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Sample records for catalytic membranes operated

  1. Novel Catalytic Membrane Reactors

    SciTech Connect

    Stuart Nemser, PhD

    2010-10-01

    There are many industrial catalytic organic reversible reactions with amines or alcohols that have water as one of the products. Many of these reactions are homogeneously catalyzed. In all cases removal of water facilitates the reaction and produces more of the desired chemical product. By shifting the reaction to right we produce more chemical product with little or no additional capital investment. Many of these reactions can also relate to bioprocesses. Given the large number of water-organic compound separations achievable and the ability of the Compact Membrane Systems, Inc. (CMS) perfluoro membranes to withstand these harsh operating conditions, this is an ideal demonstration system for the water-of-reaction removal using a membrane reactor. Enhanced reaction synthesis is consistent with the DOE objective to lower the energy intensity of U.S. industry 25% by 2017 in accord with the Energy Policy Act of 2005 and to improve the United States manufacturing competitiveness. The objective of this program is to develop the platform technology for enhancing homogeneous catalytic chemical syntheses.

  2. Catalytic membranes beckon

    SciTech Connect

    Caruana, C.M.

    1994-11-01

    Chemical engineers here and abroad are finding that the marriage of catalysts and membranes holds promise for faster and more specific reactions, although commercialization of this technology is several years away. Catalytic membrane reactors (CMRs) combine a heterogeneous catalyst and a permselective membrane. Reactions performed by CMRs provide higher yields--sometimes as much as 50% higher--because of better reaction selectivity--as opposed to separation selectivity. CMRs also can work at very high temperatures, using ceramic materials that would not be possible with organic membranes. Although the use of CMRs is not widespread presently, the development of new membranes--particularly porous ceramic and zeolite membranes--will increase the potential to improve yields of many catalytic processes. The paper discusses ongoing studies, metal and advanced materials for membranes, the need for continued research, hydrogen recovery from coal-derived gases, catalytic oxidation of sulfides, CMRs for water purification, and oxidative coupling of methane.

  3. Catalytic nanoporous membranes

    DOEpatents

    Pellin, Michael J; Hryn, John N; Elam, Jeffrey W

    2013-08-27

    A nanoporous catalytic membrane which displays several unique features Including pores which can go through the entire thickness of the membrane. The membrane has a higher catalytic and product selectivity than conventional catalysts. Anodic aluminum oxide (AAO) membranes serve as the catalyst substrate. This substrate is then subjected to Atomic Layer Deposition (ALD), which allows the controlled narrowing of the pores from 40 nm to 10 nm in the substrate by deposition of a preparatory material. Subsequent deposition of a catalytic layer on the inner surfaces of the pores reduces pore sizes to less than 10 nm and allows for a higher degree of reaction selectivity. The small pore sizes allow control over which molecules enter the pores, and the flow-through feature can allow for partial oxidation of reactant species as opposed to complete oxidation. A nanoporous separation membrane, produced by ALD is also provided for use in gaseous and liquid separations. The membrane has a high flow rate of material with 100% selectivity. Also provided is a method for producing a catalytic membrane having flow-through pores and discreet catalytic clusters adhering to the inside surfaces of the pores.

  4. Catalytic nanoporous membranes

    DOEpatents

    Pellin, Michael J.; Hryn, John N.; Elam, Jeffrey W.

    2009-12-01

    A nanoporous catalytic membrane which displays several unique features including pores which can go through the entire thickness of the membrane. The membrane has a higher catalytic and product selectivity than conventional catalysts. Anodic aluminum oxide (AAO) membranes serve as the catalyst substrate. This substrate is then subjected to Atomic Layer Deposition (ALD), which allows the controlled narrowing of the pores from 40 nm to 10 nm in the substrate by deposition of a preparatory material. Subsequent deposition of a catalytic layer on the inner surfaces of the pores reduces pore sizes to less than 10 nm and allows for a higher degree of reaction selectivity. The small pore sizes allow control over which molecules enter the pores, and the flow-through feature can allow for partial oxidation of reactant species as opposed to complete oxidation. A nanoporous separation membrane, produced by ALD is also provided for use in gaseous and liquid separations. The membrane has a high flow rate of material with 100% selectivity.

  5. Catalytic Membrane Sensors

    SciTech Connect

    Boyle, T.J.; Brinker, C.J.; Gardner, T.J.; Hughes, R.C.; Sault, A.G.

    1998-12-01

    The proposed "catalytic membrane sensor" (CMS) was developed to generate a device which would selectively identify a specific reagent in a complex mixture of gases. This was to be accomplished by modifying an existing Hz sensor with a series of thin films. Through selectively sieving the desired component from a complex mixture and identifying it by decomposing it into Hz (and other by-products), a Hz sensor could then be used to detect the presence of the select component. The proposed "sandwich-type" modifications involved the deposition of a catalyst layered between two size selective sol-gel layers on a Pd/Ni resistive Hz sensor. The role of the catalyst was to convert organic materials to Hz and organic by-products. The role of the membraneo was to impart both chemical specificity by molecukir sieving of the analyte and converted product streams, as well as controlling access to the underlying Pd/Ni sensor. Ultimately, an array of these CMS elements encompassing different catalysts and membranes were to be developed which would enable improved selectivity and specificity from a compiex mixture of organic gases via pattern recognition methodologies. We have successfully generated a CMS device by a series of spin-coat deposited methods; however, it was determined that the high temperature required to activate the catalyst, destroys the sensor.

  6. High temperature catalytic membrane reactors

    SciTech Connect

    Not Available

    1990-03-01

    Current state-of-the-art inorganic oxide membranes offer the potential of being modified to yield catalytic properties. The resulting modules may be configured to simultaneously induce catalytic reactions with product concentration and separation in a single processing step. Processes utilizing such catalytically active membrane reactors have the potential for dramatically increasing yield reactions which are currently limited by either thermodynamic equilibria, product inhibition, or kinetic selectivity. Examples of commercial interest include hydrogenation, dehydrogenation, partial and selective oxidation, hydrations, hydrocarbon cracking, olefin metathesis, hydroformylation, and olefin polymerization. A large portion of the most significant reactions fall into the category of high temperature, gas phase chemical and petrochemical processes. Microporous oxide membranes are well suited for these applications. A program is proposed to investigate selected model reactions of commercial interest (i.e. dehydrogenation of ethylbenzene to styrene and dehydrogenation of butane to butadiene) using a high temperature catalytic membrane reactor. Membranes will be developed, reaction dynamics characterized, and production processes developed, culminating in laboratory-scale demonstration of technical and economic feasibility. As a result, the anticipated increased yield per reactor pass economic incentives are envisioned. First, a large decrease in the temperature required to obtain high yield should be possible because of the reduced driving force requirement. Significantly higher conversion per pass implies a reduced recycle ratio, as well as reduced reactor size. Both factors result in reduced capital costs, as well as savings in cost of reactants and energy.

  7. Novel Catalytic Membrane Reactors

    SciTech Connect

    2009-02-01

    This factsheet describes a research project that will focus on the development and application of nonporous high gas flux perfluoro membranes with high temperature rating and excellent chemical resistance.

  8. Catalytic carbon membranes for hydrogen production

    SciTech Connect

    Damle, A.S.; Gangwal, S.K.

    1992-01-01

    Commercial carbon composite microfiltration membranes may be modified for gas separation applications by providing a gas separation layer with pores in the 1- to 10-nm range. Several organic polymeric precursors and techniques for depositing a suitable layer were investigated in this project. The in situ polymerization technique was found to be the most promising, and pure component permeation tests with membrane samples prepared with this technique indicated Knudsen diffusion behavior. The gas separation factors obtained by mixed-gas permeation tests were found to depend strongly on gas temperature and pressure indicating significant viscous flow at high-pressure conditions. The modified membranes were used to carry out simultaneous water gas shift reaction and product hydrogen separation. These tests indicated increasing CO conversions with increasing hydrogen separation. A simple process model was developed to simulate a catalytic membrane reactor. A number of simulations were carried out to identify operating conditions leading to product hydrogen concentrations over 90 percent. (VC)

  9. Catalytic membranes for fuel cells

    SciTech Connect

    Liu, Di-Jia; Yang, Junbing; Wang, Xiaoping

    2011-04-19

    A fuel cell of the present invention comprises a cathode and an anode, one or both of the anode and the cathode including a catalyst comprising a bundle of longitudinally aligned graphitic carbon nanotubes including a catalytically active transition metal incorporated longitudinally and atomically distributed throughout the graphitic carbon walls of said nanotubes. The nanotubes also include nitrogen atoms and/or ions chemically bonded to the graphitic carbon and to the transition metal. Preferably, the transition metal comprises at least one metal selected from the group consisting of Fe, Co, Ni, Mn, and Cr.

  10. Catalytic carbon membranes for hydrogen production. Final report

    SciTech Connect

    Damle, A.S.; Gangwal, S.K.

    1992-01-01

    Commercial carbon composite microfiltration membranes may be modified for gas separation applications by providing a gas separation layer with pores in the 1- to 10-nm range. Several organic polymeric precursors and techniques for depositing a suitable layer were investigated in this project. The in situ polymerization technique was found to be the most promising, and pure component permeation tests with membrane samples prepared with this technique indicated Knudsen diffusion behavior. The gas separation factors obtained by mixed-gas permeation tests were found to depend strongly on gas temperature and pressure indicating significant viscous flow at high-pressure conditions. The modified membranes were used to carry out simultaneous water gas shift reaction and product hydrogen separation. These tests indicated increasing CO conversions with increasing hydrogen separation. A simple process model was developed to simulate a catalytic membrane reactor. A number of simulations were carried out to identify operating conditions leading to product hydrogen concentrations over 90 percent. (VC)

  11. Electro Catalytic Oxidation (ECO) Operation

    SciTech Connect

    Morgan Jones

    2011-03-31

    The power industry in the United States is faced with meeting many new regulations to reduce a number of air pollutants including sulfur dioxide, nitrogen oxides, fine particulate matter, and mercury. With over 1,000 power plants in the US, this is a daunting task. In some cases, traditional pollution control technologies such as wet scrubbers and SCRs are not feasible. Powerspan's Electro-Catalytic Oxidation, or ECO{reg_sign} process combines four pollution control devices into a single integrated system that can be installed after a power plant's particulate control device. Besides achieving major reductions in emissions of sulfur dioxide (SO{sub 2}), nitrogen oxides (NOx), fine particulate matter (PM2.5) and mercury (Hg), ECO produces a highly marketable fertilizer, which can help offset the operating costs of the process system. Powerspan has been operating a 50-MW ECO commercial demonstration unit (CDU) at FirstEnergy Corp.'s R.E. Burger Plant near Shadyside, Ohio, since February 2004. In addition to the CDU, a test loop has been constructed beside the CDU to demonstrate higher NOx removal rates and test various scrubber packing types and wet ESP configurations. Furthermore, Powerspan has developed the ECO{reg_sign}{sub 2} technology, a regenerative process that uses a proprietary solvent to capture CO{sub 2} from flue gas. The CO{sub 2} capture takes place after the capture of NOx, SO{sub 2}, mercury, and fine particulate matter. Once the CO{sub 2} is captured, the proprietary solution is regenerated to release CO{sub 2} in a form that is ready for geological storage or beneficial use. Pilot scale testing of ECO{sub 2} began in early 2009 at FirstEnergy's Burger Plant. The ECO{sub 2} pilot unit is designed to process a 1-MW flue gas stream and produce 20 tons of CO{sub 2} per day, achieving a 90% CO{sub 2} capture rate. The ECO{sub 2} pilot program provided the opportunity to confirm process design and cost estimates, and prepare for large scale capture and

  12. Dense ceramic catalytic membranes and membrane reactors for energy and environmental applications.

    PubMed

    Dong, Xueliang; Jin, Wanqin; Xu, Nanping; Li, Kang

    2011-10-21

    Catalytic membrane reactors which carry out separation and reaction in a single unit are expected to be a promising approach to achieve green and sustainable chemistry with less energy consumption and lower pollution. This article presents a review of the recent progress of dense ceramic catalytic membranes and membrane reactors, and their potential applications in energy and environmental areas. A basic knowledge of catalytic membranes and membrane reactors is first introduced briefly, followed by a short discussion on the membrane materials including their structures, composition and strategies for material development. The configuration of catalytic membranes, the design of membrane reaction processes and the high temperature sealing are also discussed. The performance of catalytic membrane reactors for energy and environmental applications are summarized and typical catalytic membrane reaction processes are presented and discussed. Finally, current challenges and difficulties related to the industrialization of dense ceramic membrane reactors are addressed and possible future research is also outlined.

  13. Catalytic membrane program novation: High temperature catalytic membrane reactors. Final report

    SciTech Connect

    Kleiner, R.N.

    1998-08-28

    The original objective was to develop an energy-efficient hydrocarbon dehydrogenation process based on catalytic membrane reactors. Golden Technologies determined that the goals of this contract would be best served by novating the contract to an end user or other interested party which is better informed on the economic justification aspects of petrochemical refining processes to carry out the remaining work. In light of the Chevron results, the program objective was broadened to include development of inorganic membranes for applications in the chemical industry. The proposed membrane technologies shall offer the potential to improve chemical production processes via conversion increase and energy savings. The objective of this subcontract is to seek a party that would serve as a prime contractor to carry out the remaining tasks on the agreement and bring the agreement to a successful conclusion. Four tasks were defined to select the prime contractor. They were (1) prepare a request for proposal, (2) solicit companies as potential prime contractors as well as team members, (3) discuss modifications requested by the potential prime contractors, and (4) obtain, review and rank the proposals. The accomplishments on the tasks is described in detail in the following sections.

  14. Lipase immobilized catalytically active membrane for synthesis of lauryl stearate in a pervaporation membrane reactor.

    PubMed

    Zhang, Weidong; Qing, Weihua; Ren, Zhongqi; Li, Wei; Chen, Jiangrong

    2014-11-01

    A composite catalytically active membrane immobilized with Candida rugosa lipase has been prepared by immersion phase inversion technique for enzymatic synthesis of lauryl stearate in a pervaporation membrane reactor. SEM images showed that a "sandwich-like" membrane structure with a porous lipase-PVA catalytic layer uniformly coated on a polyvinyl alcohol (PVA)/polyethersulfone (PES) bilayer was obtained. Optimum conditions for lipase immobilization in the catalytic layer were determined. The membrane was proved to exhibit superior thermal stability, pH stability and reusability than free lipase under similar conditions. In the case of pervaporation coupled synthesis of lauryl stearate, benefited from in-situ water removal by the membrane, a conversion enhancement of approximately 40% was achieved in comparison to the equilibrium conversion obtained in batch reactors. In addition to conversion enhancement, it was also found that excess water removal by the catalytically active membrane appears to improve activity of the lipase immobilized.

  15. Polymer and Membrane Design for Low Temperature Catalytic Reactions.

    PubMed

    Villalobos, Luis Francisco; Xie, Yihui; Nunes, Suzana Pereira; Peinemann, Klaus-Viktor

    2016-04-01

    Catalytically active asymmetric membranes have been developed with high loadings of palladium nanoparticles located solely in the membrane's ultrathin skin layer. The manufacturing of these membranes requires polymers with functional groups, which can form insoluble complexes with palladium ions. Three polymers have been synthesized for this purpose and a complexation/nonsolvent induced phase separation followed by a palladium reduction step is carried out to prepare such membranes. Parameters to optimize the skin layer thickness and porosity, the palladium loading in this layer, and the palladium nanoparticles size are determined. The catalytic activity of the membranes is verified with the reduction of a nitro-compound and with a liquid phase Suzuki-Miyaura coupling reaction. Very low reaction times are observed.

  16. Solid state oxygen anion and electron mediating membrane and catalytic membrane reactors containing them

    DOEpatents

    Schwartz, Michael; White, James H.; Sammels, Anthony F.

    2000-01-01

    This invention relates to gas-impermeable, solid state materials fabricated into membranes for use in catalytic membrane reactors. This invention particularly relates to solid state oxygen anion- and electron-mediating membranes for use in catalytic membrane reactors for promoting partial or full oxidation of different chemical species, for decomposition of oxygen-containing species, and for separation of oxygen from other gases. Solid state materials for use in the membranes of this invention include mixed metal oxide compounds having the brownmillerite crystal structure.

  17. Solid state oxygen anion and electron mediating membrane and catalytic membrane reactors containing them

    DOEpatents

    Schwartz, Michael; White, James H.; Sammells, Anthony F.

    2005-09-27

    This invention relates to gas-impermeable, solid state materials fabricated into membranes for use in catalytic membrane reactors. This invention particularly relates to solid state oxygen anion- and electron-mediating membranes for use in catalytic membrane reactors for promoting partial or full oxidation of different chemical species, for decomposition of oxygen-containing species, and for separation of oxygen from other gases. Solid state materials for use in the membranes of this invention include mixed metal oxide compounds having the brownmillerite crystal structure.

  18. Thin film porous membranes for catalytic sensors

    SciTech Connect

    Hughes, R.C.; Boyle, T.J.; Gardner, T.J.

    1997-06-01

    This paper reports on new and surprising experimental data for catalytic film gas sensing resistors coated with nanoporous sol-gel films to impart selectivity and durability to the sensor structure. This work is the result of attempts to build selectivity and reactivity to the surface of a sensor by modifying it with a series of sol-gel layers. The initial sol-gel SiO{sub 2} layer applied to the sensor surprisingly showed enhanced O{sub 2} interaction with H{sub 2} and reduced susceptibility to poisons such as H{sub 2}S.

  19. Catalytic membrane reactor for conversion of syngas to liquid hydrocarbons

    SciTech Connect

    Khassin, A.A.

    2005-07-01

    Plug-through catalytically-active contractor membranes can combine high permeability ({gt} 20 m Darcy), high mechanical strength ({gt} 20 kg cm{sup -2}) and high heat-conductivity ({gt} 4 W(mK){sup -1}). Therefore, it provides isothermicity and low pressure drop. The intense mass-transfer within transport pores, high specific area of these pores and small distances between two adjacent transport pores weaken the mass-transfer constraints. Using the PCM one can achieve high space time yield of hydrocarbons and high selectivity towards heavy hydrocarbons and olefins. These advantages allow supposing the effective usage of the PCM catalytic membrane reactors in Fischer-Tropsch synthesis. Also the same approach could be efficient for some other multiphase catalytic processes, like hydrogenation of the unsaturated fatty acids. 5 figs.

  20. Study on surface properties of gamma-alumina catalytic membrane

    SciTech Connect

    Mengchenu Lu; Guoxing Xiong; Bauser, H.

    1994-12-31

    In recent years, preparation and separation applications of gamma-alumina membranes have been extensively studied. In catalysis research field, this membrane can be used not only as a separating medium but also as a catalyst or catalyst support. In this paper, a gamma-alumina catalytic membrane was prepared by a sol-gel technique, then special attention was paid to its surface properties related to catalysis, its surface acidity, hydroxyl, microstructure and pore properties was studied by IR with pyridine adsorption, XRD and N{sub 2} adsorption at low temperature, 1-butanol dehydration as a probe reaction was used to study its reaction property.

  1. Operation of staged membrane oxidation reactor systems

    SciTech Connect

    Repasky, John Michael

    2012-10-16

    A method of operating a multi-stage ion transport membrane oxidation system. The method comprises providing a multi-stage ion transport membrane oxidation system with at least a first membrane oxidation stage and a second membrane oxidation stage, operating the ion transport membrane oxidation system at operating conditions including a characteristic temperature of the first membrane oxidation stage and a characteristic temperature of the second membrane oxidation stage; and controlling the production capacity and/or the product quality by changing the characteristic temperature of the first membrane oxidation stage and/or changing the characteristic temperature of the second membrane oxidation stage.

