihiko; Ishijima, Tatsuo; Watanabe, Shu; Nakamura, Keitaro

    2015-09-01

    We have so far developed a unique and original method for a large-scale nanopowder synthesis method using pulse-modulated induction thermal plasmas with time-controlled feedstock feeding (PMITP-TCFF). The PMITP is sustained by the coil current modulated into a rectangular waveform. Such the current modulation produces an extremely high-temperature thermal plasma in on-time, and in off-time relatively low-temperature thermal plasma. In PMITP-TCFF method, feedstock powder is intermittently injected to the PMITP synchronously during only on-time for its efficient and complete evaporation. That evaporated materials are rapidly cooled down to promote nucleation of nanoparticles during off-time. This report deals with a numerical approach on influence of quenching gas injection on the temperature field in the PMITP. The thermofluid model for the PMITP was developed on the assumption of local thermodynamic equilibrium (LTE). This model accounted for the pulse-modulation of the coil current and the quenching gas injection. It was found that the quenching gas injection works to increase the PMITP temperature inside the plasma torch during on-time, and then to decrease it effectively in the reaction chamber. This work is partly supported by JSPS KAKENHI Grant No. 26249034.

  4. Regioselective synthesis of biradical negative ions in the gas phase. Generation of trimethylenemethane, m-benzyne, and p-benzyne anions

    SciTech Connect

    Wenthold, P.G.; Hu, J.; Squires, R.R. )

    1994-07-27

    We report a general regioselective method for producing high yields of biradical negative ions ([open quotes]distonic[close quotes] radical anions) in the gas phase. These species are of fundamental interest for several reasons: for use in mass spectrometric studies of free radical chemistry, for use in investigating the acid-base properties of radicals, and, most significantly, for use in negative ion photoelectron spectroscopic measurements of the electron affinities and singlet-triplet energy gaps in the corresponding neutral biradicals. We describe here the mechanism and scope of the new synthetic procedure and its application in the synthesis and characterization of m- and p-benzene anions and trimethylenemethane anion in a flowing afterglow - triple quadrupole apparatus.

  5. Slurry phase Fischer-Tropsch synthesis: Cobalt plus a water-gas shift catalyst. [Quarterly] report, October 1, 1989--December 31, 1989

    SciTech Connect

    Yates, I.C.; Satterfield, C.N.

    1989-12-31

    The rate of synthesis gas consumption over a cobalt FischerTropsch catalyst was measured in a well-mixed, continuous-flow, slurry reactor at 220 to 240{degrees}C, 0.5 to 1.5 MPa, H{sub 2}/CO feed ratios of 1.5 to 3.5 and conversions of 7 to 68% of hydrogen and 11 to 73% of carbon monoxide. The inhibiting effect of carbon monoxide was determined quantitatively and a Langmuir-Hinshelwood-type equation of the following form was found to best represent the results: -R{sub H{sub 2+Co}} = (a P{sub CO}P{sub H{sub 2}})/(1 + b P{sub CO}){sup 2}. The apparent activation energy was 93 to 95 kJ/mol. Data from previous studies on cobalt-based Fischer-Tropsch catalysts are also well correlated with this rate expression.

  6. Production of carbon nanotubes: Chemical vapor deposition synthesis from liquefied petroleum gas over Fe-Co-Mo tri-metallic catalyst supported on MgO

    NASA Astrophysics Data System (ADS)

    Setyopratomo, P.; Wulan, Praswasti P. D. K.; Sudibandriyo, M.

    2016-06-01

    Carbon nanotubes were produced by chemical vapor deposition method to meet the specifications for hydrogen storage. So far, the various catalyst had been studied outlining their activities, performances, and efficiencies. In this work, tri-metallic catalyst consist of Fe-Co-Mo supported on MgO was used. The catalyst was prepared by wet-impregnation method. Liquefied Petroleum Gas (LPG) was used as carbon source. The synthesis was conducted in atmospheric fixed bed reactor at reaction temperature range 750 - 850 °C for 30 minutes. The impregnation method applied in this study successfully deposed metal component on the MgO support surface. It found that the deposited metal components might partially replace Mg(OH)2 or MgO molecules in their crystal lattice. Compare to the original MgO powder; it was significant increases in pore volume and surface area has occurred during catalyst preparation stages. The size of obtained carbon nanotubes is ranging from about 10.83 nm OD/4.09 nm ID up to 21.84 nm OD/6.51 nm ID, which means that multiwall carbon nanotubes were formed during the synthesis. Yield as much as 2.35 g.CNT/g.catalyst was obtained during 30 minutes synthesis and correspond to carbon nanotubes growth rate of 0.2 μm/min. The BET surface area of the obtained carbon nanotubes is 181.13 m2/g and around 50 % of which is contributed by mesopores. Micropore with half pore width less than 1 nm contribute about 10% volume of total micro and mesopores volume of the carbon nanotubes. The existence of these micropores is very important to increase the hydrogen storage capacity of the carbon nanotubes.

  7. Synthesis of hematite (alpha-Fe2O3) nanorods: diameter-size and shape effects on their applications in magnetism, lithium ion battery, and gas sensors.

    PubMed

    Wu, Changzheng; Yin, Ping; Zhu, Xi; OuYang, Chuanzi; Xie, Yi

    2006-09-14

    We demonstrated in this paper the shape-controlled synthesis of hematite (alpha-Fe(2)O(3)) nanostructures with a gradient in the diameters (from less than 20 nm to larger than 300 nm) and surface areas (from 5.9 to 52.3 m(2)/g) through an improved synthetic strategy by adopting a high concentration of inorganic salts and high temperature in the synthesis systems to influence the final products of hematite nanostructures. The benefits of the present work also stem from the first report on the <20-nm-diameter and porous hematite nanorods, as well as a new facile strategy to the less-than-20-nm nanorods, because the less-than-20-nm diameter size meets the vital size domain for magnetization properties in hematite. Note that the porous and nonporous hematite one-dimensional nanostructures with diameter gradients give us the first opportunity to investigate the Morin temperature evolution of nanorod diameter and porosity. Evidently, the magnetic properties for nanorods exhibit differences compared with those for the spherical particle counterparts. Hematite nanorods are strongly dependent on their diameter size and porosity, where the magnetization is not sensitive to the size evolution from submicron particles to the 60-90 nm nanorods, while the magnetic properties change significantly in the case of <20 nm. In other words, for the magnetic properties of nanorods, in a comparable size range, the porous existence could also influence the magnetic behavior. Moreover, applications in formaldehyde (HCHO) gas sensors and lithium batteries for the hematite nanostructures with the diameter/surface area gradient reveal that the performance of electrochemical and gas-sensor properties strongly depends on the diameter size and Brunauer-Emmett-Teller (BET) surface areas, which is consistent with the crystalline point of view. Thus, this work not only provides the first example of the fabrication of hematite nanostructure sensors for detecting HCHO gas, but also reveals that the

  8. SDS-assisted hydrothermal synthesis of NiO flake-flower architectures with enhanced gas-sensing properties

    NASA Astrophysics Data System (ADS)

    Miao, Ruiyang; Zeng, Wen; Gao, Qi

    2016-10-01

    A facile hydrothermal route was developed for the preparation of well-aligned hierarchical flower-like NiO nanostructure with the assistance of SDS that served as a structure-directing agent as well as a capping agent in the process of aggregation and assembly. Notably, the NiO sensors exhibit enhanced gas-sensing performance towards ethanol, which could be explained in association with the ultrathin nanosheets that are close to Debye length (LD) scale and thus get the majority carriers fully depleted due to the ionization of adsorbed oxygen, abundant effective gas diffusion paths as well as high surface-to-volume ratio to promote sufficient contact and reaction between the NiO sample and ethanol molecules, and numerous miniature reaction rooms assembled with nanosheets to make the test gas molecules stay long enough for completed gas-sensing reactions. Besides, a novel growth mechanism with the passage of reaction time was also proposed in detail.

  9. Sustainable synthesis of aldehydes, ketones or acids from neat alcohols using nitrogen dioxide gas, and related reactions.

    PubMed

    Naimi-Jamal, M Reza; Hamzeali, Hamideh; Mokhtari, Javad; Boy, Jürgen; Kaupp, Gerd

    2009-01-01

    Benzylic alcohols are quantitatively oxidized by gaseous nitrogen dioxide to give pure aromatic aldehydes. The reaction gas mixtures are transformed to nitric acid, which renders the processes free of waste. The exothermic gas-liquid or gas-solid reactions profit from the solubility of nitrogen dioxide in the neat benzylic alcohols. The acid formed impedes further oxidation of the benzaldehydes. The neat isolated benzaldehydes and nitrogen dioxide quantitatively give the benzoic acids. Solid long-chain primary alcohols are directly and quantitatively oxidized with nitrogen dioxide gas to give the fatty acids in the solid state. The oxidations with ubiquitous nitrogen dioxide are extended to solid heterocyclic thioamides, which gives disulfides, and to diphenylamine, which gives tetraphenylhydrazine. These sustainable (green) specific oxidation procedures produce no dangerous residues from the oxidizing agent or from auxiliaries. PMID:19115303

  10. The economical production of alcohol fuels from coal-derived synthesis gas. Quarterly technical progress report No. 16, July 1, 1995--September 30, 1995

    SciTech Connect

    1995-10-01

    The objective of Task 1 is to prepare and evaluate catalysts and to develop efficient reactor systems for the selective conversion of hydrogen-lean synthesis gas to alcohol fuel extenders and octane enhancers. Task 1 is subdivided into three separate subtasks: laboratory setup; catalysis research; and reaction engineering and modeling. Research at West Virginia University (WVU) is focused on molybdenum-based catalysts for higher alcohol synthesis (HAS). Parallel research carried out at Union Carbide Chemicals and Plastics (UCC&P) is focused on transition-metal-oxide catalysts. Accomplishments to date are discussed in this report. In Task 2, during the past three months, much has been accomplished in fuel testing. Several tests have been run on pure indolene, and the data have been analyzed from these tests. The two limiting alcohol blends have been made, sent out for analysis and the results obtained. The emissions sampling system is undergoing changes necessary for running alcohol fuels. A cylinder pressure measurement system has been installed.

  11. A facile and green approach for the controlled synthesis of porous SnO₂ nanospheres: application as an efficient photocatalyst and an excellent gas sensing material.

    PubMed

    Manjula, P; Boppella, Ramireddy; Manorama, Sunkara V

    2012-11-01

    A facile and elegant methodology invoking the principles of Green Chemistry for the synthesis of porous tin dioxide nanospheres has been described. The low-temperature (∼50 °C) synthesis of SnO₂ nanoparticles and their self-assembly into organized, uniform, and monodispersed porous nanospheres with high surface area is facilitated by controlling the concentration of glucose, which acts as a stabilizing as well as structure-directing agent. A systematic control on the stannate to glucose molar concentration ratio determines the exact conditions to obtain monodispersed nanospheres, preferentially over random aggregation. Detailed characterization of the structure, morphology, and chemical composition reveals that the synthesized material, 50 nm SnO₂ porous nanospheres possess BET surface area of about 160 m²/g. Each porous nanosphere consists of a few hundred nanoparticles ∼2-3 nm in diameter with tetragonal cassiterite crystal structure. The SnO₂ nanospheres exhibit elevated photocatalytic activity toward methyl orange with good recyclability. Because of the high activity and stability of this photocatalyst, the material is ideal for applications in environmental remediation. Moreover, SnO₂ nanospheres display excellent gas sensing capabilities toward hydrogen. Surface modification of the nanospheres with Pd transforms this sensing material into a highly sensitive and selective room-temperature hydrogen sensor.

  12. Novel approaches to the production of higher alcohols from synthesis gas. Quarterly technical progress report No. 17, October 1, 1994-- December 31, 1994

    SciTech Connect

    1996-07-05

    A series of experiments in which the stirrer speed was varied during a methanol synthesis run with BASF S3-86 catalyst showed that mass transfer limitations were present at 750 psig reactor pressure and at space velocities of 5000 and 10000 sl/kg(cat.)-hr.. There was no effect of stirrer speed on reaction rate at 2500 psig reactor pressure and 16500 sl/kg(cat.)-hr. space velocity. However, this was probably due to a close approach to equilibrium rather than to the lack of a mass transfer effect. The most plausible explanation for the presence of a mass transfer influence is the position of the gas feed dip tube relative to the agitator impeller. A second set of stirrer speed experiments using the same catalyst showed that feeding into the reactor headspace produced much lower reaction rates, compared with gas feed through a dip tube. The headspace feed also showed a strong dependence on stirrer speed, consistent with the dip tube feed results. In a ``blank` run at 375{degree}C with decahydronaphthalene, about 110 mL of the initial charge of 150 mL remained in the reactor after 73 hours of operation at 375{degree}C and 850 psig of hydrogen. The rate of hydrocarbon evolution was low throughout the run. Decalin is the most stable liquid identified to date. Three stirred autoclave runs with a commercial, high-pressure methanol synthesis catalyst (zinc chromite) slurried in decahydronaphthalene ended son after the initial catalyst reduction due to failures of the liquid return pump in the overhead system. However, the catalyst appeared to be reduced and the liquid appeared to be stable. 4 figs., 1 tab.

  13. Gas-Phase Synthesis of Boronylallene (H2CCCH(BO)) under Single Collision Conditions: A Crossed Molecular Beams and Computational Study.

    PubMed

    Maity, Surajit; Parker, Dorian S N; Kaiser, Ralf I; Ganoe, Brad; Fau, Stefan; Perera, Ajith; Bartlett, Rodney J

    2014-05-15

    The gas phase reaction between the boron monoxide radical ((11)BO; X(2)Σ(+)) and allene (H2CCCH2; X(1)A1) was investigated experimentally under single collision conditions using the crossed molecular beam technique and theoretically exploiting ab initio electronic structure and statistical (RRKM) calculations. The reaction was found to follow indirect (complex forming) scattering dynamics and proceeded via the formation of a van der Waals complex ((11)BOC3H4). This complex isomerized via addition of the boron monoxide radical ((11)BO; X(2)Σ(+)) with the radical center located at the boron atom to the terminal carbon atom of the allene molecule forming a H2CCCH2(11)BO intermediate on the doublet surface. The chemically activated H2CCCH2(11)BO intermediate underwent unimolecular decomposition via atomic hydrogen elimination from the terminal carbon atom holding the boronyl group through a tight exit transition state to synthesize the boronylallene product (H2CCCH(11)BO) in a slightly exoergic reaction (55 ± 11 kJ mol(-1)). Statistical (RRKM) calculations suggest that minor reaction channels lead to the products 3-propynyloxoborane (CH2((11)BO)CCH) and 1-propynyloxoborane (CH3CC(11)BO) with fractions of 1.5% and 0.2%, respectively. The title reaction was also compared with the cyano (CN; X(2)Σ(+))-allene and boronyl-methylacetylene reactions to probe similarities, but also differences of these isoelectronic systems. Our investigation presents a novel gas phase synthesis and characterization of a hitherto elusive organyloxoborane (RBO) monomer-boronylallene-which is inherently tricky to isolate in the condensed phase except in matrix studies; our work further demonstrates that the crossed molecular beams approach presents a useful tool in investigating the chemistry and synthesis of highly reactive organyloxoboranes. PMID:24806514

  14. The economical production of alcohol fuels from coal-derived synthesis gas. Quarterly technical progress report No. 19, April 1, 1996--June 30, 1996

    SciTech Connect

    1996-07-01

    The objective of Task I is to prepare and evaluate catalysts and to develop efficient reactor systems for the selective conversion of hydrogen-lean synthesis gas to alcohol fuel extenders and octane enhancers. In Task 1, during this reporting period, we encountered and solved a problem in the analysis of the reaction products containing a small amount of heavy components. Subsequently, we continued with the major thrusts of the program. We analyzed the results from our preliminary studies on the packed-bed membrane reactor using the BASF methanol synthesis catalyst. We developed a quantitative model to describe the performance of the reactor. The effect of varying permeances and the effect of catalyst aging are being incorporated into the model. Secondly, we resumed our more- detailed parametric studies on selected non-sulfide Mo-based catalysts. Finally, we continue with the analysis of data from the kinetic study of a sulfided carbon-supported potassium-doped molybdenum-cobalt catalyst in the Rotoberty reactor. We have completed catalyst screening at UCC. The complete characterization of selected catalysts has been started. In Task 2, the fuel blends of alcohol and unleaded test gas 96 (UTG 96) have been made and tests have been completed. The testing includes knock resistance tests and emissions tests. Emissions tests were conducted when the engine was optimized for the particular blend being tested (i.e. where the engine produced the most power when running on the blend in question). The data shows that the presence of alcohol in the fuel increases the fuel`s ability to resist knock. Because of this, when the engine was optimized for use with alcohol blends, the engine produced more power and lower emission rates.

  15. Sol-gel synthesis of mesoporous CaCu{sub 3}Ti{sub 4}O{sub 12} thin films and their gas sensing response

    SciTech Connect

    Parra, R.; Savu, R.; Varela, J.A.; Bueno, P.R.

    2010-06-15

    A new sol-gel synthesis procedure of stable calcium copper titanate (CaCu{sub 3}Ti{sub 4}O{sub 12}-CCTO) precursor sols for the fabrication of porous films was developed. The composition of the sol was selected in order to avoid the precipitation of undesired phases; ethanol was used as solvent, acetic acid as modifier and poly(ethyleneglycol) as a linker agent. Films deposited by spin-coating onto oxidized silicon substrates were annealed at 700 {sup o}C. The main phase present in the samples, as detected by X-ray diffraction and Raman spectroscopy, was CaCu{sub 3}Ti{sub 4}O{sub 12}. Scanning electron microscopy analysis showed that mesoporous structures, with thicknesses between 200 and 400 nm, were developed as a result of the processing conditions. The films were tested regarding their sensibility towards oxygen and nitrogen at atmospheric pressure using working temperatures from 200 to 290 {sup o}C. The samples exhibited n-type conductivity, high sensitivity and short response times. These characteristics indicate that CCTO mesoporous structures obtained by sol-gel are suitable for application in gas sensing. - Graphical abstract: A sol-gel synthesis procedure toward stable CaCu{sub 3}Ti{sub 4}O{sub 12}-precursor sols avoiding the precipitation of undesired compounds is proposed. Films deposited by spin-coating onto oxidized silicon substrates were annealed at 700 {sup o}C. The thickness varied between 200 and 400 nm depending on sol composition. The films, tested as gas sensors for O{sub 2}, showed n-type conductivity, good sensitivity and short response times.

  16. Simultaneous amination of TiO2 nanoparticles in the gas phase synthesis for bio-medical applications

    NASA Astrophysics Data System (ADS)

    Lee, Kyoung-No; Kim, Yangeon; Lee, Chang-Woo; Lee, Jai-Sung

    2011-10-01

    A simultaneous synthesis and surface amination method to effectively modify the surface of inorganic nanoparticles is discussed in this study. As a target material system and surface functional group, TiO2 nanoparticles and amine were selected. APTES (3-aminopropyltriethoxysilane), the source of amine group, was mixed with TTIP (titanium tetraisopropoxide) and used for the synthesis of aminated TiO2 nanoparticles. XRD (X-ray diffractometry) results showed TiO2 nanoparticles of pure anatase phase, 15 nm in crystallite size, were successfully synthesized at 700°C and 50 mbar. Fourier transformation infrared (FT-IR) spectroscopy measurement and confocal microscopy study using fluoresceine isothiocyanate (FITC) confirmed that amine groups were successfully deposited and activated on the surface of TiO2 nanoparticles.

  17. Bench-scale demonstration of biological production of ethanol from coal synthesis gas. Quarterly report, October 1, 1993--December 31, 1993

    SciTech Connect

    Not Available

    1993-12-31

    This project describes a new approach to coal liquefaction, the biological conversion of coal synthesis gas into a liquid fuel, ethanol. A new bacterium, Clostridium Ijungdahlii, strain PETC, has been discovered and developed for this conversion, which also produces acetate as a by-product. Based upon the results of an exhaustive literature search and experimental data collected in the ERI laboratories, secondary and/or branched alcohols have been selected for ethanol extraction from the fermentation broth. 2,6 Methyl 4-heptanol has a measured distribution coefficient of 0.44 and a separation factor of 47. Methods to improve the results from extraction by removing water prior to distillation are under consideration. Several runs were performed in the two-stage CSTR system with Clostridium Ijungdahlii, strain PETC, with and without cell recycle between stages. Reduced gas flow rate, trypticase limitation and ammonia limitation as methods of maximizing ethanol production were the focus of the studies. With ammonia limitation, the ethanol:acetate product ratio reached 4.0.

  18. DEVELOPMENT OF NOVEL CERAMIC NANOFILM-FIBER INTEGRATED OPTICAL SENSORS FOR RAPID DETECTION OF COAL DERIVED SYNTHESIS GAS

    SciTech Connect

    Junhang Dong; Hai Xiao; Xiling Tang; Hongmin Jiang; Kurtis Remmel; Amardeep Kaur

    2012-09-30

    The overall goal of this project is to conduct fundamental studies on advanced ceramic materials and fiber optic devices for developing new types of high temperature (>500{degree}C) fiber optic chemical sensors (FOCS) for monitoring fossil (mainly coal) and biomass derived gases in power plants. The primary technical objective is to investigate and demonstrate the nanocrystalline doped-ceramic thin film enabled FOCS that possess desired stability, sensitivity and selectivity for in-situ, rapid gas detection in the syngas streams from gasification and combustion flue gases. This report summarizes research works of two integrated parts: (1) development of metal oxide solid thin films as sensing materials for detection and measurement of important gas components relevant to the coal- and biomass-derived syngas and combustion gas streams at high temperatures; and (2) development of fiber optic devices that are potentially useful for constructing FOCS in combination with the solid oxide thin films identified in this program.

  19. Synthesis and properties of nanostructured sol-gel sorbents for simultaneous removal of sulfur dioxide and nitrogen oxides from flue gas

    NASA Astrophysics Data System (ADS)

    Buelna Quijada, Genoveva

    2001-07-01

    Regenerative, alumina-supported, copper-based sorbent/catalysts provide a promising technique for simultaneous removal of SO2 and NO x from flue gas. These sorbents can remove over 90% of SO2 and 70+% of NOx while generating no wastes, reducing energy consumption, and producing valuable by-products. The lack of a cost-effective sorbent with low attrition rate and good reactivity has been the main hurdle to commercialization of this copper oxide process. Developing such a sorbent is the focus of this dissertation. This work examines using sol-gel techniques rather than traditional processes to produce gamma-alumina and copper coated 7-alumina granular sorbents. Important modifications to the established sol-gel synthesis process were made, which minimized generated wastes and reduced preparation time and sorbent cost. A laboratory scale semi-continuous process providing a basis for large-scale synthesis was developed. The effect of the copper content on the surface area and dispersion of the active species on sol-gel-derived sorbents coated by the one step and wet-impregnation methods was studied. The sol-gel-derived sorbents showed superior sulfation and regeneration properties than the existing commercial sorbents used in the copper oxide process in terms of sulfation capacity, fast regeneration, recovery of sorption capacity, and SO2 concentration in the regenerated effluent. The optimum temperature for NO reduction by NH3 over sol-gel-derived CuO/gamma-Al2O3 was found to be 350°C for both fresh and sulfated catalysts. This was also the optimum operating temperature for simultaneous removal of SO2 and NOx from simulated flue gas. At 350°C, the adsorption capacity of the sol-gel sorbent/catalyst was higher than UOP's sorbent, and very close to the capacity of ALCOA's sorbent, while the catalytic activity for NO reduction of the sol-gel-derived CuO/gamma-Al 2O3 sorbent fell between the commercial sorbents. The new mesoporous sol-gel-derived materials showed

  20. Synthesis of SnO2 nanoparticles using a solution plasma and their gas-sensing properties

    NASA Astrophysics Data System (ADS)

    Zhang, Jianbo; Hu, Xiulan; Shi, Junjun; Lu, Ping; Shen, Xiaodong; Xu, Peifeng; Saito, Nagahiro

    2016-01-01

    A simple solution plasma method was applied to the synthesis of SnO2 nanoparticles directly from tin(II) chloride solution, without adding any precipitant, stabilizer, or other agents at atmospheric pressure, because solution plasma provides a reaction field with a highly excited energy state. The results of X-ray power diffraction (XRD) analysis and transmission electron microscopy (TEM) verified that well-crystallized SnO2 nanoparticles in the size range of 2-5 nm were synthesized. SnO2 nanoparticles show satisfactory sensitivities to acetaldehyde and ethanol.

  1. The economical production of alcohol fuels from coal-derived synthesis gas. Quarterly technical progress report No. 4, July 1, 1992--September 30, 1992

    SciTech Connect

    Not Available

    1993-10-01

    A base case flow sheet for the production of higher alcohols from coal derived synthesis gas has been completed, including an economic analysis. The details of the flow sheet and economics are in Appendix 1. The pay back period for the capital investment for the plant has been calculated as a function of the market price of the product, and this figure is also shown as Figure I in Appendix 1. The estimated installed cost is almost $500 MM, and the estimated annual operating cost is $64 MM. At a price in the vicinity of $1.00/gal for the alcohol product, the pay back period for construction of the plant is four years. These values should be considered preliminary, since many of the capital costs were obtained from other paper studies sponsored by DOE and TVA and very few values could be found from actual plants which were built. This issue is currently being addressed. The most expensive capital costs were found to be the gasifier, the cryogenic air separation plant, the steam/power generation plant and the acid gas/sulfur removal processes taken as a whole. It is planned to focus attention on alternatives to the base case. The problem is that it is less expensive to make syngas from natural gas. Therefore, it is essential to reduce the cost of syngas from coal. This is where the energy park concept becomes important. In order for this process to be economical (at current market and political conditions) a method must be found to reduce the cost of syngas manufacture either by producing energy or by-products. Energy is produced in the base case, but the amount and method has not been optimized. The economic arguments for this concept are detailed in Appendix 2.

  2. Synthesis of Trace Gas and Aerosol Observations and Evaluation of Modelled Short-lived Climate Pollutants Across the Pan-Eurasian High Latitudes

    NASA Astrophysics Data System (ADS)

    Arnold, S.; Nieminen, T.

    2015-12-01

    Model calculations suggest that changes in short-lived climate pollutants (SLCPs) such as ozone and aerosol may have contributed significantly to rapid Arctic warming over the past century. Arctic tropospheric budgets of SLCPs are impacted by long-range transport of trace gases and aerosols from Europe, Asia and N. America, but also by local sources such as gas flaring, shipping and boreal fires. Recently, the POLARCAT Model Intercomparison Project (POLMIP) showed that significant model biases persist through the depth of the European and North American high latitude troposphere in modelled trace-gas abundances. Evaluation of models over the Siberian high latitudes is challenging due to a severe paucity of available observations, despite the potential importance of this region as a route for European pollution export to the Arctic. Despite the existence of a number of limited datasets, which could be used for model evaluation in this region, until now no effort has been made to synthesise and exploit these observations to evaluate modelled abundances of SLCPs such as tropospheric ozone & aerosol. In this presentation, we will show evaluation of simulated aerosol, tropospheric ozone, and precursor species in several global chemical transport models, using a synthesis of available surface, aircraft and satellite observations over the high latitude pan-Eurasian region. We use models and observations to investigate source regions contributing to remote Siberian SLCP abundances over the annual cycle, and show substantial biases in simulated aerosol and trace gas concentrations that are consistent across a suite of different models. These comparisons constitute the first multi-model evaluation of tropospheric composition in the pan-Eurasin region using observations from across the broad region. Finally, we use the model simulations to determine optimum locations for the development of future monitoring activities in high latitude Eurasia with an aim of better

  3. Synthesis, Structure, and Ethanol Gas Sensing Properties of In2O3 Nanorods Decorated with Bi2O3 Nanoparticles.

    PubMed

    Park, Sunghoon; Kim, Soohyun; Sun, Gun-Joo; Lee, Chongmu

    2015-04-22

    Bi2O3-decorated In2O3 nanorods were synthesized using a one-step process, and their structure, as well as the effects of decoration of In2O3 nanorods with Bi2O3 on the ethanol gas-sensing properties were examined. The multiple networked Bi2O3-decorated In2O3 nanorod sensor showed responses of 171-1774% at ethanol concentrations of 10-200 ppm at 200 °C. The responses of the Bi2O3-decorated In2O3 nanorod sensor were stronger than those of the pristine-In2O3 nanorod sensors by 1.5-4.9 times at the corresponding concentrations. The two sensors exhibited short response times and long recovery times. The optimal Bi concentration in the Bi2O3-decorated In2O3 nanorod sensor and the optimal operation temperature of the sensor were 20% and 200 °C, respectively. The Bi2O3-decorated In2O3 nanorod sensor showed selectivity for ethanol gas over other gases. The origin of the enhanced response, sensing speed, and selectivity for ethanol gas of the Bi2O3-decorated In2O3 nanorod sensor to ethanol gas is discussed.