  2. A hybrid process combining homogeneous catalytic ozonation and membrane distillation for wastewater treatment.

    PubMed

    Zhang, Yong; Zhao, Peng; Li, Jie; Hou, Deyin; Wang, Jun; Liu, Huijuan

    2016-10-01

    A novel catalytic ozonation membrane reactor (COMR) coupling homogeneous catalytic ozonation and direct contact membrane distillation (DCMD) was developed for refractory saline organic pollutant treatment from wastewater. An ozonation process took place in the reactor to degrade organic pollutants, whilst the DCMD process was used to recover ionic catalysts and produce clean water. It was found that 98.6% total organic carbon (TOC) and almost 100% salt were removed and almost 100% metal ion catalyst was recovered. TOC in the permeate water was less than 16 mg/L after 5 h operation, which was considered satisfactory as the TOC in the potassium hydrogen phthalate (KHP) feed water was as high as 1000 mg/L. Meanwhile, the membrane distillation flux in the COMR process was 49.8% higher than that in DCMD process alone after 60 h operation. Further, scanning electron microscope images showed less amount and smaller size of contaminants on the membrane surface, which indicated the mitigation of membrane fouling. The tensile strength and FT-IR spectra tests did not reveal obvious changes for the polyvinylidene fluoride membrane after 60 h operation, which indicated the good durability. This novel COMR hybrid process exhibited promising application prospects for saline organic wastewater treatment.

  3. Catalytic molecularly imprinted polymer membranes: development of the biomimetic sensor for phenols detection.

    PubMed

    Sergeyeva, T A; Slinchenko, O A; Gorbach, L A; Matyushov, V F; Brovko, O O; Piletsky, S A; Sergeeva, L M; Elska, G V

    2010-02-05

    Portable biomimetic sensor devices for the express control of phenols content in water were developed. The synthetic binding sites mimicking active site of the enzyme tyrosinase were formed in the structure of free-standing molecularly imprinted polymer membranes. Molecularly imprinted polymer membranes with the catalytic activity were obtained by co-polymerization of the complex Cu(II)-catechol-urocanic acid ethyl ester with (tri)ethyleneglycoldimethacrylate, and oligourethaneacrylate. Addition of the elastic component oligourethaneacrylate provided formation of the highly cross-linked polymer with the catalytic activity in a form of thin, flexible, and mechanically stable membrane. High accessibility of the artificial catalytic sites for the interaction with the analyzed phenol molecules was achieved due to addition of linear polymer (polyethyleneglycol Mw 20,000) to the initial monomer mixture before the polymerization. As a result, typical semi-interpenetrating polymer networks (semi-IPNs) were formed. The cross-linked component of the semi-IPN was represented by the highly cross-linked catalytic molecularly imprinted polymer, while the linear one was represented by polyethyleneglycol Mw 20,000. Extraction of the linear polymer from the fully formed semi-IPN resulted in formation of large pores in the membranes' structure. Concentration of phenols in the analyzed samples was detected using universal portable device oxymeter with the oxygen electrode in a close contact with the catalytic molecularly imprinted polymer membrane as a transducer. The detection limit of phenols detection using the developed sensor system based on polymers-biomimics with the optimized composition comprised 0.063 mM, while the linear range of the sensor comprised 0.063-1 mM. The working characteristics of the portable sensor devices were investigated. Storage stability of sensor systems at room temperature comprised 12 months (87%). As compared to traditional methods of phenols

  4. [Influence of UV-light on erythrocyte membrane structure and catalytic behaviour of membrane acetylcholine esterase].

    PubMed

    Volotovskiĭ, I D; Sheĭko, L M; Konev, S V

    1976-01-01

    UV-light is shown to induce the structural transitions in the erythrocyte membrane described by S-shape curves in plots of the structural response versus the irradiation dose. In contrast to the free acetylcholine esterase (AChE) UV-light acts on the membrane enzyme as a mixed inhibitor (simultaneous change in Vmax and Km). The modification of the environment structure of residual enzyme is suggested to be the main reason of this phenomenon. The effect is under the control of membrane integrity and disappears after its desintegration. Membrane AChE treated ultrasonically both prior to and after irradiation is inactivated without a Km change. The data obtained show the influence of erythrocyte membrane structure on the catalytic behaviour of membrane-bound AChE.

  5. Solid state proton and electron mediating membrane and use in catalytic membrane reactors

    DOEpatents

    White, James H.; Schwartz, Michael; Sammells, Anthony F.

    2000-01-01

    Mixed electron- and proton-conducting metal oxide materials are provided. These materials are useful in fabrication of membranes for use in catalytic membrane reactions, particularly for promoting dehydrogenation of hydrocarbons, oligomerization of hydrocarbons and for the decomposition of hydrogen-containing gases. Membrane materials are perovskite compounds of the formula: AB.sub.1-x B'.sub.x O.sub.3-y where A=Ca, Sr, or Ba; B=Ce, Tb, Pr or Th; B'=Ti, V, Cr, Mn, Fe, Co, Ni or Cu; 0.2

  6. Method for recovering catalytic elements from fuel cell membrane electrode assemblies

    SciTech Connect

    Shore, Lawrence; Matlin, Ramail; Heinz, Robert

    2012-06-26

    A method for recovering catalytic elements from a fuel cell membrane electrode assembly is provided. The method includes converting the membrane electrode assembly into a particulate material, wetting the particulate material, forming a slurry comprising the wetted particulate material and an acid leachate adapted to dissolve at least one of the catalytic elements into a soluble catalytic element salt, separating the slurry into a depleted particulate material and a supernatant containing the catalytic element salt, and washing the depleted particulate material to remove any catalytic element salt retained within pores in the depleted particulate material.

  7. Solid state proton and electron mediating membrane and use in catalytic membrane reactors

    DOEpatents

    White, James H.; Schwartz, Michael; Sammells, Anthony F.

    1998-01-01

    This invention provides catalytic proton and electron mediating membranes useful in catalytic reactors. The membranes have an oxidation and a reduction surface and comprise a single-phase mixed metal oxide material of the formula: AB.sub.1-x B'.sub.x O.sub.3-y wherein A is selected from Ca, Sr or Ba ions; B is selected from Ce, Tb, Pr, or Th ions; B' is selected from Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Al, Ga, or In ions, or combinations thereof; and x is greater than or equal to 0.02 and less than or equal to 0.5. The membranes can further comprise a catalyst on either the oxidation or reduction surface, or both. Membranes include those which are fabricated-by combining powders of metal oxides or metal carbonates of metal A ion, metal B ion and metal B' ion such that the stoichiometric ratio A:B:B' is 1:1-x:x where 0.2.ltoreq..times.0.5, repeatedly calcining and milling the combined powders until a single-phase material is obtained and pressing and sintering the singlephase material to obtain a membrane.

  8. Solid state proton and electron mediating membrane and use in catalytic membrane reactors

    DOEpatents

    White, J.H.; Schwartz, M.; Sammells, A.F.

    1998-10-13

    This invention provides catalytic proton and electron mediating membranes useful in catalytic reactors. The membranes have an oxidation and a reduction surface and comprise a single-phase mixed metal oxide material of the formula: AB{sub 1{minus}x}B{prime}{sub x}O{sub 3{minus}y} wherein A is selected from Ca, Sr or Ba ions; B is selected from Ce, Tb, Pr, or Th ions; B{prime} is selected from Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Al, Ga, or In ions, or combinations thereof; and x is greater than or equal to 0.02 and less than or equal to 0.5. The membranes can further comprise a catalyst on either the oxidation or reduction surface, or both. Membranes include those which are fabricated by combining powders of metal oxides or metal carbonates of metal A ion, metal B ion and metal B{prime} ion such that the stoichiometric ratio A:B:B{prime} is 1:1{minus}x:x where 0.2{<=}{times}0.5, repeatedly calcining and milling the combined powders until a single-phase material is obtained and pressing and sintering the single phase material to obtain a membrane. 6 figs.

  9. Solid state proton and electron mediating membrane and use in catalytic membrane reactors

    DOEpatents

    White, James H.; Schwartz, Michael; Sammells, Anthony F.

    2001-01-01

    Mixed electron- and proton-conducting metal oxide materials are provided. These materials are useful in fabrication of membranes for use in catalytic membrane reactions, particularly for promoting dehydrogenation of hydrocarbons, oligomerization of hydrocarbons and for the decomposition of hydrogen-containing gases. Membrane materials are perovskite compounds of the formula: AB.sub.1-x B'.sub.x O.sub.3-y where A=Ca, Sr, or Ba; B=Ce, Tb, Pr or Th; B'=Ti, V, Cr, Mn, Fe, Co, Ni or Cu; 0.2.ltoreq.x.ltoreq.0.5, and y is a number sufficient to neutralize the charge in the mixed metal oxide material.

  10. Oxygen transport membrane system and method for transferring heat to catalytic/process reactors

    DOEpatents

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

    2014-01-07

    A method and apparatus for producing heat used in a synthesis gas production is provided. The disclosed method and apparatus include a plurality of tubular oxygen transport membrane elements adapted to separate oxygen from an oxygen containing stream contacting the retentate side of the membrane elements. The permeated oxygen is combusted with a hydrogen containing synthesis gas stream contacting the permeate side of the tubular oxygen transport membrane elements thereby generating a reaction product stream and radiant heat. The present method and apparatus also includes at least one catalytic reactor containing a catalyst to promote the stream reforming reaction wherein the catalytic reactor is surrounded by the plurality of tubular oxygen transport membrane elements. The view factor between the catalytic reactor and the plurality of tubular oxygen transport membrane elements radiating heat to the catalytic reactor is greater than or equal to 0.5.

  11. Oxygen transport membrane system and method for transferring heat to catalytic/process reactors

    DOEpatents

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

    2016-01-19

    A method and apparatus for producing heat used in a synthesis gas production process is provided. The disclosed method and apparatus include a plurality of tubular oxygen transport membrane elements adapted to separate oxygen from an oxygen containing stream contacting the retentate side of the membrane elements. The permeated oxygen is combusted with a hydrogen containing synthesis gas stream contacting the permeate side of the tubular oxygen transport membrane elements thereby generating a reaction product stream and radiant heat. The present method and apparatus also includes at least one catalytic reactor containing a catalyst to promote the steam reforming reaction wherein the catalytic reactor is surrounded by the plurality of tubular oxygen transport membrane elements. The view factor between the catalytic reactor and the plurality of tubular oxygen transport membrane elements radiating heat to the catalytic reactor is greater than or equal to 0.5

  12. Surface-Enhanced Separation of Water from Hydrocarbons: Potential Dewatering Membranes for the Catalytic Fast Pyrolysis of Pine Biomass

    DOE PAGES

    Engtrakul, Dr. Chaiwat; Hu, Michael Z.; Bischoff, Brian L; ...

    2016-01-01

    The impact of surface-selective coatings on water permeation through a membrane when exposed to catalytic fast pyrolysis (CFP) vapor products was studied by tailoring the surface properties of the membrane coating from superhydrophilic to superhydrophobic. Our approach utilized high-performance architectured surface-selective (HiPAS) membranes that were inserted after a CFP reactor. At this insertion point, the inner wall surface of a tubular membrane was exposed to a mixture of water and upgraded product vapors, including light gases and deoxygenated hydrocarbons. Under proper membrane operating conditions, a high selectivity for water over 1-ring upgraded biomass pyrolysis hydrocarbons was observed due to amore » surface-enhanced capillary condensation process. Owing to this surface-enhanced effect, HiPAS membranes have the potential to enable high flux separations suggesting that water can be selectively removed from the CFP product vapors.« less

  13. Surface-Enhanced Separation of Water from Hydrocarbons: Potential Dewatering Membranes for the Catalytic Fast Pyrolysis of Pine Biomass

    SciTech Connect

    Engtrakul, Dr. Chaiwat; Hu, Michael Z.; Bischoff, Brian L; Jang, Gyoung Gug

    2016-01-01

    The impact of surface-selective coatings on water permeation through a membrane when exposed to catalytic fast pyrolysis (CFP) vapor products was studied by tailoring the surface properties of the membrane coating from superhydrophilic to superhydrophobic. Our approach utilized high-performance architectured surface-selective (HiPAS) membranes that were inserted after a CFP reactor. At this insertion point, the inner wall surface of a tubular membrane was exposed to a mixture of water and upgraded product vapors, including light gases and deoxygenated hydrocarbons. Under proper membrane operating conditions, a high selectivity for water over 1-ring upgraded biomass pyrolysis hydrocarbons was observed due to a surface-enhanced capillary condensation process. Owing to this surface-enhanced effect, HiPAS membranes have the potential to enable high flux separations suggesting that water can be selectively removed from the CFP product vapors.

  14. Surface-Enhanced Separation of Water from Hydrocarbons: Potential Dewatering Membranes for the Catalytic Fast Pyrolysis of Pine Biomass

    SciTech Connect

    Engtrakul, Chaiwat; Hu, Michael Z.; Bischoff, Brian L.; Jang, Gyoung G.

    2016-10-20

    The impact of surface-selective coatings on water permeation through a membrane when exposed to catalytic fast pyrolysis (CFP) vapor products was studied by tailoring the surface properties of the membrane coating from superhydrophilic to superhydrophobic. Our approach used high-performance architectured surface-selective (HiPAS) membranes that were inserted after a CFP reactor. At this insertion point, the inner wall surface of a tubular membrane was exposed to a mixture of water and upgraded product vapors, including light gases and deoxygenated hydrocarbons. Under proper membrane operating conditions, a high selectivity for water over one-ring upgraded biomass pyrolysis hydrocarbons was observed as a result of a surface-enhanced capillary condensation process. Owing to this surface-enhanced effect, HiPAS membranes have the potential to enable high flux separations, suggesting that water can be selectively removed from the CFP product vapors.

  15. Ceramic membranes for catalytic membrane reactors with high ionic conductivities and low expansion properties

    DOEpatents

    Mackay, Richard; Sammells, Anthony F.

    2000-01-01

    Ceramics of the composition: Ln.sub.x Sr.sub.2-x-y Ca.sub.y B.sub.z M.sub.2-z O.sub.5+.delta. where Ln is an element selected from the fblock lanthanide elements and yttrium or mixtures thereof; B is an element selected from Al, Ga, In or mixtures thereof; M is a d-block transition element of mixtures thereof; 0.01.ltoreq.x.ltoreq.1.0; 0.01.ltoreq.y.ltoreq.0.7; 0.01.ltoreq.z.ltoreq.1.0 and .delta. is a number that varies to maintain charge neutrality are provided. These ceramics are useful in ceramic membranes and exhibit high ionic conductivity, high chemical stability under catalytic membrane reactor conditions and low coefficients of expansion. The materials of the invention are particularly useful in producing synthesis gas.

  16. A mesoporous catalytic membrane architecture for lithium-oxygen battery systems.

    PubMed

    Ryu, Won-Hee; Gittleson, Forrest S; Schwab, Mark; Goh, Tenghooi; Taylor, André D

    2015-01-14

    Controlling the mesoscale geometric configuration of catalysts on the oxygen electrode is an effective strategy to achieve high reversibility and efficiency in Li-O2 batteries. Here we introduce a new Li-O2 cell architecture that employs a catalytic polymer-based membrane between the oxygen electrode and the separator. The catalytic membrane was prepared by immobilization of Pd nanoparticles on a polyacrylonitrile (PAN) nanofiber membrane and is adjacent to a carbon nanotube electrode loaded with Ru nanoparticles. During oxide product formation, the insulating PAN polymer scaffold restricts direct electron transfer to the Pd catalyst particles and prevents the direct blockage of Pd catalytic sites. The modified Li-O2 battery with a catalytic membrane showed a stable cyclability for 60 cycles with a capacity of 1000 mAh/g and a reduced degree of polarization (∼ 0.3 V) compared to cells without a catalytic membrane. We demonstrate the effects of a catalytic membrane on the reaction characteristics associated with morphological and structural features of the discharge products via detailed ex situ characterization.

  17. Esterification of acidified oil with methanol by SPES/PES catalytic membrane.

    PubMed

    Shi, Wenying; He, Benqiao; Li, Jianxin

    2011-05-01

    A sulfonated polyethersulfone (SPES)/polyethersulfone (PES) blend catalytic membrane was prepared and used as a heterogeneous catalyst in the esterification of the acidified oil (acid value 153 mg KOH/g) with methanol for producing biodiesel. The results showed that the free fatty acids conversion reached 97.6% using SPES/PES catalytic membrane under the optimal esterification conditions. Meanwhile, the SPES/PES membrane with 20.3% degree of sulfonation showed a good catalytic stability. A pseudo-homogeneous kinetic model was established. The results indicated that the reaction rate constant increased with increasing methanol/acidified oil molar ratio, the loading of catalytic membrane and reaction temperature. The reaction order was 2 and the activation energy decreased from 74.65 to 21.07 kJ/mol with increasing catalytic membrane loading from 0 to 0.135 meq/g(oil). It implies that the esterification is not diffusively controlled but kinetically controlled. The predicted results were in good agreement with the experimental data.

  18. Catalytic membranes for CO oxidation in fuel cells

    DOEpatents

    Sandi-Tapia, Giselle; Carrado Gregar, Kathleen; Kizilel, Riza

    2010-06-08

    A hydrogen permeable membrane, which includes a polymer stable at temperatures of about 200 C having clay impregnated with Pt or Au or Ru or Pd particles or mixtures thereof with average diameters of less than about 10 nanometers (nms) is disclosed. The membranes are useful in fuel cells or any device which requires hydrogen to be separated from carbon monoxide.

  19. Catalytic partial oxidation and membrane separation to optimize the conversion of natural gas to syngas and hydrogen.

    PubMed

    Capoferri, Daniela; Cucchiella, Barbara; Iaquaniello, Gaetano; Mangiapane, Alessia; Abate, Salvatore; Centi, Gabriele

    2011-12-16

    The multistep integration of hydrogen-selective membranes into catalytic partial oxidation (CPO) technology to convert natural gas into syngas and hydrogen is reported. An open architecture for the membrane reactor is presented, in which coupling of the reaction and hydrogen separation is achieved independently and the required feed conversion is reached through a set of three CPO reactors working at 750, 750 and 920 °C, compared to 1030 °C for conventional CPO technology. Obtaining the same feed conversion at milder operating conditions translates into less natural gas consumption (and CO(2) emissions) and a reduction of variable operative costs of around 10 %. It is also discussed how this energy-efficient process architecture, which is suited particularly to small-to-medium applications, may improve the sustainability of other endothermic, reversible reactions to form hydrogen.

  20. Modification of tubular ceramic membranes with carbon nanotubes using catalytic chemical vapor deposition.

    PubMed

    Tran, Duc Trung; Thieffry, Guillemette; Jacob, Matthieu; Batiot-Dupeyrat, Catherine; Teychene, Benoit

    2015-01-01

    In this study, carbon nanotubes (CNTs) were successfully grown on tubular ceramic membranes using the catalytic chemical vapor deposition (CCVD) method. CNTs were synthesized at 650°C for 3-6 h under a 120 mL min(-1) flow of C2H6 on ceramic membranes impregnated with iron salt. The synthesis procedure was beforehand optimized in terms of catalyst amount, impregnation duration and reaction temperature, using small pieces of tubular ceramic membranes. The yield, size and structure of the CNTs produced were characterized using thermogravimetric analysis and microscopic imaging techniques. Afterwards, preliminary filtration tests with alginate and phenol were performed on two modified tubular membranes. The results indicate that the addition of CNTs on the membrane material increased the permeability of ceramic membrane and its ability to reject alginate and adsorb phenol, yet decreased its fouling resistance.

  1. Production of an ion-exchange membrane-catalytic electrode bonded material for electrolytic cells

    NASA Technical Reports Server (NTRS)

    Takenaka, H.; Torikai, E.

    1986-01-01

    A good bond is achieved by placing a metal salt in solution on one side of a membrane and a reducing agent on the other side so that the reducing agent penetrates the membrane and reduces the metal. Thus, a solution containing Pt, Rh, etc., is placed on one side of the membrane and a reducing agent such as NaBH, is placed on the other side. The bonded metal layer obtained is superior in catalytic activity and is suitable as an electrode in a cell such as for solid polymer electrolyte water electrolysis.

  2. Block copolymer hollow fiber membranes with catalytic activity and pH-response.

    PubMed

    Hilke, Roland; Pradeep, Neelakanda; Madhavan, Poornima; Vainio, Ulla; Behzad, Ali Reza; Sougrat, Rachid; Nunes, Suzana P; Peinemann, Klaus-Viktor

    2013-08-14

    We fabricated block copolymer hollow fiber membranes with self-assembled, shell-side, uniform pore structures. The fibers in these membranes combined pores able to respond to pH and acting as chemical gates that opened above pH 4, and catalytic activity, achieved by the incorporation of gold nanoparticles. We used a dry/wet spinning process to produce the asymmetric hollow fibers and determined the conditions under which the hollow fibers were optimized to create the desired pore morphology and the necessary mechanical stability. To induce ordered micelle assembly in the doped solution, we identified an ideal solvent mixture as confirmed by small-angle X-ray scattering. We then reduced p-nitrophenol with a gold-loaded fiber to confirm the catalytic performance of the membranes.

  3. Catalytic partial oxidation coupled with membrane purification to improve resource and energy efficiency in syngas production.

    PubMed

    Iaquaniello, G; Salladini, A; Palo, E; Centi, G

    2015-02-01

    Catalytic partial oxidation coupled with membrane purification is a new process scheme to improve resource and energy efficiency in a well-established and large scale-process like syngas production. Experimentation in a semi industrial-scale unit (20 Nm(3)  h(-1) production) shows that a novel syngas production scheme based on a pre-reforming stage followed by a membrane for hydrogen separation, a catalytic partial oxidation step, and a further step of syngas purification by membrane allows the oxygen-to-carbon ratio to be decreased while maintaining levels of feed conversion. For a total feed conversion of 40 %, for example, the integrated novel architecture reduces oxygen consumption by over 50 %, with thus a corresponding improvement in resource efficiency and an improved energy efficiency and economics, these factors largely depending on the air separation stage used to produce pure oxygen.

  4. Thermoelectric Integrated Membrane Evaporation Subsystem operational improvements

    NASA Technical Reports Server (NTRS)

    Dehner, G. F.; Winkler, H. E.; Reysa, R. P.

    1984-01-01

    A three-man preprototype Thermoelectric Integrated Membrane Evaporation Subsystem (TIMES) has been developed to provide high quality water recovery from waste fluids on extended duration space flights. In the most recent effort, a number of improvements have been made to simplify subsystem operation and increase performance. These modifications include changes to the hollow fiber membrane evaporator, the condensing section of the thermoelectric heat pump, and the electronic controller logic and display. This paper describes the results of the test program that was conducted to evaluate the implemented improvements. In addition, an advanced design concept is discussed that will provide lower electrical power consumption, greater water production capacity, lower weight, and a smaller package than the present subsystem configuration.

  5. A self-catalytic mixed-conducting membrane reactor for effective production of hydrogen from methane

    NASA Astrophysics Data System (ADS)

    Dong, Xueliang; Liu, Zhengkun; Jin, Wanqin; Xu, Nanping

    A supported mixed-conducting LNCO membrane with a pore-gradient structure LNO support was successfully prepared via a dry pressing and co-sintering route. The match of sintering behaviors between membrane and support was realized by the preparation of an ABB‧B‧‧B‧BA-type membrane. A scanning electron microscopy (SEM) test demonstrated that the surface of the supported membrane was dense and crack-free and the pore-gradient structure of the support can be observed clearly. The oxygen flux of the supported membrane was about 5.6 times that of the symmetric LNCO membrane. A self-catalytic mixed-conducting membrane reactor was constructed using the prepared membrane for hydrogen production from methane. It was found that this membrane reactor exhibited high performance and good stability for hydrogen production. At 1123 K, the CH 4 conversion, hydrogen selectivity and hydrogen production remained at about 60%, 89% and 8.0 ml(STP) cm -2 min -1, respectively, for more than 120 h.

  6. Processes of particle deposition in membrane operation and fabrication.

    PubMed

    Wiesner, M R; Tarabara, V; Cortalezzi, M

    2005-01-01

    The processes that control particle deposition on surfaces that are of interest in understanding operational aspects of membrane filtration, also hold significance in controlling the morphology of particle deposits as intermediate steps in membrane fabrication. This paper summarizes processes controlling particle deposit morphology. The implications of these processes for understanding membrane fouling by particles and in fabricating membranes are then considered.

  7. Ag Nanoparticle/Polydopamine-Coated Inverse Opals as Highly Efficient Catalytic Membranes.

    PubMed

    Choi, Gwan H; Rhee, Do Kyung; Park, A Reum; Oh, Min Jun; Hong, Sunghwan; Richardson, Joseph J; Guo, Junling; Caruso, Frank; Yoo, Pil J

    2016-02-10

    Polymeric three-dimensional inverse-opal (IO) structures provide unique structural properties useful for various applications ranging from optics to separation technologies. Despite vast needs for IO functionalization to impart additional chemical properties, this task has been seriously challenged by the intrinsic limitation of polymeric porous materials that do not allow for the easy penetration of waterborne moieties or precursors. To overcome this restriction, we present a robust and straightforward method of employing a dipping-based surface modification with polydopamine (PDA) inside the IO structures, and demonstrate their application to catalytic membranes via synthetic incorporation of Ag nanoparticles. The PDA coating offers simultaneous advantages of achieving the improved hydrophilicity required for the facilitated infiltration of aqueous precursors and successful creation of nucleation sites for a reduction of growth of the Ag nanoparticles. The resulting Ag nanoparticle-incorporated IO structures are utilized as catalytic membranes for the reduction of 4-nitrophenol to its amino derivatives in the presence of NaBH4. Synergistically combined characteristics of high reactivity of Ag nanoparticles along with a greatly enhanced internal surface area of IO structures enable the implementation of remarkably improved catalytic performance, exhibiting a good conversion efficiency greater than 99% while minimizing loss in the membrane permeability.

  8. 40 CFR Table 2 to Subpart Uuu of... - Operating Limits for Metal HAP Emissions From Catalytic Cracking Units

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Emissions From Catalytic Cracking Units 2 Table 2 to Subpart UUU of Part 63 Protection of Environment... Petroleum Refineries: Catalytic Cracking Units, Catalytic Reforming Units, and Sulfur Recovery Units Pt. 63... Catalytic Cracking Units As stated in § 63.1564(a)(2), you shall meet each operating limit in the...

  9. Conversion of elemental mercury with a novel membrane delivery catalytic oxidation system (MDCOs).

    PubMed

    Guo, Yongfu; Yan, Naiqiang; Yang, Shijian; Qu, Zan; Wu, Zhongbiao; Liu, Yue; Liu, Ping; Jia, Jinping

    2011-01-15

    In order to overcome the shortcomings of the traditional catalytic oxidation (TCO) mode for the conversion of the trace level of elemental mercury (Hg(0)) in flue gas, we put forward a novel and unique assembly that integrated membrane delivery with catalytic oxidation systems (MDCOs), which combined the controlled delivery of oxidants with the catalytic oxidation of Hg(0). The results show that the demanded HCl for Hg(0) conversion in the MDCOs was less than 5% of that in the TCO mode, and over 90% of Hg(0) removal efficiency can be obtained in the MDCOs with less than 0.5 mg m(-3) of HCl escaped. Meanwhile, the inhibition of SO(2) to Hg(0) catalytic conversion in the MDCOs was also less significant than in the TCO. The MDCOs have high retainability for HCl, which is quite favorable to Hg(0) conversion and HCl utilization. The reaction mechanism on mercury conversion in the MDCOs is discussed. The MDCOs appear to be a promising method for emission control of elemental mercury.

  10. Methane steam reforming analysis in a palladium-based catalytic membrane reactor

    SciTech Connect

    Barbieri, G.; Violante, V.; Maio, F.P. di; Criscuoli, A.; Drioli, E. |

    1997-08-01

    The methane steam reforming in a catalytic membrane reactor has been studied. A previous theoretical study of this reaction has been carried out. In the model a global kinetic rate as a function of three reactions over nickel catalyst as proposed by Xu and Froment has been considered. It has been shown that the counterflow configuration has, at high temperature (500 C), a marginal advantage on parallel flow and, also, that the space velocity cannot be considered a design variable for membrane reactors. A laboratory plant was realized utilizing membranes of Pd and Pd/Ag supported on Al{sub 2}O{sub 3}. The Pd membranes utilized have been prepared using the co-condensation technique and the electroless plating method. A comparison of the overall membrane performance has also been carried out. The experiments were aimed to study the effects of several parameters such as temperature, feed flow rate, and feed molar ratio on the methane conversion. The experimental results have been compared with the data predicted by the previously developed theoretical model.

  11. Evidence that the catalytic activity of prokaryote leader peptidase depends upon the operation of a serine-lysine catalytic dyad.

    PubMed Central

    Black, M T

    1993-01-01

    Leader peptidase (LP) is the enzyme responsible for proteolytic cleavage of the amino acid leader sequence from bacterial preproteins. Recent data indicate that LP may be an unusual serine proteinase which operates without involvement of a histidine residue (M. T. Black, J. G. R. Munn, and A. E. Allsop, Biochem. J. 282:539-543, 1992; M. Sung and R. E. Dalbey, J. Biol. Chem. 267:13154-13159, 1992) and that, therefore, one or more alternative residues must perform the function of a catalytic base. With the aid of sequence alignments, site-specific mutagenesis of the gene encoding LP (lepB) from Escherichia coli has been employed to investigate the mechanism of action of the enzyme. Various mutant forms of plasmid-borne LP were tested for their abilities to complement the temperature-sensitive activity of LP in E. coli IT41. Data are presented which indicate that the only conserved amino acid residue possessing a side chain with the potential to ionize, and therefore with the potential to transfer protons, which cannot be substituted with a neutral side chain is lysine at position 145. The data suggest that the catalytic activity of LP is dependent on the operation of a serine-lysine catalytic dyad. Images PMID:8394311

  12. Instantaneous Click Chemistry by a Copper-Containing Polymeric-Membrane-Installed Microflow Catalytic Reactor.

    PubMed

    Yamada, Yoichi M A; Ohno, Aya; Sato, Takuma; Uozumi, Yasuhiro

    2015-11-23

    The copper(I)-catalyzed Huisgen cycloaddition (azide-alkyne cycloaddition) is an important reaction in click chemistry that ideally proceeds instantaneously. An instantaneous Huisgen cycloaddition has been developed that uses a novel catalytic dinuclear copper complex-containing polymeric membrane-installed microflow device. A polymeric membranous copper catalyst was prepared from poly(4-vinylpyridine), copper(II) sulfate, sodium chloride, and sodium ascorbate at the interface of two laminar flows inside microchannels. Elucidation of the structure by XANES, EXAFS, and elemental analysis, as well as second-order Møller-Plesset perturbation theory (MP2) calculations and density functional theory (DFT) calculations assigned the local structure near Cu as a μ-chloro dinuclear Cu(I) complex. The microflow device promotes the instantaneous click reaction of a variety of alkynes and organic azides to afford the corresponding triazoles in quantitative yield.

  13. Comparative catalytic activity of PET track-etched membranes with embedded silver and gold nanotubes

    NASA Astrophysics Data System (ADS)

    Mashentseva, Anastassiya; Borgekov, Daryn; Kislitsin, Sergey; Zdorovets, Maxim; Migunova, Anastassiya

    2015-12-01

    Irradiated by heavy ions nanoporous polyethylene terephthalate track-etched membranes (PET TeMs) after +15Kr84 ions bombardment (1.75 MeV/nucl with the ion fluency of 1 × 109 cm-2) and sequential etching was applied in this research as a template for development of composites with catalytically enriched properties. A highly ordered silver and gold nanotubes arrays were embedded in 100 nm pores of PET TeMs via electroless deposition technique at 4 °C during 1 h. All "as-prepared" composites were examined for catalytic activity using reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) by sodium borohydride as a common reaction to test metallic nanostructures catalysts. The effect of temperature on the catalytic activity was investigated in range of 292-313 K and activation energy were calculated. Kapp of Ag/PET composites linearly increase with an increase of the temperature thus normal Arrhenius behavior have been seen and the activation energy was calculated to be 42.13 kJ/mol. Au/PET composites exhibit not only more powerful catalytic activity but also non-linear dependence of rate constant from temperature. Kapp increased with increasing temperature throughout the 292-308 K temperature range; the reaction had an activation energy 65.32 kJ/mol. In range 311-313 K rate constant dramatically decreased and the apparent activation energy at this temperature rang was -91.44 kJ/mol due some structural changes, i.e. agglomeration of Au nanoparticles on the surface of composite.

  14. 40 CFR 60.105a - Monitoring of emissions and operations for fluid catalytic cracking units (FCCU) and fluid coking...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... for fluid catalytic cracking units (FCCU) and fluid coking units (FCU). 60.105a Section 60.105a... and operations for fluid catalytic cracking units (FCCU) and fluid coking units (FCU). (a) FCCU and... Emission Standards for Hazardous Air Pollutants for Petroleum Refineries: Catalytic Cracking...

  15. Membrane properties induced by anionic phospholipids and phosphatidylethanolamine are critical for the membrane binding and catalytic activity of human cytochrome P450 3A4.

    PubMed

    Kim, Keon-Hee; Ahn, Taeho; Yun, Chul-Ho

    2003-12-30

    Human cytochrome P450 (CYP) 3A4, a membrane anchoring protein, is the major CYP enzyme present in both liver and small intestine. The enzyme plays a major role in the metabolism of many drugs and procarcinogens. The roles of individual phospholipids and membrane properties in the catalytic activity, membrane binding, and insertion into the membrane of CYP3A4 are poorly understood. Here we report that the catalytic activity of testosterone 6beta-hydroxylation, membrane binding, and membrane insertion of CYP3A4 increase as a function of anionic phospholipid concentration in the order phosphatidic acid (PA) > phosphatidylserine (PS) in a binary system of phosphatidylcholine (PC)/anionic phospholipid and as a function of phosphatidylethanolamine (PE) content in ternary systems of PC/PE/PA or PC/PE/PS having a fixed concentration of anionic phospholipids. These results suggest that PA and PE might help the binding of CYP3A4 to the membrane and the interaction with NPR. Cytochrome b(5) (b(5)) and apolipoprotein b(5) further enhanced the testosterone 6beta-hydroxylation activities of CYP3A4 in all tested phospholipids vesicles with various compositions. Phospholipid-dependent changes of the CYP3A4 conformation were also revealed by altered Trp fluorescence and CD spectra. We also found that PE induced the formation of anionic phospholipid-enriched domains in ternary systems using extrinsic fluorescent probes incorporated into lipid bilayers. Taken together, it can be suggested that the chemical and physical properties of membranes induced by anionic phospholipids and PE are critical for the membrane binding and catalytic activity of CYP3A4.

  16. Metal nanoparticle/ionic liquid/cellulose: new catalytically active membrane materials for hydrogenation reactions.

    PubMed

    Gelesky, Marcos A; Scheeren, Carla W; Foppa, Lucas; Pavan, Flavio A; Dias, Silvio L P; Dupont, Jairton

    2009-07-13

    Transition metal-containing membrane films of 10, 20, and 40 μm thickness were obtained by the combination of irregularly shaped nanoparticles with monomodal size distributions of 4.8 ± 1.1 nm (Rh(0)) and 3.0 ± 0.4 nm (Pt(0)) dispersed in the ionic liquid (IL) 1-n-butyl-3-methylimidazolium bis(trifluoromethane sulfonyl)imide (BMI·(NTf)(2)) with a syrup of cellulose acetate (CA) in acetone. The Rh(0) and Pt(0) metal concentration increased proportionally with increases in film thickness up to 20 μm, and then the material became metal saturated. The presence of small and stable Rh(0) or Pt(0) nanoparticles induced an augmentation in the CA/IL film surface areas. The augmentation of the IL content resulted in an increase of elasticity and decrease in tenacity and toughness, whereas the stress at break was not influenced. The introduction of IL probably causes an increase in the separation between the cellulose macromolecules that results in a higher flexibility, lower viscosity, and better formability of the cellulose material. The nanoparticle/IL/CA combinations exhibit an excellent synergistic effect that enhances the activity and durability of the catalyst for the hydrogenation of cyclohexene. The nanoparticle/IL/cellulose acetate film membranes display higher catalytic activity (up to 7353 h(-1) for the 20 μm film of CA/IL/Pt(0)) and stability than the nanoparticles dispersed only in the IL.

  17. Architecture of a single membrane spanning cytochrome P450 suggests constraints that orient the catalytic domain relative to a bilayer

    PubMed Central

    Monk, Brian C.; Tomasiak, Thomas M.; Keniya, Mikhail V.; Huschmann, Franziska U.; Tyndall, Joel D. A.; O’Connell, Joseph D.; Cannon, Richard D.; McDonald, Jeffrey G.; Rodriguez, Andrew; Finer-Moore, Janet S.; Stroud, Robert M.

    2014-01-01

    Bitopic integral membrane proteins with a single transmembrane helix play diverse roles in catalysis, cell signaling, and morphogenesis. Complete monospanning protein structures are needed to show how interaction between the transmembrane helix and catalytic domain might influence association with the membrane and function. We report crystal structures of full-length Saccharomyces cerevisiae lanosterol 14α-demethylase, a membrane monospanning cytochrome P450 of the CYP51 family that catalyzes the first postcyclization step in ergosterol biosynthesis and is inhibited by triazole drugs. The structures reveal a well-ordered N-terminal amphipathic helix preceding a putative transmembrane helix that would constrain the catalytic domain orientation to lie partly in the lipid bilayer. The structures locate the substrate lanosterol, identify putative substrate and product channels, and reveal constrained interactions with triazole antifungal drugs that are important for drug design and understanding drug resistance. PMID:24613931

  18. Membrane treatment of liquid wastes from radiological decontamination operations.

    PubMed

    Svittsov, A A; Khubetsov, S B; Volchek, K

    2011-01-01

    The paper focuses on the evaluation of membrane filtration for the treatment of liquid radioactive streams generated in area decontamination operations. In this work, semi-permeable membranes were demonstrated to be effective reducing the volume of wastewater containing cesium and cobalt by two orders of a magnitude. The efficiency of membrane separation was enhanced by employing additives that enlarged the size of target radionuclide species and improved their rejection by the membranes. This was achieved by chelation with synthetic water-soluble polymers and by adsorption on micro particles of adsorbent coupled with micelle formation. The effect of wastewater composition and that of the radionuclide-binding additives on the volume reduction was investigated. Membrane treatment is expected to help simplify further processing and decrease disposal costs.

  19. Modular operation of membrane bioreactors for higher hydraulic capacity utilisation.

    PubMed

    Veltmann, K; Palmowski, L M; Pinnekamp, J

    2011-01-01

    Using data from 6 full-scale municipal membrane bioreactors (MBR) in Germany the hydraulic capacity utilisation and specific energy consumption were studied and their connexion shown. The average hydraulic capacity utilisation lies between 14% and 45%. These low values are justified by the necessity to deal with intense rain events and cater for future flow increases. However, this low hydraulic capacity utilisation leads to high specific energy consumption. The optimisation of MBR operation requires a better utilisation of MBR hydraulic capacity, particularly under consideration of the energy-intensive membrane aeration. A first approach to respond to large influent flow fluctuations consists in adjusting the number of operating modules. This is practised by most MBR operators but so far mostly with variable flux and constant membrane aeration. A second approach is the real-time adjustment of membrane aeration in line with flux variations. This adjustment is not permitted under current manufacturers' warranty conditions. A further opportunity is a discontinuous operation, in which filtration takes place over short periods at high flux and energy for membrane aeration is saved during filtration pauses. The integration of a buffer volume is thereby indispensable. Overall a modular design with small units, which can be activated/ inactivated according to the influent flow and always operate under optimum conditions, enables a better utilisation of MBR hydraulic capacity and forms a solid base to reduce MBR energy demand.