  4. Thermal oxidation synthesis hollow MoO{sub 3} microspheres and their applications in lithium storage and gas-sensing

    SciTech Connect

    Zhao, Xinyu; Cao, Minhua; Hu, Changwen

    2013-06-01

    Graphical abstract: MoO{sub 3} hollow microspheres were synthesized via a facile and template-free solvothermal route and subsequent heat treatment in air. The MoO{sub 3} hollow microspheres exhibit an improved lithium storage and gas-sensing performance. Highlights: ► Hollow MoO{sub 3} microspheres were synthesized by thermal oxidation of hollow MoO{sub 2}. ► The MoO{sub 3} hollow microspheres have a relatively high specific surface area. ► The MoO{sub 3} hollow microspheres exhibit improved lithium storage performance. ► The MoO{sub 3} hollow microspheres show good responses to ammonia gas. - Abstract: In this paper, MoO{sub 3} hollow microspheres were synthesized via a facile and template-free solvothermal route and subsequent heat treatment in air. The MoO{sub 3} hollow microspheres have a relatively high specific surface area, and with such a feature, the as-synthesized MoO{sub 3} hollow microspheres have potential applications in Li-ion battery and gas-sensor. When tested as a Li-storage anode material, the MoO{sub 3} hollow microspheres show a higher discharge capacity of 1377.1 mA h g{sup −1} in the first discharge and a high reversible capacity of 780 mA h g{sup −1} after 100 cycles at a rate of 1 C. Furthermore, as a gas sensing material, the MoO{sub 3} hollow microspheres exhibit an improved sensitivity and short response/recovery time to trace levels of ammonia gas.

  5. Synthesis, characterization and enhanced gas sensing performance of porous ZnCo2O4 nano/microspheres

    NASA Astrophysics Data System (ADS)

    Liu, Tie; Liu, Jingyuan; Liu, Qi; Song, Dalei; Zhang, Hongseng; Zhang, Hongquan; Wang, Jun

    2015-11-01

    In recent years, spinel-type compounds have attracted great interest because of their gem-like qualities. However, little is known of their gas sensing properties. We report, in this paper, on a self-assembly method to prepare porous ZnCo2O4 (ZCO) nano/microspheres by a facile one-step solvothermal process and subsequent annealing. Abundant techniques were used to characterize the morphology and structure of the as-obtained compounds. Our data indicate that the hierarchical nano/microspheres are constructed from numerous nanoparticles primarily, which have a higher specific surface area (ca. 77.3 m2 g-1) and are of uniform diameter (ca. 1 μm). To demonstrate their potential application, gas sensors based on the as-synthesized ZCO nano/microspheres were fabricated to test their sensing performance, whose sensing behaviours correspond to p-type semiconductors. The test results also indicate that porous spinel-type compounds have an excellent kinetic response to ethanol at an operating temperature of 175 °C and a superior selectivity. As such, hierarchical porous ZnCo2O4 nano/microspheres will hold promising potential in the gas sensor field.In recent years, spinel-type compounds have attracted great interest because of their gem-like qualities. However, little is known of their gas sensing properties. We report, in this paper, on a self-assembly method to prepare porous ZnCo2O4 (ZCO) nano/microspheres by a facile one-step solvothermal process and subsequent annealing. Abundant techniques were used to characterize the morphology and structure of the as-obtained compounds. Our data indicate that the hierarchical nano/microspheres are constructed from numerous nanoparticles primarily, which have a higher specific surface area (ca. 77.3 m2 g-1) and are of uniform diameter (ca. 1 μm). To demonstrate their potential application, gas sensors based on the as-synthesized ZCO nano/microspheres were fabricated to test their sensing performance, whose sensing behaviours

  6. Synthesis of Aluminum-Aluminum Nitride Nanocomposites by Gas-Liquid Reactions I. Thermodynamic and Kinetic Considerations

    NASA Astrophysics Data System (ADS)

    Borgonovo, Cecilia; Makhlouf, Makhlouf M.

    2016-10-01

    In-situ fabrication of the reinforcing particles directly in the metal matrix is an answer to many of the challenges encountered in manufacturing metal matrix nanocomposite materials. In this method, the nanosized particles are formed directly within the melt by means of a chemical reaction between a specially designed metallic alloy and a reactive gas. The thermodynamic and kinetic characteristics of this chemical reaction dictate the particle size and distribution in the matrix alloy, as well as the nature of the particle/matrix interface, and consequently, they govern many of the material's mechanical and physical properties. This article focuses on aluminum-aluminum-nitride nanocomposite materials that are synthesized by injecting a nitrogen-bearing gas into a molten aluminum alloy. The thermodynamic and kinetic aspects of the process are modeled, and the detrimental role of oxygen is elucidated.

  7. Synthesis of Aluminum-Aluminum Nitride Nanocomposites by Gas-Liquid Reactions I. Thermodynamic and Kinetic Considerations

    NASA Astrophysics Data System (ADS)

    Borgonovo, Cecilia; Makhlouf, Makhlouf M.

    2016-07-01

    In-situ fabrication of the reinforcing particles directly in the metal matrix is an answer to many of the challenges encountered in manufacturing metal matrix nanocomposite materials. In this method, the nanosized particles are formed directly within the melt by means of a chemical reaction between a specially designed metallic alloy and a reactive gas. The thermodynamic and kinetic characteristics of this chemical reaction dictate the particle size and distribution in the matrix alloy, as well as the nature of the particle/matrix interface, and consequently, they govern many of the material's mechanical and physical properties. This article focuses on aluminum-aluminum-nitride nanocomposite materials that are synthesized by injecting a nitrogen-bearing gas into a molten aluminum alloy. The thermodynamic and kinetic aspects of the process are modeled, and the detrimental role of oxygen is elucidated.

  8. Selective interfacial synthesis of metal-organic frameworks on a polybenzimidazole hollow fiber membrane for gas separation.

    PubMed

    Biswal, Bishnu P; Bhaskar, Anand; Banerjee, Rahul; Kharul, Ulhas K

    2015-04-28

    Metal-organic frameworks (MOFs) have gained immense attention as new age materials due to their tuneable properties and diverse applicability. However, efforts on developing promising materials for membrane based gas separation, and control over the crystal growth positions on polymeric hollow fiber membranes still remain key challenges. In this investigation, a new, convenient and scalable room temperature interfacial method for growing MOFs (ZIF-8 and CuBTC) on either the outer or inner side of a polybenzimidazole based hollow fiber (PBI-BuI-HF) membrane surface has been achieved in a controlled manner. This was made possible by the appropriate selection of an immiscible solvent pair and the synthetic conditions. The growth of MOFs on the PBI-BuI-HF membrane by the interfacial method was continuous and showed an appreciable gas separation performance, conveying promise for their applicability.

  9. Selective interfacial synthesis of metal-organic frameworks on a polybenzimidazole hollow fiber membrane for gas separation

    NASA Astrophysics Data System (ADS)

    Biswal, Bishnu P.; Bhaskar, Anand; Banerjee, Rahul; Kharul, Ulhas K.

    2015-04-01

    Metal-organic frameworks (MOFs) have gained immense attention as new age materials due to their tuneable properties and diverse applicability. However, efforts on developing promising materials for membrane based gas separation, and control over the crystal growth positions on polymeric hollow fiber membranes still remain key challenges. In this investigation, a new, convenient and scalable room temperature interfacial method for growing MOFs (ZIF-8 and CuBTC) on either the outer or inner side of a polybenzimidazole based hollow fiber (PBI-BuI-HF) membrane surface has been achieved in a controlled manner. This was made possible by the appropriate selection of an immiscible solvent pair and the synthetic conditions. The growth of MOFs on the PBI-BuI-HF membrane by the interfacial method was continuous and showed an appreciable gas separation performance, conveying promise for their applicability.Metal-organic frameworks (MOFs) have gained immense attention as new age materials due to their tuneable properties and diverse applicability. However, efforts on developing promising materials for membrane based gas separation, and control over the crystal growth positions on polymeric hollow fiber membranes still remain key challenges. In this investigation, a new, convenient and scalable room temperature interfacial method for growing MOFs (ZIF-8 and CuBTC) on either the outer or inner side of a polybenzimidazole based hollow fiber (PBI-BuI-HF) membrane surface has been achieved in a controlled manner. This was made possible by the appropriate selection of an immiscible solvent pair and the synthetic conditions. The growth of MOFs on the PBI-BuI-HF membrane by the interfacial method was continuous and showed an appreciable gas separation performance, conveying promise for their applicability. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr00299k

  10. Ethanol synthesis and water gas shift over bifunctional sulfide catalysts. Technical progress report, September 1993--November 1993

    SciTech Connect

    Klier, K.; Herman, R.; Deemer, M.

    1994-03-01

    During calcination of the precipitated and dried MoS{sub 3} to form MOS{sub 2}, it was found that small sample sizes were needed to provide thermal control of the highly exothermic decomposition reaction in the 8 mm ID quartz tube used for this purpose. Characterization of MoS{sub 2} and Cs/MoS{sub 2} catalysts have been carried out by X-ray powder diffraction (XRD) after each synthesis step. In addition, the XRD analyses were conducted after prolonged air exposure of the Cs-doped MoS{sub 2} catalyst. It was shown that prolonged exposure to the ambient atmosphere led to segregation and crystallization of the cesium formate dopant. Thus, catalytic testing should be carried out with freshly prepared samples that are protected from the ambient atmosphere. Catalytic testing is underway to determine if there is an inverse correlation of catalytic activity and selectivity with prolonged air exposure of the catalyst.

  11. Controllable Low-Temperature Hydrothermal Synthesis and Gas-Sensing Investigation of Crystalline SnO2 Nanoparticles

    NASA Astrophysics Data System (ADS)

    Lu, Ping; Hu, Xiulan; Huang, Huihong; Hu, Ning; Zhang, Jianbo; Shen, Xiaodong

    2016-04-01

    SnO2 nanoparticles have been successfully synthesized by a facile hydrothermal method from SnCl2·2H2O, hexamethylenetetramine, and trisodium citrate in water at 120 °C for 12 h. The effects of surfactant and precipitant on SnO2 synthesis were investigated. SnO2 nanoparticles can be synthesized in the temperature range of 120-180 °C with long reaction time in the presence of trisodium citrate. When NaOH was used as precipitant instead of hexamethylenetetramine, it is difficult to obtain SnO2 nanoparticles at 120 °C in the presence of trisodium citrate. SnO2 nanoparticles with an average size of about 5 nm show good crystallinity and excellent sensitivity to ethanol and acetaldehyde in about 55% relative humidity.

  12. Biological conversion of synthesis gas. [Quarterly] technical report No. 2-1, September 5, 1991--December 4, 1991

    SciTech Connect

    Not Available

    1992-01-06

    The anaerobic bacterium Rhodospirillum rubrum has been chosen for catalysis of the biological water gas shift reaction. Two bacteria, Chlorobium thiosulfatophilum and Chlorobium phaeobacteroides, are being evaluated as candidates for H{sub 2}S conversion to elemental sulfur. Since these latter two organisms both grow and convert H{sub 2}S in batch culture using standard basal medium, the choice of a suitable bacterium must be made in consideration of specific growth and uptake rates. Produced elemental sulfur stability against further oxidation to sulfate, and minimal use of H{sub 2} as a producing agent must also be considered. The effects of temperature on the performance of R. rubrum were evaluated. It was found that the cell concentration was highest at temperatures of 25 and 30{degree}C, and that the specific uptake rate was highest at temperatures of 30, 32 and 34{degree}C. No growth was observed at 37{degree}C. Also, temperature did not affect the yield of H{sub 2} from CO. Thus, R. rubrum may be used for biological rates gas shift at any temperature between 30 and 34{degree}C, although growth is maximized at lower temperatures. Preliminary studies with C. thiosulfatophilum showed rapid utilization of H{sub 2}S from the gas and liquid phases with subsequent production of elemental sulfur. Elemental sulfur production interfered with cell concentrations measurements, although a technique has been developed to rectify this problem.

  13. Synthesis, characterization and enhanced gas sensing performance of porous ZnCo2O4 nano/microspheres.

    PubMed

    Liu, Tie; Liu, Jingyuan; Liu, Qi; Song, Dalei; Zhang, Hongseng; Zhang, Hongquan; Wang, Jun

    2015-12-14

    In recent years, spinel-type compounds have attracted great interest because of their gem-like qualities. However, little is known of their gas sensing properties. We report, in this paper, on a self-assembly method to prepare porous ZnCo2O4 (ZCO) nano/microspheres by a facile one-step solvothermal process and subsequent annealing. Abundant techniques were used to characterize the morphology and structure of the as-obtained compounds. Our data indicate that the hierarchical nano/microspheres are constructed from numerous nanoparticles primarily, which have a higher specific surface area (ca. 77.3 m(2) g(-1)) and are of uniform diameter (ca. 1 μm). To demonstrate their potential application, gas sensors based on the as-synthesized ZCO nano/microspheres were fabricated to test their sensing performance, whose sensing behaviours correspond to p-type semiconductors. The test results also indicate that porous spinel-type compounds have an excellent kinetic response to ethanol at an operating temperature of 175 °C and a superior selectivity. As such, hierarchical porous ZnCo2O4 nano/microspheres will hold promising potential in the gas sensor field.

  14. Physical synthesis methodology and enhanced gas sensing and photoelectrochemical performance of 1D serrated zinc oxide-zinc ferrite nanocomposites.

    PubMed

    Liang, Yuan-Chang; Liu, Shang-Luen; Hsia, Hao-Yuan

    2015-12-01

    We successfully prepared one-dimensional ZnO-ZnFe2O4 (ZFO) heterostructures for acetone gas-sensing and photoelectrochemical applications, by using sputter deposition of ZFO crystallites on ZnO nanostructure templates. The nanoscale ZFO crystallites were homogeneously coated on the surfaces of the ZnO nanostructures. Electron microscope images revealed that the ZnO-ZFO heterostructures exhibited a serrated surface morphology. Coating the ZnO nanostructures with a ZFO aggregated layer appreciably enhanced their acetone gas-sensing capability at 250 °C in comparison with pure ZnO nanostructures. The presence of many depleted nanoscale ZFO crystallites, the rugged surface of the heterostructures, and electron depletion at the ZnO/ZFO interface might contribute to the enhanced acetone gas-sensing response. Furthermore, the larger surface area and higher light absorption of ZnO-ZFO relative to the surface area and light absorption of ZnO were correlated with a substantial enhancement of the photocurrent value of ZnO-ZFO in photoelectrochemical tests produced by the simulated solar light irradiation.

  15. Synthesis and enhanced NO2 gas sensing properties of ZnO nanorods/TiO2 nanoparticles heterojunction composites.

    PubMed

    Zou, C W; Wang, J; Xie, W

    2016-09-15

    ZnO nanorods/TiO2 nanoparticles composites were synthesized and the effects of TiO2 concentrations on the NO2 sensing properties were studied in detail. The as-prepared composites were characterized by XRD, SEM, TEM, PL, I-V and gas sensing measurements. The gas sensing results demonstrated that all the sensors based on ZnO/TiO2 nanocomposites exhibited much higher response than that of sensors based on pure ZnO nanorods. At the optimum operating temperature of 180°C, the response values of the sensors based on ZnO/TiO2 nanocomposites decorated with TiO2 concentrations of 0, 3, 5, 8 and 10wt% were 50, 140, 310, 350 and 258, respectively. The PL and I-V results indicated that the increased charge transfer between the ZnO nanorods mediated by TiO2 nanoparticles enhanced the conductivity of the ZnO/TiO2 nanocomposites. The gas sensing mechanism was also carefully analyzed. The attachment of TiO2 nanoparticles onto ZnO nanorods induced more active sites for the adsorption of oxygen molecules (O(2)) and O(2) which can be more easily adsorbed on the surface of ZnO nanorods. Furthermore, the conduction channel of ZnO/TiO2 was much narrower as a result of the formation of heterojunction which may further contribute to the enhanced NO2 sensing properties.

  16. COMPARISON OF SODIUM AND POTASSIUM CARBONATES AS LITHIUM ZIRCONATE MODIFIERS FOR HIGH-TEMPERATURE CARBON DIOXIDE CAPTURE FROM BIOMASS-DERIVED SYNTHESIS GAS

    SciTech Connect

    Olstad, J.L.; Phillips, S.D.

    2009-01-01

    The process of gasifi cation converts biomass into synthesis gas (syngas), which can be used to produce biofuels. Solid-phase sorbents were investigated for the removal of CO2 from a N2/CO2 gas stream using a CO2 concentration similar to that found in a biomass gasifi cation process. During the gasifying process, large amounts of carbon dioxide (CO2) are created along with the syngas. The produced CO2 must be removed before the syngas can be used for fuel synthesis and to avoid the possible formation of unwanted byproducts. A thermogravimetric analyzer was used to test the CO2 absorption rates of sorbents composed of lithium zirconate (Li2ZrO3), as well as mixtures of Li2ZrO3 with potassium carbonate (K2CO3) and sodium carbonate (Na2CO3). The experimental results show that Li2ZrO3 has a low absorption rate, but sorbents containing combinations of Li2ZrO3 and the K2CO3 and Na2CO3 additives have high uptake rates. Using different proportions of K2CO3 and Na2CO3 produces varying uptake rates, so an optimization experiment was performed to obtain an improved sorbent. The CO2 absorption and regeneration stability of the solid-phase sorbents were also examined. A sorbent composed of Li2ZrO3 and 12.1 weight % Na2CO3 was shown to be stable, based on the consistent CO2 uptake rates. Sorbents prepared with Li2ZrO3, 17.6 weight % K2CO3 and 18.1 weight % Na2CO3 showed instability during regeneration cycles in air at 800 °C. Sorbent stability improved during regeneration cycles at 700 °C. Further testing of the Li2ZrO3 sorbent under actual syngas conditions, including higher pressure and composition, should be done. Once the optimum sorbent has been found, a suitable support will be needed to use the sorbent in an actual reactor.

  17. Synthesis, characterization, and hydrogen gas sensing properties of AuNs-catalyzed ZnO sputtered thin films

    NASA Astrophysics Data System (ADS)

    Drmosh, Q. A.; Yamani, Z. H.

    2016-07-01

    Hydrogen present in concentration up to 4 vol.% forms an explosive mixture with air. Its propensity to escape in the event of leak, could lead to quick build-up and formation of an explosive mixture with air in confined spaces, such as an automobile. This necessitates its detection at very low concentration. Zinc oxide (ZnO) is a well-known wide band gap (∼3.37 eV) semiconducting oxide that has been widely used for gas sensing applications. This work reports on the fabrication, characterization and gas sensing performance of nanogold decorated ZnO thin films made by DC reactive sputtering. The sensor films were fabricated by depositing a very thin layer of gold on the sputtered ZnO thin film. The as deposited Au@ZnO films were converted into highly crystalline ZnO film covered with gold nanostructures (AuNs@ZnO) by mild heat treatment. The structural and morphological as well as the compositional homogeneity of the as-deposited and heat-treated ZnO, Au@ZnO and AuNs@ZnO thin films were ascertained. The gas sensing behavior of the AuNs@ZnO thin films towards hydrogen as a function of temperature at different H2 concentrations was investigated and compared with that of pure and heat-treated ZnO films. The effect of the presence of gold nanoparticles on imparting improvement (in terms of higher response signal, high reproducibility and complete reversibility) was established; the optimal operating temperature was about 400 °C. A plausible mechanism for the observed enhancement in the sensing behavior of AuNs@ZnO films towards H2 is proposed.

  18. Synthesis of trapezohedral indium oxide nanoparticles with high-index {211} facets and high gas sensing activity.

    PubMed

    Han, Xiguang; Han, Xiao; Sun, Linqiang; Gao, Shengguang; Li, Liang; Kuang, Qin; Xie, Zhaoxiong; Wang, Chao

    2015-06-14

    Nanocrystals with high-index facets usually exhibit higher catalytic activities than those with only low-index facets. Trapezohedron-shaped (TS) In2O3 particles with exposed high-index {211} facets were successfully synthesized in an oleic acid (OA) and trioctylamine (TOA) system. It has been demonstrated that the gas sensing activity of TS In2O3 particles with exposed high-index {211} facets is higher than that of octahedron-shaped In2O3 particles with exposed low-index {111} facets. PMID:25930122

  19. Direct synthesis of large size ferromagnetic SmCo{sub 5} nanoparticles by a gas-phase condensation method

    SciTech Connect

    He Shihai; Jing Ying; Wang Jianping

    2013-04-07

    Ferromagnetic SmCo{sub 5} nanoparticles with large size have been directly synthesized by a magnetron-sputtering-based gas-phase condensation method. Based on this method, we studied the effect of thermodynamic environment for the growth of SmCo{sub 5} nanoparticles. It was found that the well-crystallized SmCo{sub 5} nanoparticle tends to form a hexagonal disk shape with its easy axis perpendicular to the disk plane. More importantly, under the condition of high sputtering current, well-crystallized nanoparticles were found to be formed through a three-stage growth process: aggregation, coalescence, and second crystallization.

  20. Synthesis of trapezohedral indium oxide nanoparticles with high-index {211} facets and high gas sensing activity.

    PubMed

    Han, Xiguang; Han, Xiao; Sun, Linqiang; Gao, Shengguang; Li, Liang; Kuang, Qin; Xie, Zhaoxiong; Wang, Chao

    2015-06-14

    Nanocrystals with high-index facets usually exhibit higher catalytic activities than those with only low-index facets. Trapezohedron-shaped (TS) In2O3 particles with exposed high-index {211} facets were successfully synthesized in an oleic acid (OA) and trioctylamine (TOA) system. It has been demonstrated that the gas sensing activity of TS In2O3 particles with exposed high-index {211} facets is higher than that of octahedron-shaped In2O3 particles with exposed low-index {111} facets.

  1. Rapid synthesis and characterization of hybrid ZnO@Au core-shell nanorods for high performance, low temperature NO2 gas sensor applications

    NASA Astrophysics Data System (ADS)

    Ponnuvelu, Dinesh Veeran; Pullithadathil, Biji; Prasad, Arun K.; Dhara, Sandip; Ashok, Anuradha; Mohamed, Kamruddin; Tyagi, Ashok Kumar; Raj, Baldev

    2015-11-01

    A rapid synthesis route for hybrid ZnO@Au core-shell nanorods has been realized for ultrasensitive, trace-level NO2 gas sensor applications. ZnO nanorods and hybrid ZnO@Au core-shell nanorods are structurally analyzed using X-ray diffraction (XRD), high resolution transmission electron microscopy (HR-TEM) and X-ray photoelectron spectroscopy (XPS). Optical characterization using UV-visible (UV-vis), photoluminescence (PL) and Raman spectroscopies elucidate alteration in the percentage of defect and charge transport properties of ZnO@Au core-shell nanorods. The study reveals the accumulation of electrons at metal-semiconductor junctions leading to upward band bending for ZnO and thus favors direct electron transfer from ZnO to Au nanoclusters, which mitigates charge carrier recombination process. The operating temperature of ZnO@Au core-shell nanorods based sensor significantly decreased to 150 °C compared to alternate NO2 sensors (300 °C). Moreover, a linear sensor response in the range of 0.5-5 ppm of NO2 concentration was observed with a lowest detection limit of 500 ppb using conventional electrodes. The defects with deep level, observed in ZnO nanorods and hybrid ZnO@Au core-shell nanorods influences local electron density, which in-turn indirectly influence the gas sensing properties. The ZnO@Au core-shell nanorods based sensor exhibited good selectivity toward NO2 and was found to be very stable.

  2. Hybrid organotin and tin oxide-based thin films processed from alkynylorganotins: synthesis, characterization, and gas sensing properties.

    PubMed

    Renard, Laetitia; Brötz, Joachim; Fuess, Hartmut; Gurlo, Aleksander; Riedel, Ralf; Toupance, Thierry

    2014-10-01

    Hydrolysis-condensation of bis(triprop-1-ynylstannyl)butylene led to nanostructured bridged polystannoxane films yielding tin dioxide thin layers upon UV-treatment or annealing in air. According to Fourier transform infrared (FTIR) spectroscopy, contact angle measurements, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and scanning electron microscopy (SEM) data, the films were composed of a network of aggregated "pseudo-particles", as calcination at 600 °C is required to form cassiterite nanocrystalline SnO2 particles. In the presence of reductive gases such as H2 and CO, these films gave rise to highly sensitive, reversible, and reproducible responses. The best selectivity toward H2 was reached at 150 °C with the hybrid thin films that do not show any response to CO at 20-200 °C. On the other hand, the SnO2 films prepared at 600 °C are more sensitive to H2 than to CO with best operating temperature in the 300-350 °C range. This organometallic approach provides an entirely new class of gas-sensing materials based on a class II organic-inorganic hybrid layer, along with a new way to include organic functionality in gas sensing metal oxides. PMID:25192546

  3. Facile synthesis of α-Fe{sub 2}O{sub 3} nanoparticles for high-performance CO gas sensor

    SciTech Connect

    Cuong, Nguyen Duc; Khieu, Dinh Quang; Hoa, Tran Thai; Quang, Duong Tuan; Viet, Pham Hung; Lam, Tran Dai; Hoa, Nguyen Duc; Hieu, Nguyen Van

    2015-08-15

    Highlights: • We have demonstrated a facile method to prepare Fe{sub 2}O{sub 3} nanoparticles. • The gas sensing properties of α-Fe{sub 2}O{sub 3} have been invested. • The results show potential application of α-Fe{sub 2}O{sub 3} NPs for CO sensors in environmental monitoring. - Abstract: Iron oxide nanoparticles (NPs) were prepared via a simple hydrothermal method for high performance CO gas sensor. The synthesized α-Fe{sub 2}O{sub 3} NPs were characterized by X-ray diffraction, nitrogen adsorption/desorption isotherm, scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), and selected area electron diffraction (SAED). The SEM, TEM results revealed that obtained α-Fe{sub 2}O{sub 3} particles had a peanut-like geometry with hemispherical ends. The response of the α-Fe{sub 2}O{sub 3} NPs based sensor to carbon monoxide (CO) and various concentrations of other gases were measured at different temperatures. It found that the sensor based on the peanut-like α-Fe{sub 2}O{sub 3} NPs exhibited high response, fast response–recovery, and good selectivity to CO at 300 °C. The experimental results clearly demonstrated the potential application of α-Fe{sub 2}O{sub 3} NPs as a good sensing material in the fabrication of CO sensor.

  4. Synthesis and morphology of iron-iron oxide core-shell nanoparticles produced by high pressure gas condensation

    NASA Astrophysics Data System (ADS)

    Xing, Lijuan; ten Brink, Gert H.; Chen, Bin; Schmidt, Franz P.; Haberfehlner, Georg; Hofer, Ferdinand; Kooi, Bart J.; Palasantzas, George

    2016-05-01

    Core-shell structured Fe nanoparticles (NPs) produced by high pressure magnetron sputtering gas condensation were studied using transmission electron microscopy (TEM) techniques, electron diffraction, electron energy-loss spectroscopy (EELS), tomographic reconstruction, and Wulff shape construction analysis. The core-shell structure, which is composed of an Fe core surrounded by a maghemite (γ-Fe2O3) and/or magnetite (Fe3O4) shell, was confirmed by fast Fourier transform (FFT) analysis combined with EELS. It was found that the particle size and shape strongly depend on the gas environment. Moreover, extensive analysis showed that NPs with a size between 10-20 nm possess a truncated cubic morphology, which is confined by the 6 {100} planes that are truncated by the 12 {110} planes at different degrees. For NPs larger than 20 nm, the rhombic dodecahedron defined by the 12 {110} planes is the predominant crystal shape, while truncated rhombic dodecahedrons, as well as non-truncated and truncated cubic NPs, were also observed. The NPs without truncation showed a characteristic inward relaxation indicating that besides thermodynamics kinetics also plays a crucial role during particle growth.

  5. Hybrid organotin and tin oxide-based thin films processed from alkynylorganotins: synthesis, characterization, and gas sensing properties.