  20. Final Report - Membranes and MEA's for Dry, Hot Operating Conditions

    SciTech Connect

    Hamrock, Steven J

    2011-06-30

    The focus of this program was to develop a new Proton Exchange Membrane (PEM) which can operate under hotter, dryer conditions than the state of the art membranes today and integrate it into a Membrane Electrode Assembly (MEA). These MEA's should meet the performance and durability requirements outlined in the solicitation, operating under low humidification conditions and at temperatures ranging from -20ºC to 120ºC, to meet 2010 DOE technical targets for membranes. This membrane should operate under low humidification conditions and at temperatures ranging from -20ºC to 120ºC in order to meet DOE HFCIT 2010 commercialization targets for automotive fuel cells. Membranes developed in this program may also have improved durability and performance characteristics making them useful in stationary fuel cell applications. The new membranes, and the MEA's comprising them, should be manufacturable at high volumes and at costs which can meet industry and DOE targets. This work included: A) Studies to better understand factors controlling proton transport within the electrolyte membrane, mechanisms of polymer degradation (in situ and ex situ) and membrane durability in an MEA; B) Development of new polymers with increased proton conductivity over the range of temperatures from -20ºC to 120ºC and at lower levels of humidification and with improved chemical and mechanical stability; C) Development of new membrane additives for increased durability and conductivity under these dry conditions; D) Integration of these new materials into membranes and membranes into MEA's, including catalyst and gas diffusion layer selection and integration; E) Verification that these materials can be made using processes which are scalable to commercial volumes using cost effective methods; F) MEA testing in single cells using realistic automotive testing protocols. This project addresses technical barriers A (Durability) and C (Performance) from the Fuel Cells section of the 2005 Hydrogen

  1. Modeling and simulation of ammonia removal from purge gases of ammonia plants using a catalytic Pd-Ag membrane reactor.

    PubMed

    Rahimpour, M R; Asgari, A

    2008-05-01

    In this work, the removal of ammonia from synthesis purge gas of an ammonia plant has been investigated. Since the ammonia decomposition is thermodynamically limited, a membrane reactor is used for complete decomposition. A double pipe catalytic membrane reactor is used to remove ammonia from purge gas. The purge gas is flowing in the reaction side and is converted to hydrogen and nitrogen over nickel-alumina catalyst. The hydrogen is transferred through the Pd-Ag membrane of tube side to the shell side. A mathematical model including conservation of mass in the tube and shell side of reactor is proposed. The proposed model was solved numerically and the effects of different parameters on the rector performance were investigated. The effects of pressure, temperature, flow rate (sweep ratio), membrane thickness and reactor diameter have been investigated in the present study. Increasing ammonia conversion was observed by raising the temperature, sweep ratio and reducing membrane thickness. When the pressure increases, the decomposition is gone toward completion but, at low pressure the ammonia conversion in the outset of reactor is higher than other pressures, but complete destruction of the ammonia cannot be achieved. The proposed model can be used for design of an industrial catalytic membrane reactor for removal of ammonia from ammonia plant and reducing NO(x) emissions.

  2. Sustainable operation of submerged Anammox membrane bioreactor with recycling biogas sparging for alleviating membrane fouling.

    PubMed

    Li, Ziyin; Xu, Xindi; Xu, Xiaochen; Yang, FengLin; Zhang, ShuShen

    2015-12-01

    A submerged anaerobic ammonium oxidizing (Anammox) membrane bioreactor with recycling biogas sparging for alleviating membrane fouling has been successfully operated for 100d. Based on the batch tests, a recycling biogas sparging rate at 0.2m(3)h(-1) was fixed as an ultimate value for the sustainable operation. The mixed liquor volatile suspended solid (VSS) of the inoculum for the long operation was around 3000mgL(-1). With recycling biogas sparging rate increasing stepwise from 0 to 0.2m(3)h(-1), the reactor reached an influent total nitrogen (TN) up to 1.7gL(-1), a stable TN removal efficiency of 83% and a maximum specific Anammox activity (SAA) of 0.56kg TNkg(-1) VSSd(-1). With recycling biogas sparging rate at 0.2 m(3) h(-1) (corresponding to an aeration intensity of 118m(3)m(-2)h(-1)), the membrane operation circle could prolong by around 20 times compared to that without gas sparging. Furthermore, mechanism of membrane fouling was proposed. And with recycling biogas sparging, the VSS and EPS content increasing rate in cake layer were far less than the ones without biogas sparging. The TN removal performance and sustainable membrane operation of this system showed the appealing potential of the submerged Anammox MBR with recycling biogas sparging in treating high-strength nitrogen-containing wastewaters.

  3. Hybrid membrane operations in water desalination and industrial process rationalisation.

    PubMed

    Drioli, E; Di Profio, G; Curcio, E

    2005-01-01

    Membrane science and technology are recognized today as powerful tools in resolving some important global problems, and developing newer industrial processes, needed from the imperative of sustainable industrial growth. In seawater desalination, for resolving the dramatic increase of freshwater demand in many regions of the world, membrane unitary operations or the combination of some of them in integrated systems are already a real means for producing water from the sea, at lower costs and minimum environmental impact, with a very interesting prospective in particular for poor economy countries. However, membranes are used or are becoming used in some important industrial fields, for developing more efficient productive cycles, with reduced waste of raw-material, reducing the polluting charge by controlling byproduct generation, and reducing overall costs. In the present paper, other than for seawater desalination applications, some industrial applications where membrane technology has led already to match the goal of process intensification are discussed.

  4. Development of catalytically active and highly stable catalyst supports for polymer electrolyte membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Kim, Taekeun; Xie, Tianyuan; Jung, Wonsuk; Gadala-Maria, Francis; Ganesan, Prabhu; Popov, Branko N.

    2015-01-01

    Novel procedures are developed for the synthesis of highly stable carbon composite catalyst supports (CCCS-800 °C and CCCS-1100 °C) and an activated carbon composite catalyst support (A-CCCS). These supports are synthesized through: (i) surface modification with acids and inclusion of oxygen groups, (ii) metal-catalyzed pyrolysis, and (iii) chemical leaching to remove excess metal used to dope the support. The procedure results in increasing carbon graphitization and inclusion of non-metallic active sites on the support surface. Catalytic activity of CCCS indicates an onset potential of 0.86 V for the oxygen reduction reaction (ORR) with well-defined kinetic and mass-transfer regions and ∼2.5% H2O2 production in rotating ring disk electrode (RRDE) studies. Support stability studies at 1.2 V constant potential holding for 400 h indicate high stability for the 30% Pt/A-CCCS catalyst with a cell potential loss of 27 mV at 800 mA cm-2 under H2-air, 32% mass activity loss, and 30% ECSA loss. Performance evaluation in polymer electrolyte membrane (PEM) fuel cell shows power densities (rated) of 0.18 and 0.23 gPt kW-1 for the 30% Pt/A-CCCS and 30% Pt/CCCS-800 °C catalysts, respectively. The stabilities of various supports developed in this study are compared with those of a commercial Pt/C catalyst.

  5. Effect of activated sludge properties and membrane operation conditions on fouling characteristics in membrane bioreactors.

    PubMed

    Choi, Hyeok; Zhang, Kai; Dionysiou, Dionysios D; Oerther, Daniel B; Sorial, George A

    2006-06-01

    Biofouling control is considered to be a major challenge in operating membrane bioreactors (MBRs) for the treatment of wastewater. This study examined the impact of biological, chemical, and physical properties of activated sludge on membrane filtration performance in laboratory-scale MBRs. Sludges with different microbial communities were produced using pseudo-continuous stirred-tank reactors and pseudo-plug flow reactors treating a synthetic paper mill wastewater. Various filtration resistances were used to investigate membrane fouling characteristics, and molecular biology tools targeting 16S ribosomal DNA gene sequences were used to identify predominant bacterial populations in the sludges or attached to the fouled membranes. Filtration experiments using axenic cultures of Escherichia coli, Acinetobacter calcoaceticus, and Gordonia amarae were also performed to better understand the initiation and development of biofouling. The results showed that the tendency of membranes to biofoul depended upon membrane operating conditions as well as the properties of the activated sludge in the MBR systems. Specific bacterial populations, which were not dominant in the activated sludges, were selectively accumulated on the membrane surface leading to the development of irreversible biofouling.

  6. Microwave assisted esterification of acidified oil from waste cooking oil by CERP/PES catalytic membrane for biodiesel production.

    PubMed

    Zhang, Honglei; Ding, Jincheng; Zhao, Zengdian

    2012-11-01

    The traditional heating and microwave assisted method for biodiesel production using cation ion-exchange resin particles (CERP)/PES catalytic membrane were comparatively studied to achieve economic and effective method for utilization of free fatty acids (FFAs) from waste cooking oil (WCO). The optimal esterification conditions of the two methods were investigated and the experimental results showed that microwave irradiation exhibited a remarkable enhanced effect for esterification compared with that of traditional heating method. The FFAs conversion of microwave assisted esterification reached 97.4% under the optimal conditions of reaction temperature 60°C, methanol/acidified oil mass ratio 2.0:1, catalytic membrane (annealed at 120°C) loading 3g, microwave power 360W and reaction time 90min. The study results showed that it is a fast, easy and green way to produce biodiesel applying microwave irradiation.

  7. 40 CFR Table 23 to Subpart Uuu of... - Operating Limits for Inorganic HAP Emission Limitations for Catalytic Reforming Units

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... adsorption system must not exceed the design or manufacturer's recommended limit (1.8 weight percent for the... 40 Protection of Environment 12 2011-07-01 2009-07-01 true Operating Limits for Inorganic HAP... Pollutants for Petroleum Refineries: Catalytic Cracking Units, Catalytic Reforming Units, and Sulfur...

  8. 40 CFR Table 14 to Subpart Uuu of... - Continuous Compliance With Operating Limits for Organic HAP Emissions From Catalytic Cracking Units

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Limits for Organic HAP Emissions From Catalytic Cracking Units 14 Table 14 to Subpart UUU of Part 63... Hazardous Air Pollutants for Petroleum Refineries: Catalytic Cracking Units, Catalytic Reforming Units, and... Compliance With Operating Limits for Organic HAP Emissions From Catalytic Cracking Units As stated in §...

  9. The development of manganese oxide coated ceramic membranes for combined catalytic ozonation and ultrafiltration of drinking water

    NASA Astrophysics Data System (ADS)

    Corneal, Lindsay Marie

    A novel method for the preparation of hydrated MnO2 by the ozonation of MnCl2 in water is described. The hydrated MnO 2 was used to coat titania water filtration membranes using a layer-by-layer technique. The coated membranes were then sintered in air at 500°C for 45 minutes. Upon sintering, the MnO2 is converted to alpha-Mn 2O3 (as characterized by x-ray and electron diffraction). Atomic force microscopy (AFM) imaging showed no significant change in the roughness or height of the surface features of coated membranes, while scanning electron microscopy (SEM) imaging showed an increase in grain size with increasing number of coating layers. Energy dispersive x-ray spectroscopy (EDS) mapping and line scans revealed manganese present throughout the membrane, indicating that manganese dispersed into the porous membrane during the coating process and diffused into the titania grains during sintering. Selected area diffraction (SAD) of the coated and sintered membrane was used to index the surface layer as alpha-Mn2O3. The surface layer was uneven, although there was a trend of increasing thickness with increasing coating layers. The coating acts as a catalyst for the oxidation of organic matter when coated membranes are used in a hybrid ozonation-membrane filtration system. A trend of decreasing total organic carbon (TOC) in the permeate water was observed with increasing number of coating layers. The catalytic activity also manifests itself as improved recovery of the water flux due to oxidation of foulants on the membrane surface. Ceramic nanoparticle coatings on ceramic water filtration membranes must undergo high temperature sintering. However, this means that the underlying membrane, which has been engineered for a given molecular weight cut-off (MWCO), also undergoes a high temperature heat treatment that serves to increase pore size that have resulted in increases in permeability of titania membranes. Coating the titania membrane with manganese oxide followed

  10. Driven chemical kinetics: Optimalization of catalytic action of membrane proteins by rectangular alternating electric field

    NASA Astrophysics Data System (ADS)

    Fuliński, Andrzej

    1992-03-01

    The chemical kinetics driven by external force in the form of a train of alternating rectangular impulses is discussed. The model of the conformational transition of a membrane protein exposed to an ac electric field, proposed by R. D. Astumian and B. Robertson [J. Chem. Phys. 91, 4891 (1989)], is reconsidered. On the example of this model we show that the use of the driving field in the form of rectangular impulses has two distinct advantages over the usual sinusoidal driving. The first one is that the use of a rectangular driving field makes it possible to obtain the exact solution of the basic kinetic equation of the system. This in turn enables one to write down the simple and very good approximate solution for any form of the driving field, better than the harmonic expansion used by Astumian and Robertson. A more important advantage is the greater flexibility of the rectangular driving, which makes possible the better optimalization of the process of interest. Astumian and Robertson demonstrated that the movement of charge within the catalytic cycle provides a mechanism for the enzyme to absorb energy from an ac electric field and to use that energy to enhance the catalyzed process. In this paper we show that the use of the driving ac field in the form of alternating rectangular impulses of variable duration and amplitude (instead of the usual sinusoidal modulation) leads to further optimalization of the process. The efficiency of the energy transduction, for example, can be increased from about 25% for sinusoidal driving to about 37% for suitably chosen alternating rectangular pulses.

  11. Fast Pyrolysis Oil Stabilization: An Integrated Catalytic and Membrane Approach for Improved Bio-oils. Final Report

    SciTech Connect

    George W. Huber; Upadhye, Aniruddha A.; Ford, David M.; Bhatia, Surita R.; Badger, Phillip C.

    2012-10-19

    with model AFBO excluding guaiacol were also conducted. NF membranes showed retention factors of glucose greater than 80% and of acetic acid less than 15% when operated at transmembrane pressures near 60 bar. Task 3.0 Acid Removal by Catalytic Processing It was found that the TAN reduction in bio-oil was very difficult using low temperature hydrogenation in flow and batch reactors. Acetic acid is very resilient to hydrogenation and we could only achieve about 16% conversion for acetic acid. Although it was observed that acetic acid was not responsible for instability of aqueous fraction of bio-oil during ageing studies (described in task 5). The bimetallic catalyst PtRe/ceria-zirconia was found to be best catalyst because its ability to convert the acid functionality with low conversion to gas phase carbon. Hydrogenation of the whole bio-oil was carried out at 125°C, 1450 psi over Ru/C catalyst in a flow reactor. Again, negligible acetic acid conversion was obtained in low temperature hydrogenation. Hydrogenation experiments with whole bio-oil were difficult to perform because of difficulty to pumping the high viscosity oil and reactor clogging. Task 4.0 Acid Removal using Ion Exchange Resins DOWEX M43 resin was used to carry out the neutralization of bio-oil using a packed bed column. The pH of the bio-oil increased from 2.43 to 3.7. The GC analysis of the samples showed that acetic acid was removed from the bio-oil during the neutralization and recovered in the methanol washing. But it was concluded that process would not be economical at large scale as it is extremely difficult to regenerate the resin once the bio-oil is passed over it. Task 5.0 Characterization of Upgraded Bio-oils We investigated the viscosity, microstructure, and chemical composition of bio-oils prepared by a fast pyrolysis approach, upon aging these fuels at 90ºC for periods of several days. Our results suggest that the viscosity increase is not correlated with the acids or char present in the

  12. Catalytic membrane program. Quarterly report for the period August 1999--October 1999

    SciTech Connect

    Liu, Paul K.T.

    1999-11-12

    For both power generation and pipeline-quality gas applications, the projected performance of the membrane currently under development is economically attractive. Aspects of membrane development include hollow fiber substrate production, reproducibility of membrane synthesis, chemical vapor deposition as a post treatment technique, and testing of membrane thermal and hydrothermal stability.

  13. Characteristics of Subfreezing Operation of Polymer Electrolyte Membrane Fuel Cells

    NASA Astrophysics Data System (ADS)

    Mishler, Jeffrey Harris

    Polymer Electrolyte Membrane (PEM) Fuel Cells are capable of high efficiency operation, and are free of NOx, SOx, and CO2 emissions when using hydrogen fuel, and ideally suited for use in transportation applications due to their high power density and low operating temperatures. However, under subfreezing conditions which may be encountered during winter seasons in some areas, product water will freeze within the membrane, cathode side catalyst layer and gas diffusion media, leading to voltage loss and operation failure. Experiments were undertaken in order to characterize the amount and location of water during fuel cell operation. First, in-situ neutron radiography was undertaken on the fuel cells at a normal operating temperature for various operating current densities, inlet relative humidities, and diffusion media hydrophobicities. It was found that more hydrophobic cathode microporous layer (MPL) or hydrophilic anode MPL may result in a larger amount of water transporting back to the anode. The water profiles along the channels were measured and the point of liquid water emergence, where two phase flow begins, was compared to previous models. Secondly, under subfreezing temperatures, neutron imaging showed that water ice product accumulates because of lack of a water removal mechanism. Water was observed under both the lands and channels, and increased almost linearly with time. It is found that most ice exists in the cathode side. With evidence from experimental observation, a cold start model was developed and explained, following existing approaches in the literature. Three stages of cold start are explained: membrane saturation, ice storage in catalyst layer pores, and then ice melting. The voltage losses due to temperature change, increased transport resistance, and reduced electrochemical surface area. The ionic conductivity of the membrane at subfreezing temperatures was modeled. Voltage evolution over time for isothermal cold starts was predicted and

  14. Operation of passive membrane systems for drinking water treatment.

    PubMed

    Oka, P A; Khadem, N; Bérubé, P R

    2017-05-15

    The widespread adoption of submerged hollow fibre ultrafiltration (UF) for drinking water treatment is currently hindered by the complexity and cost of these membrane systems, especially in small/remote communities. Most of the complexity is associated with auxiliary fouling control measures, which include backwashing, air sparging and chemical cleaning. Recent studies have demonstrated that sustained operation without fouling control measures is possible, but little is known regarding the conditions under which extended operation can be sustained with minimal to no fouling control measures. The present study investigated the contribution of different auxiliary fouling control measures to the permeability that can be sustained, with the intent of minimizing the mechanical and operational complexity of submerged hollow fiber UF membrane systems while maximizing their throughput capacity. Sustained conditions could be achieved without backwashing, air sparging or chemical cleaning (i.e. passive operation), indicating that these fouling control measures can be eliminated, substantially simplifying the mechanical and operational complexity of submerged hollow fiber UF systems. The adoption of hydrostatic pressure (i.e. gravity) to provide the driving force for permeation further reduced the system complexity. Approximately 50% of the organic material in the raw water was removed during treatment. The sustained passive operation and effective removal of organic material was likely due to the microbial community that established itself on the membrane surface. The permeability that could be sustained was however only approximately 20% of that which can be maintained with fouling control measures. Retaining a small amount of air sparging (i.e. a few minutes daily) and incorporating a daily 1-h relaxation (i.e. permeate flux interruption) period prior to sparging more than doubled the permeability that could be sustained. Neither the approach used to interrupt the permeate

  15. Catalytic Reforming

    SciTech Connect

    Little, D.M.

    1985-01-01

    Don Little's Catalytic Reforming deals exclusively with reforming. With the increasing need for unleaded gasoline, the importance of this volume has escalated since it combines various related aspects of reforming technology into a single publication. For those with no practical knowledge of catalytic reforming, the chemical reactions, flow schemes and how the cat reformer fits into the overall refinery process will be of interest. Contents include: Catalytic reforming in refinery processing: How catalytic reformers work - chemical reactions; Process design; The catalyst, process variables and unit operation; Commercial processes; BTX operation; Feed preparation; naphtha hydrotreating and catalytic reforming; Index.

  16. Osmotic membrane bioreactor for phenol biodegradation under continuous operation.

    PubMed

    Praveen, Prashant; Loh, Kai-Chee

    2016-03-15

    Continuous phenol biodegradation was accomplished in a two-phase partitioning osmotic membrane bioreactor (TPPOMBR) system, using extractant impregnated membranes (EIM) as the partitioning phase. The EIMs alleviated substrate inhibition during prolonged operation at influent phenol concentrations of 600-2000mg/L, and also at spiked concentrations of 2500mg/L phenol restricted to 2 days. Filtration of the effluent through forward osmosis maintained high biomass concentration in the bioreactor and improved effluent quality. Steady state was reached in 5-6 days at removal rates varying between 2000 and 5500mg/L-day under various conditions. Due to biofouling and salt accumulation, the permeate flux varied from 1.2-7.2 LMH during 54 days of operation, while maintaining an average hydraulic retention time of 7.4h. A washing cycle, comprising 1h osmotic backwashing using 0.5M NaCl and 2h washing with water, facilitated biofilm removal from the membranes. Characterization of the extracellular polymeric substances (EPS) through FTIR showed peaks between 1700 and 1500cm(-1), 1450-1450cm(-1) and 1200-1000cm(-1), indicating the presence of proteins, phenols and polysaccharides, respectively. The carbohydrate to protein ratio in the EPS was estimated to be 0.3. These results indicate that TPPOMBR can be promising in continuous treatment of phenolic wastewater.

  17. One-year operation of single household membrane bioreactor plant.

    PubMed

    Matulova, Z; Hlavinek, P; Drtil, M

    2010-01-01

    This paper evaluates the results from a 12-month study of a single-household wastewater treatment plant with submerged membrane module (household MBR plant) that was monitored from winter to winter season. The samples were collected at least twice a week (an intensive research study at real conditions). The household MBR (membrane bioreactor) plant was linked to a family house with 4 residents. In this study the treatment plant was fed by real domestic wastewater. In contrast to most other experiments with small-scale WWTPs (wastewater treatment plants) carried out in laboratories and facilities of large municipal WWTPs (polygons) which guarantee stable and flexible operation but the characteristics of wastewater and activated sludge in these studies usually differ from those that occur in real small-scale/single-household WWTPs. One of the main goals of this research was to test the response of membrane and activated sludge to different conditions during real operation of the household MBR plant, such as a long period of zero influent/load, or vice versa the presence of a large amount of concentrated wastewater (e.g. during the weekend), very low winter temperatures (water temperature below 5-6 degrees C), high pH values, and the presence of domestic detergents.

  18. Advanced treatment of biologically pretreated coal gasification wastewater by a novel integration of three-dimensional catalytic electro-Fenton and membrane bioreactor.

    PubMed

    Jia, Shengyong; Han, Hongjun; Hou, Baolin; Zhuang, Haifeng

    2015-12-01

    Laboratorial scale experiments were conducted to investigate a novel system three-dimensional catalytic electro-Fenton (3DCEF, catalyst of sewage sludge based activated carbon which loaded Fe3O4) integrating with membrane bioreactor (3DCEF-MBR) on advanced treatment of biologically pretreated coal gasification wastewater. The results indicated that 3DCEF-MBR represented high efficiencies in eliminating COD and total organic carbon, giving the maximum removal efficiencies of 80% and 75%, respectively. The integrated 3DCEF-MBR system significantly reduced the transmembrane pressure, giving 35% lower than conventional MBR after 30 days operation. The enhanced hydroxyl radical oxidation and bacteria self repair function were the mechanisms for 3DCEF-MBR performance. Therefore, the integrated 3DCEF-MBR was expected to be the promising technology for advanced treatment in engineering applications.

  19. Continuous esterification to produce biodiesel by SPES/PES/NWF composite catalytic membrane in flow-through membrane reactor: experimental and kinetic studies.

    PubMed

    Shi, Wenying; He, Benqiao; Cao, Yuping; Li, Jianxin; Yan, Feng; Cui, Zhenyu; Zou, Zhiqun; Guo, Shiwei; Qian, Xiaomin

    2013-02-01

    A novel composite catalytic membrane (CCM) was prepared from sulfonated polyethersulfone (SPES) and polyethersulfone (PES) blend supported by non-woven fabrics, as a heterogeneous catalyst to produce biodiesel from continuous esterification of oleic acid with methanol in a flow-through mode. A kinetic model of esterification was established based on a plug-flow assumption. The effects of the CCM structure (thickness, area, porosity, etc.), reaction temperature and the external and internal mass transfer resistances on esterification were investigated. The results showed that the CCM structure had a significant effect on the acid conversion. The external mass transfer resistance could be neglected when the flow rate was over 1.2 ml min(-1). The internal mass transfer resistance impacted on the conversion when membrane thickness was over 1.779 mm. An oleic acid conversion kept over 98.0% for 500 h of continuous running. The conversions obtained from the model are in good agreement with the experimental data.

  20. Performance of a catalytic reactor at simulated gas turbine combustor operating conditions

    NASA Technical Reports Server (NTRS)

    Anderson, D. N.; Tacina, R. R.; Mroz, T. S.

    1975-01-01

    The performance of a catalytic reactor 12 cm in diameter and 17 cm long was evaluated at simulated gas turbine combustor operating conditions using premixed propane and air. Inlet temperatures of 600 and 800 K, pressures of 3 and 6 atm, and reference velocities of 9 to 30 m/s were tested. Data were taken for equivalence ratios as high as 0.43. The operating range was limited on the low-temperature side by very poor efficiency; the minimum exit temperature for good performance ranged from 1400 to 1600 K depending on inlet conditions. As exit temperatures were raised above this minimum, emissions of unburned hydrocarbons decreased, carbon monoxide emissions became generally less than 1 g CO/kg fuel, and nitrogen oxides were less than about 0.1 g NO2/kg fuel.

  1. 40 CFR Table 9 to Subpart Uuu of... - Operating Limits for Organic HAP Emissions From Catalytic Cracking Units

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 13 2013-07-01 2012-07-01 true Operating Limits for Organic HAP Emissions From Catalytic Cracking Units 9 Table 9 to Subpart UUU of Part 63 Protection of Environment... Units Pt. 63, Subpt. UUU, Table 9 Table 9 to Subpart UUU of Part 63—Operating Limits for Organic...

  2. 40 CFR Table 16 to Subpart Uuu of... - Operating Limits for Organic HAP Emissions From Catalytic Reforming Units

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 13 2012-07-01 2012-07-01 false Operating Limits for Organic HAP Emissions From Catalytic Reforming Units 16 Table 16 to Subpart UUU of Part 63 Protection of Environment... Units Pt. 63, Subpt. UUU, Table 16 Table 16 to Subpart UUU of Part 63—Operating Limits for Organic...

  3. 40 CFR Table 9 to Subpart Uuu of... - Operating Limits for Organic HAP Emissions From Catalytic Cracking Units

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 12 2010-07-01 2010-07-01 true Operating Limits for Organic HAP Emissions From Catalytic Cracking Units 9 Table 9 to Subpart UUU of Part 63 Protection of Environment..., Subpt. UUU, Table 9 Table 9 to Subpart UUU of Part 63—Operating Limits for Organic HAP Emissions...

  4. 40 CFR Table 9 to Subpart Uuu of... - Operating Limits for Organic HAP Emissions From Catalytic Cracking Units

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 13 2012-07-01 2012-07-01 false Operating Limits for Organic HAP Emissions From Catalytic Cracking Units 9 Table 9 to Subpart UUU of Part 63 Protection of Environment... Units Pt. 63, Subpt. UUU, Table 9 Table 9 to Subpart UUU of Part 63—Operating Limits for Organic...

  5. 40 CFR Table 16 to Subpart Uuu of... - Operating Limits for Organic HAP Emissions From Catalytic Reforming Units

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 13 2013-07-01 2012-07-01 true Operating Limits for Organic HAP Emissions From Catalytic Reforming Units 16 Table 16 to Subpart UUU of Part 63 Protection of Environment... Units Pt. 63, Subpt. UUU, Table 16 Table 16 to Subpart UUU of Part 63—Operating Limits for Organic...

  6. 40 CFR Table 9 to Subpart Uuu of... - Operating Limits for Organic HAP Emissions From Catalytic Cracking Units

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 13 2014-07-01 2014-07-01 false Operating Limits for Organic HAP Emissions From Catalytic Cracking Units 9 Table 9 to Subpart UUU of Part 63 Protection of Environment... Units Pt. 63, Subpt. UUU, Table 9 Table 9 to Subpart UUU of Part 63—Operating Limits for Organic...

  7. 40 CFR Table 16 to Subpart Uuu of... - Operating Limits for Organic HAP Emissions From Catalytic Reforming Units

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 13 2014-07-01 2014-07-01 false Operating Limits for Organic HAP Emissions From Catalytic Reforming Units 16 Table 16 to Subpart UUU of Part 63 Protection of Environment... Units Pt. 63, Subpt. UUU, Table 16 Table 16 to Subpart UUU of Part 63—Operating Limits for Organic...

  8. 40 CFR Table 9 to Subpart Uuu of... - Operating Limits for Organic HAP Emissions From Catalytic Cracking Units

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 12 2011-07-01 2009-07-01 true Operating Limits for Organic HAP Emissions From Catalytic Cracking Units 9 Table 9 to Subpart UUU of Part 63 Protection of Environment..., Subpt. UUU, Table 9 Table 9 to Subpart UUU of Part 63—Operating Limits for Organic HAP Emissions...

  9. 40 CFR Table 2 to Subpart Uuu of... - Operating Limits for Metal HAP Emissions From Catalytic Cracking Units

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 13 2013-07-01 2012-07-01 true Operating Limits for Metal HAP Emissions From Catalytic Cracking Units 2 Table 2 to Subpart UUU of Part 63 Protection of Environment... Units Pt. 63, Subpt. UUU, Table 2 Table 2 to Subpart UUU of Part 63—Operating Limits for Metal...

  10. Advanced treatment of biologically pretreated coal gasification wastewater by a novel integration of catalytic ultrasound oxidation and membrane bioreactor.

    PubMed

    Jia, Shengyong; Han, Hongjun; Zhuang, Haifeng; Xu, Peng; Hou, Baolin

    2015-01-01

    Laboratorial scale experiments were conducted to investigate a novel system integrating catalytic ultrasound oxidation (CUO) with membrane bioreactor (CUO-MBR) on advanced treatment of biologically pretreated coal gasification wastewater. Results indicated that CUO with catalyst of FeOx/SBAC (sewage sludge based activated carbon (SBAC) which loaded Fe oxides) represented high efficiencies in eliminating TOC as well as improving the biodegradability. The integrated CUO-MBR system with low energy intensity and high frequency was more effective in eliminating COD, BOD5, TOC and reducing transmembrane pressure than either conventional MBR or ultrasound oxidation integrated MBR. The enhanced hydroxyl radical oxidation, facilitation of substrate diffusion and improvement of cell enzyme secretion were the mechanisms for CUO-MBR performance. Therefore, the integrated CUO-MBR was the promising technology for advanced treatment in engineering applications.

  11. Operation of polymer electrolyte membrane fuel cells with dry feeds: Design and operating strategies

    NASA Astrophysics Data System (ADS)

    Hogarth, Warren H. J.; Benziger, Jay B.

    The operation of polymer electrolyte membrane fuel cells (PEMFCs) with dry feeds has been examined with different fuel cell flow channel designs as functions of pressure, temperature and flow rate. Auto-humidified (or self-humidifying) PEMFC operation is improved at higher pressures and low gas velocities where axial dispersion enhances "back-mixing" of the product water with the dry feed. We demonstrate auto-humidified operation of the channel-less, self-draining fuel cell, based on a stirred tank reactor; data is presented showing auto-humidified operation from 25 to 115 °C at 1 and 3 atm. Design and operating requirements are derived for the auto-humidified operation of the channel-less, self-draining fuel cell. The auto-humidified self-draining fuel cell outperforms a fully humidified serpentine flow channel fuel cell at high current densities. The new design offers substantial benefits for simplicity of operation and control including: the ability to self-drain reducing flooding, the ability to uniformly disperse water removing current gradients and the ability to operate on dry feeds eliminating the need for humidifiers. Additionally, the design lends itself well to a modular design concept.

  12. Expression, purification and crystallization of a membrane-associated, catalytically active type I signal peptidase from Staphylococcus aureus.

    PubMed

    Ting, Yi Tian; Batot, Gaëlle; Baker, Edward N; Young, Paul G

    2015-01-01

    Staphylococcus aureus infections are becoming increasingly difficult to treat as they rapidly develop resistance to existing antibiotics. Bacterial type I signal peptidases are membrane-associated, cell-surface serine proteases with a unique catalytic mechanism that differs from that of eukaryotic endoplasmic reticulum signal peptidases. They are thus potential antimicrobial targets. S. aureus has a catalytically active type I signal peptidase, SpsB, that is essential for cell viability. To elucidate its structure, the spsB gene from S. aureus Newman strain was cloned and overexpressed in Escherichia coli. After exploring many different protein-modification constructs, SpsB was expressed as a fusion protein with maltose-binding protein and crystallized by hanging-drop vapour diffusion. The crystals belonged to the monoclinic space group P2(1) and diffracted to 2.05 Å resolution. The crystal structure of SpsB is anticipated to provide structural insight into Gram-positive signal peptidases and to aid in the development of antibacterial agents that target type I signal peptidases.

  13. Spatially resolved characterization of catalyst-coated membranes by distance-controlled scanning mass spectrometry utilizing catalytic methanol oxidation as gas-solid probe reaction.

    PubMed

    Li, Nan; Assmann, Jens; Schuhmann, Wolfgang; Muhler, Martin

    2007-08-01

    The spatially resolved catalytic activity of a catalyst-coated membrane (CCM), which is the essential part of PEM fuel cells, was visualized rapidly without any damage by a distance-controlled scanning mass spectrometer with an improved resolution of 250 microm. Methanol oxidation was identified as a suitable gas-solid probe reaction for the characterization of local catalytic activity. In addition, defects were manually generated in the CCM to simulate inhomogeneous coating and pinholes. The measurements successfully demonstrated that catalytically active and less active regions can be clearly distinguished. Simultaneously, the local topography was recorded, providing additional information on the location of the scratches and pinholes. The catalytic results were highly reproducible due to the constant-distance feedback loop rendering scanning mass spectrometry a promising tool for the quantitative quality control of CCMs.

  14. Removal of diatrizoate with catalytically active membranes incorporating microbially produced palladium nanoparticles.

    PubMed

    Hennebel, Tom; De Corte, Simon; Vanhaecke, Lynn; Vanherck, Katrien; Forrez, Ilse; De Gusseme, Bart; Verhagen, Pieter; Verbeken, Kim; Van der Bruggen, Bart; Vankelecom, Ivo; Boon, Nico; Verstraete, Willy

    2010-03-01

    There is an increasing concern about the fate of iodinated contrast media (ICM) in the environment. Limited removal efficiencies of currently applied techniques such as advanced oxidation processes require more performant strategies. The aim of this study was to establish an innovative degradation process for diatrizoate, a highly recalcitrant ICM, by using biogenic Pd nanoparticles as free suspension or immobilized in polyvinylidene fluoride (PVDF) and polysulfone (PSf) membranes. As measured by HPLC-UV, the removal of 20mg L(-1) diatrizoate by a 10mg L(-1) Pd suspension was completed after 4h at a pH of 10. LC-MS analysis provided evidence for the sequential hydrodeiodination of diatrizoate. Pd did not lose its activity after incorporation in the PVDF and PSf matrix and the highest activity (k(cat)=30.0+/-0.4h(-1) L g(-1) Pd) was obtained with a casting solution of 10% PSf and 500mg L(-1) Pd. Subsequently, water containing 20mg L(-1) diatrizoate was treated in a membrane contactor, in which the water was supplied at one side of the membrane while hydrogen was provided at the other side. In a fed batch configuration, a removal efficiency of 77% after a time period of 48h was obtained. This work showed that membrane contactors with encapsulated biogenic nanoparticles can be instrumental for treatment of water contaminated with diatrizoate.

  15. Catalytic and electrochemical behaviour of solid oxide fuel cell operated with simulated-biogas mixtures

    NASA Astrophysics Data System (ADS)

    Dang-Long, T.; Quang-Tuyen, T.; Shiratori, Y.

    2016-06-01

    Being produced from organic matters of wastes (bio-wastes) through a fermentation process, biogas mainly composed of CH4 and CO2 and can be considered as a secondary energy carrier derived from solar energy. To generate electricity from biogas through the electrochemical process in fuel cells is a state-of-the-art technology possessing higher energy conversion efficiency without harmful emissions compared to combustion process in heat engines. Getting benefits from high operating temperature such as direct internal reforming ability and activation of electrochemical reactions to increase overall system efficiency, solid oxide fuel cell (SOFC) system operated with biogas becomes a promising candidate for distributed power generator for rural applications leading to reductions of environmental issues caused by greenhouse effects and bio-wastes. CO2 reforming of CH4 and electrochemical oxidation of the produced syngas (H2-CO mixture) are two main reaction processes within porous anode material of SOFC. Here catalytic and electrochemical behavior of Ni-ScSZ (scandia stabilized-zirconia) anode in the feed of CH4-CO2 mixtures as simulated-biogas at 800 °C were evaluated. The results showed that CO2 had strong influences on both reaction processes. The increase in CO2 partial pressure resulted in the decrease in anode overvoltage, although open-circuit voltage was dropped. Besides that, the simulation result based on a power-law model for equimolar CH4-CO2 mixture revealed that coking hazard could be suppressed along the fuel flow channel in both open-circuit and closed-circuit conditions.

  16. Membrane Bioreactor/Ultra Low Energy Reverse Osmosis Membrane Process for Forward Operating Base Wastewater Reuse

    DTIC Science & Technology

    2014-08-01

    membranes in the test cells without recycling the permeate for 30 minutes to remove any residual chemicals and dyes. Afterwards, synthetic brackish water...The membrane performed consistently well over the entire study period with minimal membrane cleaning (Figure 75). The RO concentrate was recycled ...compared to the current practice of using bottled water. Assuming the same range of cost for membrane cleaning chemicals, Table 29 shows that the

  17. Sustainable membrane operation design for the treatment of the synthetic coke wastewater in SMBR.

    PubMed

    Zhou, Ying; Xu, Zhen-Liang; Munib, Shahda; Chen, Gui-e; Lu, Qiong

    2009-01-01

    Membrane fouling in the membrane bioreactor (MBR) is typically caused by the interaction of microbial characteristics, hydrodynamic behavior, operation environment, wastewater characteristics and membrane properties, which result in the deterioration of performance and increasing energy consumption and cost of membrane replacement. The effect of the crucial MBR parameters (the microbial loading and characteristics, dissolved oxygen (DO), hydraulic retention time (HRT), backwashing conditions and membrane characteristics) on membrane fouling was investigated in a submerged membrane bioreactor (SMBR) during the long term treatment of synthetic coke wastewater. Also the optimum operation strategies were further utilized in order to satisfy the minimal membrane fouling operation through a long-term evaluation of the MBR performance. It has been demonstrated that with application of these optimal designed conditions, significant membrane fouling improvements were achieved over a long operating time, so it was possible to perform in sustainable operation for MBR. In this study, the upper limit of the sustainable flux is found to be as much as 18.6 L/m(2) h and the optimum sustainable flux value should be 50 approximately 75% of critical flux to satisfy the desired sustainable operation period.

  18. Integration of Methane Steam Reforming and Water Gas Shift Reaction in a Pd/Au/Pd-Based Catalytic Membrane Reactor for Process Intensification

    PubMed Central

    Castro-Dominguez, Bernardo; Mardilovich, Ivan P.; Ma, Liang-Chih; Ma, Rui; Dixon, Anthony G.; Kazantzis, Nikolaos K.; Ma, Yi Hua

    2016-01-01

    Palladium-based catalytic membrane reactors (CMRs) effectively remove H2 to induce higher conversions in methane steam reforming (MSR) and water-gas-shift reactions (WGS). Within such a context, this work evaluates the technical performance of a novel CMR, which utilizes two catalysts in series, rather than one. In the process system under consideration, the first catalyst, confined within the shell side of the reactor, reforms methane with water yielding H2, CO and CO2. After reforming is completed, a second catalyst, positioned in series, reacts with CO and water through the WGS reaction yielding pure H2O, CO2 and H2. A tubular composite asymmetric Pd/Au/Pd membrane is situated throughout the reactor to continuously remove the produced H2 and induce higher methane and CO conversions while yielding ultrapure H2 and compressed CO2 ready for dehydration. Experimental results involving (i) a conventional packed bed reactor packed (PBR) for MSR, (ii) a PBR with five layers of two catalysts in series and (iii) a CMR with two layers of two catalysts in series are comparatively assessed and thoroughly characterized. Furthermore, a comprehensive 2D computational fluid dynamics (CFD) model was developed to explore further the features of the proposed configuration. The reaction was studied at different process intensification-relevant conditions, such as space velocities, temperatures, pressures and initial feed gas composition. Finally, it is demonstrated that the above CMR module, which was operated for 600 h, displays quite high H2 permeance and purity, high CH4 conversion levels and reduced CO yields. PMID:27657143

  19. 40 CFR Table 14 to Subpart Uuu of... - Continuous Compliance With Operating Limits for Organic HAP Emissions From Catalytic Cracking Units

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Limits for Organic HAP Emissions From Catalytic Cracking Units 14 Table 14 to Subpart UUU of Part 63... Reforming Units, and Sulfur Recovery Units Pt. 63, Subpt. UUU, Table 14 Table 14 to Subpart UUU of Part 63—Continuous Compliance With Operating Limits for Organic HAP Emissions From Catalytic Cracking Units As...