    PubMed

    Renard, Laetitia; Brötz, Joachim; Fuess, Hartmut; Gurlo, Aleksander; Riedel, Ralf; Toupance, Thierry

    2014-10-01

    Hydrolysis-condensation of bis(triprop-1-ynylstannyl)butylene led to nanostructured bridged polystannoxane films yielding tin dioxide thin layers upon UV-treatment or annealing in air. According to Fourier transform infrared (FTIR) spectroscopy, contact angle measurements, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and scanning electron microscopy (SEM) data, the films were composed of a network of aggregated "pseudo-particles", as calcination at 600 °C is required to form cassiterite nanocrystalline SnO2 particles. In the presence of reductive gases such as H2 and CO, these films gave rise to highly sensitive, reversible, and reproducible responses. The best selectivity toward H2 was reached at 150 °C with the hybrid thin films that do not show any response to CO at 20-200 °C. On the other hand, the SnO2 films prepared at 600 °C are more sensitive to H2 than to CO with best operating temperature in the 300-350 °C range. This organometallic approach provides an entirely new class of gas-sensing materials based on a class II organic-inorganic hybrid layer, along with a new way to include organic functionality in gas sensing metal oxides.

  6. Synthesis, Characterization, and Gas-Sensing Properties of Mesoporous Nanocrystalline Sn(x)Ti(1-x)O2.

    PubMed

    Zhong, Cheng; Lin, Zhidong; Guo, Fei; Wang, Xuehua

    2015-06-01

    A nanocomposite mesoporous material composed by SnO2 and TiO2 with the size of -5-9 nm were prepared via a facile wet-chemical approach combining with an annealing process. The microstructure of obtained Sn(x)Ti(1-x)O2 powders were characterized by X-ray diffraction, X-ray Photo-electronic Spectroscopy, scanning electron microscope, transmission electron microscope and nitrogen adsorption-desorption experiment. The gas sensing performances to several gases of the mesoporous material were studied. The sensors of Sn(x)Ti(1-x)O2 (ST10, with 9.1% Ti) exhibited very high responses to volatile organic compounds at 160 degrees C. The order of the responses to volatile gases based on ST10 was ethanol > formaldehyde > acetone > toluene > benzene > methane. Sensor based on ST10 displays a highest sensitivity to hydrogen at 200 degrees C. Sensor responses to H2 at 200 degrees C have been measured and analyzed in a wide concentration range from 5 to 2000 ppm. The solid solution Sn(x)Ti(1-x)O2 can be served as a potential gas-sensing material for a broad range of future sensor applications.

  7. Synthesis and morphology of iron-iron oxide core-shell nanoparticles produced by high pressure gas condensation.

    PubMed

    Xing, Lijuan; Ten Brink, Gert H; Chen, Bin; Schmidt, Franz P; Haberfehlner, Georg; Hofer, Ferdinand; Kooi, Bart J; Palasantzas, George

    2016-05-27

    Core-shell structured Fe nanoparticles (NPs) produced by high pressure magnetron sputtering gas condensation were studied using transmission electron microscopy (TEM) techniques, electron diffraction, electron energy-loss spectroscopy (EELS), tomographic reconstruction, and Wulff shape construction analysis. The core-shell structure, which is composed of an Fe core surrounded by a maghemite (γ-Fe2O3) and/or magnetite (Fe3O4) shell, was confirmed by fast Fourier transform (FFT) analysis combined with EELS. It was found that the particle size and shape strongly depend on the gas environment. Moreover, extensive analysis showed that NPs with a size between 10-20 nm possess a truncated cubic morphology, which is confined by the 6 {100} planes that are truncated by the 12 {110} planes at different degrees. For NPs larger than 20 nm, the rhombic dodecahedron defined by the 12 {110} planes is the predominant crystal shape, while truncated rhombic dodecahedrons, as well as non-truncated and truncated cubic NPs, were also observed. The NPs without truncation showed a characteristic inward relaxation indicating that besides thermodynamics kinetics also plays a crucial role during particle growth.

  8. Synthesis and analysis of novel polymers with high permselectivity and permeability in gas separation applications. Final report

    SciTech Connect

    Koros, W.J.; Paul, D.R.

    1995-05-01

    During the three years of support under this grant, ten novel polymer structures have been synthesized and characterized in detail in terms of sorption and transport properties to test the hypotheses on strategies to develop advanced materials for gas separation membranes. The extremely important O{sub 2}/N{sub 2} and CO{sub 2}/CH{sub 4} systems have been the focus of this work. Data for permeabilities and permselectivities for O{sub 2}/N{sub 2} and CO{sub 2}/CH{sub 4} at 35 C at approximately 2 atm feed pressure for O{sub 2} and N{sub 2} and 10 atm for CO{sub 2} and CH{sub 4} are reported in two tables and will be discussed in two parts, one related to each of the groups of structures in these two tables. For the sake of efficiency, the author will only consider the O{sub 2}/N{sub 2} data; however, similar trends apply for the CO{sub 2}/CH{sub 4} system as well. This gas pair is useful, since solubility selectivity effects are generally of much smaller importance than for the CO{sub 2}/CH{sub 4} pair, so even without detailed solubility and diffusivity data, mobility selectivity based arguments tend to be adequate.

  9. Design of Gas-phase Synthesis of Core-Shell Particles by Computational Fluid – Aerosol Dynamics

    PubMed Central

    Buesser, B.; Pratsinis, S.E.

    2013-01-01

    Core-shell particles preserve the bulk properties (e.g. magnetic, optical) of the core while its surface is modified by a shell material. Continuous aerosol coating of core TiO2 nanoparticles with nanothin silicon dioxide shells by jet injection of hexamethyldisiloxane precursor vapor downstream of titania particle formation is elucidated by combining computational fluid and aerosol dynamics. The effect of inlet coating vapor concentration and mixing intensity on product shell thickness distribution is presented. Rapid mixing of the core aerosol with the shell precursor vapor facilitates efficient synthesis of hermetically coated core-shell nanoparticles. The predicted extent of hermetic coating shells is compared to the measured photocatalytic oxidation of isopropanol by such particles as hermetic SiO2 shells prevent the photocatalytic activity of titania. Finally the performance of a simpler, plug-flow coating model is assessed by comparisons to the present detailed CFD model in terms of coating efficiency and silica average shell thickness and texture. PMID:23729817

  10. Elimination of acetate production to improve ethanol yield during continuous synthesis gas fermentation by engineered biocatalyst Clostridium sp. MTEtOH550.

    PubMed

    Berzin, Vel; Kiriukhin, Michael; Tyurin, Michael

    2012-05-01

    Acetogen strain Clostridum sp. MT653 produced acetate 273 mM (p < 0.005) and ethanol 250 mM (p < 0.005) from synthesis gas blend mixture of 64% CO and 36% H(2). Clostridum sp. MT653 was metabolically engineered to the biocatalyst strain Clostridium sp. MTEtOH550. The biocatalyst increased ethanol yield to 590 mM with no acetate production during single-stage continuous syngas fermentation due to expression of synthetic adh cloned in a multi-copy number expression vector. The acetate production was eliminated by inactivation of the pta gene in Clostridium sp. MTEtOH550. Gene introduction and gene elimination were achieved only using Syngas Biofuels Energy, Inc. electroporation generator. The electrotransformation efficiencies were 8.0 ± 0.2 × 10(6) per microgram of transforming DNA of the expression vector at cell viability ~15%. The frequency of suicidal vector integration to inactivate pta was ~10(-5) per the number of recipient cells. This is the first report on elimination of acetate production and overexpression of synthetic adh gene to engineer acetogen biocatalyst for selective biofuel ethanol production during continuous syngas fermentation.

  11. GAS PHASE SYNTHESIS OF (ISO)QUINOLINE AND ITS ROLE IN THE FORMATION OF NUCLEOBASES IN THE INTERSTELLAR MEDIUM

    SciTech Connect

    Parker, Dorian S. N.; Kaiser, Ralf I.; Kostko, Oleg; Troy, Tyler P.; Ahmed, Musahid; Mebel, Alexander M.; Tielens, Alexander G. G. M.

    2015-04-20

    Nitrogen-substituted polycyclic aromatic hydrocarbons (NPAHs) have been proposed to play a key role in the astrochemical evolution of the interstellar medium, yet the formation mechanisms of even their simplest prototypes—quinoline and isoquinoline—remain elusive. Here, we reveal a novel concept that under high temperature conditions representing circumstellar envelopes of carbon stars, (iso)quinoline can be synthesized via the reaction of pyridyl radicals with two acetylene molecules. The facile gas phase formation of (iso)quinoline in circumstellar envelopes defines a hitherto elusive reaction class synthesizing aromatic structures with embedded nitrogen atoms that are essential building blocks in contemporary biological-structural motifs. Once ejected from circumstellar shells and incorporated into icy interstellar grains in cold molecular clouds, these NPAHs can be functionalized by photo processing forming nucleobase-type structures as sampled in the Murchison meteorite.

  12. Gas phase studies of the Pesci decarboxylation reaction: synthesis, structure, and unimolecular and bimolecular reactivity of organometallic ions.

    PubMed

    O'Hair, Richard A J; Rijs, Nicole J

    2015-02-17

    CONSPECTUS: Decarboxylation chemistry has a rich history, and in more recent times, it has been recruited in the quest to develop cheaper, cleaner, and more efficient bond-coupling reactions. Thus, over the past two decades, there has been intense investigation into new metal-catalyzed reactions of carboxylic substrates. Understanding the elementary steps of metal-mediated transformations is at the heart of inventing new reactions and improving the performance of existing ones. Fortunately, during the same time period, there has been a convergence in mass spectrometry (MS) techniques, which allows these catalytic processes to be examined efficiently in the gas phase. Thus, electrospray ionization (ESI) sources have been combined with ion-trap mass spectrometers, which in turn have been modified to either accept radiation from tunable OPO lasers for spectroscopy based structural assignment of ions or to allow the study of ion-molecule reactions (IMR). The resultant "complete" gas-phase chemical laboratories provide a platform to study the elementary steps of metal-catalyzed decarboxylation reactions in exquisite detail. In this Account, we illustrate how the powerful combination of ion trap mass spectrometry experiments and DFT calculations can be systematically used to examine the formation of organometallic ions and their chemical transformations. Specifically, ESI-MS allows the transfer of inorganic carboxylate complexes, [RCO2M(L)n](x), (x = charge) from the condensed to the gas phase. These mass selected ions serve as precursors to organometallic ions [RM(L)n](x) via neutral extrusion of CO2, accessible by slow heating in the ion trap using collision induced dissociation (CID). This approach provides access to an array of organometallic ions with well-defined stoichiometry. In terms of understanding the decarboxylation process, we highlight the role of the metal center (M), the organic group (R), and the auxiliary ligand (L), along with cluster nuclearity, in

  13. Gas phase studies of the Pesci decarboxylation reaction: synthesis, structure, and unimolecular and bimolecular reactivity of organometallic ions.

    PubMed

    O'Hair, Richard A J; Rijs, Nicole J

    2015-02-17

    CONSPECTUS: Decarboxylation chemistry has a rich history, and in more recent times, it has been recruited in the quest to develop cheaper, cleaner, and more efficient bond-coupling reactions. Thus, over the past two decades, there has been intense investigation into new metal-catalyzed reactions of carboxylic substrates. Understanding the elementary steps of metal-mediated transformations is at the heart of inventing new reactions and improving the performance of existing ones. Fortunately, during the same time period, there has been a convergence in mass spectrometry (MS) techniques, which allows these catalytic processes to be examined efficiently in the gas phase. Thus, electrospray ionization (ESI) sources have been combined with ion-trap mass spectrometers, which in turn have been modified to either accept radiation from tunable OPO lasers for spectroscopy based structural assignment of ions or to allow the study of ion-molecule reactions (IMR). The resultant "complete" gas-phase chemical laboratories provide a platform to study the elementary steps of metal-catalyzed decarboxylation reactions in exquisite detail. In this Account, we illustrate how the powerful combination of ion trap mass spectrometry experiments and DFT calculations can be systematically used to examine the formation of organometallic ions and their chemical transformations. Specifically, ESI-MS allows the transfer of inorganic carboxylate complexes, [RCO2M(L)n](x), (x = charge) from the condensed to the gas phase. These mass selected ions serve as precursors to organometallic ions [RM(L)n](x) via neutral extrusion of CO2, accessible by slow heating in the ion trap using collision induced dissociation (CID). This approach provides access to an array of organometallic ions with well-defined stoichiometry. In terms of understanding the decarboxylation process, we highlight the role of the metal center (M), the organic group (R), and the auxiliary ligand (L), along with cluster nuclearity, in

  14. Facile synthesis of ZnO nanorod arrays and hierarchical nanostructures for photocatalysis and gas sensor applications.

    PubMed

    Ma, Shuaishuai; Li, Rong; Lv, Changpeng; Xu, Wei; Gou, Xinglong

    2011-08-30

    A facile one-step hydrothermal route was demonstrated to grow ZnO nanorod arrays and hierarchical nanostructures on arbitrary substrates without any catalysts and seeds coated before the reaction, which are prerequisite in the current two-step protocol. Meanwhile, ZnO nanoflowers composed of nanorods were obtained at the bottom of the autoclaves in the absence of substrates. An in situ spontaneous-seeds-assisted growth mechanism was tentatively proposed on the basis of the experimental data to explain the growth process of ZnO nanostructures. Moreover, the obtained ZnO nanorod arrays exhibited superior photocatalytic activity for decomposing methyl orange, and the nanoflowers showed better gas sensing performance towards some flammable gases and corrosive vapors with high sensitivity, rapid response-recovery characteristics, good selectivity and long-term stability.

  15. Combined plasma gas-phase synthesis and colloidal processing of InP/ZnS core/shell nanocrystals

    PubMed Central

    2011-01-01

    Indium phosphide nanocrystals (InP NCs) with diameters ranging from 2 to 5 nm were synthesized with a scalable, flow-through, nonthermal plasma process at a rate ranging from 10 to 40 mg/h. The NC size is controlled through the plasma operating parameters, with the residence time of the gas in the plasma region strongly influencing the NC size. The NC size distribution is narrow with the standard deviation being less than 20% of the mean NC size. Zinc sulfide (ZnS) shells were grown around the plasma-synthesized InP NCs in a liquid phase reaction. Photoluminescence with quantum yields as high as 15% were observed for the InP/ZnS core-shell NCs. PMID:21711589

  16. Novel Approaches to the Production of Higher Alcohols From Synthesis Gas. Quarterly report, January 1 - March 31, 1997

    SciTech Connect

    Roberts, George W

    1998-12-11

    A modified analytical system was assembled and calibrated, in preparation for a second run with cesium (Cs)-promoted "zinc chromite" catalyst. A new column for the on-line gas chromatography (GC) was purchased for the analysis of various light olefin and paraffin isomers. A run was carried out in the continuous stirred autoclave using the Cs-promoted catalyst. Decahydronaphfialene was used as the slurry liquid. Reaction conditions were 375°C, 2000 psig total pressure, 0.5 H₂/CO ratio, and 5000 sL/Kg (cat.)-hr. Analysis of the data from this run is in progress. A manuscript on the thermal stability of potential slurry liquids was submitted to 'Industrial and Engineering Chemistry Research,' and a paper was presented at the 1997 Spring National Meeting of the American Institute of Chemical Engineers, Houston, Texas.

  17. Synthesis and microwave modification of CuO nanoparticles: crystallinity and morphological variations, catalysis, and gas sensing.

    PubMed

    Yang, Chao; Xiao, Feng; Wang, Jide; Su, Xintai

    2014-12-01

    CuO nanoparticles with different morphologies were synthesized by chemical precipitation and subsequently modified by microwave hydrothermal processing. The nanoparticles were precipitated by the introduction of a strong base to an aqueous solution of copper cations in the presence/absence of the polyethylene glycol and urea additives. The modification of the nanoparticles was subsequently carried out by a microwave hydrothermal treatment of suspensions of the precipitates, precipitated with and without the additives. X-ray powder diffraction analysis indicated that the crystallinity and crystallite size of the CuO nanoparticles increased after the microwave hydrothermal modification. Microscopy observations revealed the morphology changes induced by microwave hydrothermal processing. The thermal decomposition of ammonium perchlorate and the detection of volatile gases were performed to evaluate the catalytic and gas sensing properties of the synthesized CuO nanoparticles.

  18. Development of alternative fuels from coal-derived synthesis gas: Final topical report, demonstration of one-step slurry-phase process for the co-production of methanol and isobutanol

    SciTech Connect

    1996-06-01

    Liquid phase co-production of methanol and isobutanol (LPIBOH) was de, demonstrated at DOE`s Alternative Fuels Development Unit (AFDU) in LaPorte, Texas. Methanol and isobutanol are key intermediates in a synthesis gas-based route to methyl t-butyl ether (MTBE). The technology was demonstrated in a new 18 in. slurry bubble-column reactor that was designed to demonstrate higher pressures and temperatures,higher gas superficial velocities, and lower gas hourly space velocities--all of which are conducive to obtaining optimal isobutanol yield. The integration of the new reactor into the AFDU included the addition of a high-pressure synthesis gas compressor, a high-pressure hydrogen feed source, and a closed-loop methanol- solvent absorption system to remove CO{sub 2} from the unconverted synthesis gas. These modifications were completed in January 1994. The LPIBOH run followed after a short turnaround. It employed a cesium- promoted Cu/ZnO/Al{sub 2}O{sub 3} catalyst developed in Air Products` laboratories and subsequently scaled up to a production- sized batch. Over a thirteen day campaign on simulated Shell gasifier gas, the catalyst and reactor system were tested at a matrix of pressures (750, 1300, 1735 psig) and space velocities (3000, 5000, 8200 sL/kg-hr), representing numerous first-of-a-kind run conditions for the AFDU. Inlet gas superficial velocities spanned an impressive 0.16 to 1.0 ft/sec. Stable reactor performance for a full twelve-hour data period at 1.0 ft/sec was another significant milestone for the liquid phase technology program. Apart from the catalyst deactivation, the run successfully demonstrated mixed alcohol synthesis in a slurry bubble-column reactor, as well as all of the new equipment installed for the trial. Although the full capabilities of the new oxygenates system will not be tested until future runs, the design objectives for the modifications were met with respect to the LPIBOH run.

  19. The influence of N-acetyl-L-cysteine on oxidative stress and nitric oxide synthesis in stimulated macrophages treated with a mustard gas analogue

    PubMed Central

    Paromov, Victor; Qui, Min; Yang, Hongsong; Smith, Milton; Stone, William L

    2008-01-01

    Background Sulphur mustard gas, 2, 2'-dichlorodiethyl sulphide (HD), is a chemical warfare agent. Both mustard gas and its monofunctional analogue, 2-chloroethyl ethyl sulphide (CEES), are alkylating agents that react with and diminish cellular thiols and are highly toxic. Previously, we reported that lipopolysaccharide (LPS) significantly enhances the cytotoxicity of CEES in murine RAW 264.7 macrophages and that CEES transiently inhibits nitric oxide (NO) production via suppression of inducible NO synthase (iNOS) protein expression. NO generation is an important factor in wound healing. In this paper, we explored the hypotheses that LPS increases CEES toxicity by increasing oxidative stress and that treatment with N-acetyl-L-cysteine (NAC) would block LPS induced oxidative stress and protect against loss of NO production. NAC stimulates glutathione (GSH) synthesis and also acts directly as a free radical scavenger. The potential therapeutic use of the antibiotic, polymyxin B, was also evaluated since it binds to LPS and could thereby block the enhancement of CEES toxicity by LPS and also inhibit the secondary infections characteristic of HD/CEES wounds. Results We found that 10 mM NAC, when administered simultaneously or prior to treatment with 500 μM CEES, increased the viability of LPS stimulated macrophages. Surprisingly, NAC failed to protect LPS stimulated macrophages from CEES induced loss of NO production. Macrophages treated with both LPS and CEES show increased oxidative stress parameters (cellular thiol depletion and increased protein carbonyl levels). NAC effectively protected RAW 264.7 cells simultaneously treated with CEES and LPS from GSH loss and oxidative stress. Polymyxin B was found to partially block nitric oxide production and diminish CEES toxicity in LPS-treated macrophages. Conclusion The present study shows that oxidative stress is an important mechanism contributing to CEES toxicity in LPS stimulated macrophages and supports the notion

  20. Synthesis of activated carbon from oil fly ash for removal of H2S from gas stream

    NASA Astrophysics Data System (ADS)

    Aslam, Zaheer; Shawabkeh, Reyad A.; Hussein, Ibnelwaleed A.; Al-Baghli, Nadhir; Eic, Mladen

    2015-02-01

    Activated carbon (AC) is made from waste oil fly ash (OFA) which is produced in large quantities from power generation plants through combustion of heavy fuel oil. OFA contains ∼80% carbon that makes it suitable for producing AC by physicochemical treatments using a mixture of HNO3, H2SO4, and H3PO4 acids to remove non-carbonaceous impurities. The acid treated OFA is then activated by CO2 at 990 °C. The physico-chemical treatments of OFA have increased the surface area from 4 to 375 m2/g. Surface morphology and pore volume of AC are characterized by combined SEM and EDX techniques. Elemental analysis shows that sulfur content is reduced from 7.1 wt% in untreated OFA to 0.51 wt% for the treated OFA. The AC is further treated with HNO3 and NH4OH solutions in order to attach the carboxylic and amine groups on the surface, respectively. FTIR characterization is used to confirm the presence of the functional groups on the surface of AC at different stages of its development. The performance of functionalized AC samples is tested for the removal of H2S from a synthetic natural gas by carrying out breakthrough experiments. The results from these tests have shown maximum adsorption capacity of 0.3001 mg/g for NH4OH functionalized activated carbon with 86.43% regeneration efficiency. The ammonium hydroxide treated AC is found to be more effective for H2S removal than acid treated AC as confirmed by breakthrough experiments. The results indicate that the presence of more acidic functionalities on the surface reduces the H2S adsorption efficiency from the gas mixture.

  1. Synthesis and characterization of nickel and zinc ferrite nanocatalysts for decomposition of CO2 greenhouse effect gas.

    PubMed

    Lin, Kuen-Song; Adhikari, Abhijit Krishna; Wang, Chi-Yu; Hsu, Pei-Ju; Chan, Ho-Yang

    2013-04-01

    The decomposition of CO2 over oxygen deficient nickel ferrite nanoparticles (NFNs) and zinc ferrite nanoparticles (ZFNs) at 573 K was studied. The oxidation states with fine structure of Fe/Ni or Fe/Zn species were also measured in NFNs and ZFNs catalysts, respectively. Oxygen deficiency of catalysts was obtained by reduction in hydrogen. Decomposition of CO2 into carbon and oxygen has been carried out within few minutes when it comes into contact with oxygen deficient catalysts through incorporation of oxygen into ferrite nanoparticles. Oxygen and carbon rather than CO were produced in the decomposition process. The complete decomposition of CO2 was possible because of higher degree of oxygen deficiency andsurface-to-volume ratio of the catalysts. The pre-edge XANES spectra of Fe species in both catalysts exhibit an absorbance feature at 7114 eV for the 1s to 3d transition which is forbidden by the selection rule in case of perfect octahedral symmetry. The EXAFS data showed that the NFNs had two central Fe atoms coordinated by primarily Fe-O and Fe-Fe with bond distances of 1.871 and 3.051 angstroms, respectively. In case of ZFNs these values are 1.889 and 3.062 A, respectively. Methane gas was produced during the reactivation of NFNs by flowing hydrogen gas. Decomposition of CO2, moreover, recovery of valuable methane using heat energy of offgas produced from power generation plant or steel industry is an appealing alternative for energy recovery. PMID:23763127

  2. Isobutanol-methanol mixtures from synthesis gas. Quarterly technical progress report, 1 April--30 June 30 1996

    SciTech Connect

    1996-07-25

    A series of CuMgCeO{sub x} catalysts have been prepared by coprecipitating the corresponding metal nitrates with a mixed solution of potassium carbonate and potassium hydroxide. Kinetic studies of methanol and ethanol coupling reactions on K-Cu/MgO/CeO{sub 2} and MgO/CeO{sub 2} catalysts indicate that Cu enhances the rates of alcohol dehydrogenation. The cross-coupling reactions of acetaldehyde and {sup 13}C-labeled methanol produce singly-labeled propionaldehyde, suggesting that it forms by the condensation of acetaldehyde and a reactive intermediate derived from methanol. Isobutyraldehyde, a precursor to isobutanol, forms via the condensation of propionaldehyde and a reactive C{sub 1} intermediate resulting from methanol. CO{sub 2}, one of the reaction products, poisons both basic and metal sites on Ce-containing CuMgO{sub x} catalysts, resulting in decreases in the rates of both alcohol dehydrogenation (Cu sites) and chain-growth condensation reactions (basic sites). CO{sub 2} inhibits ethanol dehydrogenation on both low-Cu and high-Cu CuMgCeO{sub x} catalysts; however, CO{sub 2} has no effect on the activity of low-Cu Ce-free Cu-MgO{sub x} catalysts, suggesting that the Cu on CuMgCeO{sub x} catalysts is more likely to be oxidized by CO{sub 2} to Cu{sup +} species that can be subsequently stabilized by CeO{sub 2}. CO{sub 2} effects on high-pressure isobutanol synthesis from CO/H{sub 2} have been studied on low- and high-Cu CuMgCeO{sub x} catalysts at 320{degrees}C and 4.5 MPa. CO{sub 2} addition and removal on low- and high-Cu catalysts show similar directional effects on CO conversion. CO conversion is lower at all space velocities in the presence of CO{sub 2}, and removal Of CO{sub 2} from the feed partially recovers CO conversion. CO{sub 2} decreases methanol and isobutanol productivities on both catalysts. Addition of 1-propanol to CO/H{sub 2} feed increases isobutanol production, suggesting that 1-propanol is a precursor to isobutanol.

  3. Synthesis and characterization of nano-structured molybdenum-iron intermetallics by gas-solid reaction technique

    NASA Astrophysics Data System (ADS)

    El-Geassy, A. A.; Seetheraman, S.

    2016-03-01

    Ammonium molybdate and ferrous oxalate were used for the synthesis of nano-structured Mo-Fe intermetallics. Co-precipitation technique was applied to produce Mo/Fe precursors containing 58/42, 72/28 and 30/70 mass% respectively. The different phases formed were identified by XRD. The macro- and microstructures were microscopically examined by Reflected Light Microscope (RLM) and Scanning Electron Microscope (SEM) coupled with Electron Dispersion Spectroscopy (EDS). TG-DTA-DSC technique was applied to follow up the behavior of precursors up to 900oC (10K/min.). Endothermic peaks were detected at 97.8, 196.9 and 392.7oC due to the decomposition reactions to produce MoO3 and Fe2O3. The exothermic peak resulted at 427.8oC is due to the solid state reaction between these oxides to form Fe2(MoO4)3. Precursors were isothermally reduced at 600-850oC in a flow of purified H2 and the O2-weight loss from the reduction reactions was continuously recorded as a function of time. The isothermal reduction behavior of precursors was investigated. The structures of reduced products and the different phases formed were investigated and correlated with the reduction conditions. At >60% reduction extents, Fe2(MoO4)3] phase was first reduced to Fe2MoO3O8 before the formation of FeMo, while FeMoO4 and MoO2 were reduced to FeMo and Mo. In precursors containing higher content of Fe2O3, FeMo, Fe3Mo and Fe phases were produced. The visual observation of reduced samples showed that the volume was gradually shrinking with rise in temperature up to 800oC and beyond which a measurable swelling was observed reaching about 170% at 900oC.

  4. Gas-phase synthesis and structure of monomeric ZnOH: a model species for metalloenzymes and catalytic surfaces.

    PubMed

    Zack, Lindsay N; Sun, Ming; Bucchino, Matthew P; Clouthier, Dennis J; Ziurys, Lucy M

    2012-02-16

    Monomeric ZnOH has been studied for the first time using millimeter and microwave gas-phase spectroscopy. ZnOH is important in surface processes and at the active site of the enzyme carbonic anhydrase. In the millimeter-wave direct-absorption experiments, ZnOH was synthesized by reacting zinc vapor, produced in a Broida-type oven, with water. In the Fourier-transform microwave measurements, ZnOH was produced in a supersonic jet expansion of CH(3)OH and zinc vapor, created by laser ablation. Multiple rotational transitions of six ZnOH isotopologues in their X(2)A' ground states were measured over the frequency range of 22-482 GHz, and splittings due to fine and hyperfine structure were resolved. An asymmetric top pattern was observed in the spectra, showing that ZnOH is bent, indicative of covalent bonding. From these data, spectroscopic constants and an accurate structure were determined. The Zn-O bond length was found to be similar to that in carbonic anhydrase and other model enzyme systems.

  5. Synthesis of single-walled carbon nanotubes from Pd catalysts by gas source method using ethanol in high vacuum

    NASA Astrophysics Data System (ADS)

    Kozawa, Akinari; Saida, Takahiro; Naritsuka, Shigeya; Maruyama, Takahiro

    2016-01-01

    We carried out single-walled carbon nanotube (SWCNT) growth at 600 °C using Pd catalysts by the alcohol gas source method. When Pd catalysts deposited on SiO2/Si substrates were used, the G band in the Raman spectra was broad and weak RBM peaks were observed at ethanol pressures between 1 × 10-3 and 1 × 10-1 Pa. On the other hand, using Al2Ox buffer layers, a sharp G band with a shoulder peak (G- peak) and several radial breathing mode (RBM) peaks were observed, which indicates the growth of SWCNTs. Scanning electron microscopy (SEM) observation showed that dense web like SWCNTs were formed, and the diameters of SWCNTs estimated from the wavenumbers of RBM peaks were 1.3-2.9 nm, which were larger than those from Pt catalysts. Transmission electron microscopy (TEM) observation showed that the larger migration distance of Pd caused an enlargement of catalyst particle sizes, resulting in the larger diameters of SWCNTs from Pd catalysts.

  6. Synthesis of ZnO Nanoparticles-Reduced Graphene Oxide Composites and Their Intrinsic Gas Sensing Properties

    NASA Astrophysics Data System (ADS)

    Uddin, Abu Sadat Mohammad Iftekhar; Phan, Duy-Thach; Chung, Gwiy-Sang

    2014-09-01

    A ZnO nanoparticles (NPs)/reduced graphene oxide (rGO) composite was fabricated via a simple one-step solvothermal method with graphene oxide (GO) and Zn(NO3)2 ṡ 6H2O as the precursors. The morphology, crystal structure and optical properties of the synthesized materials were characterized by field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Raman spectroscopy and photoluminescence (PL) spectroscopy. The synthesized composite exhibited rGO layers assorted with tiny ZnO NPs. rGO supposedly acted as a template in the solvothermal process, that may promote the preferential attachment of ZnO NPs and prevented the agglomeration of ZnO NPs in the synthesized composite. It was also found that the electrical properties of the composite improved markedly with bare ZnO NPs, without significantly changing the morphology and crystal structure of the ZnO NPs. The main aim of this research is to develop an efficient sensor and to understand the effect of graphene in sensing characteristics. The synthesized composite was exposed to H2, CO and C2H2 gases to confirm its feasibility for gas sensing, and the results showed preferential detection of reducing gases at low temperature.

  7. Synthesis of one-dimensional SnO2 lines by using electrohydrodynamic jet printing for a NO gas sensor

    NASA Astrophysics Data System (ADS)

    Kim, Chang-Yeoul; Jung, Hyunsung; Choi, Hannah; Choi, Duck-kyun

    2016-01-01

    One-dimensional (1-D) SnO2 lines as a representative semiconducting oxide were formed by using electrohydrodynamic (EHD) jet-printing of a tin chloride pentahydrate and polyvinylpyrrolidone (PVP, 1,200k, Aldrich) solution ink. The 1-D polymer lines, including Sn precursors, were created by controlling the viscosity, that is, the polymer/tin precursor ratio, and by adjusting printing conditions such as the tip-to-substrate distance, the applied voltage, the flow rate of ink and its velocity. The printed lines were dried at 200 °C to get rid of solvent and were finally heat-treated at 600 °C to burn out PVP and form a tin oxide line. We found that the linearity and the shape of the aligned 1-D SnO2 could be controlled by adjusting various parameters such as the viscosity of the precursor solution, the ratio of Sn to the PVP polymer in the solution, the shape of the cone, the size of a droplet, the applied voltage, the working distance, and the flow rate on glass slides and Si wafers with a SiO2 layer. We found that the heat treatment for removal of the polymers should be tailored to produce continuous 1-D SnO2 lines due to the drastic volume reduction (> 90%) of the aligned fibers during the annealing process. The electrical and the NO-gas-sensing properties of the 1-D SnO2 aligned on Si wafers with Au electrode patterns were evaluated.

  8. Gas phase synthesis and field emission properties of 3D aligned double walled carbon nanotube/anatase hybrid architectures.

    PubMed

    Joshi, Ravi K; Engstler, Jörg; Navitski, Aliaksandr; Sakharuk, Vitali; Müller, Günter; Schneider, Jörg J

    2011-08-01

    A 3D hybrid architecture composed of macroscopic, vertically aligned CNT blocks which are formed via a metal catalyzed CVD process followed by deposition of TiO(2) on the CNT side walls in nanocrystalline or amorphous form is presented. The morphology of the deposited TiO(2) can be tailored by the deposition method employed. Depositing TiO(2) from the gas phase by employing the organometallic precursor Ti[OCH(CH(3))(2)](4) leads to formation of nanocrystalline anatase or rutile particles with a dense coverage on the surface and within the 3D CNT scaffold. Phase pure TiO(2) (anatase) is formed between 500 and 700 °C, while higher temperatures resulted in rutile modification of TiO(2). Below 500 °C, TiO(2) forms an amorphous oxide layer. At higher temperatures such initially formed TiO(2) layers segregate into particles which tend to crystallize. In contrast, when generating TiO(2) by oxidation of Ti metal which is deposited by vaporization onto the 3D CNT block array, and subsequently oxidized in air or controlled O(2) atmosphere this leads to a porous layer with a particular nanostructure on top of the CNT blocks. First studies of the fabrication and field emission of the new 3D CNT/TiO(2) hybrid cathodes display good and stable FE characteristics with onset fields for current density of 1 μA cm(-2) of 1.7 to 1.9 V μm(-1), while the average field enhancement factor is in the range between 2000 and 2500 depending on the O(2) base pressure during the measurements.

  9. Synthesis of chemically-modified single-walled carbon nanotubes by counter-current ammonia gas injection into the induction thermal plasma process

    NASA Astrophysics Data System (ADS)

    Shahverdi, Ali

    Pristine single-walled carbon nanotubes (SWCNTs) are poorly dispersible and insoluble in many solvents and need to be chemically modified prior to their use in many applications. This work is focused on the investigation of the synthesis of chemically modified SWCNTs material through an in situ approach. The main objectives of the presented research are: 1) to explore the in situ chemical process during the synthesis of SWCNT and 2) to closely examine the effect of a reactive environment on SWCNTs. Effects of the catalyst type and content on the SWCNTs final product, synthesized by induction thermal plasma (ITP), were studied to replace toxic cobalt (Co) in the feedstock. In this regard, three different catalyst mixtures (i.e. Ni-Y2O3, Ni-Co-Y2O3, and Ni-Mo-Y2O3) were used. Experimental results showed that the catalyst type affects the quality of the SWCNT final product. Similar quality SWCNTs can be produced when the same amount of Co was replaced by Ni. Moreover, the results observed in this experimental work were further explained by thermodynamic calculation results. Thermogravimetry (TG) was used throughout the work to characterize the SWCNTs product. TG was firstly standardized by studying the effects of three main instrumental parameters (temperature ramp, TR, initial mass of the sample, IM, and gas flow rate, FR) on the Tonset and full-width half maximum (FWHM) obtained from TG and derivative TG graphs of carbon black, respectively. Therefore, a two-level factorial statistical design was performed. The statistical analysis showed that the effect of TR, IM, and to a lower extent, FR, is significant on FWHM and insignificant on Tonset. A methodology was then developed based upon the SWCNTs synthesis using the ITP system, through an in situ chemistry approach. Ammonia (NH3) was selected and counter-currently injected into the ITP reactor at three different flow rates and by four different nozzle designs. Numerical simulation indicated a better mixing of NH3 in

  10. Synthesis and characterizations of nanoscale single crystal GaN grown by ion assisted gas source MBE

    NASA Astrophysics Data System (ADS)

    Cui, Bentao; Cohen, P. I.

    2004-03-01

    Nanoscale patterns could be induced by ion bombardment [1, 2]. In this study, an in-situ real time light scattering technique, combined with Reflection High Energy Electron Diffraction (RHEED), were used to study the surface morphology evolution during the ion beam assisted growth of GaN in a gas source MBE system. Ga was provided by a thermal effusion cell. Ammonia was used as the nitrogen source. A hot-filament Kaufman ion source was used to supply sub-KeV ion beams. Sapphire and MOCVD GaN templates were used as the substrates. A custom-designed Desorption Mass Spectrometer (DMS) was used to calibrate the growth temperature and determine the growth rate. Before growing GaN, the sapphire substrates were pretreated in an ion flux and then annealed for cleaning. The sapphire surface was then nitrided in ammonia at 1100K for about 10 min. After nitridation, a thin GaN buffer layer was prepared by a sequence of adsorption and annealing steps. During the growth, the short-range surface morphology and film quality were monitored in situ by RHEED. In a real-time way, the long-range surface morphology was monitored in-situ by light scattering technique. Photodiode array detector and CCD camera were used to record the reflected light scattering intensity and spectra profile respectively. Periodical patterns, such as ripple, have been observed during ion bombardment on GaN with or without growth. A linear theory (from Bradley and Harper 1988 [3]) has been modified to explain the dependence of ripple wavelength on ion species and ion energy. Partially supported by the National Science Foundation and the Air Force Office of Scientific Research. [1]. J. Erlebacher, M. J. Aziz, E. Chason, M. B. Sinclair, and J. A. Floro, Phys. Rev. Lett. 82, 2330 (1998); J. Erlebacher, M. J. Aziz, E. Chason, M. B. Sinclair, and J. A. Floro, Phys. Rev. Lett. 84, 5800 (2000). [2]. S. Facsko, T. Dekorsy, C. Koerdt, C. Trappe, H. Kurz, A. Vogt et al.. Science 285, 1551 (1999). [3]. R. M. Bradley

  11. Synthesis of Pure and N-substituted Cyclic Hydrocarbons (e.g. Pyrimidine) via Gas-Phase Ion-Molecule Reactions

    NASA Astrophysics Data System (ADS)

    Bera, Partha P.; Peverati, Roberto; Head-Gordon, Martin; Lee, Timothy J.

    2015-08-01

    Large polyatomic carbonaceous molecules, known as polycyclic aromatic hydrocarbons, are known to exist in the outflows of carbon stars. How these large polyatomic molecules are synthesized in such exotic conditions is, thus far, unknown. Molecular ions, including positive and negative ions, are in relative abundance in the high radiation fields present under such conditions. Hence, barrierless ion-molecule interactions may play a major role in guiding molecules towards each other and initiating reactions. We study these condensation pathways to determine whether they are a viable means of forming large pure hydrocarbon molecules, and nitrogen-containing carbonaceous chains, stacks, and even cyclic compounds. By employing accurate quantum chemical methods we have investigated the processes of growth, structures, nature of bonding, mechanisms, and spectroscopic properties of the ensuing ionic products after pairing small carbon, hydrogen, and nitrogen-containing molecules. We have also studied the ion-neutral association pathways involving pure-carbon molecules e.g. acetylene, ethylene and other hydrocarbons, and their dissociation fragments in a plasma discharge as well as how nitrogen atoms are incorporated into the carbon ring during growth. Specifically, we explored the mechanisms by which the synthesis of pyrimidine will be feasible in the gas phase in conjunction with ion-mobility experiments. We have used accurate ab initio coupled cluster theory, Møller-Plesset and Z-averaged perturbation theories, density functional theory, and coupled cluster theory quantum chemical methods together with large correlation consistent basis sets in these investigations. We found that a series of hydrocarbons with a specific stoichiometric composition prefers cyclic molecule formation rather than chains. Some of the association products we investigated have large oscillator strengths for charge-transfer type electronic excitations in the near infrared and visible regions of

  12. Biochemistry of methyl-coenzyme M reductase: the nickel metalloenzyme that catalyzes the final step in synthesis and the first step in anaerobic oxidation of the greenhouse gas methane.

    PubMed

    Ragsdale, Stephen W

    2014-01-01

    Methane, the major component of natural gas, has been in use in human civilization since ancient times as a source of fuel and light. Methanogens are responsible for synthesis of most of the methane found on Earth. The enzyme responsible for catalyzing the chemical step of methanogenesis is methyl-coenzyme M reductase (MCR), a nickel enzyme that contains a tetrapyrrole cofactor called coenzyme F430, which can traverse the Ni(I), (II), and (III) oxidation states. MCR and methanogens are also involved in anaerobic methane oxidation. This review describes structural, kinetic, and computational studies aimed at elucidating the mechanism of MCR. Such studies are expected to impact the many ramifications of methane in our society and environment, including energy production and greenhouse gas warming.

  13. Electrochemical synthesis of ultrafast and gram-scale surfactant-free tellurium nanowires by gas-solid transformation and their applications as supercapacitor electrodes for p-doping of graphene transistors.

    PubMed

    Tsai, Hung-Wei; Yaghoubi, Alireza; Chan, Tsung-Cheng; Wang, Chun-Chieh; Liu, Wei-Ting; Liao, Chien-Neng; Lu, Shih-Yuan; Chen, Lih-Juann; Chueh, Yu-Lun

    2015-05-01

    We herein report a gas-solid transformation mechanism for the surfactant-free synthesis of Te NWs at room temperature by electrolysis of bulk Bi2Te3 using H2Te gas. Te NWs, with an average diameter below 20 nm, grow along the [001] direction due to the unique spiral chains in the crystal structure and show an enhanced Raman scattering effect, a broad absorption band over the range of 350-750 nm and an emission band over the range of 400-700 nm in the photoluminescence spectrum. In terms of device applications, we demonstrate how Te NWs can be directly applied as a p-type dopant source in order to shift the Dirac point in ambipolar field effect graphene transistors. Finally, the favorable capacitive properties of Te NWs are established as supercapacitor electrodes with negligible internal resistance and excellent electrochemical reversibility and a specific capacitance of 24 F g(-1).

  14. Water-gas shift reaction

    SciTech Connect

    Newsome, D.S.

    1980-01-01

    A review covers the industrial applications of the water-gas shift reaction in hydrogen manufacturing, removing CO from ammonia synthesis feeds, and detoxifying town gas; and the catalyst characteristics, reaction kinetics, and reaction mechanisms of the water-gas shift reactions catalyzed by iron-based, copper-based, or sulfided cobalt-molybdenum catalysts.

  15. Synthesis gas to alcohols process

    SciTech Connect

    Prada-Silva, G.; Patel, J.A.; Bhattacharya, A.K.

    1988-10-04

    This patent describes a method of preparing a mixture of lower aliphatic alcohols which comprises reacting carbon monoxide and hydrogen in the presence of a sulfide-containing heavy metal catalyst under carbon monoxide-hydrogenation conditions. The catalyst consists of: (1) at least one sulfided heavy metal element selected from the group consisting of molybdenum; tungsten, and rhenium, (2) a sulfided heavy metal element form the group consisting of cobalt, iron, and nickel, (3) a promoter comprising an alkali or alkaline earth element in free or combined form, and optionally, (4) a support, the improvement which comprises improving the selectivity to the alcohols by treating the sulfided heavy metal elements with a nitrogen-containing base prior to treatment with the promoter, the nitrogen-containing base being selected from the group consisting of urea, dimethylolurea, cyanuric acid, melamine, melam, melem, and melon.

  16. Biological conversion of synthesis gas

    SciTech Connect

    Ackerson, M.D.; Clausen, E.C.; Gaddy, J.L.

    1992-06-30

    Overall mass transfer coefficients for CO have been determined in a continuous stirred-tank reactor at agitation rates of 300--700 rpm using a biological system with the photosynthetic bacterium Rhodospirillum rubrum. A non-steady state approach was employed in order to separate mass transfer and kinetic limited regions of the fermentation. As a result, a kinetic model could be developed for specific CO uptake by the culture including the apparent CO inhibition. The maximum specific CO uptake rate found matched the earlier results obtained in batch culture and by other investigators. CO inhibition was more predominant in CSTR culture than in batch culture, perhaps due to CO acclimation. The growth of the photosynthetic bacterium Chlorobium thiosulfatophilum on CO[sub 2] has been studied at light intensities ranging from 27-1723 lux in batch culture. Modeling results indicate that growth is dependent upon light intensity according to a Monod type relationship.

  17. Morphology controlled synthesis of platinum nanoparticles performed on the surface of graphene oxide using a gas-liquid interfacial reaction and its application for high-performance electrochemical sensing.

    PubMed

    Bai, Wushuang; Sheng, Qinglin; Zheng, Jianbin

    2016-07-21

    In this paper, we report a novel morphology-controlled synthetic method. Platinum (Pt) nanoparticles with three kinds of morphology (aggregation-like, cube-like and globular) were grown on the surface of graphene oxide (GO) using a simple gas-liquid interfacial reaction and Pt/GO nanocomposites were obtained successfully. According to the experimental results, the morphology of the Pt nanoparticles can be controlled by adjusting the reaction temperature with the protection of chitosan. The obtained Pt/GO nanocomposites were characterized using transmission electron microscopy (TEM), X-ray diffraction (XRD) and fourier transform infrared spectroscopy (FTIR). Then the Pt/GO nanocomposites with the three kinds of morphology were all used to fabricate electrochemical sensors. The electrochemical experimental results indicated that compared with various reported electrochemical sensors, the Pt/GO modified sensors in this work exhibit a low detection limit, high sensitivity and an extra wide linear range for the detection of nitrite. In addition, the synthesis of Pt particles based on a gas-liquid interfacial reaction provides a new platform for the controllable synthesis of nanomaterials. PMID:27181605

  18. Morphology controlled synthesis of platinum nanoparticles performed on the surface of graphene oxide using a gas-liquid interfacial reaction and its application for high-performance electrochemical sensing.

    PubMed

    Bai, Wushuang; Sheng, Qinglin; Zheng, Jianbin

    2016-07-21

    In this paper, we report a novel morphology-controlled synthetic method. Platinum (Pt) nanoparticles with three kinds of morphology (aggregation-like, cube-like and globular) were grown on the surface of graphene oxide (GO) using a simple gas-liquid interfacial reaction and Pt/GO nanocomposites were obtained successfully. According to the experimental results, the morphology of the Pt nanoparticles can be controlled by adjusting the reaction temperature with the protection of chitosan. The obtained Pt/GO nanocomposites were characterized using transmission electron microscopy (TEM), X-ray diffraction (XRD) and fourier transform infrared spectroscopy (FTIR). Then the Pt/GO nanocomposites with the three kinds of morphology were all used to fabricate electrochemical sensors. The electrochemical experimental results indicated that compared with various reported electrochemical sensors, the Pt/GO modified sensors in this work exhibit a low detection limit, high sensitivity and an extra wide linear range for the detection of nitrite. In addition, the synthesis of Pt particles based on a gas-liquid interfacial reaction provides a new platform for the controllable synthesis of nanomaterials.

  19. Preliminary screening: Technical and economic assessment of synthesis gas to fuels and chemicals with emphasis on the potential for biomass-derived syngas

    SciTech Connect

    Spath, P. L.; Dayton, D. C.

    2003-12-01

    This report reviews the many syngas to products processes and summarizes the technology status and description, chemistry, catalysts, reactors, gas cleanliness requirements, process and environmental performances, and economics.

  20. Sensitivity of Fischer-Tropsch Synthesis and Water-Gas Shift Catalysts to Poisons from High-Temperature High-Pressure Entrained-Flow (EF) Oxygen-Blown Gasifier Gasification of Coal/Biomass Mixtures

    SciTech Connect

    Burton Davis; Gary Jacobs; Wenping Ma; Dennis Sparks; Khalid Azzam; Janet Chakkamadathil Mohandas; Wilson Shafer; Venkat Ramana Rao Pendyala

    2011-09-30

    There has been a recent shift in interest in converting not only natural gas and coal derived syngas to Fischer-Tropsch synthesis products, but also converting biomass-derived syngas, as well as syngas derived from coal and biomass mixtures. As such, conventional catalysts based on iron and cobalt may not be suitable without proper development. This is because, while ash, sulfur compounds, traces of metals, halide compounds, and nitrogen-containing chemicals will likely be lower in concentration in syngas derived from mixtures of coal and biomass (i.e., using entrained-flow oxygen-blown gasifier gasification gasification) than solely from coal, other compounds may actually be increased. Of particular concern are compounds containing alkali chemicals like the chlorides of sodium and potassium. In the first year, University of Kentucky Center for Applied Energy Research (UK-CAER) researchers completed a number of tasks aimed at evaluating the sensitivity of cobalt and iron-based Fischer-Tropsch synthesis (FT) catalysts and a commercial iron-chromia high temperature water-gas shift catalyst (WGS) to alkali halides. This included the preparation of large batches of 0.5%Pt-25%Co/Al{sub 2}O{sub 3} and 100Fe: 5.1Si: 3.0K: 2.0Cu (high alpha) catalysts that were split up among the four different entities participating in the overall project; the testing of the catalysts under clean FT and WGS conditions; the testing of the Fe-Cr WGS catalyst under conditions of co-feeding NaCl and KCl; and the construction and start-up of the continuously stirred tank reactors (CSTRs) for poisoning investigations. In the second and third years, researchers from the University of Kentucky Center for Applied Energy Research (UK-CAER) continued the project by evaluating the sensitivity of a commercial iron-chromia high temperature water-gas shift catalyst (WGS) to a number of different compounds, including KHCO{sub 3}, NaHCO{sub 3}, HCl, HBr, HF, H{sub 2}S, NH{sub 3}, and a combination of H

  1. Sensitivity of Fischer-Tropsch Synthesis and Water-Gas Shift Catalysts to Poisons from High-Temperature High-Pressure Entrained-Flow (EF) Oxygen-Blown Gasifier Gasification of Coal/Biomass Mixtures

    SciTech Connect

    Burtron Davis; Gary Jacobs; Wenping Ma; Khalid Azzam; Dennis Sparks; Wilson Shafer

    2010-09-30

    The successful adaptation of conventional cobalt and iron-based Fischer-Tropsch synthesis catalysts for use in converting biomass-derived syngas hinges in part on understanding their susceptibility to byproducts produced during the biomass gasification process. With the possibility that oil production will peak in the near future, and due to concerns in maintaining energy security, the conversion of biomass-derived syngas and syngas derived from coal/biomass blends to Fischer-Tropsch synthesis products to liquid fuels may provide a sustainable path forward, especially considering if carbon sequestration can be successfully demonstrated. However, one current drawback is that it is unknown whether conventional catalysts based on iron and cobalt will be suitable without proper development because, while ash, sulfur compounds, traces of metals, halide compounds, and nitrogen-containing chemicals will likely be lower in concentration in syngas derived from mixtures of coal and biomass (i.e., using an entrained-flow oxygen-blown gasifier) than solely from coal, other byproducts may be present in higher concentrations. The current project examines the impact of a number of potential byproducts of concern from the gasification of biomass process, including compounds containing alkali chemicals like the chlorides of sodium and potassium. In the second year, researchers from the University of Kentucky Center for Applied Energy Research (UK-CAER) continued the project by evaluating the sensitivity of a commercial iron-chromia high temperature water-gas shift catalyst (WGS) to a number of different compounds, including KHCO{sub 3}, NaHCO{sub 3}, HCl, HBr, HF, H{sub 2}S, NH{sub 3}, and a combination of H{sub 2}S and NH{sub 3}. Cobalt and iron-based Fischer-Tropsch synthesis (FT) catalysts were also subjected to a number of the same compounds in order to evaluate their sensitivities.

  2. Bacterial detection using a carbon nanotube gas sensor coupled with a microheater for ammonia synthesis by aerobic oxidisation of organic components.

    PubMed

    Suehiro, J; Ikeda, N; Ohtsubo, A; Imasaka, K

    2009-06-01

    In this study, the authors propose a new bacteria detection method using a carbon nanotube (CNT) gas sensor and a microheater, which were coupled into a Bio-MEMS (microelectromechanical systems)-type device. Bacteria were heated by the microheater in air so that ammonia (NH(3)) gas can be generated by the oxidation reaction of organic components of bacteria. Thus generated NH(3) gas was detected by using the CNT gas sensor, which was fabricated by dielectrophoresis (DEP) and combined with the microheater to form a small chamber. Cyclic pulsed heating operation was employed so that the CNT response to elevated temperature did not mask NH(3) response. It was demonstrated that the proposed device could detect and quantify 10(7) bacteria cells (Escherichia coli). Possible application of DEP to trap and enrich target bacteria on the microheater was also discussed.

  3. Sensitivity of Fischer-Tropsch Synthesis and Water-Gas Shift Catalystes to Poisons form High-Temperature High-Pressure Entrained-Flow (EF) Oxygen-Blown Gasifier Gasification of Coal/Biomass Mixtures

    SciTech Connect

    Burton Davis; Gary Jacobs; Wenping Ma; Khalid Azzam; Janet ChakkamadathilMohandas; Wilson Shafer

    2009-09-30

    There has been a recent shift in interest in converting not only natural gas and coal derived syngas to Fischer-Tropsch synthesis products, but also converting biomass-derived syngas, as well as syngas derived from coal and biomass mixtures. As such, conventional catalysts based on iron and cobalt may not be suitable without proper development. This is because, while ash, sulfur compounds, traces of metals, halide compounds, and nitrogen-containing chemicals will likely be lower in concentration in syngas derived from mixtures of coal and biomass (i.e., using entrained-flow oxygen-blown gasifier gasification gasification) than solely from coal, other compounds may actually be increased. Of particular concern are compounds containing alkali chemicals like the chlorides of sodium and potassium. In the first year, University of Kentucky Center for Applied Energy Research (UK-CAER) researchers completed a number of tasks aimed at evaluating the sensitivity of cobalt and iron-based Fischer-Tropsch synthesis (FT) catalysts and a commercial iron-chromia high temperature water-gas shift catalyst (WGS) to alkali halides. This included the preparation of large batches of 0.5%Pt-25%Co/Al{sub 2}O{sub 3} and 100Fe: 5.1Si: 3.0K: 2.0Cu (high alpha) catalysts that were split up among the four different entities participating in the overall project; the testing of the catalysts under clean FT and WGS conditions; the testing of the Fe-Cr WGS catalyst under conditions of co-feeding NaCl and KCl; and the construction and start-up of the continuously stirred tank reactors (CSTRs) for poisoning investigations.

  4. Synthesis of α-MoO3 nano-flakes by dry oxidation of RF sputtered Mo thin films and their application in gas sensing

    NASA Astrophysics Data System (ADS)

    Dwivedi, Priyanka; Dhanekar, Saakshi; Das, Samaresh

    2016-11-01

    Synthesis of orthorhombic (α) MoO3 nano-flakes by dry oxidation of RF sputtered Mo thin film is presented. The influence of Mo thickness variation, oxidation temperature and time on the crystallographic structure, surface morphology and roughness of MoO3 thin films was studied using SEM, AFM, XRD and Raman spectroscopy. A structural study shows that MoO3 is polycrystalline in nature with an α phase. It was noticed that oxidation temperature plays an important role in the formation of nano-flakes. The synthesis technique proposed is simple and suitable for large scale productions. The synthesis parameters were optimized for the fabrication of sensors. Chrome gold-based IDE (interdigitated electrodes) structures were patterned for the electrical detection of organic vapors. Sensors were exposed to wide range 5–100 ppm of organic vapors like ethanol, acetone, IPA (isopropanol alcohol) and water vapors. α-MoO3 nano-flakes have demonstrated selective sensing to acetone in the range of 10–100 ppm at 150 °C. The morphology of such nanostructures has potential in applications such as sensor devices due to their high surface area and thermal stability.