  20. 40 CFR Table 14 to Subpart Uuu of... - Continuous Compliance With Operating Limits for Organic HAP Emissions From Catalytic Cracking Units

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Limits for Organic HAP Emissions From Catalytic Cracking Units 14 Table 14 to Subpart UUU of Part 63... Reforming Units, and Sulfur Recovery Units Pt. 63, Subpt. UUU, Table 14 Table 14 to Subpart UUU of Part 63—Continuous Compliance With Operating Limits for Organic HAP Emissions From Catalytic Cracking Units As...

  1. Performance comparison of long and short-side chain perfluorosulfonic membranes for high temperature polymer electrolyte membrane fuel cell operation

    NASA Astrophysics Data System (ADS)

    Stassi, A.; Gatto, I.; Passalacqua, E.; Antonucci, V.; Arico, A. S.; Merlo, L.; Oldani, C.; Pagano, E.

    A new Aquivion™ E79-03S short-side chain perfluorosulfonic membrane with a thickness of 30 μm (dry form) and an equivalent weight (EW) of 790 g/equiv recently developed by Solvay-Solexis for high-temperature operation was tested in a pressurised (3 bar abs.) polymer electrolyte membrane (PEM) single cell at a temperature of 130 °C. For comparison, a standard Nafion™ membrane (EW 1100 g/equiv) of similar thickness (50 μm) was investigated under similar operating conditions. Both membranes were tested for high temperature operation in conjunction with an in-house prepared carbon supported Pt electrocatalyst. The electrocatalyst consisted of nanosized Pt particles (particle size ∼2 nm) dispersed on a high surface area carbon black. The electrochemical tests showed better performance for the Aquivion™ membrane as compared to Nafion™ with promising properties for high temperature PEM fuel cell applications. Beside the higher open circuit voltage and lower ohmic constraints, a higher electrocatalytic activity was observed at high temperature for the electrocatalyst-Aquivion™ ionomer interface indicating a better catalyst utilization.

  2. Tunable catalytic tubular micro-pumps operating at low concentrations of hydrogen peroxide.

    PubMed

    Solovev, Alexander A; Sanchez, Samuel; Mei, Yongfeng; Schmidt, Oliver G

    2011-06-07

    Catalytic micropumps consisting of Ti/Cr/Pt microtubes with diameters of 5-10 μm and tunable lengths in the range of 20-1000 μm are reported. Micropumps were fabricated by rolling up metallic nanomembranes into microtubes with an inner platinum layer. When immersed into a solution of hydrogen peroxide, the micropumps are activated by the catalytic decomposition of peroxide into oxygen microbubbles and water. Fluid pumping is demonstrated by the movement of polystyrene particles with a diameter of 1 μm through the catalytic microtubes. Concentrations from 0.009 to 11% H(2)O(2) were employed to study the catalytic generation of microbubbles in micropumps with different lengths. A minimum concentration of 0.06% fuel was determined to be sufficient to actuate the micropumps. Such devices based on rolled-up nanomembranes hold great promise for the integration into Lab-on-a-chip systems for sensing, sorting of particles and drug delivery.

  3. Membrane Operational Impedance Spectra in Chara corallina Estimated by Laplace Transforms Analysis 1

    PubMed Central

    Homblé, Fabrice; Jenard, André

    1986-01-01

    The membrane operational impedance spectrum of Chara corallina Klein ex Willd. (R. Brown) cells is investigated using Laplace transform analysis. The spectrum changes with both amplitude and sign of the electrical stimulation when time- and voltage-dependent K+ channels contribute to the membrane conductance. We compare the advantages and disadvantage of this technique for studying membrane impedance with those of the alternating current method and the white noise method. PMID:16664925

  4. High performance RO membranes for desalination and wastewater reclamation and their operation results.

    PubMed

    Henmi, M; Fusaoka, Y; Tomioka, H; Kurihara, M

    2010-01-01

    Reverse osmosis (RO) membrane is one of the most powerful tools for solving the global water crisis, and is used in a variety of water treatment scenes such as drinking water purification, waste-water treatment, boiler feed water production, ultra pure water production for semiconductor industry, etc. The desired performance of RO membrane varies according to quality of feed water being treated, and Toray has been developing RO membranes with suitable characteristic for each operating condition. RO membranes for seawater desalination and wastewater reclamation are especially regarded as most promising targets. Recently, high boron removal and energy saving RO membrane for seawater desalination and low fouling RO membrane for wastewater reclamation have been developed. In this paper, the prospect of attaining these renovative RO membrane, and furthermore, job references will be discussed.

  5. Influence of electrolytes and membranes on cell operation for syn-gas production

    SciTech Connect

    Eric J. Dufek; Tedd E. Lister; Michael E. McIlwain

    2012-02-01

    The impact of membrane type and electrolyte composition for the electrochemical generation of synthesis gas (CO + H2) using a Ag gas diffusion electrode are presented. Changing from a cation exchange membrane to an anion exchange membrane (AEM) extended the cell operational time at low Ecell values (up to 4x) without impacting product composition. The use of KOH as the catholyte decreased the Ecell and resulted in a minimum electrolyte cost reduction of 39%. The prime factor in determining operational time at low Ecell values was the ability to maintain a sufficiently high anolyte pH.

  6. Ultrasonic irradiation for ultrafiltration membrane cleaning in MBR systems: operational conditions and consequences.

    PubMed

    Ruiz, L M; Perez, J I; Gómez, A; Letona, A; Gómez, M A

    2017-02-01

    Ultrasonic irradiation is one of the most promising membrane cleaning techniques for membrane bioreactors (MBRs) because of several advantages such as high flux-recovery capacity and in situ application without interrupting the filtration process. However, significant contradictions may be found and, consequently, this method has not yet been widely developed. In this paper, four MBRs equipped with hollow-fibre polyvinylidene fluoride ultrafiltration membranes were operated continuously. The cleaning method applied consisted of sonication at low power (15 W) with different frequencies (20, 25, 30, and 40 kHz) for each module and aerated backwashing. The different MBRs were analysed comparatively between them and with a conventional MBR in order to check the effects of the irradiated waves on membrane integrity, effluent quality and process performance. Effluent turbidity and chemical oxygen demand, total and volatile suspended solid concentration and activated sludge viscosity were affected by biomass fragmentation or membrane cake removal, mainly at lower frequencies. The best transmembrane pressure control was achieved at the frequency of 20 kHz without a significant effect on membrane integrity. The results showed that under these operational conditions, no negative effects on effluent quality or membrane integrity were found, suggesting that this method was suitable for this type of membrane.

  7. 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.

  8. Modified by air plasma polymer tack membranes as drainage material for antiglaucomatous operations

    NASA Astrophysics Data System (ADS)

    Ryazantseva, T. V.; Kravets, L. I.; Elinson, V. M.

    2014-06-01

    The morphological and clinical studies of poly(ethylene terephthalate) track membranes modified by air plasma as drainage materials for antiglaucomatous operations were performed. It was demonstrated their compatibility with eye tissues. Moreover, it was shown that a new drainage has a good lasting hypotensive effect and can be used as operation for refractory glaucoma surgery.

  9. Enzymatic hydrolysis of cellulose in a membrane bioreactor: assessment of operating conditions.

    PubMed

    Liu, Jianguo; Lu, Jianren; Cui, Zhanfeng

    2011-06-01

    The optimization of operating conditions for cellulose hydrolysis was systemically undertaken using an ultra-scaled down membrane bioreactor based on the parameter scanning ultrafiltration apparatus. The bioconversion of cellulose saccharification was carried out with freely suspended cellulase from Aspergillus niger as the biocatalyst. The polyethersulfone ultrafiltration membranes with a molecular weight cutoff of 10 kDa were used to construct the enzymatic membrane bioreactor, with the membrane showing a complete retaining of cellulase and cellobiase. The influence of solution pH, temperature, salt (NaCl) concentration, presence of cellobiase, cellulose-to-enzyme ratio and stirring speed on reducing sugar production was examined. The results showed that the addition of an appropriate amount of NaCl or cellobiase had a positive effect on reducing sugar formation. Under the identified optimal conditions, cellulose hydrolysis in the enzymatic membrane bioreactor was tested for a long period of time up to 75 h, and both enzymes and operation conditions demonstrated good stability. Also, the activation energy (E(a)) of the enzymatic hydrolysis, with a value of 34.11 ± 1.03 kJ mol(-1), was estimated in this study. The operational and physicochemical conditions identified can help guide the design and operation of enzymatic membrane bioreactors at the industrial scale for cellulose hydrolysis.

  10. Oxygen-selective immobilized liquid membranes for operation of lithium-air batteries in ambient air

    SciTech Connect

    Zhang, Jian; Xu, Wu; Liu, Wei

    2010-11-01

    In this paper, nonaqueous-electrolyte-based Li-air batteries with O2-selective immobilized liquid membranes have been developed and operated in ambient air with 20~30% relative humidity(RH). Continuous anhydrous O2 can be supplied from the ambient through a membrane barrier layer at interface of the cathode and ambient air. The membranes allow O2 permeate through while blocking moisture. These membranes were prepared by loading O2-selective liquid fluids such as silicone oils into porous supports such as porous metal sheets and Teflon (PTFE) films. It was found that silicone oil of high viscosity shows better performance. The membrane performance was not affected by the oil loading temperature. The immobilized silicone oil (viscosity 100,000cst) membrane in porous PTFE film enabled the Li-air batteries with Ketjen black carbon air electrodes to operate in ambient air (with 20% RH) for 16.3 days with a specific capacity of 789 mAh/g carbon and a specific energy of 2182 Wh/kg carbon. Its performance is much better than reference battery assembled with the same battery material but by use of a commercial, porous PTFE diffusion membranes as the moisture barrier layer on the cathode, which only had a discharge time of 5.5 days corresponding to a specific capacity of 267 mAh/g carbon and a specific energy of 704 Wh/kg carbon. The Li-air battery with the present selective membrane barrier layer even showed better performance in ambient air operation (20% RH) than the reference battery tested in the dry air box (< 1% RH).

  11. Removals of pharmaceutical compounds from hospital wastewater in membrane bioreactor operated under short hydraulic retention time.

    PubMed

    Prasertkulsak, S; Chiemchaisri, C; Chiemchaisri, W; Itonaga, T; Yamamoto, K

    2016-05-01

    Pilot-scale membrane bioreactor (MBR) was operated at a short hydraulic retention time (HRT) of 3 h for the treatment of hospital wastewater. The removals of eleven pharmaceutical compounds in MBR operated at different mixed liquor suspended solids (MLSS) level were investigated during which nitrification degree was differed. The results experiments revealed the importance of immediate adsorption onto the colloidal particles in supernatant of MBR sludge and subsequently removed by membrane filtration for the recalcitrant pharmaceutical compounds. Nevertheless, the removals through biodegradation during short HRT were also found significant for some compounds. DGGE profile revealed the development of pharmaceutical degrading microorganisms in MBR.

  12. Selective catalytic reduction operation with heavy fuel oil: NOx, NH3, and particle emissions.

    PubMed

    Lehtoranta, Kati; Vesala, Hannu; Koponen, Päivi; Korhonen, Satu

    2015-04-07

    To meet stringent NOx emission limits, selective catalytic reduction (SCR) is increasingly utilized in ships, likely also in combination with low-priced higher sulfur level fuels. In this study, the performance of SCR was studied by utilizing NOx, NH3, and particle measurements. Urea decomposition was studied with ammonia and isocyanic acid measurements and was found to be more effective with heavy fuel oil (HFO) than with light fuel oil. This is suggested to be explained by the metals found in HFO contributing to metal oxide particles catalyzing the hydrolysis reaction prior to SCR. At the exhaust temperature of 340 °C NOx reduction was 85-90%, while at lower temperatures the efficiency decreased. By increasing the catalyst loading, the low temperature behavior of the SCR was enhanced. The drawback of this, however, was the tendency of particle emissions (sulfate) to increase at higher temperatures with higher loaded catalysts. The particle size distribution results showed high amounts of nanoparticles (in 25-30 nm size), the formation of which SCR either increased or decreased. The findings of this work provide a better understanding of the usage of SCR in combination with a higher sulfur level fuel and also of ship particle emissions, which are a growing concern.

  13. Upgrading naphtha in a multiple riser fluid catalytic cracking operation employing a catalyst mixture

    SciTech Connect

    Herbst, J.A.; Owen, H.; Schipper, P.H.

    1989-05-16

    A process is described for producing gasoline comprising contacting a hydrocarbon feed having an initial boiling-point of at least 400/sup 0/F., a 50% boiling of at least 500/sup 0/F. and an end boiling point of at least 600/sup 0/F., in a first riser, with a two component catalyst under fluid catalytic cracking conditions. At least one component of the catalyst is stripped in a stripping unit to remove entrained hydrocarbons, and regenerated wherein the two component catalyst comprises a first catalyst component selected from the group consisting of an amorphous cracking catalyst and a large pore cracking catalyst, whereby a product comprising olefins and naphtha is produced. Ethylene introduced together with the two component catalyst to a second riser, for contacting ethylene with a second catalyst component which is a shape selective medium pore crystalline silicate zeolite to produce products heavier than ethylene and to increase the temperature of the catalyst to an optimum temperature for upgrading naphtha; and naphtha is introduced to the second riser, down stream of the point of ethylene introduction, for contact with the catalyst at the optimum temperature and the naphtha is upgraded to gasoline product.

  14. The acidic domain of the endothelial membrane protein GPIHBP1 stabilizes lipoprotein lipase activity by preventing unfolding of its catalytic domain.

    PubMed

    Mysling, Simon; Kristensen, Kristian Kølby; Larsson, Mikael; Beigneux, Anne P; Gårdsvoll, Henrik; Fong, Loren G; Bensadouen, André; Jørgensen, Thomas Jd; Young, Stephen G; Ploug, Michael

    2016-01-03

    GPIHBP1 is a glycolipid-anchored membrane protein of capillary endothelial cells that binds lipoprotein lipase (LPL) within the interstitial space and shuttles it to the capillary lumen. The LPL•GPIHBP1 complex is responsible for margination of triglyceride-rich lipoproteins along capillaries and their lipolytic processing. The current work conceptualizes a model for the GPIHBP1•LPL interaction based on biophysical measurements with hydrogen-deuterium exchange/mass spectrometry, surface plasmon resonance, and zero-length cross-linking. According to this model, GPIHBP1 comprises two functionally distinct domains: (1) an intrinsically disordered acidic N-terminal domain; and (2) a folded C-terminal domain that tethers GPIHBP1 to the cell membrane by glycosylphosphatidylinositol. We demonstrate that these domains serve different roles in regulating the kinetics of LPL binding. Importantly, the acidic domain stabilizes LPL catalytic activity by mitigating the global unfolding of LPL's catalytic domain. This study provides a conceptual framework for understanding intravascular lipolysis and GPIHBP1 and LPL mutations causing familial chylomicronemia.

  15. Catalytic unit-independent phosphorylation and dephosphorylation of type II regulatory subunit of cyclic AMP-dependent protein kinase in rat liver plasma membranes.

    PubMed Central

    Kiss, Z; Luo, Y; Vereb, G

    1986-01-01

    Rat liver plasma membranes contain a 55 kDa protein which proved to be identical with type II regulatory subunit (RII) of the cyclic AMP-dependent protein kinase (kinase A) by several criteria (gel electrophoretic behaviour, peptide map, position of the autophosphorylated site). Analysis of phosphopeptide maps revealed that the membrane-bound RII was phosphorylated by a kinase which is unrelated to the catalytic unit (C) of kinase A. Dephosphorylation of the membrane-bound RII by an endogenous phosphatase was stimulated by both cyclic AMP and fluoride. Addition of C did not stimulate dephosphorylation even in the presence of ADP; moreover, protein inhibitor of C did not modify the effects of cyclic AMP or fluoride. The effects of both cyclic AMP and fluoride were, however, inhibited by C. Results indicate that rat liver plasma membranes contain a phosphorylation-dephosphorylation system for which RII is a relatively specific substrate. Images Fig. 1. Fig. 2. Fig. 3. Fig. 4. Fig. 5. Fig. 6. PMID:3010951

  16. Magnetic resonance imaging of water content across the Nafion membrane in an operational PEM fuel cell.

    PubMed

    Zhang, Ziheng; Martin, Jonathan; Wu, Jinfeng; Wang, Haijiang; Promislow, Keith; Balcom, Bruce J

    2008-08-01

    Water management is critical to optimize the operation of polymer electrolyte membrane fuel cells. At present, numerical models are employed to guide water management in such fuel cells. Accurate measurements of water content variation in polymer electrolyte membrane fuel cells are required to validate these models and to optimize fuel cell behavior. We report a direct water content measurement across the Nafion membrane in an operational polymer electrolyte membrane fuel cell, employing double half k-space spin echo single point imaging techniques. The MRI measurements with T2 mapping were undertaken with a parallel plate resonator to avoid the effects of RF screening. The parallel plate resonator employs the electrodes inherent to the fuel cell to create a resonant circuit at RF frequencies for MR excitation and detection, while still operating as a conventional fuel cell at DC. Three stages of fuel cell operation were investigated: activation, operation and dehydration. Each profile was acquired in 6 min, with 6 microm nominal resolution and a SNR of better than 15.

  17. Magnetic resonance imaging of water content across the Nafion membrane in an operational PEM fuel cell

    NASA Astrophysics Data System (ADS)

    Zhang, Ziheng; Martin, Jonathan; Wu, Jinfeng; Wang, Haijiang; Promislow, Keith; Balcom, Bruce J.

    2008-08-01

    Water management is critical to optimize the operation of polymer electrolyte membrane fuel cells. At present, numerical models are employed to guide water management in such fuel cells. Accurate measurements of water content variation in polymer electrolyte membrane fuel cells are required to validate these models and to optimize fuel cell behavior. We report a direct water content measurement across the Nafion membrane in an operational polymer electrolyte membrane fuel cell, employing double half k-space spin echo single point imaging techniques. The MRI measurements with T2 mapping were undertaken with a parallel plate resonator to avoid the effects of RF screening. The parallel plate resonator employs the electrodes inherent to the fuel cell to create a resonant circuit at RF frequencies for MR excitation and detection, while still operating as a conventional fuel cell at DC. Three stages of fuel cell operation were investigated: activation, operation and dehydration. Each profile was acquired in 6 min, with 6 μm nominal resolution and a SNR of better than 15.

  18. Impact of operating conditions on the removal of endocrine disrupting chemicals by membrane photocatalytic reactor.

    PubMed

    López Fernández, Raquel; Coleman, Heather M; Le-Clech, Pierre

    2014-08-01

    This study focuses on the performance of a submerged membrane photocatalytic reactor for the removal of 17beta-oestradiol (E2) in the presence of humic acid (HA). In addition to the impact of operating parameters, such as membrane pore size, ultraviolet (UV) intensity and hydraulic retention time (HRT), the influence of long-term operation was also assessed by advanced characterization of the fouling layer formed on the membrane. The tighter (0.04 microm) hollow fibre polyvinylydene fluoride (PVDF) membrane was found to exhibit not only higher HA removal than the (0.2 microm) module (85% and 75%, respectively), but also greater transmembrane pressure (TMP) values and higher irreversible fouling. Long-term operation conditions have been simulated by conducting an ageing catalyst process and demonstrated a decrease in performance obtained with time. The artificially aged TiO2 resulted in higher TMP values and lower HA removals (about 10-20% decrease) compared with the non-aged catalyst. For E2 removal in the presence of HA, the passive adsorption of the oestrogen onto the organic matter was found to be significant (40% of the E2 adsorbed after I h), demonstrating the importance of the nature of the water matrix for this type of treatment process. An increase in the UV light intensity was observed to favour the E2 elimination, leading to more than 90% removal when using 64 W combined with PVDF membrane and an HRT of 3 h.

  19. Reverse osmosis filtration for space mission wastewater: membrane properties and operating conditions

    NASA Technical Reports Server (NTRS)

    Lee, S.; Lueptow, R. M.

    2001-01-01

    Reverse osmosis (RO) is a compact process that has potential for the removal of ionic and organic pollutants for recycling space mission wastewater. Seven candidate RO membranes were compared using a batch stirred cell to determine the membrane flux and the solute rejection for synthetic space mission wastewaters. Even though the urea molecule is larger than ions such as Na+, Cl-, and NH4+, the rejection of urea is lower. This indicates that the chemical interaction between solutes and the membrane is more important than the size exclusion effect. Low pressure reverse osmosis (LPRO) membranes appear to be most desirable because of their high permeate flux and rejection. Solute rejection is dependent on the shear rate, indicating the importance of concentration polarization. A simple transport model based on the solution-diffusion model incorporating concentration polarization is used to interpret the experimental results and predict rejection over a range of operating conditions. Grant numbers: NAG 9-1053.

  20. The catalytic activity of the endoplasmic reticulum-resident protein microsomal epoxide hydrolase towards carcinogens is retained on inversion of its membrane topology.

    PubMed Central

    Friedberg, T; Holler, R; Löllmann, B; Arand, M; Oesch, F

    1996-01-01

    Diol epoxides formed by the sequential action of cytochrome P-450 and the microsomal epoxide hydrolase (mEH) in the endoplasmic reticulum (ER) represent an important class of ultimate carcinogenic metabolites of polycyclic aromatic hydrocarbons. The role of the membrane orientation of cytochrome P-450 and mEH relative to each other in this catalytic cascade is not known. Cytochrome P-450 is known to have a type I topology. According to the algorithm of Hartman, Rapoport and Lodish [(1989) Proc. Natl. Acad. Sci. U.S.A. 86, 5786-5790], which allows the prediction of the membrane topology of proteins, mEH should adopt a type II membrane topology. Experimentally, mEH membrane topology has been disputed. Here we demonstrate that, in contrast with the theoretical prediction, the rat mEH has exclusively a type I membrane topology. Moreover we show that this topology can be inverted without affecting the catalytic activity of mEH. Our conclusions are supported by the observation that two mEH constructs (mEHg1 and mEHg2), containing engineered potential glycosylation sites at two separate locations after the C-terminal site of the membrane anchor, were not glycosylated in fibroblasts. However, changing the net charge at the N-terminus of these engineered mEH proteins by +3 resulted in proteins (++mEHg1 and ++mEHg2) that became glycosylated and consequently had a type II topology. The sensitivity of these glycosylated proteins to endoglycosidase H indicated that, like the native mEH, they are still retained in the ER. The engineered mEH proteins were integrated into membranes as they were resistant to alkaline extraction. Interestingly, an insect mEH with a charge distribution in its N-terminus similar to ++mEHg1 has recently been isolated. This enzyme might well display a type II topology instead of the type I topology of the rat mEH. Importantly, mEHg1, having the natural cytosolic orientation, as well as ++mEHg1, having an artificial huminal orientation, displayed rather

  1. Long-term testing of a high-temperature proton exchange membrane fuel cell short stack operated with improved polybenzimidazole-based composite membranes

    NASA Astrophysics Data System (ADS)

    Pinar, F. Javier; Cañizares, Pablo; Rodrigo, Manuel A.; Úbeda, Diego; Lobato, Justo

    2015-01-01

    In this work, the feasibility of a 150 cm2 high-temperature proton exchange membrane fuel cell (HT-PEMFC) stack operated with modified proton exchange membranes is demonstrated. The short fuel cell stack was manufactured using a total of three 50 cm2 membrane electrode assemblies (MEAs). The PEM technology is based on a polybenzimidazole (PBI) membrane. The obtained results were compared with those obtained using a HT-PEMFC stack with unmodified membranes. The membranes were cast from a PBI polymer synthesized in the laboratory, and the modified membranes contained 2 wt.% micro-sized TiO2 as a filler. Long-term tests were performed in both constant and dynamic loading modes. The fuel cell stack with 2 wt.% TiO2 composite PBI membranes exhibited an irreversible voltage loss of less than 2% after 1100 h of operation. In addition, the acid loss was reduced from 2% for the fuel cell stack with unmodified membranes to 0.6% for the fuel cell stack with modified membranes. The results demonstrate that introducing filler into the membranes enhances the durability and stability of this type of fuel cell technology. Moreover, the fuel cell stack system also exhibits very rapid and stable power and voltage output responses under dynamic load regimes.

  2. BSM-MBR: a benchmark simulation model to compare control and operational strategies for membrane bioreactors.

    PubMed

    Maere, Thomas; Verrecht, Bart; Moerenhout, Stefanie; Judd, Simon; Nopens, Ingmar

    2011-03-01

    A benchmark simulation model for membrane bioreactors (BSM-MBR) was developed to evaluate operational and control strategies in terms of effluent quality and operational costs. The configuration of the existing BSM1 for conventional wastewater treatment plants was adapted using reactor volumes, pumped sludge flows and membrane filtration for the water-sludge separation. The BSM1 performance criteria were extended for an MBR taking into account additional pumping requirements for permeate production and aeration requirements for membrane fouling prevention. To incorporate the effects of elevated sludge concentrations on aeration efficiency and costs a dedicated aeration model was adopted. Steady-state and dynamic simulations revealed BSM-MBR, as expected, to out-perform BSM1 for effluent quality, mainly due to complete retention of solids and improved ammonium removal from extensive aeration combined with higher biomass levels. However, this was at the expense of significantly higher operational costs. A comparison with three large-scale MBRs showed BSM-MBR energy costs to be realistic. The membrane aeration costs for the open loop simulations were rather high, attributed to non-optimization of BSM-MBR. As proof of concept two closed loop simulations were run to demonstrate the usefulness of BSM-MBR for identifying control strategies to lower operational costs without compromising effluent quality.

  3. New nanosized catalytic membrane reactors for hydrogenation with stored hydrogen: Prerequisites and the experimental basis for their creation

    NASA Astrophysics Data System (ADS)

    Soldatov, A. P.; Tsodikov, M. V.; Parenago, O. P.; Teplyakov, V. V.

    2010-12-01

    The prerequisites and prospects for creating a new generation of nanosized membrane reactors are considered. For the first time, hydrogenation reactions take place in ceramic membrane pores with hydrogen adsorbed beforehand in mono- and multilayered oriented carbon nanotubes with graphene walls (OCNTGs) formed on the internal pore surface. It is shown for Trumem microfiltration membranes with D avg ˜130 nm that oxidation reactions of CO on a Cu0.03Ti0.97O2 ± δ catalyst and the oxidative conversion of methane into synthesis gas and light hydrocarbons on La + Ce/MgO are considerably enhanced when they occur in membranes. Regularities of hydrogen adsorption, storage, and desorption in nanosized membrane reactors are investigated through OCNTG formation in Trumem ultrafiltration membrane pores with D avg = 50 and 90 nm and their saturation with hydrogen at a pressure of 10-13 MPa. It is shown that the amount of adsorbed hydrogen reaches 14.0% of OCNTG mass. Using thermogravimetric analysis in combination with mass-spectrometric analysis, hydrogen adsorption in OCNTG is first determined and its desorption is found to proceed at atmospheric pressure at a temperature of ˜175°C. It is shown that adsorbed hydrogen affects the transport properties of the membranes, reducing their efficiency with respect to liquids by 4-26 times. This is indirect confirmation of its high activity, due apparently the dissociative mechanism of adsorption.

  4. Novel membranes for proton exchange membrane fuel cell operation above 120°C. Final report for period October 1, 1998 to December 31, 1999

    SciTech Connect

    Srinivasan, Supramaniam; Lee, Seung-Jae; Costamagna, Paola; Yang, Christopher; Adjemian, Kevork; Bocarsly, Andrew; Ogden, Joan M.; Benziger, Jay

    2000-05-01

    In this project we investigated the experimental performance of three new classes of membranes, composites of perfluorosulfonic acid polymers with heteropolyacides, hydrated oxides and fast proton conducting glasses, which are promising candidates as electrolytes for proton exchange membrane fuel cells (PEMFCs), capable of operation at temperatures above 120°C. The motivations for PEMFC's operation at this temperature are to: 1) minimize the CO poisoning problem (adsorption of CO onto the platinum catalyst is greatly reduced at these temperatures), 2) find better solutions for the water and thermal management problems in proton exchange membrane fuel cells, 3) find potentially lower cost materials for proton exchange membranes. We prepared and characterized a variety of novel membrane materials. The most promising of these have been evaluated for performance in a single, small area (5cm2) fuel cell run on hydrogen and oxygen. Our results establish the technical feasibility of PEMFC operation above 120°C.

  5. Treatment of municipal landfill leachate by catalytic wet air oxidation: Assessment of the role of operating parameters by factorial design

    SciTech Connect

    Anglada, Angela; Urtiaga, Ane; Ortiz, Inmaculada; Diamadopoulos, Evan

    2011-08-15

    Highlights: > Landfill leachates can be treated effectively by catalytic wet oxidation. > Addition of H{sub 2}O{sub 2} in the presence of transition metals promotes degradation. > Factorial design evaluates the statistically significant operating conditions. > H{sub 2}O{sub 2}, reaction time and temperature are critical in determining performance. - Abstract: The wet air oxidation (WAO) of municipal landfill leachate catalyzed by cupric ions and promoted by hydrogen peroxide was investigated. The effect of operating conditions such as WAO treatment time (15-30 min), temperature (160-200 deg. C), Cu{sup 2+} concentration (250-750 mg L{sup -1}) and H{sub 2}O{sub 2} concentration (0-1500 mg L{sup -1}) on chemical oxygen demand (COD) removal was investigated by factorial design considering a two-stage, sequential process comprising the heating-up of the reactor and the actual WAO. The leachate, at an initial COD of 4920 mg L{sup -1}, was acidified to pH 3 leading to 31% COD decrease presumably due to the coagulation/precipitation of colloidal and other organic matter. During the 45 min long heating-up period of the WAO reactor under an inert atmosphere, COD removal values up to 35% (based on the initial COD value) were recorded as a result of the catalytic decomposition of H{sub 2}O{sub 2} to reactive hydroxyl radicals. WAO at 2.5 MPa oxygen partial pressure advanced treatment further; for example, 22 min of oxidation at 200 deg. C, 250 mg L{sup -1} Cu{sup 2+} and 0-1500 mg L{sup -1} H{sub 2}O{sub 2} resulted in an overall (i.e. including acidification and heating-up) COD reduction of 78%. Amongst the operating variables in question, temperature had the strongest influence on both the heating-up and WAO stages, while H{sub 2}O{sub 2} concentration strongly affected the former and reaction time the latter. Nonetheless, the effects of temperature and H{sub 2}O{sub 2} concentration were found to depend on the concentration levels of catalyst as suggested by the

  6. Optimising the operation of a MBR pilot plant by quantitative analysis of the membrane fouling mechanism.

    PubMed

    Jiang, T; Kennedy, M D; Guinzbourg, B F; Vanrolleghem, P A; Schippers, J C

    2005-01-01

    In order to optimize some operational conditions of MBR systems, a MBR pilot plant equipped with a submerged hollow fibre membrane module was employed in this study. The pilot MBR was fed with real municipal wastewater and the filtration flux, backwashing interval, aeration frequency and temperature were varied. A filtration flux below 25 I/m2h is generally recommended, at below this flux, the MBR operated at sub-critical flux conditions, the filter cake was minimized and membrane fouling was mainly attributed to the membrane pore blocking. Moreover, the membrane fouling, at below 25 I/m2h, was more reversible to backwashing; above this value, backwashing became less efficient to clean the membrane. Less frequent backwashing (e.g. 600 s filtration/45 s backwashing) decreased the amount of fouling irreversible to backwashing and its performance was superior to that of frequent backwashing (e.g. 200 s filtration/15 s backwashing). The MBR suffered more fouling at low temperature conditions (e.g. at 13-14 degrees C) than at high temperature conditions (e.g. at 17-18 degrees C). A conceptual model was built up and successfully interpreted this temperature effect.

  7. The effects of operating parameters on spiramycin removal by nanofiltration membrane.

    PubMed

    Zhao, Changwei; Fan, Weihong; Wang, Tao; Hou, Deyin; Luan, Zhaokun

    2013-01-01

    Spiramycin removal from wastewater using four nanofiltration (NF) membranes (NF270, NF90, ESNA1-K1 and ESNA1-LF2-LD) was studied. The effects of operating pressure, feed temperature, feed concentration, cation and anion ions on the permeate flux rate and spiramycin rejection were investigated. The results show that increasing operating pressure resulted in the increase of both permeate flux and spiramycin rejection. The flux rate increased almost linearly with temperature, while the spiramycin rejection decreased. The permeate flux rate declined relatively with increasing feed concentration of spiramycin for NF270 and ESNA1-LF2-LD membranes compared with NF90 and ESNA1-K membranes. The presence of cations reduced spiramycin rejection, with the strength of influence for the NF270 NF membrane following the order Mg(2+)>Ca(2+)>K(+). The presence of anions also resulted in decreased spiramycin rejection, the strength of the effect following the order NO(3)(-)>Cl(-)>SO(4)(2-) for the NF270 membrane.

  8. Pressure retarded osmosis for energy production: membrane materials and operating conditions.

    PubMed

    Kim, H; Choi, J-S; Lee, S

    2012-01-01

    Pressure retarded osmosis (PRO) is a novel membrane process to produce energy. PRO has the potential to convert the osmotic pressure difference between fresh water (i.e. river water) and seawater to electricity. Moreover, it can recover energy from highly concentrated brine in seawater desalination. Nevertheless, relatively little research has been undertaken for fundamental understanding of the PRO process. In this study, the characteristics of the PRO process were examined using a proof-of-concept device. Forward osmosis (FO), reverse osmosis (RO), and nanofiltration (NF) membranes were compared in terms of flux rate and concentration polarization ratio. The results indicated that the theoretical energy production by PRO depends on the membrane type as well as operating conditions (i.e. back pressure). The FO membrane had the highest energy efficiency while the NF membrane had the lowest efficiency. However, the energy production rate was low due to high internal concentration polarization (ICP) in the PRO membrane. This finding suggests that the control of the ICP is essential for practical application of PRO for energy production.

  9. The intra-operative radius joystick test to diagnose complete disruption of the interosseous membrane.

    PubMed

    Soubeyrand, M; Ciais, G; Wassermann, V; Kalouche, I; Biau, D; Dumontier, C; Gagey, O

    2011-10-01

    Disruption of the interosseous membrane is easily missed in patients with Essex-Lopresti syndrome. None of the imaging techniques available for diagnosing disruption of the interosseous membrane are completely dependable. We undertook an investigation to identify whether a simple intra-operative test could be used to diagnose disruption of the interosseous membrane during surgery for fracture of the radial head and to see if the test was reproducible. We studied 20 cadaveric forearms after excision of the radial head, ten with and ten without disruption of the interosseous membrane. On each forearm, we performed the radius joystick test: moderate lateral traction was applied to the radial neck with the forearm in maximal pronation, to look for lateral displacement of the proximal radius indicating that the interosseous membrane had been disrupted. Each of six surgeons (three junior and three senior) performed the test on two consecutive days. Intra-observer agreement was 77% (95% confidence interval (CI) 67 to 85) and interobserver agreement was 97% (95% CI 92 to 100). Sensitivity was 100% (95% CI 97 to 100), specificity 88% (95% CI 81 to 93), positive predictive value 90% (95% CI 83 to 94), and negative predictive value 100%). This cadaveric study suggests that the radius joystick test may be useful for detecting disruption of the interosseous membrane in patients undergoing open surgery for fracture of the radial head and is reproducible. A confirmatory study in vivo is now required.

  10. The Translocation Domain of Botulinum Neurotoxin A Moderates the Propensity of the Catalytic Domain to Interact with Membranes at Acidic pH

    PubMed Central

    Araye, Anne; Goudet, Amélie; Barbier, Julien; Pichard, Sylvain; Baron, Bruno; England, Patrick; Pérez, Javier; Zinn-Justin, Sophie; Chenal, Alexandre; Gillet, Daniel

    2016-01-01

    Botulinum neurotoxin A (BoNT/A) is composed of three domains: a catalytic domain (LC), a translocation domain (HN) and a receptor-binding domain (HC). Like most bacterial toxins BoNT/A is an amphitropic protein, produced in a soluble form that is able to interact, penetrate and/or cross a membrane to achieve its toxic function. During intoxication BoNT/A is internalized by the cell by receptor-mediated endocytosis. Then, LC crosses the membrane of the endocytic compartment and reaches the cytosol. This translocation is initiated by the low pH found in this compartment. It has been suggested that LC passes in an unfolded state through a transmembrane passage formed by HN. We report here that acidification induces no major conformational change in either secondary or tertiary structures of LC and HN of BoNT/A in solution. GdnHCl-induced denaturation experiments showed that the stability of LC and HN increases as pH drops, and that HN further stabilizes LC. Unexpectedly we found that LC has a high propensity to interact with and permeabilize anionic lipid bilayers upon acidification without the help of HN. This property is downplayed when LC is linked to HN. HN thus acts as a chaperone for LC by enhancing its stability but also as a moderator of the membrane interaction of LC. PMID:27070312

  11. The effect of intermittent operation on a wind-powered membrane system for brackish water desalination.

    PubMed

    Park, G L; Schäfer, A I; Richards, B S

    2012-01-01

    Renewable energy powered membrane systems that are directly-connected must take account of both the inherent fluctuations and the intermittency of the energy resource. In order to determine the effect of intermittent operation, a membrane system was tested with variables of (i) amplitude from 60 to 300 W and (ii) length of time with no power from 0.5 to 3 min. This was performed over one hour periods with six on/off cycles to simulate the system operating under intermittent operation for short periods of time when directly-connected to a small wind turbine. The setup used a Filmtec BW30-4040 brackish water reverse osmosis membrane with feed waters of 2,750 mg/L and 5,500 mg/L NaCl. The results showed that the membrane system produced potable water under the majority of intermittency experiments performed. There was a relatively large increase in the average salt concentration of the permeate, especially when the system was off for shorter periods of time (0.5-1 min). Longer periods of no power (1-3 min) did not have as significant an effect on the average water quality. This is important when the need for energy buffering or short term storage is considered for these systems as it shows the potential for improving the overall flux and water quality using temporary energy storage.

  12. Near-infrared imaging of water in a polymer electrolyte membrane during a fuel cell operation.

    PubMed

    Morita, Shigeaki; Jojima, Yuki; Miyata, Yasushi; Kitagawa, Kuniyuki

    2010-11-15

    A novel technique of spectroscopic imaging using a near-infrared (NIR) laser sheet beam was developed for visualization of liquid water in a proton-exchange membrane (PEM) sandwiched between two opaque electrodes set in a polymer electrolyte fuel cell (PEFC). In-plane two-dimensional distribution of water in the thin membrane was clearly visualized during the fuel cell operation. Under the condition of fuel feeding into the PEFC without humidification, water was generated by the fuel cell reaction in the whole electrode area. In contrast, under the condition of fuel feeding with humidification, the PEM got wet in the vicinity of a gas flow field locally.