  5. Facile synthesis of Cu/Cu{sub x}O nanoarchitectures with adjustable phase composition for effective NO{sub x} gas sensor at room temperature

    SciTech Connect

    Yang, Lixue; Li, Li; Yang, Ying; Zhang, Guo; Gong, Lihong; Jing, Liqiang; Fu, Honggang; Shi, Keying

    2013-10-15

    Graphical abstract: The Cu/Cu{sub x}O nanoarchitectures with 30–70 nm hollow nanospheres reduced by 3 mmol NaBH{sub 4} exhibits excellent gas-sensing property to low-concentration NO{sub x} gas at room temperature. - Highlights: • The Cu/Cu{sub x}O nanoarchitectures with hollow nanospheres are successfully synthesized. • The method is used for preparing the with Cu/Cu{sub x}O adjustable phase composition. • The C3 sample exhibites excellent gas-sensing propertie to NO{sub x} at room temperation. • The Cu/Cu{sub x}O nanoarchitectures have significant for application of gas sensor. - Abstract: The Cu/Cu{sub x}O nanoarchitectures with 30–70 nm hollow nanospheres are successfully synthesized by a facile wet chemical method. The synthesized products have been studied by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and thermo gravimetric-differential scanning calorimetry (TG-DSC) analysis. The Cu/Cu{sub x}O sensors based on the nanoarchitectures are used to detect the NO{sub x} at room temperature. The results demonstrate that the obtained Cu/Cu{sub x}O nanoarchitectures reduced by 3 mmol NaBH{sub 4} exhibits excellent gas-sensing properties: low detection limit of 0.97 ppm, relatively high sensitivity, short response time, broad linear range and high selectivity. The reasons for gas-sensing activity enhancement on Cu/Cu{sub x}O nanoarchitectures are discussed. The Cu/Cu{sub x}O nanocrystalline with the hierarchical pores structure and tunable compositions have significant for application of gas sensor.

  6. Performance of Na 2O promoted alumina as CO 2 chemisorbent in sorption-enhanced reaction process for simultaneous production of fuel-cell grade H 2 and compressed CO 2 from synthesis gas

    NASA Astrophysics Data System (ADS)

    Lee, Ki Bong; Beaver, Michael G.; Caram, Hugo S.; Sircar, Shivaji

    The performance of a novel thermal swing sorption-enhanced reaction (TSSER) concept for simultaneous production of fuel-cell grade hydrogen and compressed carbon dioxide as a by-product from a synthesis gas feed is simulated using Na 2O promoted alumina as a CO 2 chemisorbent in the process. The process simultaneously carries out the water gas shift (WGS) reaction and removal of CO 2 from the reaction zone by chemisorption in a single unit. Periodic regeneration of the chemisorbent is achieved by using the principles of thermal swing adsorption employing super-heated steam purge. Recently measured equilibrium and kinetic data for chemisorption and desorption of CO 2 on the promoted alumina using conventional column dynamic tests as well as new experimental data demonstrating the concept of sorption-enhanced WGS reaction using the material are reviewed. The simulated performance of the TSSER process employing this material as a chemisorbent is compared with the process performance using K 2CO 3 promoted hydrotalcite as the chemisorbent. The promoted alumina exhibited (i) ∼15% lower H 2 productivity at a slightly reduced CO to H 2 conversion, and (ii) comparable compressed CO 2 productivity at a higher CO 2 recovery, albeit at a relatively lower product pressure. However, the steam duty for regeneration of the chemisorbent was reduced by ∼50% for the promoted alumina.

  7. Advanced bioreactor systems for gaseous substrates: Conversion of synthesis gas to liquid fuels and removal of SO{sub X} and NO{sub X} from coal combustion gases

    SciTech Connect

    Selvaraj, P.T.; Kaufman, E.N.

    1996-06-01

    The purpose of this research program is the development and demonstration of a new generation of gaseous substrate based bioreactors for the production of liquid fuels from coal synthesis gas and the removal of NO{sub x} and SO{sub x} species from combustion flue gas. This R&D program is a joint effort between the staff of the Bioprocessing Research and Development Center (BRDC) of ORNL and the staff of Bioengineering Resources, Inc. (BRI) under a Cooperative Research and Development Agreement (CRADA). The Federal Coordinating Council for Science, Engineering, and Technology report entitled {open_quotes}Biotechnology for the 21st Century{close_quotes} and the recent Energy Policy Act of 1992 emphasizes research, development, and demonstration of the conversion of coal to gaseous and liquid fuels and the control of sulfur and nitrogen oxides in effluent streams. This R&D program presents an innovative approach to the use of bioprocessing concepts that will have utility in both of these identified areas.

  8. Two-stage process for conversion of synthesis gas to high quality transportation fuels. Quarterly report, 8 June-30 September 1983

    SciTech Connect

    Kuo, J.C.W.

    1983-11-01

    The design of two large hot-flow models, to be used for slurry bubble-column hydrodynamic studies, is described. Scoping experiments were performed in smaller models to study the effects of feed-gas distributor type, column diameter, and liquid medium on gas holdup and bubble sizes. In addition, a literature review of bubble-column hydrodynamics is presented. Modifications to improve the operation and flexibility of the existing two stage pilot plant have been designed and construction initiated. Also, a sample of reactor-wax was fractionated under vacuum in a laboratory still. 8 figures, 4 tables.

  9. Structure and mechanism of the formation of core-shell nanoparticles obtained through a one-step gas-phase synthesis by electron beam evaporation.

    PubMed

    Nomoev, Andrey V; Bardakhanov, Sergey P; Schreiber, Makoto; Bazarova, Dashima G; Romanov, Nikolai A; Baldanov, Boris B; Radnaev, Bair R; Syzrantsev, Viacheslav V

    2015-01-01

    The structure of core-shell Cu@silica and Ag@Si nanoparticles obtained in one-step through evaporation of elemental precursors by a high-powered electron beam are investigated. The structure of the core and shell of the particles are investigated in order to elucidate their mechanisms of formation and factors affecting the synthesis. It is proposed that the formation of Cu@silica particles is mainly driven by surface tension differences between Cu and Si while the formation of Ag@Si particles is mainly driven by differences in the vapour concentration of the two components.

  10. The economical production of alcohol fuels from coal-derived synthesis gas. Seventh quarterly technical progress report, April 1, 1993--June 30, 1993

    SciTech Connect

    Not Available

    1993-07-01

    An analysis of the current base cases has been undertaken to determine if the economic status of the proposed alcohol fuels may benefit from economies of scale. This analysis was based on a literature review which suggested that plants of capacities substantially below 5000 metric tons/day are unlikely to be competitive for the bulk production of alcohols for fuel consumption or chemicals manufacture. The preliminary results of this scale up procedure would indicate that the capacity of the current base cases be increased by a factor of eight. This would yield annual production of 4.1 million metric tons and essentially reduce the plant gate cost by approximately 41 percent in both cases. A facility of this size would be the equivalent of a medium sized oil refinery and would be capable of sustaining local market demands for fuel oxygenates. The actual competitiveness of this product with current oxygenates such as MTBE remains to be determined. The alcohol synthesis loop is being used to evaluate optimization procedures which will eventually be used to optimize the entire process. A more detailed design of the synthesis reactor is required, and a preliminary design of this reactor has been completed.

  11. Effect of gas flow rates on the anatase-rutile transformation temperature of nanocrystalline TiO2 synthesised by chemical vapour synthesis.

    PubMed

    Ahmad, Md Imteyaz; Bhattacharya, S S; Fasel, Claudia; Hahn, Horst

    2009-09-01

    Of the three crystallographic allotropes of nanocrystalline titania (rutile, anatase and brookite), anatase exhibits the greatest potential for a variety of applications, especially in the area of catalysis and sensors. However, with rutile being thermodynamically the most stable phase, anatase tends to transform into rutile on heating to temperatures in the range of 500 degrees C to 700 degrees C. Efforts made to stabilize the anatase phase at higher temperatures by doping with metal oxides suffer from the problems of having a large amorphous content on synthesis as well as the formation of secondary impurity phases on doping. Recent studies have suggested that the as-synthesised phase composition, crystallite size, initial surface area and processing conditions greatly influence the anatase to rutile transformation temperature. In this study nanocrystalline titania was synthesised in the anatase form bya chemical vapour synthesis (CVS) method using titanium tetra iso-propoxide (TTIP) as a precursor under varying flow rates of oxygen and helium. The anatase to rutile transformation was studied using high temperature X-ray diffraction (HTXRD) and simultaneous thermogravimetric analysis (STA), followed by transmission electron microscopy (TEM). It was demonstrated that the anatase-rutile transformation temperatures were dependent on the oxygen to helium flow rate ratio during CVS and the results are presented and discussed. PMID:19928267

  12. Synthesis and analysis of novel polymers with high permselectivity and permeability in gas separation applications. Progress report, December 1991--December 1992

    SciTech Connect

    Koros, W.J.; Paul, D.R.

    1991-12-31

    Significant progress was made toward developing advanced materials for gas separation membrane applications and rationalizing molecular structure and efficacy: Synthesized and tested polyarylates based on terephthalic or isophthalic acid or a tertiary butyl derivative of the isophthalic acid with different diols to illustrate the effects of: ``opening`` the matrix by incorporation of bulky packing inhibiting groups such as the tertiary butyl moiety inhibition of backbone motion via meta connected backbone connections and ``tightening`` of the matrix by incorporation of polar halogens. Completed high temperature characterization of sorption and transport properties for novel materials. Continued studies of the phenyl-substituted polymers aimed at producing super stable high temperature useful polymers for gas separations. Synthesized a polyarylate based on the spirobiindane diol and bibenzoyl acid chloride to incorporate long flat packable bibenzoyl units between packing disruptive spirobiindane units in an attempt to control the segmental level morphology to produce highly selective ``bottleneck`` regions between highly open regions.

  13. Gas-phase synthesis of nitrogen-doped TiO{sub 2} nanorods by microwave plasma torch at atmospheric pressure

    SciTech Connect

    Hong, Yong Cheol; Kim, Jong Hun; Bang, Chan Uk; Uhm, Han Sup

    2005-11-15

    Nitrogen (N)-doped titanium dioxide (TiO{sub 2}) nanorods were directly synthesized via decomposition of gas-phase titanium tetrachloride (TiCl{sub 4}) by an atmospheric microwave plasma torch. X-ray diffraction, field-emission scanning electron microscope, field-emission transmission electron microscope, and electron-energy-loss spectroscopy (EELS) have been employed to investigate fraction of the anatase and rutile phases, diameter and length, and chemical composition of the nanorods, respectively. The diameters of the nanorods are approximately 30-80 nm and the length is several micrometers. EELS data show that incorporation of N into the O site of TiO{sub 2} nanorods was enhanced in N{sub 2} gas by the microwave plasma torch. Also, a growth model of the rods was proposed on the basis of vapor-liquid-solid mechanism.

  14. Synthesis and analysis of novel polymers with high permselectivity and permeability in gas separation applications. Progress report, December 1990--November 1991

    SciTech Connect

    Koros, W.J.; Paul, D.R.

    1991-11-15

    We have synthesized and completed characterization of permeability and selectivity properties of a group of polysulfones and polyether ketones with the potential for higher use temperatures, as well as members of a series of polyesters derived from spirobiindane bisphenol monomer in conjunction with meta and para substituted diacid chlorides. We have also synthesized and characterized the gas transport and thermal properties of diphenyl substituted polyphenylene oxide. The diphenyl substituted material has a potential for higher temperature applications than the standard dimethyl substituted polymer. The temperature dependence of the gas transport properties for the oxygen/nitrogen system was characterized over the range from 35 to 65{degree}C for both of these analog materials.

  15. Gas-liquid interface-mediated room-temperature synthesis of "clean" PdNiP alloy nanoparticle networks with high catalytic activity for ethanol oxidation.

    PubMed

    Wang, Rongfang; Ma, Yuanyuan; Wang, Hui; Key, Julian; Ji, Shan

    2014-11-01

    PdNiP alloy nanoparticle networks (PdNiP NN) were prepared by simultaneous reduction of PdCl2, NiCl2 and NaH2PO2 with NaBH4via a gas-liquid interface reaction at room temperature using N2 bubbles. PdNiP NN had markedly higher activity and durability for ethanol oxidation than PdNi nanoparticle networks and PdNiP grain aggregates.

  16. Facile synthesis of novel 3D nanoflower-like Cu(x)O/multilayer graphene composites for room temperature NO(x) gas sensor application.

    PubMed

    Yang, Ying; Tian, Chungui; Wang, Jingchao; Sun, Li; Shi, Keying; Zhou, Wei; Fu, Honggang

    2014-07-01

    3D nanoflower-like CuxO/multilayer graphene composites (CuMGCs) have been successfully synthesized as a new type of room temperature NOx gas sensor. Firstly, the expanded graphite (EG) was activated by KOH and many moderate functional groups were generated; secondly, Cu(CH3COO)2 and CTAB underwent full infusion into the interlayers of activated EG (aEG) by means of a vacuum-assisted technique and then reacted with the functional groups of aEG accompanied by the exfoliation of aEG via reflux. Eventually, the 3D nanoflower consisting of 5-9 nm CuxO nanoparticles homogeneously grow in situ on aEG. The KOH activation of EG plays a key role in the uniform formation of CuMGCs. When being used as gas sensors for detection of NOx, the CuMGCs achieved a higher response at room temperature than that of the corresponding CuxO. In detail, the CuMGCs show a higher NOx gas sensing performance with low detection limit of 97 ppb, high gas response of 95.1% and short response time of 9.6 s to 97.0 ppm NOx at room temperature. Meanwhile, the CuMGC sensor presents a favorable linearity, good selectivity and stability. The enhancement of the sensing response is mainly attributed to the improved conductivity of the CuMGCs. A series of Mott-Schottky and EIS measurements demonstrated that the CuMGCs have much higher donor densities than CuxO and can easily capture and migrate electrons from the conduction band, resulting in the enhancement of electrical conductivity.

  17. Hydrothermal synthesis of WO3·H2O with different nanostructures from 0D to 3D and their gas sensing properties

    NASA Astrophysics Data System (ADS)

    Yu, Yangchun; Zeng, Wen; Xu, Mengxue; Peng, Xianghe

    2016-05-01

    In this paper, WO3·H2O with different nanostructures from 0D to 3D were successfully synthesized via a simple yet cost-effective hydrothermal method with the assistance of surfactants. The structures and morphologies of products were investigated by XRD and SEM. Besides, we systematically explained the evolution process and formation mechanisms of different WO3·H2O morphologies. It is noted that both the kinds and amounts of surfactants strongly affect the formation of WO3·H2O crystals, as reflected in the tailoring of WO3·H2O morphologies. Furthermore, the gas sensing performance of the as-prepared samples towards methanol was also investigated. 3D flower-like hierarchical architecture displayed outstanding response to target gas among the four samples. We hoped our results could be of great benefit to further investigations of synthesizing different dimensional WO3·H2O nanostructures and their gas sensing applications.

  18. Electrochemical synthesis of urea at gas-diffusion electrodes. 4: Simultaneous reduction of carbon dioxide and nitrate ions with various metal catalysts

    SciTech Connect

    Shibata, Masami; Yoshida, Kohji; Furuya, Nagakazu

    1998-07-01

    Simultaneous reduction of carbon dioxide and nitrate ions was examined at gas-diffusion electrodes with various catalysts (Cr, Mo, Mn, Ru, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, An, Cd, In, Tl, Sn and Pb). The formation of urea, CO, formic acid, nitrite ions, and ammonia at the gas-diffusion electrodes with groups 11--14 catalysts, except for Au, was found in the simultaneous reduction. The maximum faradaic efficiency of urea formation on Zn catalysts is approximately 35% at {minus}1.75 V. The formation of urea at the gas-diffusion electrodes with groups 6--10 catalysts was not found in the simultaneous reduction of CO{sub 2} and nitrate. Relationship of the ability for urea formation to the ability for CO and NH{sub 3} formation was investigated with various catalysts. The ability for urea formation with the catalysts depends on the ability for CO and NH{sub 3} formation. The catalysts with high ability for CO and NU{sub 3} formation could form large amounts of CO-like and ammonia-like precursors. The faradaic efficiency of urea formation for simultaneous reduction with nitrate ions is lower than that with nitrite ions. This result seems to be related to the ability for ammonia-like precursor formation.

  19. Microwave-assisted hydrothermal synthesis of Cu/Cu2O hollow spheres with enhanced photocatalytic and gas sensing activities at room temperature.

    PubMed

    Zou, Xinwei; Fan, Huiqing; Tian, Yuming; Zhang, Mingang; Yan, Xiaoyan

    2015-05-01

    Cu/Cu2O nano-heterostructure hollow spheres with a submicron diameter (200-500 nm) were prepared by a microwave-assisted hydrothermal method using Cu(OAc)2·H2O, PVP and ascorbic acid solution as the precursors. The morphology of the products could evolve with the hydrothermal time from solid spheres to thick-shell hollow spheres, then to thin-shell hollow spheres, and finally to nanoparticles. Moreover, the content of Cu in the products could be controlled by adjusting the hydrothermal time. The spontaneous forming of the hollow structure spheres was found to result from the Ostwald ripening effect during the low temperature (100 °C) hydrothermal reaction process. The photocatalytic degradation activities on MO under visible-light irradiation and the gas sensing activities toward the oxidizing NO2 gas of different Cu/Cu2O nano-heterostructure hollow spheres were investigated. As a result, the Cu/Cu2O nano-heterostructure hollow spheres obtained at the hydrothermal time of 30 min, with a rough/porous thin-shell structure and a Cu content of about 10.5 wt%, exhibited the best photocatalytic and gas sensing performances compared with others.

  20. In situ synthesis of porous array films on a filament induced micro-gap electrode pair and their use as resistance-type gas sensors with enhanced performances.

    PubMed

    Xu, Zongke; Duan, Guotao; Zhang, Hongwen; Wang, Yingying; Xu, Lei; Cai, Weiping

    2015-09-14

    Resistance-type metal-oxide semiconductor gas sensors with high sensitivity and low detection limit have been explored for practical applications. They require both sensing films with high sensitivity to target gases and an appropriate structure of the electrode-equipped substrate to support the sensing films, which is still challenging. In this paper, a new gas sensor of metal-oxide porous array films on a micro-gap electrode pair is designed and implemented by taking ZnO as a model material. First, a micro-gap electrode pair was constructed by sputtering deposition on a filament template, which was used as the sensor's supporting substrate. Then, the sensing film, made up of ZnO porous periodic arrays, was in situ synthesized onto the supporting substrate by a solution-dipping colloidal lithography strategy. The results demonstrated the validity of the strategy, and the as-designed sensor shows a small device-resistance, an enhanced sensing performance with high resolution and an ultralow detection limit. This work provides an alternative method to promote the practical application of resistance-type gas sensors.

  1. Mustard Gas: Its Pre-World War I History

    ERIC Educational Resources Information Center

    Duchovic, Ronald J.; Vilensky, Joel A.

    2007-01-01

    The Meyer-Clarke synthetic method was used in the German process for large scale production of mustard gas during World War I, which clearly shows the historical connection of synthesis of mustard gas.

  2. Model Catalysis of Ammonia Synthesis ad Iron-Water Interfaces - ASum Frequency Generation Vibrational Spectroscopic Study of Solid-GasInterfaces and Anion Photoelectron Spectroscopic Study of Selected Anionclusters

    SciTech Connect

    Ferguson, Michael James

    2005-01-01

    The ammonia synthesis reaction has been studied using single crystal model catalysis combined with sum frequency generation (SFG) vibrational spectroscopy. The adsorption of gases N2, H2, O2 and NH3 that play a role in ammonia synthesis have been studied on the Fe(111) crystal surface by sum frequency generation vibrational spectroscopy using an integrated Ultra-High Vacuum (UHV)/high-pressure system. SFG spectra are presented for the dissociation intermediates, NH2 (~3325 cm-1) and NH (~3235 cm-1) under high pressure of ammonia or equilibrium concentrations of reactants and products on Fe(111) surfaces. Special attention was paid to understand how potassium promotion of the iron catalyst affects the intermediates of ammonia synthesis. An Fe(111) surface promoted with 0.2 monolayers of potassium red shifts the vibrational frequencies of the reactive surface intermediates, NH and NH2, providing evidence for weakened the nitrogen-hydrogen bonds relative to clean Fe(111). Spectral features of these surface intermediates persisted to higher temperatures for promoted iron surfaces than for clean Fe(111) surfaces implying that nitrogen-iron bonds are stronger for the promoted surface. The ratio of the NH to NH2 signal changed for promoted surfaces in the presence of equilibrium concentrations of reactants and products. The order of adding oxygen and potassium to promoted surfaces does not alter the spectra indicating that ammonia induces surface reconstruction of the catalyst to produce the same surface morphology. When oxygen is co-adsorbed with nitrogen, hydrogen, ammonia or potassium on Fe(111), a relative phase shift of the spectra occurs as compared to the presence of adsorbates on clean iron surfaces. Water adsorption on iron was also probed using SFG vibrational spectroscopy. For both H2O and D2O, the only spectral feature was in the range of

  3. Synthesis of one-dimensional porous Co{sub 3}O{sub 4} nanobelts and their ethanol gas sensing properties

    SciTech Connect

    Che, Hongwei; Liu, Aifeng; Hou, Junxian; Zhang, Xiaoliang; Bai, Yongmei; Mu, Jingbo; Wang, Renliang

    2014-11-15

    Graphical abstract: 1D porous porous Co{sub 3}O{sub 4} nanobelts were synthesized via a facile route without use of any surfactants or organic solvent, exhibiting ethanol gas sensing properties superior to the commercial Co{sub 3}O{sub 4} powders. - Highlights: • One-dimensional porous Co{sub 3}O{sub 4} nanobelts were synthesized. • The belt-like morphology can be finely controlled via adjusting the reaction parameters. • The evolution process of porous Co{sub 3}O{sub 4} nanobelts was investigated. • Porous Co{sub 3}O{sub 4} nanobelts exhibit superior ethanol gas sensing properties. - Abstract: In this paper, one-dimensional porous Co{sub 3}O{sub 4} nanobelts were synthesized via a facile template-free hydrothermal method and subsequent the thermal decomposition. Their microstructures and morphologies were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, thermogravimetric analysis, fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and N{sub 2} adsorption–desorption techniques. The results indicate that the reaction parameters such as the molar ratio of Co(NO{sub 3}){sub 2}·6H{sub 2}O to C{sub 2}H{sub 4}N{sub 4}, the amount of Co(NO{sub 3}){sub 2}·6H{sub 2}O, the hydrothermal temperature and time play crucial rules in controlling the microstructures and morphologies of the as-prepared cobalt precursors. A possible formation mechanism was proposed. Moreover, the obtained porous Co{sub 3}O{sub 4} nanobelts exhibit ethanol gas sensing properties superior to the commercial Co{sub 3}O{sub 4} powders at a working temperature of 200 °C, suggesting their potential applications as nanosensors.

  4. Silver(I)-Catalyzed Synthesis of β-Oxopropylcarbamates from Propargylic Alcohols and CO2 Surrogate: A Gas-Free Process.

    PubMed

    Song, Qing-Wen; Zhou, Zhi-Hua; Yin, Hong; He, Liang-Nian

    2015-12-01

    The utilization of carbon dioxide poses major challenges owing to its high thermodynamic stability and kinetic inertness. To circumvent these problems, a simple reaction system is reported comprising ammonium carbamates as carbon dioxide surrogates, propargylic alcohols, and a silver(I) catalyst, for the effective conversion of a wide range of alcohols and secondary amines into the corresponding β-oxopropylcarbamates. A key feature of this strategy includes quantitative use of a carbon resource with high product yields under gas-free and mild reaction conditions. Notably, this catalytic protocol also works well for the carboxylative cyclization of propargylic amines and carbon dioxide surrogates to afford 2-oxazolidinones.

  5. In situ synthesis and hardness of TiC/Ti5Si3 composites on Ti-5Al-2.5Sn substrates by gas tungsten arc welding

    NASA Astrophysics Data System (ADS)

    Yan, Wen-qing; Dai, Le; Gui, Chi-bin

    2013-03-01

    TiC/Ti5Si3 composites were fabricated on Ti-5Al-2.5Sn substrates by gas tungsten arc welding (GTAW). Identification of the phases was performed using X-ray diffraction (XRD). The microstructures were analyzed using scanning electron microscopy (SEM) combined with energy-dispersive X-ray spectrometry (EDS) and optical microscopy (OM). The Vickers hardness was measured with a micro-hardness tester. The TiC/Ti5Si3 composites were obtained in a double-layer track, and the Vickers hardness of the track increased by two to three times compared with the Ti-5Al-2.5Sn substrate.

  6. Low cost hydrogen/novel membrane technology for hydrogen separation from synthesis gas, Phase 1. Quarterly technical progress report for the period ending December 31, 1986

    SciTech Connect

    Not Available

    1986-12-31

    During the last quarter several high performance membranes for the separation of hydrogen from nitrogen, carbon monoxide, hydrogen sulfide and carbon dioxide. The heat-resistant resin poly(etherimide) has been selected as the polymer with the most outstanding properties for the separation of hydrogen from nitrogen and carbon monoxide. Flat sheet and hollow fiber poly(etherimide) membranes have been prepared and evaluated with pure gases and gas mixtures at elevated pressures and temperatures. Multilayer composite poly(ether-ester-amide) membranes were also developed. These membranes are useful for the separation of carbon dioxide and hydrogen sulfide hydrogen. They have very high selectivities and extremely high normalized carbon dioxide and hydrogen sulfide fluxes. Separation of carbon dioxide/hydrogen streams is a key problem in hydrogen production from coal. The development of the two membranes now gives us two approaches to separate these gas streams, depending on the stream`s composition. If the stream contains small quantities of hydrogen, the hydrogen- permeable poly(etherimide) membrane would be used to produce a hydrogen-enriched permeate. If the stream contains small quantities of carbon dioxide or hydrogen sulfide, the poly(ether-ester-amide) membrane would be used to produce a carbon dioxide/hydrogen sulfide-free, hydrogen-enriched residue stream. 6 fig., 4 tabs.

  7. The economical production of alcohol fuels from coal-derived synthesis gas. Sixth quarterly technical progress report, January 1, 1993--March 31, 1993

    SciTech Connect

    Not Available

    1993-04-01

    Preliminary economic investigations have focused on cost reduction measures in the production of syngas from coal. A spread sheet model has been developed which can determine the cost of syngas production based upon the cost of equipment and raw materials and the market value of energy and by-products. In comparison to natural gas derived syngas, coal derived syngas is much more expensive, suggesting a questionable economic status of coal derived alcohol fuels. While it is possible that use of less expensive coal or significant integration of alcohol production and electricity production may reduce the cost of coal derived syngas, it is unlikely to be less costly to produce than syngas from natural gas. Fuels evaluation is being conducted in three parts. First, standard ASTM tests are being used to analyze the blend characteristics of higher alcohols. Second, the performance characteristics of higher alcohols are being evaluated in a single-cylinder research engine. Third, the emissions characteristics of higher alcohols are being investigated. The equipment is still under construction and the measurement techniques are still being developed. Of particular interest is n-butanol, since the MoS{sub 2} catalyst produces only linear higher alcohols. There is almost no information on the combustion and emission characteristics of n-butanol, hence the importance of gathering this information in this research.

  8. Modeling mass transfer in solid oxide fuel cell anode: II. H2/CO co-oxidation and surface diffusion in synthesis-gas operation

    NASA Astrophysics Data System (ADS)

    Bao, Cheng; Jiang, Zeyi; Zhang, Xinxin

    2016-08-01

    Following the previous work on comparing performance of Fickian, Stefan-Maxwell and dusty-gas model for mass transfer in single fuel system, this article is focused on the electrochemistry and transport in the anode of solid oxide fuel cell using H2sbnd H2Osbnd COsbnd CO2sbnd N2 hybrid fuel. Under the standard framework of the dusty-gas model combined with the Butler-Volmer equation, it carries out a macroscopic area-specific modeling work. More specifically, two variables of hydrogen current fraction and enhancement factor are well defined and solved for the electrochemical co-oxidation of H2 and CO, and the diffusion equivalent circuit model is introduced to describe more comprehensively the resistance of mass transfer including molecular/Knudsen diffusion and surface diffusion. The model has been validated well in full region of Vsbnd I performance of an experimental anode-supported button cell. An approximate analytical solution of the hydrogen current fraction is also presented for explicit computation. Comparison between the results by different approaches for the effective diffusivity shows the importance of right mass-transfer modeling.

  9. Biomolecule-assisted synthesis and gas-sensing properties of porous nanosheet-based corundum In{sub 2}O{sub 3} microflowers

    SciTech Connect

    Zhang Wenhui; Zhang Weide

    2012-02-15

    Porous nanosheet-based corundum In{sub 2}O{sub 3} microflowers were fabricated by one-pot hydrothermal treatment of D-fructose and In(NO{sub 3}){sub 3} mixture using urea as a precipitating agent followed by calcination. The products were characterized by X-ray diffraction, scanning and transmission electron microscopy. The effects of D-fructose and urea on the fabrication of nanosheet-based corundum In{sub 2}O{sub 3} microflowers were investigated and a possible mechanism is proposed to explain the formation of the hierarchical nanostructures. The gas sensor based on the In{sub 2}O{sub 3} microflowers exhibits excellent sensing properties for the detection of formaldehyde. - Graphical abstract: Nanosheets-based corundum In{sub 2}O{sub 3} microflowers were fabricated by one-pot hydrothermal treatment of D-fructose/In(NO{sub 3}){sub 3} mixture followed by calcination, which show high performance for formaldehyde sensing. Highlights: Black-Right-Pointing-Pointer Preparation of porous nanosheet-based corundum In{sub 2}O{sub 3} microflowers. Black-Right-Pointing-Pointer Morphology and phase control of In{sub 2}O{sub 3}. Black-Right-Pointing-Pointer Gas sensor based on the In{sub 2}O{sub 3} microflowers exhibits excellent sensing properties for the detection of formaldehyde.

  10. The synthesis of porous Co{sub 3}O{sub 4} micro cuboid structures by solvothermal approach and investigation of its gas sensing properties and catalytic activity

    SciTech Connect

    Jamil, Saba; Jing, Xiaoyan; Wang, Jun; Li, Songnan; Liu, Jingyuan; Zhang, Milin

    2013-11-15

    Graphical abstract: - Highlights: • Micro cuboid Co{sub 3}O{sub 4} particle prepared by solvothermal method. • Study of morphology of synthesized cuboids before and after calcinations. • Investigation of formation mechanism of porous Co{sub 3}O{sub 4} from cuboid CoCO{sub 3}. • Investigation of gas sensing properties of porous Co{sub 3}O{sub 4}. • Study of catalytic activity of product. - Abstract: The cobalt carbonate cuboids are prepared by adopting a simple solvothermal approach by using diethylene glycol and water in specific ratio as solvent. The prepared cobalt carbonate is subjected to different instrumentation to investigate its morphology and other properties. It is clear from the scanning electron microscopy (SEM) and transmission electron microscopy (TEM) that the product is distinct cuboid in shape with a size of approximately 3 μm from each face of the cube. Each particle of cuboid cobalt carbonate seems to comprise of layer by layer assembly of unit cells that consequently leads to a cuboid geometry. The cuboid cobalt carbonate was calcined at 700 °C in a furnace under argon atmosphere that decompose cobalt carbonate into porous Co{sub 3}O{sub 4} with the loosely packed arrangement of nano architectures. The gas sensing properties and catalytic activity of porous cuboids Co{sub 3}O{sub 4} are also investigated.

  11. A New Process for Maleic Anhydride Synthesis from a Renewable Building Block: The Gas-Phase Oxidehydration of Bio-1-butanol.

    PubMed

    Pavarelli, Giulia; Velasquez Ochoa, Juliana; Caldarelli, Aurora; Puzzo, Francesco; Cavani, Fabrizio; Dubois, Jean-Luc

    2015-07-01

    We investigated the synthesis of maleic anhydride by oxidehydration of a bio-alcohol, 1-butanol, as a possible alternative to the classical process of n-butane oxidation. A vanadyl pyrophosphate catalyst was used to explore the one-pot reaction, which involved two sequential steps: 1) 1-butanol dehydration to 1-butene, catalysed by acid sites, and 2) the oxidation of butenes to maleic anhydride, catalysed by redox sites. A non-negligible amount of phthalic anhydride was also formed. The effect of different experimental parameters was investigated with chemically sourced 1-butanol, and the results were then confirmed by using genuinely bio-sourced 1-butanol. In the case of bio-1-butanol, however, the purity of the product remarkably affected the yield of maleic anhydride. It was found that the reaction mechanism includes the oxidation of butenes to crotonaldehyde and the oxidation of the latter to either furan or maleic acid, both of which are transformed to produce maleic anhydride.

  12. Controllable synthesis of 3D BiVO₄ superstructures with visible-light-induced photocatalytic oxidation of NO in the gas phase and mechanistic analysis.

    PubMed

    Ou, Man; Nie, Haoyu; Zhong, Qin; Zhang, Shule; Zhong, Lei

    2015-11-21

    A surfactant-free solvothermal method was developed for the controlled synthesis of diverse 3D ms-BiVO4 superstructures, including a flower, a double-layer half-open flower and a hollow tube with square cross-sections, via facilely adjusting the pH values with the aid of NH3·H2O. The effects of the morphologies of the prepared 3D ms-BiVO4 superstructure on the photocatalytic oxidation of NO were investigated, indicating that the enhanced photoactivity was not related to the surface area, but associated with the unique morphology, surface structure and good crystallinity. Moreover, the flower-like ms-BiVO4 photocatalyst with a more (040) reactive crystal plane exhibited higher photoactivity than those of other samples. The unique morphology helped with flushing the oxidation products accumulated on the surface of photocatalysts in the H2O2 system, and further improved the photoactivity. A trapping experiment was also conducted to examine the effects of the active species involved in the PCO of NO intuitively.

  13. A New Process for Maleic Anhydride Synthesis from a Renewable Building Block: The Gas-Phase Oxidehydration of Bio-1-butanol.

    PubMed

    Pavarelli, Giulia; Velasquez Ochoa, Juliana; Caldarelli, Aurora; Puzzo, Francesco; Cavani, Fabrizio; Dubois, Jean-Luc

    2015-07-01

    We investigated the synthesis of maleic anhydride by oxidehydration of a bio-alcohol, 1-butanol, as a possible alternative to the classical process of n-butane oxidation. A vanadyl pyrophosphate catalyst was used to explore the one-pot reaction, which involved two sequential steps: 1) 1-butanol dehydration to 1-butene, catalysed by acid sites, and 2) the oxidation of butenes to maleic anhydride, catalysed by redox sites. A non-negligible amount of phthalic anhydride was also formed. The effect of different experimental parameters was investigated with chemically sourced 1-butanol, and the results were then confirmed by using genuinely bio-sourced 1-butanol. In the case of bio-1-butanol, however, the purity of the product remarkably affected the yield of maleic anhydride. It was found that the reaction mechanism includes the oxidation of butenes to crotonaldehyde and the oxidation of the latter to either furan or maleic acid, both of which are transformed to produce maleic anhydride. PMID:26073302

  14. Single Step Bi-reforming and Oxidative Bi-reforming of Methane (Natural Gas) with Steam and Carbon Dioxide to Metgas (CO-2H2) for Methanol Synthesis: Self-Sufficient Effective and Exclusive Oxygenation of Methane to Methanol with Oxygen.

    PubMed

    Olah, George A; Goeppert, Alain; Czaun, Miklos; Mathew, Thomas; May, Robert B; Prakash, G K Surya

    2015-07-15

    Catalysts based on suitable metal oxide supports, such as NiO/MgO and CoO/MgO, were shown to be active for single step bi-reforming, the combined steam and dry reforming of methane or natural gas with H2O and CO2 exclusively to metgas (CO-2H2) for efficient methanol synthesis. Reactions were carried out in a tubular flow reactor under pressures up to 42 bar at 830-910 °C. Using a CH4 to steam to CO2 ratio of ∼3:2:1 in the gas feed, the H2/CO ratio of 2:1 was achieved, which is desired for subsequent methanol synthesis. The needed 2/1 steam/CO2 feed ratio together with the reaction heat for the endothermic bi-reforming can be conveniently obtained by the complete combustion of a quarter part of the overall used methane (natural gas) with oxygen of the air (oxidative bi-reforming). Complete combustion of a part of methane followed by bi-reforming leads to the production of metgas (H2/CO in 2:1 mol ratio) for self-sufficient exclusive methanol synthesis. The long sought after but elusive efficient and selective oxygenation of methane to methanol is thus achieved in an effective and economic way without any oxidation byproduct formation according to CH4 + 1/2O2 → CH3OH.

  15. Single Step Bi-reforming and Oxidative Bi-reforming of Methane (Natural Gas) with Steam and Carbon Dioxide to Metgas (CO-2H2) for Methanol Synthesis: Self-Sufficient Effective and Exclusive Oxygenation of Methane to Methanol with Oxygen.

    PubMed

    Olah, George A; Goeppert, Alain; Czaun, Miklos; Mathew, Thomas; May, Robert B; Prakash, G K Surya

    2015-07-15

    Catalysts based on suitable metal oxide supports, such as NiO/MgO and CoO/MgO, were shown to be active for single step bi-reforming, the combined steam and dry reforming of methane or natural gas with H2O and CO2 exclusively to metgas (CO-2H2) for efficient methanol synthesis. Reactions were carried out in a tubular flow reactor under pressures up to 42 bar at 830-910 °C. Using a CH4 to steam to CO2 ratio of ∼3:2:1 in the gas feed, the H2/CO ratio of 2:1 was achieved, which is desired for subsequent methanol synthesis. The needed 2/1 steam/CO2 feed ratio together with the reaction heat for the endothermic bi-reforming can be conveniently obtained by the complete combustion of a quarter part of the overall used methane (natural gas) with oxygen of the air (oxidative bi-reforming). Complete combustion of a part of methane followed by bi-reforming leads to the production of metgas (H2/CO in 2:1 mol ratio) for self-sufficient exclusive methanol synthesis. The long sought after but elusive efficient and selective oxygenation of methane to methanol is thus achieved in an effective and economic way without any oxidation byproduct formation according to CH4 + 1/2O2 → CH3OH. PMID:26086090

  16. Rh promoted La0.75Sr0.25(Fe0.8Co0.2)1-xGaxO3-δ perovskite catalysts: Characterization and catalytic performance for methane partial oxidation to synthesis gas

    NASA Astrophysics Data System (ADS)

    Palcheva, R.; Olsbye, U.; Palcut, M.; Rauwel, P.; Tyuliev, G.; Velinov, N.; Fjellvåg, H. H.

    2015-12-01

    Synthesis gas production via selective oxidation of methane at 600 °C in a pulse reaction over La0.75Sr0.25(Fe0.8Co0.2)1-xGaxO3-δ (x = 0.1, 0.25, 0.4) perovskite-supported rhodium catalysts, was investigated. The perovskite oxides were prepared by sol-gel citrate method and characterized by X-ray Diffraction (XRD), Moessbauer Spectroscopy (MS), Temperature Programmed Reduction (TPR-H2), X-ray Photoelectron Spectroscopy (XPS) and High Resolution Transmission Electron Microscopy (HRTEM). According to XRD analysis, the synthesized samples were a single perovskite phase. The perovskite structure of Ga substituted samples remained stable after TPR-H2, as confirmed by XRD. Data of MS identified Fe3+ ions in two distinctive coordination environments, and Fe4+ ions. The Rh2O3 thin overlayer was detected by the HRTEM for the Rh impregnated perovskite oxides. During the interaction of methane with oxidized perovskite-supported Rh (0.5 wt.%) catalysts, besides CO, H2, and surface carbon, CO2 and H2O were formed. The Rh perovskite catalyst with x = 0.25 gallium exhibits the highest catalytic activity of 83% at 600 °C. The CO selectivity was affected by the reducibility of La0.75Sr0.25(Fe0.8Co0.2)1-xGaxO3-δ perovskite materials.

  17. Fluoro- and perfluoralkylsulfonylpentafluoroanilides: synthesis and characterization of NH acids for weakly coordinating anions and their gas-phase and solution acidities.

    PubMed

    Kögel, Julius F; Linder, Thomas; Schröder, Fabian G; Sundermeyer, Jörg; Goll, Sascha K; Himmel, Daniel; Krossing, Ingo; Kütt, Karl; Saame, Jaan; Leito, Ivo

    2015-04-01

    Fluoro- and perfluoralkylsulfonyl pentafluoroanilides [HN(C6F5)(SO2X); X = F, CF3, C4F9, C8F17] are a class of imides with two different strongly electron-withdrawing substituents attached to a nitrogen atom. They are NH acids, the unsymmetrical hybrids of the well-known symmetrical bissulfonylimides and bispentafluorophenylamine. The syntheses, the structures of these perfluoroanilides, their solvates, and some selected lithium salts give rise to a structural variety beyond the symmetrical parent compounds. The acidities of representative subsets of these novel NH acids have been investigated experimentally and quantum-chemically and their gas-phase acidities (GAs) are reported, as well as the pKa values of these compounds in acetonitrile (MeCN) and DMSO solution. In quantum chemical investigations with the vertical and relaxed COSMO cluster-continuum models (vCCC/rCCC), the unusual situation is encountered that the DMSO-solvated acid Me2SO-H-N(SO2CF3)2, optimized in the gas phase (vCCC model), dissociates to Me2SO-H(+)-N(SO2CF3)2(-) during structural relaxation and full optimization with the solvation model turned on (rCCC model). This proton transfer underlines the extremely high acidity of HN(SO2CF3)2. The importance of this effect is studied computationally in DMSO and MeCN solution. Usually this effect is less pronounced in MeCN and is of higher importance in the more basic solvent DMSO. Nevertheless, the neglect of the structural relaxation upon solvation causes typical changes in the computational pKa values of 1 to 4 orders of magnitude (4-20 kJ mol(-1)). The results provide evidence that the published experimental DMSO pKa value of HN(SO2CF3)2 should rather be interpreted as the pKa of a Me2SO-H(+)-N(SO2CF3)2(-) contact ion pair. PMID:25727401

  18. Fluoro- and perfluoralkylsulfonylpentafluoroanilides: synthesis and characterization of NH acids for weakly coordinating anions and their gas-phase and solution acidities.

    PubMed

    Kögel, Julius F; Linder, Thomas; Schröder, Fabian G; Sundermeyer, Jörg; Goll, Sascha K; Himmel, Daniel; Krossing, Ingo; Kütt, Karl; Saame, Jaan; Leito, Ivo

    2015-04-01

    Fluoro- and perfluoralkylsulfonyl pentafluoroanilides [HN(C6F5)(SO2X); X = F, CF3, C4F9, C8F17] are a class of imides with two different strongly electron-withdrawing substituents attached to a nitrogen atom. They are NH acids, the unsymmetrical hybrids of the well-known symmetrical bissulfonylimides and bispentafluorophenylamine. The syntheses, the structures of these perfluoroanilides, their solvates, and some selected lithium salts give rise to a structural variety beyond the symmetrical parent compounds. The acidities of representative subsets of these novel NH acids have been investigated experimentally and quantum-chemically and their gas-phase acidities (GAs) are reported, as well as the pKa values of these compounds in acetonitrile (MeCN) and DMSO solution. In quantum chemical investigations with the vertical and relaxed COSMO cluster-continuum models (vCCC/rCCC), the unusual situation is encountered that the DMSO-solvated acid Me2SO-H-N(SO2CF3)2, optimized in the gas phase (vCCC model), dissociates to Me2SO-H(+)-N(SO2CF3)2(-) during structural relaxation and full optimization with the solvation model turned on (rCCC model). This proton transfer underlines the extremely high acidity of HN(SO2CF3)2. The importance of this effect is studied computationally in DMSO and MeCN solution. Usually this effect is less pronounced in MeCN and is of higher importance in the more basic solvent DMSO. Nevertheless, the neglect of the structural relaxation upon solvation causes typical changes in the computational pKa values of 1 to 4 orders of magnitude (4-20 kJ mol(-1)). The results provide evidence that the published experimental DMSO pKa value of HN(SO2CF3)2 should rather be interpreted as the pKa of a Me2SO-H(+)-N(SO2CF3)2(-) contact ion pair.

  19. Synthesis of silver nanoparticle at a gas/liquid interface in the presence of silver seeds and its application for electrochemical sensing.

    PubMed

    Yang, Ziyin; Qi, Chengcheng; Zheng, Xiaohui; Zheng, Jianbin

    2015-08-01

    Silver nanoparticles were synthesized by reducing [Ag(NH3)2](+) at a gas/liquid interface in the presence of silver seeds. Transmission electron microscopy (TEM) observations reveal that the size of these silver nanoparticles is around 35-40 nm with the average particle size of 37 nm. The silver nanoparticles were applied for the electrochemical sensor and electrochemical investigations indicate that the nanoparticles possess an excellent performance toward H2O2. The linear range is estimated to be from 5.0 μM to 4.0 mM with a low detection limit of 1.7 μM, a sensitivity of 166.7 μA mM(-1) cm(-2) and a response time of 3 s. Additionally, the sensor exhibits good anti-interference.

  20. Palladium-catalyzed synthesis of ammonium sulfinates from aryl halides and a sulfur dioxide surrogate: a gas- and reductant-free process.

    PubMed

    Emmett, Edward J; Hayter, Barry R; Willis, Michael C

    2014-09-15

    Sulfonyl-derived functional groups populate a broad range of useful molecules and materials, and despite a variety of preparative methods being available, processes which introduce the most basic sulfonyl building block, sulfur dioxide, using catalytic methods, are rare. Described herein is a simple reaction system consisting of the sulfur dioxide surrogate DABSO, triethylamine, and a palladium(0) catalyst for effective convertion of a broad range of aryl and heteroaryl halides into the corresponding ammonium sulfinates. Key features of this gas- and reductant-free reaction include the low loadings of palladium (1 mol%) and ligand (1.5 mol%) which can be employed, and the use of isopropyl alcohol as both a solvent and formal reductant. The ammonium sulfinate products are converted in situ into a variety of sulfonyl-containing functional groups, including sulfones, sulfonyl chlorides, and sulfonamides.

  1. Rotational spectroscopy of ClZnCH3 (X1A1): Gas-phase synthesis and characterization of a monomeric Grignard-type reagent

    NASA Astrophysics Data System (ADS)

    Min, J.; Bucchino, M. P.; Kilchenstein, K. M.; Ziurys, L. M.

    2016-02-01

    The pure rotational spectrum of the organozinc halide, ClZnCH3 (X1A1), has been measured using Fourier-transform microwave (FTMW) and millimeter-wave direct-absorption methods in the frequency range 10-296 GHz. This work is the first study of ClZnCH3 by gas-phase spectroscopy. The molecule was created in a DC discharge from the reaction of zinc vapor, produced either by a Broida-type oven or by laser ablation, with chloromethane in what appears to be a metal insertion process. Rotational and chlorine quadrupole constants were determined for three zinc isotopologues. The Znsbnd Cl bond was found to be partly ionic and significantly shorter than in EtZnCl.

  2. Rapid synthesis of ZnO nano-rods by one-step, room-temperature, solid-state reaction and their gas-sensing properties

    NASA Astrophysics Data System (ADS)

    Sun, Zhi-Peng; Liu, Lang; Zhang, Li; Jia, Dian-Zeng

    2006-05-01

    ZnO nano-rods are prepared by one-step solid-state reaction of zinc acetate dihydrate, sodium hydroxide and cetyltrimethylammonium bromide (CTAB) at room temperature. The samples are characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The gas-sensing properties of the prepared material have been investigated. The results indicate that the as-prepared ZnO nano-rods are uniform with diameters of 10-30 nm and lengths of about 150-250 nm. The relatively high sensor signal and stability of sensors made from ZnO nano-rods demonstrate the potential for developing a new class of sensitive sensors.

  3. A new 3D Co(II)–organic framework with acylamide-containing tetracarboxylate ligand: Solvothermal synthesis, crystal structure, gas adsorption and magnetic property

    SciTech Connect

    Zhang, Qingfu Zhang, Haina; Geng, Aijing; Wang, Suna; Zhang, Chong

    2014-04-01

    A new cobalt(II)–organic framework, [Co{sub 2}(L)(py){sub 2}(DMSO)]{sub n}• 0.5nDMF• 2nDMSO (1) [H{sub 4}L=5,5'-((naphthalene-2,6-dicarbonyl)bis(azanediyl))diisophthalic acid, py=pyridine, DMSO=dimethyl sulfoxide, DMF=N,N-dimethylformamide], has been solvothermally synthesized and characterized by elemental analysis, IR, TGA, PXRD and single-crystal X-ray crystallography. The structural analysis reveals that complex 1 is a 3D framework built from nanosized acylamide-containing tetracarboxylate ligands (L{sup 4−}) and dinuclear [Co{sub 2}(CO{sub 2}){sub 4}] secondary building units (SBUs), exhibiting a uninodal (4,4)-connected crb topology with the Schläfli symbol of (4• 6{sup 5}). The desolvated complex (1a) displays higher adsorption capability for CO{sub 2} than N{sub 2}, which may be due to the relatively strong binding affinity between the CO{sub 2} molecules and acylamide groups in the framework. The magnetic investigation shows that the dominant antiferromagnetic interaction is observed in complex 1. - Graphical abstract: A new 3D Co(II)–organic framework with nanosized acylamide-containing tetracarboxylate ligand was solvothermally synthesized and structurally characterized, its thermal stability, gas adsorption and magnetic property were studied. - Highlights: • A new 3D Co(II)–organic framework with nanosized acylamide-containing tetracarboxylate ligand has been solvothermally synthesized and characterized. • Complex 1 exhibits a uninodal (4,4)-connected crb topology. • The thermal stability, gas adsorption and magnetic property were studied.

  4. Environmental controls of energy and trace gas exchanges at the water-air interface: Global synthesis of eddy fluxes over inland waters

    NASA Astrophysics Data System (ADS)

    Golub, M.; Desai, A. R.; Bohrer, G.; Blanken, P.; Deshmukh, C. S.; Franz, D.; Guérin, F.; Heiskanen, J. J.; Jammet, M.; Jonsson, A.; Karlsson, J.; Koebsch, F.; Liu, H.; Lohila, A.; Lundin, E.; Mammarella, I.; Rutgersson, A.; Sachs, T.; Serça, D.; Spence, C.; Strachan, I. B.; Vesala, T.; Weyhenmeyer, G. A.; Xiao, W.; Glatzel, S.

    2015-12-01

    Current estimates of energy and trace gases from inland waters often rely on limited point in time measurements, therefore, short time variation of fluxes and mechanism controlling the fluxes are particularly understudied. Here we present the results of a global synthesis of eddy fluxes from 29 globally distributed aquatic sites. The objective of this study was to quantify the magnitudes and variation of energy and CO2 fluxes and investigate their responses to environmental controls across half-hourly to monthly time scales. The coupled observations of in-lake physical and biogeochemical parameters with meteorology and eddy covariance fluxes were analyzed using decomposed correlation and wavelength coherence analysis to quantify the critical time scales that are associated with variation of energy and CO2 fluxes, and related drivers. The rates of fluxes were synthesized according to time scale, climate, and water body type. The diurnal cycles of both energy and CO2 fluxes variation were attributed to wind speed, solar radiation cycle, vapor pressure deficit, temperature gradients at water-air interface, and metabolism. Weekly time scales of variations were correlated with synoptic weather patterns. The monthly sums of energy fluxes showed a latitudinal gradient with the maxima observed in mid-latitude waterbodies. We found an inconsistent latitudinal pattern of monthly CO2 fluxes. Instead, we found correlation with proxies of lake productivity suggesting lake-specific characteristics play an important role in controlling flux magnitudes and variation. The results presented here highlight the importance of quantifying short-term variation of energy and trace gases fluxes towards improving the understanding of the water and carbon cycles and linked ecological processes.

  5. Water Stress and Protein Synthesis

    PubMed Central

    Dhindsa, R. S.; Cleland, R. E.

    1975-01-01

    Water stress causes a reduction in hydrostatic pressure and can cause an increase in abscisic acid in plant tissues. To assess the possible role of abscisic acid and hydrostatic pressure in water stress effects, we have compared the effects of water stress, abscisic acid, and an imposed hydrostatic pressure on the rate and pattern of protein synthesis in Avena coleoptiles. Water stress reduces the rate and changes the pattern of protein synthesis as judged by a double labeling ratio technique, Abscisic acid reduces the rate but does not alter the pattern of protein synthesis. Gibberellic acid reverses the abscisic acid-induced but not the stress-induced inhibition of protein synthesis. The effect of hydrostatic pressure depends on the gas used. With a 19: 1 N2-air mixture, the rate of protein synthesis is increased in stressed but not in turgid tissues. An imposed hydrostatic pressure alters the pattern of synthesis in stressed tissues, but does not restore the pattern to that found in turgid tissues. Because of the differences in response, we conclude that water stress does not affect protein synthesis via abscisic acid or reduced hydrostatic pressure. PMID:16659167

  6. Low-Temperature Synthesis of Single-Walled Carbon Nanotubes in a High Vacuum Using Pt Catalyst in Alcohol Gas Source Method

    NASA Astrophysics Data System (ADS)

    Fukuoka, Naoya; Mizutani, Yoshihiro; Naritsuka, Shigeya; Maruyama, Takahiro; Iijima, Sumio

    2012-06-01

    The growth of single-walled carbon nanotubes (SWCNTs) was carried out on SiO2/Si substrates with Pt catalysts between 500 and 700 °C under various ethanol pressures using an alcohol gas source method in a high vacuum and the grown SWCNTs were characterized by scanning electron microscopy (SEM) and Raman spectroscopy. It was found that, irrespective of the growth temperature, the optimal ethanol pressures were 1×10-3-1×10-4 Pa, which were much smaller than those used in the SWCNT growth with Co catalysts. SEM observations showed that the yield of SWCNTs grown with a Pt catalyst under 1×10-3 Pa at 700 °C was similar to that with a Co catalyst under the optimal growth condition, even though the ethanol pressure was fairly lower in the growth with Pt. By optimizing the growth pressure, SWCNTs could be grown even at 500 °C by using a Pt catalyst.

  7. Gas-phase reactions of molecular oxygen with uranyl(V) anionic complexes-synthesis and characterization of new superoxides of uranyl(VI).

    PubMed

    Lucena, Ana F; Carretas, José M; Marçalo, Joaquim; Michelini, Maria C; Gong, Yu; Gibson, John K

    2015-04-16

    Gas-phase complexes of uranyl(V) ligated to anions X(-) (X = F, Cl, Br, I, OH, NO3, ClO4, HCO2, CH3CO2, CF3CO2, CH3COS, NCS, N3), [UO2X2](-), were produced by electrospray ionization and reacted with O2 in a quadrupole ion trap mass spectrometer to form uranyl(VI) anionic complexes, [UO2X2(O2)](-), comprising a superoxo ligand. The comparative rates for the oxidation reactions were measured, ranging from relatively fast [UO2(OH)2](-) to slow [UO2I2](-). The reaction rates of [UO2X2](-) ions containing polyatomic ligands were significantly faster than those containing the monatomic halogens, which can be attributed to the greater number of vibrational degrees of freedom in the polyatomic ligands to dissipate the energy of the initial O2-association complexes. The effect of the basicity of the X(-) ligands was also apparent in the relative rates for O2 addition, with a general correlation between increasing ligand basicity and O2-addition efficiency for polyatomic ligands. Collision-induced dissociation of the superoxo complexes showed in all cases loss of O2 to form the [UO2X2](-) anions, indicating weaker binding of the O2(-) ligand compared to the X(-) ligands. Density functional theory computations of the structures and energetics of selected species are in accord with the experimental observations.

  8. Facile synthesis of core/shell ZnO/ZnS nanofibers by electrospinning and gas-phase sulfidation for biosensor applications.

    PubMed

    Baranowska-Korczyc, Anna; Sobczak, Kamil; Dłużewski, Piotr; Reszka, Anna; Kowalski, Bogdan J; Kłopotowski, Łukasz; Elbaum, Danek; Fronc, Krzysztof

    2015-10-01

    This study describes a new method of passivating ZnO nanofiber-based devices with a ZnS layer. This one-step process was carried out in H2S gas at room temperature, and resulted in the formation of core/shell ZnO/ZnS nanofibers. This study presents the structural, optical and electrical properties of ZnO/ZnS nanofibers formed by a 2 nm ZnS sphalerite crystal shell covering a 5 nm ZnO wurtzite crystal core. The passivation process prevented free carriers from capture by oxygen molecules and significantly reduced the impact of O2 on nanostructure conductivity. The conductivity of the nanofibers was increased by three orders of magnitude after the sulfidation, the photoresponse time was reduced from 1500 s to 30 s, and the cathodoluminescence intensity increased with the sulfidation time thanks to the removal of ZnO surface defects by passivation. The ZnO/ZnS nanofibers were stable in water for over 30 days, and in phosphate buffers of acidic, neutral and alkaline pH for over 3 days. The by-products of the passivation process did not affect the conductivity of the devices. The potential of ZnO/ZnS nanofibers for protein biosensing is demonstrated using biotin and streptavidin as a model system. The presented ZnS shell preparation method can facilitate the construction of future sensors and protects the ZnO surface from dissolving in a biological environment.

  9. Reviews and syntheses: Greenhouse gas emissions in natural and agricultural lands in sub-Saharan Africa: synthesis of available data and suggestions for further studies

    NASA Astrophysics Data System (ADS)

    Kim, D.-G.; Thomas, A. D.; Pelster, D.; Rosenstock, T. S.; Sanz-Cobena, A.

    2015-10-01

    This paper summarizes currently available data on greenhouse gas (GHG) emissions from African natural and agricultural lands, outlines the knowledge gaps and suggests future directions and strategies for GHG emission studies. GHG emission data were collected from 73 studies conducted in 22 countries in sub-Saharan Africa (SSA). Soil GHG emissions from African natural terrestrial systems ranged from 3.3 to 57.0 Mg carbon dioxide (CO2) ha-1 yr-1, -4.8 to 3.5 kg methane (CH4) ha-1 yr-1 and -0.1 to 13.7 kg nitrous oxide (N2O) ha-1 yr-1. Soil physical and chemical properties, rewetting, vegetation type, forest management and land-use changes were all found to be important factors affecting soil GHG emissions. Greenhouse gas emissions from African aquatic systems ranged from 5.7 to 232.0 Mg CO2 ha-1 yr-1, -26.3 to 2741.9 kg CH4 ha-1 yr-1 and 0.2 to 3.5 kg N2O ha-1 yr-1 and were strongly affected by discharge. Soil GHG emissions from African croplands ranged from 1.7 to 141.2 Mg CO2 ha-1 yr-1, -1.3 to 66.7 kg CH4 ha-1 yr-1and 0.05 to 112.0 kg N2O ha-1 yr-1 and the N2O emission factor (EF) ranged from 0.01 to 4.1 %. Incorporation of crop residues or manure with inorganic fertilizers resulted in significant changes in GHG emissions but these were different for CO2 and N2O. Soil GHG emissions in vegetable gardens ranged from 73.3 to 132.0 Mg CO2 ha-1 yr-1 and 53.4 to 177.6 kg N2O ha-1 yr-1 and N2O EFs ranged from 3 to 4 %. Soil CO2 and N2O emissions from agroforestry were 38.6 Mg CO2 ha-1 yr-1 and 0.2 to 26.7 kg N2O ha-1 yr-1, respectively. Improving fallow with nitrogen (N)-fixing trees increased CO2 and N2O emissions compared to conventional croplands and type and quality of plant residue is likely to be an important control factor affecting N2O emissions. Throughout agricultural lands, N2O emissions slowly increased with N inputs below 150 kg N ha-1 yr-1 and increased exponentially with N application rates up to 300 kg N ha-1 yr-1. The lowest yield-scaled N2O emissions

  10. Facile synthesis of core/shell ZnO/ZnS nanofibers by electrospinning and gas-phase sulfidation for biosensor applications.

    PubMed

    Baranowska-Korczyc, Anna; Sobczak, Kamil; Dłużewski, Piotr; Reszka, Anna; Kowalski, Bogdan J; Kłopotowski, Łukasz; Elbaum, Danek; Fronc, Krzysztof

    2015-10-01

    This study describes a new method of passivating ZnO nanofiber-based devices with a ZnS layer. This one-step process was carried out in H2S gas at room temperature, and resulted in the formation of core/shell ZnO/ZnS nanofibers. This study presents the structural, optical and electrical properties of ZnO/ZnS nanofibers formed by a 2 nm ZnS sphalerite crystal shell covering a 5 nm ZnO wurtzite crystal core. The passivation process prevented free carriers from capture by oxygen molecules and significantly reduced the impact of O2 on nanostructure conductivity. The conductivity of the nanofibers was increased by three orders of magnitude after the sulfidation, the photoresponse time was reduced from 1500 s to 30 s, and the cathodoluminescence intensity increased with the sulfidation time thanks to the removal of ZnO surface defects by passivation. The ZnO/ZnS nanofibers were stable in water for over 30 days, and in phosphate buffers of acidic, neutral and alkaline pH for over 3 days. The by-products of the passivation process did not affect the conductivity of the devices. The potential of ZnO/ZnS nanofibers for protein biosensing is demonstrated using biotin and streptavidin as a model system. The presented ZnS shell preparation method can facilitate the construction of future sensors and protects the ZnO surface from dissolving in a biological environment. PMID:26313635

  11. Synthesis, structural characterization, gas sorption and guest-exchange studies of the lightweight, porous metal-organic framework alpha-[Mg3(O2CH)6].

    PubMed

    Rood, Jeffrey A; Noll, Bruce C; Henderson, Kenneth W

    2006-07-10

    Unsolvated magnesium formate crystallizes upon reaction of the metal nitrate with formic acid in DMF at elevated temperatures. Single-crystal XRD studies reveal the formation of [Mg3(O2CH)6 [symbol: see text] DMF], 1, a metal-organic framework with DMF molecules filling the channels of an extended diamondoid lattice. The DMF molecules in 1 can be entirely removed without disruption to the framework, giving the guest-free material alpha-[Mg3(O2CH)6], 2. Compound 2 has been characterized by both powder and single-crystal XRD studies. Thermogravimetric analyses of 1 show guest loss from 120 to 190 degrees C, with decomposition of the sample at approximately 417 degrees C. Gas sorption studies using both N2 and H2 indicate that the framework displays permanent porosity. The porosity of the framework is further demonstrated by the ability of 2 to uptake a variety of small molecules upon soaking. Single-crystal XRD studies have been completed on the six inclusion compounds [Mg3(O2CH)6 [symbol: see text] THF], 3; [Mg3(O2CH)6 [symbol: see text] Et2O], 4; [Mg3(O2CH)6 [symbol: see text] Me2CO], 5; [Mg3(O2CH)6 [symbol: see text] C6H6], 6; [Mg3(O2CH)6 [symbol: see text] EtOH], 7; and [Mg3(O2CH)(6) [symbol: see text] MeOH], 8. Analyses of the metrical parameters of 1-8 indicate that the framework has the ability to contract or expand depending on the nature of the guest present.

  12. Non-Interpenetrated Metal-Organic Frameworks Based on Copper(II) Paddlewheel and Oligoparaxylene-Isophthalate Linkers: Synthesis, Structure, and Gas Adsorption.

    PubMed

    Yan, Yong; Juríček, Michal; Coudert, François-Xavier; Vermeulen, Nicolaas A; Grunder, Sergio; Dailly, Anne; Lewis, William; Blake, Alexander J; Stoddart, J Fraser; Schröder, Martin

    2016-03-16

    Two metal-organic framework materials, MFM-130 and MFM-131 (MFM = Manchester Framework Material), have been synthesized using two oligoparaxylene (OPX) tetracarboxylate linkers containing four and five aromatic rings, respectively. Both fof-type non-interpenetrated networks contain Kagomé lattice layers comprising [Cu2(COO)4] paddlewheel units and isophthalates, which are pillared by the OPX linkers. Desolvated MFM-130, MFM-130a, shows permanent porosity (BET surface area of 2173 m(2)/g, pore volume of 1.0 cm(3)/g), high H2 storage capacity at 77 K (5.3 wt% at 20 bar and 2.2 wt% at 1 bar), and a higher CH4 adsorption uptake (163 cm(3)(STP)/cm(3) (35 bar and 298 K)) compared with its structural analogue, NOTT-103. MFM-130a also shows impressive selective adsorption of C2H2, C2H4, and C2H6 over CH4 at room temperature, indicating its potential for separation of C2 hydrocarbons from CH4. The single-crystal structure of MFM-131 confirms that the methyl substituents of the paraxylene units block the windows in the Kagomé lattice layer of the framework, effectively inhibiting network interpenetration in MFM-131. This situation is to be contrasted with that of the doubly interpenetrated oligophenylene analogue, NOTT-104. Calculation of the mechanical properties of these two MOFs confirms and explains the instability of MFM-131 upon desolvation in contrast to the behavior of MFM-130. The incorporation of paraxylene units, therefore, provides an efficient method for preventing network interpenetration as well as accessing new functional materials with modified and selective sorption properties for gas substrates.

  13. A novel zinc(ii) metal-organic framework with a diamond-like structure: synthesis, study of thermal robustness and gas adsorption properties.

    PubMed

    Almáši, Miroslav; Zeleňák, Vladimír; Zukal, Arnošt; Kuchár, Juraj; Čejka, Jiří

    2016-01-21

    A solvothermal reaction of Zn(ii) salt with methanetetrabenzoic acid (H4MTB) and 1,4,8,11-tetraazacyclotetradecane (cyclam, CYC) created a new microporous metal-organic framework {[Zn2(μ4-MTB)(κ(4)-CYC)2]·2DMF·7H2O}n (DMF = N,N'-dimethylformamide). Single crystal X-ray diffraction showed that the complex exhibits a four-fold interpenetrated diamond-like structure topology with 1D jar-like channels with sizes about 14.1 × 14.1 and 2.4 × 2.4 Å(2). The stability of the framework and activation conditions of the compound have been studied by high-energy powder X-ray diffraction during in situ heating, thermogravimetric analysis coupled with mass spectrometry and infrared spectroscopy performed at different temperatures. The gas adsorption behaviour of {[Zn2(μ4-MTB)(κ(4)-CYC)2]·2DMF·7H2O}n was studied by adsorption of Ar, N2, CO2 and H2. Nitrogen and argon adsorption showed that the activated sample exhibits Brunauer-Emmet-Teller (BET) specific surface areas of 644 m(2) g(-1) (N2) and 562 m(2) g(-1) (Ar). The complex adsorbs carbon dioxide with a maximum storage capacity of 10.5 wt% at 273 K and 101 kPa. The observed hydrogen uptake was 1.27 wt% at 77 K and 800 Torr, which is the highest value reported for the compounds containing a MTB(4-) linker. The adsorption heats of carbon dioxide and hydrogen, calculated according to the Clausius-Clapeyron equation, were in the range 22.8-22.4 kJ mol(-1) for CO2 and 8.9-3.2 kJ mol(-1) for H2, indicating weak interactions of the gases with the framework.

  14. Greenhouse gas emissions from natural ecosystems and agricultural lands in sub-Saharan Africa: synthesis of available data and suggestions for further research

    NASA Astrophysics Data System (ADS)

    Kim, Dong-Gill; Thomas, Andrew D.; Pelster, David; Rosenstock, Todd S.; Sanz-Cobena, Alberto

    2016-08-01

    This paper summarizes currently available data on greenhouse gas (GHG) emissions from African natural ecosystems and agricultural lands. The available data are used to synthesize current understanding of the drivers of change in GHG emissions, outline the knowledge gaps, and suggest future directions and strategies for GHG emission research. GHG emission data were collected from 75 studies conducted in 22 countries (n = 244) in sub-Saharan Africa (SSA). Carbon dioxide (CO2) emissions were by far the largest contributor to GHG emissions and global warming potential (GWP) in SSA natural terrestrial systems. CO2 emissions ranged from 3.3 to 57.0 Mg CO2 ha-1 yr-1, methane (CH4) emissions ranged from -4.8 to 3.5 kg ha-1 yr-1 (-0.16 to 0.12 Mg CO2 equivalent (eq.) ha-1 yr-1), and nitrous oxide (N2O) emissions ranged from -0.1 to 13.7 kg ha-1 yr-1 (-0.03 to 4.1 Mg CO2 eq. ha-1 yr-1). Soil physical and chemical properties, rewetting, vegetation type, forest management, and land-use changes were all found to be important factors affecting soil GHG emissions from natural terrestrial systems. In aquatic systems, CO2 was the largest contributor to total GHG emissions, ranging from 5.7 to 232.0 Mg CO2 ha-1 yr-1, followed by -26.3 to 2741.9 kg CH4 ha-1 yr-1 (-0.89 to 93.2 Mg CO2 eq. ha-1 yr-1) and 0.2 to 3.5 kg N2O ha-1 yr-1 (0.06 to 1.0 Mg CO2 eq. ha-1 yr-1). Rates of all GHG emissions from aquatic systems were affected by type, location, hydrological characteristics, and water quality. In croplands, soil GHG emissions were also dominated by CO2, ranging from 1.7 to 141.2 Mg CO2 ha-1 yr-1, with -1.3 to 66.7 kg CH4 ha-1 yr-1 (-0.04 to 2.3 Mg CO2 eq. ha-1 yr-1) and 0.05 to 112.0 kg N2O ha-1 yr-1 (0.015 to 33.4 Mg CO2 eq. ha-1 yr-1). N2O emission factors (EFs) ranged from 0.01 to 4.1 %. Incorporation of crop residues or manure with inorganic fertilizers invariably resulted in significant changes in GHG emissions, but results were inconsistent as the magnitude and direction of

  15. Combustion synthesis method and products

    DOEpatents

    Holt, J. Birch; Kelly, Michael

    1993-01-01

    Disclosed is a method of producing dense refractory products, comprising: (a) obtaining a quantity of exoergic material in powder form capable of sustaining a combustion synthesis reaction; (b) removing absorbed water vapor therefrom; (c) cold-pressing said material into a formed body; (d) plasma spraying said formed body with a molten exoergic material to form a coat thereon; and (e) igniting said exoergic coated formed body under an inert gas atmosphere and pressure to produce self-sustained combustion synthesis. Also disclosed are products produced by the method.

  16. Combustion synthesis method and products

    DOEpatents

    Holt, J.B.; Kelly, M.

    1993-03-30

    Disclosed is a method of producing dense refractory products, comprising: (a) obtaining a quantity of exoergic material in powder form capable of sustaining a combustion synthesis reaction; (b) removing absorbed water vapor therefrom; (c) cold-pressing said material into a formed body; (d) plasma spraying said formed body with a molten exoergic material to form a coat thereon; and (e) igniting said exoergic coated formed body under an inert gas atmosphere and pressure to produce self-sustained combustion synthesis. Also disclosed are products produced by the method.

  17. High velocity gas in external galaxies

    NASA Technical Reports Server (NTRS)

    Kamphuis, J.; Vanderhulst, J. M.; Sancisi, R.

    1990-01-01

    Two nearby, nearly face-on spiral galaxies, M 101 and NGC 6946, observed in the HI with the Westerbork Synthesis Radio Telescope (WSRT) as part of a program to search for high velocity gas in other galaxies, are used to illustrate the range of properties of high velocity gas in other galaxies found thusfar.

  18. Tunable composite membranes for gas separations. Quarterly technical progress report, November 1, 1995--January 31, 1996

    SciTech Connect

    Ferraris, J.P.; Balkus, K.J. Jr.; Musselman, I.H.

    1996-01-01

    Research continued on composite membranes for gas separations. This report describes work in the following: instrument development; polymer synthesis; membrane fabrication; and permeability measurements.

  19. Gas storage using fullerene based adsorbents

    NASA Technical Reports Server (NTRS)

    Loutfy, Raouf O. (Inventor); Lu, Xiao-Chun (Inventor); Li, Weijiong (Inventor); Mikhael, Michael G. (Inventor)

    2000-01-01

    This invention is directed to the synthesis of high bulk density high gas absorption capacity adsorbents for gas storage applications. Specifically, this invention is concerned with novel gas absorbents with high gravimetric and volumetric gas adsorption capacities which are made from fullerene-based materials. By pressing fullerene powder into pellet form using a conventional press, then polymerizing it by subjecting the fullerene to high temperature and high inert gas pressure, the resulting fullerene-based materials have high bulk densities and high gas adsorption capacities. By pre-chemical modification or post-polymerization activation processes, the gas adsorption capacities of the fullerene-based adsorbents can be further enhanced. These materials are suitable for low pressure gas storage applications, such as oxygen storage for home oxygen therapy uses or on-board vehicle natural gas storage. They are also suitable for storing gases and vapors such as hydrogen, nitrogen, carbon dioxide, and water vapor.

  20. Combustion synthesis of advanced composite materials

    NASA Technical Reports Server (NTRS)

    Moore, John J.

    1993-01-01

    Self-propagating high temperature (combustion) synthesis (SHS), has been investigated as a means of producing both dense and expanded (foamed) ceramic and ceramic-metal composites, ceramic powders and whiskers. Several model exothermic combustion synthesis reactions were used to establish the importance of certain reaction parameters, e.g., stoichiometry, green density, combustion mode, particle size, etc. on the control of the synthesis reaction, product morphology and properties. The use of an in situ liquid infiltration technique and the effect of varying the reactants and their stoichiometry to provide a range of reactant and product species i.e., solids, liquids and gases, with varying physical properties e.g., volatility and thermal conductivity, on the microstructure and morphology of synthesized composite materials is discussed. Conducting the combustion synthesis reaction in a reactive gas environment to take advantage of the synergistic effects of combustion synthesis and vapor phase transport is also examined.

  1. Combustion synthesis continuous flow reactor

    DOEpatents

    Maupin, G.D.; Chick, L.A.; Kurosky, R.P.

    1998-01-06

    The present invention is a reactor for combustion synthesis of inorganic powders. The reactor includes a reaction vessel having a length and a first end and a second end. The reaction vessel further has a solution inlet and a carrier gas inlet. The reactor further has a heater for heating both the solution and the carrier gas. In a preferred embodiment, the reaction vessel is heated and the solution is in contact with the heated reaction vessel. It is further preferred that the reaction vessel be cylindrical and that the carrier gas is introduced tangentially into the reaction vessel so that the solution flows helically along the interior wall of the reaction vessel. As the solution evaporates and combustion produces inorganic material powder, the carrier gas entrains the powder and carries it out of the reactor. 10 figs.

  2. Combustion synthesis continuous flow reactor

    DOEpatents

    Maupin, Gary D.; Chick, Lawrence A.; Kurosky, Randal P.

    1998-01-01

    The present invention is a reactor for combustion synthesis of inorganic powders. The reactor includes a reaction vessel having a length and a first end and a second end. The reaction vessel further has a solution inlet and a carrier gas inlet. The reactor further has a heater for heating both the solution and the carrier gas. In a preferred embodiment, the reaction vessel is heated and the solution is in contact with the heated reaction vessel. It is further preferred that the reaction vessel be cylindrical and that the carrier gas is introduced tangentially into the reaction vessel so that the solution flows helically along the interior wall of the reaction vessel. As the solution evaporates and combustion produces inorganic material powder, the carrier gas entrains the powder and carries it out of the reactor.

  3. Biogas as a fuel for solid oxide fuel cells and synthesis gas production: effects of ceria-doping and hydrogen sulfide on the performance of nickel-based anode materials.

    PubMed

    Laycock, Christian J; Staniforth, John Z; Ormerod, R Mark

    2011-05-28

    Numerous investigations have been carried out into the conversion of biogas into synthesis gas (a mixture of H(2) + CO) over Ni/YSZ anode cermet catalysts. Biogas is a variable mixture of gases consisting predominantly of methane and carbon dioxide (usually in a 2 : 1 ratio, but variable with source), with other constituents including sulfur-containing gases such as hydrogen sulfide, which can cause sulfur poisoning of nickel catalysts. The effect of temperature on carbon deposition and sulfur poisoning of 90 : 10 mol% Ni/YSZ under biogas conversion conditions has been investigated by carrying out a series of catalytic reactions of methane-rich (2 : 1) CH(4)/CO(2) mixtures in the absence and presence of H(2)S over the temperature range 750-1000 °C. The effect of ceria-doping on carbon dioxide reforming, carbon deposition and sulfur tolerance has also been investigated by carrying out a similar series of reactions over ceria-doped Ni/YSZ. Ceria was doped at 5 mol% of the nickel content to give an anode catalyst composition of 85.5 : 4.5 : 10 mol% Ni/CeO(2)/YSZ. Reactions were followed using quadrupolar mass spectrometry (QMS) and the amount of carbon deposition was analysed by subjecting the reacted catalyst samples to a post-reaction temperature programmed oxidation (TPO). On undoped Ni/YSZ, carbon deposition occurred predominantly through thermal decomposition of methane. Ceria-doping significantly suppressed methane decomposition and at high temperatures simultaneously promoted the reverse Boudouard reaction, significantly lowering carbon deposition. Sulfur poisoning of Ni/YSZ occurred in two phases, the first of which caused the most activity loss and was accelerated on increasing the reaction temperature, while the second phase had greater stability and became more favourable with increasing reaction temperature. Adding H(2)S significantly inhibited methane decomposition, resulting in much less carbon deposition. Ceria-doping significantly increased the sulfur

  4. Biogas as a fuel for solid oxide fuel cells and synthesis gas production: effects of ceria-doping and hydrogen sulfide on the performance of nickel-based anode materials.

    PubMed

    Laycock, Christian J; Staniforth, John Z; Ormerod, R Mark

    2011-05-28

    Numerous investigations have been carried out into the conversion of biogas into synthesis gas (a mixture of H(2) + CO) over Ni/YSZ anode cermet catalysts. Biogas is a variable mixture of gases consisting predominantly of methane and carbon dioxide (usually in a 2 : 1 ratio, but variable with source), with other constituents including sulfur-containing gases such as hydrogen sulfide, which can cause sulfur poisoning of nickel catalysts. The effect of temperature on carbon deposition and sulfur poisoning of 90 : 10 mol% Ni/YSZ under biogas conversion conditions has been investigated by carrying out a series of catalytic reactions of methane-rich (2 : 1) CH(4)/CO(2) mixtures in the absence and presence of H(2)S over the temperature range 750-1000 °C. The effect of ceria-doping on carbon dioxide reforming, carbon deposition and sulfur tolerance has also been investigated by carrying out a similar series of reactions over ceria-doped Ni/YSZ. Ceria was doped at 5 mol% of the nickel content to give an anode catalyst composition of 85.5 : 4.5 : 10 mol% Ni/CeO(2)/YSZ. Reactions were followed using quadrupolar mass spectrometry (QMS) and the amount of carbon deposition was analysed by subjecting the reacted catalyst samples to a post-reaction temperature programmed oxidation (TPO). On undoped Ni/YSZ, carbon deposition occurred predominantly through thermal decomposition of methane. Ceria-doping significantly suppressed methane decomposition and at high temperatures simultaneously promoted the reverse Boudouard reaction, significantly lowering carbon deposition. Sulfur poisoning of Ni/YSZ occurred in two phases, the first of which caused the most activity loss and was accelerated on increasing the reaction temperature, while the second phase had greater stability and became more favourable with increasing reaction temperature. Adding H(2)S significantly inhibited methane decomposition, resulting in much less carbon deposition. Ceria-doping significantly increased the sulfur

  5. Synthesis of carbon nanofibers on copper particles

    NASA Astrophysics Data System (ADS)

    Kol'tsova, T. S.; Larionova, T. V.; Shusharina, N. N.; Tolochko, O. V.

    2015-08-01

    We analyze the synthesis of carbon nanostructures from the gas phase (mixture of acetylene or ethylene with hydrogen) on the surface of copper particles without using other catalysts. The synthesized structures (multilayer graphene and carbon nanofibers) are analyzed by transmission electron microscopy and Raman scattering. It is shown that the fiber structure is determined by the C: H ratio in the gas phase. The kinetics of synthesis is analyzed in terms of the formal kinetics of conversion in accordance with the Johnson—Mehl—Avrami equation.

  6. Speech Synthesis

    NASA Astrophysics Data System (ADS)

    Dutoit, Thierry; Bozkurt, Baris

    Text-to-speech (TTS) synthesis is the art of designing talking machines. It is often seen by engineers as an easy task, compared to speech recognition.1 It is true, indeed, that it is easier to create a bad, first trial text-to-speech (TTS) system than to design a rudimentary speech recognizer.

  7. GLUTATHIONE SYNTHESIS

    PubMed Central

    Lu, Shelly C.

    2012-01-01

    BACKGROUND Glutathione (GSH) is present in all mammalian tissues as the most abundant non-protein thiol that defends against oxidative stress. GSH is also a key determinant of redox signaling, vital in detoxification of xenobiotics, regulates cell proliferation, apoptosis, immune function, and fibrogenesis. Biosynthesis of GSH occurs in the cytosol in a tightly regulated manner. Key determinants of GSH synthesis are the availability of the sulfur amino acid precursor, cysteine, and the activity of the rate-limiting enzyme, glutamate cysteine ligase (GCL), which is composed of a catalytic (GCLC) and a modifier (GCLM) subunit. The second enzyme of GSH synthesis is GSH synthetase (GS). SCOPE OF REVIEW This review summarizes key functions of GSH and focuses on factors that regulate the biosynthesis of GSH, including pathological conditions where GSH synthesis is dysregulated. MAJOR CONCLUSIONS GCL subunits and GS are regulated at multiple levels and often in a coordinated manner. Key transcription factors that regulate the expression of these genes include NF-E2 related factor 2 (Nrf2) via the antioxidant response element (ARE), AP-1, and nuclear factor kappa B (NFκB). There is increasing evidence that dysregulation of GSH synthesis contributes to the pathogenesis of many pathological conditions. These include diabetes mellitus, pulmonary and liver fibrosis, alcoholic liver disease, cholestatic liver injury, endotoxemia and drug-resistant tumor cells. GENERAL SIGNIFICANCE GSH is a key antioxidant that also modulates diverse cellular processes. A better understanding of how its synthesis is regulated and dysregulated in disease states may lead to improvement in the treatment of these disorders. PMID:22995213

  8. Synthesis and Transformation of Carbonaceous Nanoparticles

    NASA Astrophysics Data System (ADS)

    Mennella, Vito

    2015-03-01

    The physical properties of carbonaceous nanoparticles depend on the production conditions. In addition, these properties are modified by heat, UV and ion irradiation and gas interaction. We will discuss the synthesis and transformation of carbon nanoparticles that have been proposed as carriers of aromatic and aliphatic spectroscopic features observed in the interstellar medium.

  9. Gas gangrene

    MedlinePlus

    Tissue infection - Clostridial; Gangrene - gas; Myonecrosis; Clostridial infection of tissues; Necrotizing soft tissue infection ... Gas gangrene is most often caused by bacteria called Clostridium perfringens. It also can be caused by ...

  10. Gas Research Institute experience in solar fuel research

    NASA Astrophysics Data System (ADS)

    Krist, Kevin

    Between 1981-1989, the Gas Research Institute (GRI) conducted a fundamental research program aimed at low-cost conversion of inorganic materials to gaseous fuels, using solar energy. Although the program focussed on photochemical approaches, thermochemical pathways were also evaluated. General conclusions are presented in the following areas: photochemical fuel synthesis, thermochemical fuel synthesis, photochemical processes, thermal processes, and collector systems.

  11. Gas separating

    DOEpatents

    Gollan, Arye

    1988-01-01

    Feed gas is directed tangentially along the non-skin surface of gas separation membrane modules comprising a cylindrical bundle of parallel contiguous hollow fibers supported to allow feed gas to flow from an inlet at one end of a cylindrical housing through the bores of the bundled fibers to an outlet at the other end while a component of the feed gas permeates through the fibers, each having the skin side on the outside, through a permeate outlet in the cylindrical casing.

  12. Gas separating

    DOEpatents

    Gollan, Arye Z. [Newton, MA

    1990-12-25

    Feed gas is directed tangentially along the non-skin surface of gas separation membrane modules comprising a cylindrical bundle of parallel contiguous hollow fibers supported to allow feed gas to flow from an inlet at one end of a cylindrical housing through the bores of the bundled fibers to an outlet at the other end while a component of the feed gas permeates through the fibers, each having the skin side on the outside, through a permeate outlet in the cylindrical casing.

  13. Gaseous detonation synthesis and characterization of nano-oxide

    NASA Astrophysics Data System (ADS)

    Yan, Honghao; Wu, Linsong; Li, Xiaojie; Wang, Xiaohong

    2015-07-01

    Gaseous detonation is a new method of heating the precursor of nanomaterials into gas, and integrating it with combustible gas as mixture to be detonated for the synthesis of nanomaterials. In this paper, the mixed gas of oxygen and hydrogen is used as the source for detonation, to synthesize nano TiO2, nano SiO2 and nano SnO2 through gaseous detonation method, characterization and analysis of the products, it was found that the products from gaseous detonation method were of high purity, good dispersion, smaller particle size and even distribution. It also shows that for the synthesis of nano-oxides, gaseous detonation is universal.

  14. Gas vesicles.

    PubMed Central

    Walsby, A E

    1994-01-01

    The gas vesicle is a hollow structure made of protein. It usually has the form of a cylindrical tube closed by conical end caps. Gas vesicles occur in five phyla of the Bacteria and two groups of the Archaea, but they are mostly restricted to planktonic microorganisms, in which they provide buoyancy. By regulating their relative gas vesicle content aquatic microbes are able to perform vertical migrations. In slowly growing organisms such movements are made more efficiently than by swimming with flagella. The gas vesicle is impermeable to liquid water, but it is highly permeable to gases and is normally filled with air. It is a rigid structure of low compressibility, but it collapses flat under a certain critical pressure and buoyancy is then lost. Gas vesicles in different organisms vary in width, from 45 to > 200 nm; in accordance with engineering principles the narrower ones are stronger (have higher critical pressures) than wide ones, but they contain less gas space per wall volume and are therefore less efficient at providing buoyancy. A survey of gas-vacuolate cyanobacteria reveals that there has been natural selection for gas vesicles of the maximum width permitted by the pressure encountered in the natural environment, which is mainly determined by cell turgor pressure and water depth. Gas vesicle width is genetically determined, perhaps through the amino acid sequence of one of the constituent proteins. Up to 14 genes have been implicated in gas vesicle production, but so far the products of only two have been shown to be present in the gas vesicle: GvpA makes the ribs that form the structure, and GvpC binds to the outside of the ribs and stiffens the structure against collapse. The evolution of the gas vesicle is discussed in relation to the homologies of these proteins. Images PMID:8177173

  15. Gas magnetometer

    DOEpatents

    Walker, Thad Gilbert; Lancor, Brian Robert; Wyllie, Robert

    2016-05-03

    Measurement of a precessional rate of a gas, such as an alkali gas, in a magnetic field is made by promoting a non-uniform precession of the gas in which substantially no net magnetic field affects the gas during a majority of the precession cycle. This allows sensitive gases that would be subject to spin-exchange collision de-phasing to be effectively used for extremely sensitive measurements in the presence of an environmental magnetic field such as the Earth's magnetic field.

  16. Gas chromatography

    NASA Astrophysics Data System (ADS)

    Guiochon, Georges; Guillemin, Claude L.

    1990-11-01

    Gas chromatography is a powerful separation technique for gas and vapor mixtures. Combining separation and on-line detection permits accurate quantitative analysis of complex mixtures, including traces of compounds down to parts per trillions in some particular cases. The importance of gas chromatography in quality control and process control in the chemical and drug industry, in environmental pollution investigations and in clinical analysis is critical. The principles of the technique are discussed, the main components of a gas chromatograph are described and some idea of the importance of the applications is given.

  17. Gas separating

    DOEpatents

    Gollan, A.

    1988-03-29

    Feed gas is directed tangentially along the non-skin surface of gas separation membrane modules comprising a cylindrical bundle of parallel contiguous hollow fibers supported to allow feed gas to flow from an inlet at one end of a cylindrical housing through the bores of the bundled fibers to an outlet at the other end while a component of the feed gas permeates through the fibers, each having the skin side on the outside, through a permeate outlet in the cylindrical casing. 3 figs.

  18. Gas separating

    DOEpatents

    Gollan, A.Z.

    1990-12-25

    Feed gas is directed tangentially along the non-skin surface of gas separation membrane modules comprising a cylindrical bundle of parallel contiguous hollow fibers supported to allow feed gas to flow from an inlet at one end of a cylindrical housing through the bores of the bundled fibers to an outlet at the other end while a component of the feed gas permeates through the fibers, each having the skin side on the outside, through a permeate outlet in the cylindrical casing. 3 figs.

  19. CATALYST ACTIVITY MAINTENANCE FOR THE LIQUID PHASE SYNTHESIS GAS-TO-DIMETHYL ETHER PROCESS PART II: DEVELOPMENT OF ALUMINUM PHOSPHATE AS THE DEHYDRATION CATALYST FOR THE SINGLE-STEP LIQUID PHASE SYNGAS-TO-DME PROCESS

    SciTech Connect

    Xiang-Dong Peng

    2002-05-01

    At the heart of the single-step liquid phase syngas-to-DME process (LPDME{trademark}) is a catalyst system that can be active as well as stable. In the Alternative Fuels I program, a dual-catalyst system containing a Cu-based commercial methanol synthesis catalyst (BASF S3-86) and a commercial dehydration material ({gamma}-alumina) was demonstrated. It provided the productivity and selectivity expected from the LPDME process. However, the catalyst system deactivated too rapidly to warrant a viable commercial process [1]. The mechanistic investigation in the early part of the DOE's Alternative Fuels II program revealed that the accelerated catalyst deactivation under LPDME conditions is due to detrimental interaction between the methanol synthesis catalyst and methanol dehydration catalyst [2,3]. The interaction was attributed to migration of Cu- and/or Zn-containing species from the synthesis catalyst to the dehydration catalyst. Identification of a dehydration catalyst that did not lead to this detrimental interaction while retaining adequate dehydration activity was elusive. Twenty-nine different dehydration materials were tested, but none showed the desired performance [2]. The search came to a turning point when aluminum phosphate was tested. This amorphous material is prepared by precipitating a solution containing Al(NO{sub 3}){sub 3} and H{sub 3}PO{sub 4} with NH{sub 4}OH, followed by washing, drying and calcination. The aluminum phosphate catalyst has adequate dehydration activity and good stability. It can co-exist with the Cu-based methanol synthesis catalyst without negatively affecting the latter catalyst's stability. This report documents the details of the development of this catalyst. These include initial leads, efforts in improving activity and stability, investigation and development of the best preparation parameters and procedures, mechanistic understanding and resulting preparation guidelines, and the accomplishments of this work.

  20. Gas Chromatography.

    ERIC Educational Resources Information Center

    Karasek, Francis W.; And Others

    1984-01-01

    This review covers fundamental developments in gas chromatography during 1982 and 1983. Literature is considered under these headings: columns; liguid phases; solid supports; sorption processes and solvents; open tubular column gas chromatography; instrumentation; high-resolution columns and applications; other techniques; qualitative and…

  1. Microporous metal organic framework [M2(hfipbb)2(ted)] (M=Zn, Co; H2hfipbb=4,4-(hexafluoroisopropylidene)-bis(benzoic acid); ted=triethylenediamine): Synthesis, structure analysis, pore characterization, small gas adsorption and CO2/N2 separation properties

    NASA Astrophysics Data System (ADS)

    Xu, William W.; Pramanik, Sanhita; Zhang, Zhijuan; Emge, Thomas J.; Li, Jing

    2013-04-01

    Carbon dioxide is a greenhouse gas that is a major contributor to global warming. Developing methods that can effectively capture CO2 is the key to reduce its emission to the atmosphere. Recent research shows that microporous metal organic frameworks (MOFs) are emerging as a promising family of adsorbents that may be promising for use in adsorption based capture and separation of CO2 from power plant waste gases. In this work we report the synthesis, crystal structure analysis and pore characterization of two microporous MOF structures, [M2(hfipbb)2(ted)] (M=Zn (1), Co (2); H2hfipbb=4,4-(hexafluoroisopropylidene)-bis(benzoic acid); ted=triethylenediamine). The CO2 and N2 adsorption experiments and IAST calculations are carried out on [Zn2(hfipbb)2(ted)] under conditions that mimic post-combustion flue gas mixtures emitted from power plants. The results show that the framework interacts with CO2 strongly, giving rise to relatively high isosteric heats of adsorption (up to 28 kJ/mol), and high adsorption selectivity for CO2 over N2, making it promising for capturing and separating CO2 from CO2/N2 mixtures.

  2. THE ECONOMICAL PRODUCTION OF ALCOHOL FUELS FROM COAL-DERIVED SYNTHESIS GAS. Includes quarterly technical progress report No.25 from 10/01/1997-12/31/1997, and quarterly technical progress report No.26 from 01/01/1998-03/31/1998

    SciTech Connect

    1999-03-01

    This project was divided into two parts. One part evaluated possible catalysts for producing higher-alcohols (C{sub 2} to C{sub 5+}) as fuel additives. The other part provided guidance by looking both at the economics of mixed-alcohol production from coal-derived syngas and the effect of higher alcohol addition on gasoline octane and engine performance. The catalysts studied for higher-alcohol synthesis were molybdenum sulfides promoted with potassium. The best catalysts produced alcohols at a rate of 200 g/kg of catalyst/h. Higher-alcohol selectivity was over 40%. The hydrocarbon by-product was less than 20%. These catalysts met established success criteria. The economics for mixed alcohols produced from coal were poor compared to mixed alcohols produced from natural gas. Syngas from natural gas was always less expensive than syngas from coal. Engine tests showed that mixed alcohols added to gasoline significantly improved fuel quality. Mixed-alcohols as produced by our catalysts enhanced gasoline octane and decreased engine emissions. Mixed-alcohol addition gave better results than adding individual alcohols as had been done in the 1980's when some refiners added methanol or ethanol to gasoline.

  3. Development of iron-aluminide hot-gas filters

    SciTech Connect

    Tortorelli, P.F.; Wright, I.G.; Judkins, R.R.

    1996-06-01

    Removal of particles from hot synthesis gas produced by coal gasification is vital to the success of these systems. In Integrated [Coal] Gasification Combined Cycle systems, the synthesis gas is the fuel for gas turbines. To avoid damage to turbine components, it is necessary that particles be removed from the fuel gas prior to combustion and introduction into the turbine. Reliability and durability of the hot-gas filtering devices used to remove the particles is, of course, of special importance. Hot-gas filter materials include both ceramics and metals. Numerous considerations must be made in selecting materials for these filters. Constituents in the hot gases may potentially degrade the properties and performance of the filters to the point that they are ineffective in removing the particles. Very significant efforts have been made by DOE and others to develop effective hot-particle filters and, although improvements have been made, alternative materials and structures are still needed.

  4. Sol-Gel Thin Films for Plasmonic Gas Sensors

    PubMed Central

    Della Gaspera, Enrico; Martucci, Alessandro

    2015-01-01

    Plasmonic gas sensors are optical sensors that use localized surface plasmons or extended surface plasmons as transducing platform. Surface plasmons are very sensitive to dielectric variations of the environment or to electron exchange, and these effects have been exploited for the realization of sensitive gas sensors. In this paper, we review our research work of the last few years on the synthesis and the gas sensing properties of sol-gel based nanomaterials for plasmonic sensors. PMID:26184216

  5. IGNITION IMPROVEMENT OF LEAN NATURAL GAS MIXTURES

    SciTech Connect

    Jason M. Keith

    2005-02-01

    This report describes work performed during a thirty month project which involves the production of dimethyl ether (DME) on-site for use as an ignition-improving additive in a compression-ignition natural gas engine. A single cylinder spark ignition engine was converted to compression ignition operation. The engine was then fully instrumented with a cylinder pressure transducer, crank shaft position sensor, airflow meter, natural gas mass flow sensor, and an exhaust temperature sensor. Finally, the engine was interfaced with a control system for pilot injection of DME. The engine testing is currently in progress. In addition, a one-pass process to form DME from natural gas was simulated with chemical processing software. Natural gas is reformed to synthesis gas (a mixture of hydrogen and carbon monoxide), converted into methanol, and finally to DME in three steps. Of additional benefit to the internal combustion engine, the offgas from the pilot process can be mixed with the main natural gas charge and is expected to improve engine performance. Furthermore, a one-pass pilot facility was constructed to produce 3.7 liters/hour (0.98 gallons/hour) DME from methanol in order to characterize the effluent DME solution and determine suitability for engine use. Successful production of DME led to an economic estimate of completing a full natural gas-to-DME pilot process. Additional experimental work in constructing a synthesis gas to methanol reactor is in progress. The overall recommendation from this work is that natural gas to DME is not a suitable pathway to improved natural gas engine performance. The major reasons are difficulties in handling DME for pilot injection and the large capital costs associated with DME production from natural gas.

  6. Microporous metal organic framework [M{sub 2}(hfipbb){sub 2}(ted)] (M=Zn, Co; H{sub 2}hfipbb=4,4-(hexafluoroisopropylidene)-bis(benzoic acid); ted=triethylenediamine): Synthesis, structure analysis, pore characterization, small gas adsorption and CO{sub 2}/N{sub 2} separation properties

    SciTech Connect

    Xu, William W.; Pramanik, Sanhita; Zhang, Zhijuan; Emge, Thomas J.; Li, Jing

    2013-04-15

    Carbon dioxide is a greenhouse gas that is a major contributor to global warming. Developing methods that can effectively capture CO{sub 2} is the key to reduce its emission to the atmosphere. Recent research shows that microporous metal organic frameworks (MOFs) are emerging as a promising family of adsorbents that may be promising for use in adsorption based capture and separation of CO{sub 2} from power plant waste gases. In this work we report the synthesis, crystal structure analysis and pore characterization of two microporous MOF structures, [M{sub 2}(hfipbb){sub 2}(ted)] (M=Zn (1), Co (2); H{sub 2}hfipbb=4,4-(hexafluoroisopropylidene)-bis(benzoic acid); ted=triethylenediamine). The CO{sub 2} and N{sub 2} adsorption experiments and IAST calculations are carried out on [Zn{sub 2}(hfipbb){sub 2}(ted)] under conditions that mimic post-combustion flue gas mixtures emitted from power plants. The results show that the framework interacts with CO{sub 2} strongly, giving rise to relatively high isosteric heats of adsorption (up to 28 kJ/mol), and high adsorption selectivity for CO{sub 2} over N{sub 2}, making it promising for capturing and separating CO{sub 2} from CO{sub 2}/N{sub 2} mixtures. - Graphical abstract: Microporous [Zn{sub 2}(hfipbb){sub 2}(ted)] demonstrates high adsorption selectivity for CO{sub 2} over N{sub 2} under conditions that mimic flue gas mixtures. Highlights: ► Two new porous MOFs were synthesized and characterized by rational design. ► The small pore size leads to greatly enhanced CO{sub 2}–MOF interaction. ► High adsorption selectivity of the Zn–MOF for CO{sub 2} over N{sub 2} is achieved.

  7. Ethylene synthesis and sensitivity in crop plants

    NASA Technical Reports Server (NTRS)

    Klassen, Stephen P.; Bugbee, Bruce

    2004-01-01

    Closed and semi-closed plant growth chambers have long been used in studies of plant and crop physiology. These studies include the measurement of photosynthesis and transpiration via photosynthetic gas exchange. Unfortunately, other gaseous products of plant metabolism can accumulate in these chambers and cause artifacts in the measurements. The most important of these gaseous byproducts is the plant hormone ethylene (C2H4). In spite of hundreds of manuscripts on ethylene, we still have a limited understanding of the synthesis rates throughout the plant life cycle. We also have a poor understanding of the sensitivity of intact, rapidly growing plants to ethylene. We know ethylene synthesis and sensitivity are influenced by both biotic and abiotic stresses, but such whole plant responses have not been accurately quantified. Here we present an overview of basic studies on ethylene synthesis and sensitivity.

  8. Synthesis of p-xylene from ethylene.

    PubMed

    Lyons, Thomas W; Guironnet, Damien; Findlater, Michael; Brookhart, Maurice

    2012-09-26

    As oil supplies dwindle, there is a growing need to develop new routes to chemical intermediates that utilize alternative feedstocks. We report here a synthesis of para-xylene, one of the highest volume chemicals derived from petroleum, using only ethylene as a feedstock. Ethylene is an attractive alternative feedstock, as it can be derived from renewable biomass resources or harnessed from large domestic shale gas deposits. The synthesis relies on the conversion of hexene (from trimerization of ethylene) to 2,4-hexadiene followed by a Diels-Alder reaction with ethylene to form 3,6-dimethylcyclohexene. This monoene is readily dehydrogenated to para-xylene uncontaminated by the ortho and meta isomers. We report here a selective synthesis of para-xylene, uncontaminated by the ortho or meta isomers, using ethylene as the sole feedstock. PMID:22934909

  9. Gas Chromatography

    NASA Astrophysics Data System (ADS)

    Hansen, Patrick; Whisnant, C. Steven

    2010-02-01

    To prepare frozen-spin HD targets for photonuclear physics at JLab, high purity HD is required. Commercially available gas is only ˜98% HD. To reach the purity required to make nuclear targets, the gas is distilled at low temperature to remove the H2 and D2 impurities. To monitor the distillation process and correlate the gas purity with the spin relaxation times, a low temperature gas chromatograph system has been developed that produces good separation of H2, HD and D2. The system uses a PLOT 5A column in a mixture of LN2 and i-pentane at temperatures between 110K and 135K. With this system, the relative concentrations can be determined with uncertainties of ˜10%. The chromatography process and the resulting chromatograms will be discussed. )

  10. Volcanic Gas

    MedlinePlus

    ... Hazards Tephra/Ash Lava Flows Lahars Volcanic Gas Climate Change Pyroclastic Flows Volcanic Landslides Preparedness Volcano Hazard Zones ... Please see our discussion of volcanic gases and climate change for additional information. Hydrogen sulfide (H 2 S) is ...

  11. Gas Chromatography.

    ERIC Educational Resources Information Center

    Cram, Stuart P.; And Others

    1980-01-01

    Selects fundamental developments in theory, methodology, and instrumentation in gas chromatography (GC). A special section reviews GC in the People's Republic of China. Over 1,000 references are cited. (CS)

  12. Gas Analyzer

    NASA Astrophysics Data System (ADS)

    1989-01-01

    The M200 originated in the 1970's under an Ames Research Center/Stanford University contract to develop a small, lightweight gas analyzer for Viking Landers. Although the unit was not used on the spacecraft, it was further developed by The National Institute for Occupational Safety and Health (NIOSH). Three researchers from the project later formed Microsensor Technology, Inc. (MTI) to commercialize the analyzer. The original version (Micromonitor 500) was introduced in 1982, and the M200 in 1988. The M200, a more advanced version, features dual gas chromatograph which separate a gaseous mixture into components and measure concentrations of each gas. It is useful for monitoring gas leaks, chemical spills, etc. Many analyses are completed in less than 30 seconds, and a wide range of mixtures can be analyzed.

  13. A model for synthesis of methane in lunar soil

    NASA Astrophysics Data System (ADS)

    Tamhane, A. S.

    A model for the synthesis of indigenous methane observed in lunar soil samples is presented. The gas bubbles observed in the grains of lunar soil and breccia are considered here as the possible site for synthesis. It is shown that the physical conditions in the bubbles would be suitable for the synthesis by a process similar to the Bergius process of synthesis of hydrocarbons from coal. The probability of synthesis of ammonia at this site would be low, and it would also explain the immunity of the methane molecule from destruction by ionization. A rough calculation indicates that the amount of methane produced in the existing bubbles would be of about the same order as that observed in lunar soil samples.

  14. Phosphatidylcholine Synthesis

    PubMed Central

    Datko, Anne H.; Mudd, S. Harvey

    1988-01-01

    The methylation steps in the biosynthesis of phosphatidylcholine by tissue culture preparations of carrot (Daucus carota L.) and soybean (Glycine max), and by soybean leaf discs, have been studied. Preparations were incubated with tracer concentrations of l-[3H3C]methionine and the kinetics of appearance of radioactivity in phosphomethylethanolamine, phosphodimethylethanolamine, phosphocholine, phosphatidylmethylethanolamine, phosphatidyldimethylethanolamine, phosphatidylcholine, methylethanolamine, dimethylethanolamine, and choline followed at short incubation times. With soybean (tissue culture or leaves), an initial methylation utilizes phosphoethanolamine as substrate, forming phosphomethylethanolamine. The latter is converted to phosphatidylmethylethanolamine, which is successively methylated to phosphatidyldimethyethanolamine and to phosphatidylcholine. With carrot, again, an initial methylation is of phosphoethanolamine. Subsequent methylations occur at both the phospho-base and phosphatidyl-base levels. Both of these patterns differ qualitatively from that previously demonstrated in Lemna (SH Mudd, AH Datko 1986 Plant Physiol 82: 126-135) in which all three methylations occur at the phospho-base level. For soybean and carrot, some added contribution from initial methylation of phosphatidylethanolamine has not been excluded. These results, together with those from similar experiments carried out with water-stressed barley leaves (WD Hitz, D Rhodes, AD Hanson 1981 Plant Physiol 68: 814-822) and salinized sugarbeet leaves (AD Hanson, D Rhodes 1983 Plant Physiol 71: 692-700) suggest that in higher plants some, perhaps all, phosphatidylcholine synthesis occurs via a common committing step (conversion of phosphoethanolamine to phosphomethylethanolamine) followed by a methylation pattern which differs from plant to plant. PMID:16666397

  15. Synthesis of azoimidazolium dyes with nitrous oxide.

    PubMed

    Tskhovrebov, Alexander G; Naested, Lara C E; Solari, Euro; Scopelliti, Rosario; Severin, Kay

    2015-01-19

    A new method for the synthesis of industrially important azoimidazolium dyes is presented. The procedure is based on a reagent which is rarely used in the context of synthetic organic chemistry: nitrous oxide ("laughing gas"). N2O is first coupled to N-heterocyclic carbenes. Subsequent reaction with aromatic compounds through an AlCl3-induced C-H activation process provides azoimidazolium dyes in good yields. PMID:25420599

  16. Offshore Texas and Louisiana marine ecosystems data synthesis. Volume 2: Synthesis report. Final report

    SciTech Connect

    Phillips, N.W.; James, B.M.

    1988-11-01

    This study provided a synthesis of available environmental information for the continental shelf from the shallow sublittoral to a depth of 500 m for the area between Corpus Christi Bay, Texas and the Mississippi River Delta. The Synthesis Report consists of separate chapters devoted to marine geology, physical oceanography and meteorology, marine chemistry, marine biology, socioeconomics, and conceptual modeling of the area's major ecosystems with emphasis on the environmental effects of oil and gas operations. There is a summary of data gaps and information needs and suggestions for future field studies.

  17. Method for hot gas conditioning

    DOEpatents

    Paisley, Mark A.

    1996-02-27

    A method for cracking and shifting a synthesis gas by the steps of providing a catalyst consisting essentially of alumina in a reaction zone; contacting the catalyst with a substantially oxygen free mixture of gases comprising water vapor and hydrocarbons having one or more carbon atoms, at a temperature between about 530.degree. C. (1000.degree. F.) to about 980.degree. C. (1800.degree. F.); and whereby the hydrocarbons are cracked to form hydrogen, carbon monoxide and/or carbon dioxide and the hydrogen content of the mixture increases with a corresponding decrease in carbon monoxide, and carbon formation is substantially eliminated.

  18. Normal-pressure microwave rapid synthesis of hierarchical SnO₂@rGO nanostructures with superhigh surface areas as high-quality gas-sensing and electrochemical active materials.

    PubMed

    Yin, Li; Chen, Deliang; Cui, Xue; Ge, Lianfang; Yang, Jing; Yu, Lanlan; Zhang, Bing; Zhang, Rui; Shao, Guosheng

    2014-11-21

    Hierarchical SnO2@rGO nanostructures with superhigh surface areas are synthesized via a simple redox reaction between Sn(2+) ions and graphene oxide (GO) nanosheets under microwave irradiation. XRD, SEM, TEM, XPS, TG-DTA and N2 adsorption-desorption are used to characterize the compositions and microstructures of the SnO2@rGO samples obtained. The SnO2@rGO nanostructures are used as gas-sensing and electroactive materials to evaluate their property-microstructure relationship. The results show that SnO2 nanoparticles (NPs) with particle sizes of 3-5 nm are uniformly anchored on the surfaces of reduced graphene oxide (rGO) nanosheets through a heteronucleation and growth process. The as-obtained SnO2@rGO sample with a hierarchically sesame cake-like microstructure and a superhigh specific surface area of 2110.9 m(2) g(-1) consists of 92 mass% SnO2 NPs and ∼8 mass% rGO nanosheets. The sensitivity of the SnO2@rGO sensor upon exposure to 10 ppm H2S is up to 78 at the optimal operating temperature of 100 °C, and its response time is as short as 7 s. Compared with SnO2 nanocrystals (5-10 nm), the hierarchical SnO2@rGO nanostructures have enhanced gas-sensing behaviors (i.e., high sensitivity, rapid response and good selectivity). The SnO2@rGO nanostructures also show excellent electroactivity in detecting sunset yellow (SY) in 0.1 M phosphate buffer solution (pH = 2.0). The enhancement in gas-sensing and electroactive performance is mainly attributed to the unique hierarchical microstructure, high surface areas and the synergistic effect of SnO2 NPs and rGO nanosheets. PMID:25277111

  19. Normal-pressure microwave rapid synthesis of hierarchical SnO2@rGO nanostructures with superhigh surface areas as high-quality gas-sensing and electrochemical active materials

    NASA Astrophysics Data System (ADS)

    Yin, Li; Chen, Deliang; Cui, Xue; Ge, Lianfang; Yang, Jing; Yu, Lanlan; Zhang, Bing; Zhang, Rui; Shao, Guosheng

    2014-10-01

    Hierarchical SnO2@rGO nanostructures with superhigh surface areas are synthesized via a simple redox reaction between Sn2+ ions and graphene oxide (GO) nanosheets under microwave irradiation. XRD, SEM, TEM, XPS, TG-DTA and N2 adsorption-desorption are used to characterize the compositions and microstructures of the SnO2@rGO samples obtained. The SnO2@rGO nanostructures are used as gas-sensing and electroactive materials to evaluate their property-microstructure relationship. The results show that SnO2 nanoparticles (NPs) with particle sizes of 3-5 nm are uniformly anchored on the surfaces of reduced graphene oxide (rGO) nanosheets through a heteronucleation and growth process. The as-obtained SnO2@rGO sample with a hierarchically sesame cake-like microstructure and a superhigh specific surface area of 2110.9 m2 g-1 consists of 92 mass% SnO2 NPs and ~8 mass% rGO nanosheets. The sensitivity of the SnO2@rGO sensor upon exposure to 10 ppm H2S is up to 78 at the optimal operating temperature of 100 °C, and its response time is as short as 7 s. Compared with SnO2 nanocrystals (5-10 nm), the hierarchical SnO2@rGO nanostructures have enhanced gas-sensing behaviors (i.e., high sensitivity, rapid response and good selectivity). The SnO2@rGO nanostructures also show excellent electroactivity in detecting sunset yellow (SY) in 0.1 M phosphate buffer solution (pH = 2.0). The enhancement in gas-sensing and electroactive performance is mainly attributed to the unique hierarchical microstructure, high surface areas and the synergistic effect of SnO2 NPs and rGO nanosheets.

  20. Normal-pressure microwave rapid synthesis of hierarchical SnO₂@rGO nanostructures with superhigh surface areas as high-quality gas-sensing and electrochemical active materials.

    PubMed

    Yin, Li; Chen, Deliang; Cui, Xue; Ge, Lianfang; Yang, Jing; Yu, Lanlan; Zhang, Bing; Zhang, Rui; Shao, Guosheng

    2014-11-21

    Hierarchical SnO2@rGO nanostructures with superhigh surface areas are synthesized via a simple redox reaction between Sn(2+) ions and graphene oxide (GO) nanosheets under microwave irradiation. XRD, SEM, TEM, XPS, TG-DTA and N2 adsorption-desorption are used to characterize the compositions and microstructures of the SnO2@rGO samples obtained. The SnO2@rGO nanostructures are used as gas-sensing and electroactive materials to evaluate their property-microstructure relationship. The results show that SnO2 nanoparticles (NPs) with particle sizes of 3-5 nm are uniformly anchored on the surfaces of reduced graphene oxide (rGO) nanosheets through a heteronucleation and growth process. The as-obtained SnO2@rGO sample with a hierarchically sesame cake-like microstructure and a superhigh specific surface area of 2110.9 m(2) g(-1) consists of 92 mass% SnO2 NPs and ∼8 mass% rGO nanosheets. The sensitivity of the SnO2@rGO sensor upon exposure to 10 ppm H2S is up to 78 at the optimal operating temperature of 100 °C, and its response time is as short as 7 s. Compared with SnO2 nanocrystals (5-10 nm), the hierarchical SnO2@rGO nanostructures have enhanced gas-sensing behaviors (i.e., high sensitivity, rapid response and good selectivity). The SnO2@rGO nanostructures also show excellent electroactivity in detecting sunset yellow (SY) in 0.1 M phosphate buffer solution (pH = 2.0). The enhancement in gas-sensing and electroactive performance is mainly attributed to the unique hierarchical microstructure, high surface areas and the synergistic effect of SnO2 NPs and rGO nanosheets.