  13. Nafion-porous cerium oxide nanotubes composite membrane for polymer electrolyte fuel cells operated under dry conditions

    NASA Astrophysics Data System (ADS)

    Ketpang, Kriangsak; Oh, Kwangjin; Lim, Sung-Chul; Shanmugam, Sangaraju

    2016-10-01

    A composite membrane operated in polymer electrolyte fuel cells (PEFCs) under low relative humidity (RH) is developed by incorporating cerium oxide nanotubes (CeNT) into a perfluorosulfonic acid (Nafion®) membrane. Porous CeNT is synthesized by direct heating a precursor impregnated polymer fibers at 500 °C under an air atmosphere. Compared to recast Nafion and commercial Nafion (NRE-212) membranes, the Nafion-CeNT composite membrane generates 1.1 times higher power density at 0.6 V, operated at 80 °C under 100% RH. Compared to Nafion-cerium oxide nanoparticles (Nafion-CeNP) membrane, the Nafion-CeNT provides 1.2 and 1.7 times higher PEFC performance at 0.6 V when operated at 80 °C under 100% and 18% RH, respectively. Additionally, the Nafion-CeNT composite membrane exhibits a good fuel cell operation under 18% RH at 80 °C. Specifically, the fluoride emission rate of Nafion-CeNT composite membrane is 20 times lower than that of the commercial NRE-212 membrane when operated under 18% RH at 80 °C for 96 h. The outstanding PEFC performance and durability operated under dry conditions is mainly attributed to the facile water diffusion capability as well as the effective hydroxyl radical scavenging property of the CeNT filler, resulting in significantly mitigating both the ohmic resistance and Nafion membrane degradation.

  14. Use of silicone membranes to enhance gas transfer during microbial fuel cell operation on carbon monoxide.

    PubMed

    Hussain, A; Tartakovsky, B; Guiot, S R; Raghavan, V

    2011-12-01

    Electricity generation in a microbial fuel cell (MFC) using carbon monoxide (CO) or synthesis gas (syngas) as a carbon source has been demonstrated recently. A major challenge associated with CO or syngas utilization is the mass transfer limitation of these sparingly soluble gases in the aqueous phase. This study evaluated the applicability of a dense polymer silicone membrane and thin wall silicone tubing for CO mass transfer in MFCs. Replacing the sparger used in our previous study with the membrane systems for CO delivery resulted in improved MFC performance and CO transformation efficiency. A power output and CO transformation efficiency of up to 18 mW LR(-1) (normalized to anode compartment volume) and 98%, respectively, was obtained. The use of membrane systems offers the advantage of improved mass transfer and reduced reactor volume, thus increasing the volumetric power output of MFCs operating on a gaseous substrate such as CO.

  15. The impact of different operating conditions on membrane fouling and EPS production.

    PubMed

    Dvořák, Lukáš; Gómez, Marcel; Dvořáková, Markéta; Růžičková, Iveta; Wanner, Jiří

    2011-07-01

    The main goal of this research was to investigate how different factors influence membrane fouling. The impact of the different concentrations of activated sludge and the amount of extracellular polymer substances (EPS) were monitored. Two pilot plants with submerged membrane modules (hollow fiber and flat sheet) were operated and the raw wastewater was used. Humic substances were identified as the major components of EPS in the activated sludge (more than 34%) in both pilot plants. As the basic constituent in permeate, humic substances were identified as the most dominant components in the effluent (61%) in both pilot plants. Conversely, proteins were mostly analyzed in permeate and supernatant below the detection limit. The total amount of EPS [mgg(-1) (VSS)] was similar for concentrations of activated sludge 6, 10 and 14 g L(-1). Carbohydrates were identified as the component of EPS which tends most to clog membranes.

  16. Recent Operational Experience with the Internal Thermal Control System Dual-Membrane Gas Trap

    NASA Technical Reports Server (NTRS)

    Leimkuehler, Thomas O.; Lukens, Clark; Reeves, Daniel R.; Holt, James M.

    2004-01-01

    A dual-membrane gas trap is currently used to remove gas bubbles from the Internal Thermal Control System (ITCS) coolant on board the International Space Station. The gas trap consists of concentric tube membrane pairs, comprised of outer hydrophilic tubes and inner hydrophobic fibers. Liquid coolant passes through the outer hydrophilic membrane, which traps the gas bubbles. The inner hydrophobic fiber allows the trapped gas bubbles to pass through and vent to the ambient atmosphere in the cabin. The gas removal performance and operational lifetime of the gas trap have been affected by contamination in the ITCS coolant. However, the gas trap has performed flawlessly with regard to its purpose of preventing gas bubbles from causing depriming, overspeed, and shutdown of the ITCS pump. This paper discusses on-orbit events over the course of the last year related to the performance and functioning of the gas trap.

  17. Influence of operating conditions on ceramic ultrafiltration membrane performance when treating textile effluents.

    PubMed

    Barredo-Damas, S; Alcaina-Miranda, M I; Gemma, M; Iborra-Clar, M I; Mendoza-Roca, J A

    2011-01-01

    This work studies the performance of three commercial ceramic ultrafiltration membranes (ZrO(2)-TiO(2)) treating raw effluent from a textile industry. The effect of crossflow velocity at 3, 4 and 5 m s(-1) as well as membrane characteristics, such as molecular weight cut-off (30, 50 and 150 kDa), on process performance were studied. Experiments were carried out in concentration mode in order to observe the effect of volume reduction factor simultaneously. Results showed a combined influence of both crossflow velocity and molecular weight cut-off on flux performance. TOC and COD removals up to 70% and 84% respectively were reached. On the other hand, almost complete color (>97%) and turbidity (>99%) removals were achieved for all the membranes and operating conditions.

  18. Colloidal Fouling of Nanofiltration Membranes: Development of a Standard Operating Procedure

    PubMed Central

    Al Mamun, Md Abdullaha; Bhattacharjee, Subir; Pernitsky, David; Sadrzadeh, Mohtada

    2017-01-01

    Fouling of nanofiltration (NF) membranes is the most significant obstacle to the development of a sustainable and energy-efficient NF process. Colloidal fouling and performance decline in NF processes is complex due to the combination of cake formation and salt concentration polarization effects, which are influenced by the properties of the colloids and the membrane, the operating conditions of the test, and the solution chemistry. Although numerous studies have been conducted to investigate the influence of these parameters on the performance of the NF process, the importance of membrane preconditioning (e.g., compaction and equilibrating with salt water), as well as the determination of key parameters (e.g., critical flux and trans-membrane osmotic pressure) before the fouling experiment have not been reported in detail. The aim of this paper is to present a standard experimental and data analysis protocol for NF colloidal fouling experiments. The developed methodology covers preparation and characterization of water samples and colloidal particles, pre-test membrane compaction and critical flux determination, measurement of experimental data during the fouling test, and the analysis of that data to determine the relative importance of various fouling mechanisms. The standard protocol is illustrated with data from a series of flat sheet, bench-scale experiments. PMID:28106775

  19. Colloidal Fouling of Nanofiltration Membranes: Development of a Standard Operating Procedure.

    PubMed

    Al Mamun, Md Abdullaha; Bhattacharjee, Subir; Pernitsky, David; Sadrzadeh, Mohtada

    2017-01-18

    Fouling of nanofiltration (NF) membranes is the most significant obstacle to the development of a sustainable and energy-efficient NF process. Colloidal fouling and performance decline in NF processes is complex due to the combination of cake formation and salt concentration polarization effects, which are influenced by the properties of the colloids and the membrane, the operating conditions of the test, and the solution chemistry. Although numerous studies have been conducted to investigate the influence of these parameters on the performance of the NF process, the importance of membrane preconditioning (e.g., compaction and equilibrating with salt water), as well as the determination of key parameters (e.g., critical flux and trans-membrane osmotic pressure) before the fouling experiment have not been reported in detail. The aim of this paper is to present a standard experimental and data analysis protocol for NF colloidal fouling experiments. The developed methodology covers preparation and characterization of water samples and colloidal particles, pre-test membrane compaction and critical flux determination, measurement of experimental data during the fouling test, and the analysis of that data to determine the relative importance of various fouling mechanisms. The standard protocol is illustrated with data from a series of flat sheet, bench-scale experiments.

  20. Operational Experience with the Internal Thermal Control System Dual-Membrane Gas Trap

    NASA Technical Reports Server (NTRS)

    Leimkuehler, Thomas O.; Lukens, Clark; Reeves, Daniel R.; Holt, James M.

    2003-01-01

    A dual-membrane gas trap is currently used to remove non-condensed gases (NCG) from the Internal Thermal Control System (ITCS) coolant on board the International Space Station. The gas trap consists of concentric tube membrane pairs, comprised of outer hydrophilic tubes and inner hydrophobic fibers. Liquid coolant passes through the outer hydrophilic membrane, which traps the NCG. The inner hydrophobic fiber allows the trapped NCG to pass through and vent to the ambient atmosphere in the cabin. The purpose of the gas trap is to prevent gas bubbles from causing depriming, overspeed, and shutdown of the ITCS pump, and the current gas trap has performed flawlessly in this regard. However, because of actual operational conditions on-orbit, its gas removal performance and operational lifetime have been affected. This paper discusses experiences with several of these dual- membrane gas traps, including on-orbit gas venting rate, effects due to the presence of nickel in the ITCS coolant, and subsequent refurbishing to remove the nickel from the gas trap.

  1. Fuel cell using novel electrolyte membrane

    SciTech Connect

    Polak, A.J.; Beuhler, A.J.

    1986-06-10

    An apparatus is described for producing electricity from a fuel gas having a gaseous component which is capable, in the presence of a catalytic agent, of dissociating to yield hydrogen ions comprising: (a) a thin film organic-inorganic membrane which comprises a single phase blend from about 1% to about 70% by weight of a heteropoly acid and salts; (b) a membrane housing comprising a fuel gas chamber and an oxidant gas chamber separated by a substantially imporous partition comprising the membrane defined in element (a), the membrane having a first surface in communication with the fuel gas chamber and a second surface in communication with the oxidant gas chamber; (c) two separate portions of catalytic agent effective to promote dissociation and combination, one portion in contact with the first surface of the membrane and one portion in contact with the second surface of the membrane; and, (d) means for forming electrical connection in operative contact with the catalytic agent in contact with the first surface of the membrane and in operative contact with the catalytic agent in contact with the second surface of the membrane.

  2. Optimal operating policy of the ultrafiltration membrane bioreactor for enzymatic hydrolysis of cellulose

    SciTech Connect

    Lee, SeungGoo; Kim, HakSung . Dept. of Biotechnology)

    1993-09-05

    The dilution rate of an ultrafiltration membrane bioreactor in the enzymatic hydrolysis of cellulose was optimized using the kinetic model developed by Fan and Lee.' The sequence of optimal dilution rates was found to generally consist of an initial period of a minimal value (batch period), a subsequent period of maximum dilution rate, a period of a second batch, and a final period of a singular dilution rate. The effects of operating conditions, such as [beta]-glucosidase activity, operating time, maximum dilution rate, substrate feeding rate, and enzyme-to-substrate ratio on both the conversion yield and the sequence of optimal dilution rates were investigated. To evaluate the validity of kinetic model employed in this work, enzymatic hydrolysis was carried out using -cellulose as a substrate in the ultrafiltration membrane bioreactor. The experimental data were well consistent with the simulation results.

  3. Treatment of municipal landfill leachate by catalytic wet air oxidation: Assessment of the role of operating parameters by factorial design.

    PubMed

    Anglada, Angela; Urtiaga, Ane; Ortiz, Inmaculada; Mantzavinos, Dionissios; Diamadopoulos, Evan

    2011-08-01

    The wet air oxidation (WAO) of municipal landfill leachate catalyzed by cupric ions and promoted by hydrogen peroxide was investigated. The effect of operating conditions such as WAO treatment time (15-30min), temperature (160-200°C), Cu(2+) concentration (250-750mgL(-1)) and H(2)O(2) concentration (0-1500mgL(-1)) on chemical oxygen demand (COD) removal was investigated by factorial design considering a two-stage, sequential process comprising the heating-up of the reactor and the actual WAO. The leachate, at an initial COD of 4920mgL(-1), was acidified to pH 3 leading to 31% COD decrease presumably due to the coagulation/precipitation of colloidal and other organic matter. During the 45min long heating-up period of the WAO reactor under an inert atmosphere, COD removal values up to 35% (based on the initial COD value) were recorded as a result of the catalytic decomposition of H(2)O(2) to reactive hydroxyl radicals. WAO at 2.5MPa oxygen partial pressure advanced treatment further; for example, 22min of oxidation at 200°C, 250mgL(-1) Cu(2+) and 0-1500mgL(-1) H(2)O(2) resulted in an overall (i.e. including acidification and heating-up) COD reduction of 78%. Amongst the operating variables in question, temperature had the strongest influence on both the heating-up and WAO stages, while H(2)O(2) concentration strongly affected the former and reaction time the latter. Nonetheless, the effects of temperature and H(2)O(2) concentration were found to depend on the concentration levels of catalyst as suggested by the significance of their 3rd order interaction term.

  4. Durability of Membrane Electrode Assemblies (MEAs) in PEM Fuel Cells Operated on Pure Hydrogen and Oxygen

    NASA Technical Reports Server (NTRS)

    Stanic, Vesna; Braun, James; Hoberecht, Mark

    2003-01-01

    Proton exchange membrane (PEM) fuel cells are energy sources that have the potential to replace alkaline fuel cells for space programs. Broad power ranges, high peak-to-nominal power capabilities, low maintenance costs, and the promise of increased life are the major advantages of PEM technology in comparison to alkaline technology. The probability of PEM fuel cells replacing alkaline fuel cells for space applications will increase if the promise of increased life is verified by achieving a minimum of 10,000 hours of operating life. Durability plays an important role in the process of evaluation and selection of MEAs for Teledyne s Phase I contract with the NASA Glenn Research Center entitled Proton Exchange Membrane Fuel cell (PEMFC) Power Plant Technology Development for 2nd Generation Reusable Launch Vehicles (RLVs). For this contract, MEAs that are typically used for H2/air operation were selected as potential candidates for H2/O2 PEM fuel cells because their catalysts have properties suitable for O2 operation. They were purchased from several well-established MEA manufacturers who are world leaders in the manufacturing of diverse products and have committed extensive resources in an attempt to develop and fully commercialize MEA technology. A total of twelve MEAs used in H2/air operation were initially identified from these manufacturers. Based on the manufacturers specifications, nine of these were selected for evaluation. Since 10,000 hours is almost equivalent to 14 months, it was not possible to perform continuous testing with each MEA selected during Phase I of the contract. Because of the lack of time, a screening test on each MEA was performed for 400 hours under accelerated test conditions. The major criterion for an MEA pass or fail of the screening test was the gas crossover rate. If the gas crossover rate was higher than the membrane intrinsic permeability after 400 hours of testing, it was considered that the MEA had failed the test. Three types of

  5. Self-humidified proton exchange membrane fuel cells: Operation of larger cells and fuel cell stacks

    SciTech Connect

    Dhar, H.P.; Lee, J.H.; Lewinski, K.A.

    1996-12-31

    The PEM fuel cell is promising as the power source for use in mobile and stationary applications primarily because of its high power density, all solid components, and simplicity of operation. For wide acceptability of this power source, its cost has to be competitive with the presently available energy sources. The fuel cell requires continuous humidification during operation as a power source. The humidification unit however, increases fuel cell volume, weight, and therefore decreases its overall power density. Great advantages in terms of further fuel cell simplification can be achieved if the humidification process can be eliminated or minimized. In addition, cost reductions are associated with the case of manufacturing and operation. At BCS Technology we have developed a technology of self-humidified operation of PEM fuel cells based on the mass balance of the reactants and products and the ability of membrane electrode assembly (MEA) to retain water necessary for humidification under the cell operating conditions. The reactants enter the fuel cell chambers without carrying any form of water, whether in liquid or vapor form. Basic principles of self-humidified operation of fuel cells as practiced by BCS Technology, Inc. have been presented previously in literature. Here, we report the operation of larger self-humidified single cells and fuel cell stacks. Fuel cells of areas Up to 100 cm{sup 2} have been operated. We also show the self-humidified operation of fuel cell stacks of 50 and 100 cm{sup 2} electrode areas.

  6. Effect of dynamic operation on chemical degradation of a polymer electrolyte membrane fuel cell

    NASA Astrophysics Data System (ADS)

    Jung, Minjae; Williams, Keith A.

    2011-03-01

    Dynamic operation is known as one of the factors for accelerating chemical degradation of the polymer electrolyte membrane in a polymer electrolyte membrane fuel cell (PEMFC). However, little effort has been made dealing with the quantification of the degradation process. In this investigation, cyclic current operation is carried out on a fuel cell system, and the frequency effect of cyclic operation on chemical degradation is investigated. The dynamic behavior of a fuel cell system is analyzed first with the modified Randles model, where the charge double layer is modeled by three components; a charge transfer resistance (Rct), and two RC cells for the Warburg impedance. After calculating each parameter value through exponential curve fitting, the dynamic behaviors of the three components are simulated using MATLAB Simulink®. Fluoride release as a function of the frequency of cyclic operation is evaluated by measuring the concentration of fluoride ion in effluent from a fuel cell exhaust. The frequency effect on chemical degradation is explained by comparing the simulated results and the fluoride release results. Two possible reasons for the accelerated degradation at cyclic operation are also suggested.

  7. CO{sub 2} Capture by Sub-ambient Membrane Operation

    SciTech Connect

    Kulkarni, S.; Hasse, D.; Sanders, E.; Chaubey, T.

    2012-11-30

    The main objective of the project was to develop a CO{sub 2} capture process based on sub-ambient temperature operation of a hollow fiber membrane. The program aims to reach the eventual DOE program goal of > 90% CO{sub 2} capture from existing PC fired power plants with < 35% increase in the cost of electricity. The project involves closed-loop testing of commercial fiber bundles under simulated process conditions to test the mechanical integrity and operability of membrane module structural component under sub ambient temperature. A commercial MEDAL 12” bundle exhibited excellent mechanical integrity for 2 months. However, selectivity was ~25% lower than expected at sub-ambient conditions. This could be attributed to a small feed to permeate leak or bundle non-ideality. To investigate further, and due to compressor flow limitations, the 12” bundle was replaced with a 6” bundle to conduct tests with lower permeate/feed ratios, as originally planned. The commercial 6” bundle was used for both parametric testing as well as long-term stability testing at sub-ambient conditions. Parametric studies were carried out both near the start and end of the long-term test. The parametric studies characterized membrane performance over a broad range of feed conditions: temperature (-25°C to -45°C), pressure (160 psig to 200 psig), and CO{sub 2} feed concentration (18% to 12%). Performance of the membrane bundle was markedly better at lower temperature (-45ºC), higher pressure (200 psig) and higher CO{sub 2} feed concentration (18%). The long-term test was conducted at these experimentally determined “optimum” feed conditions. Membrane performance was stable over 8 months at sub-ambient temperature operation. The experimentally measured high performance of the membrane bundle at sub-ambient operating conditions provides justification for interest in sub-ambient membrane processing of flue gas. In a parallel activity, the impact of contaminants (100 ppm SOx and NOx

  8. Investigation of high temperature operation of proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Adjemian, Kevork Tro

    Proton exchange membrane fuel cells (PEMFCs) have garnered much attention in the media over the past years as they can provide a clean, environmentally friendly alternative to internal combustion engines. PEMFCs also have the flexibility to operate on many different types of fuels, thereby diminishing our reliance on foreign oil. PEMFCs, however, suffer from many drawbacks which need to be overcome before mass production becomes viable. One drawback is the expense of the fuel cell system, costing several times more than existing technologies. Another problem is that if the fuel cell is running on reformed fuels, trace amounts of carbon monoxide (10 ppm) in the hydrogen gas stream will completely poison the anode electrocatalyst, killing the PEMFC. Also, as a lot of waste heat is generated, a very elaborate cooling system needs to be used, making the overall system more expensive and complex. A possible solution to both the carbon monoxide poisoning and thermal management of a PEMFC is to elevate its operating temperature above 100°C. Unfortunately, current state-of-the-art electrolytes used in PEMFCs, i.e. Nafion 115, rely on water for the conduction of protons and by elevating the temperature, water loss occurs due to evaporation resulting in inadequate PEMFC performance. This thesis delves into the modification of Nafion and similar electrolytes to permit PEMFC operation above 100°C. This was accomplished by impregnating the pores of the Nafion with hydrophilic inorganic materials-silicon oxide via sol-gel processing and various inorganic particles. By performing these modifications to the various electrolytes, several composite membranes performed exceptionally well at an operating temperature of 130°C and demonstrated carbon monoxide tolerance of up to 500 ppm. In addition, a theory on how these materials help improve the water management characteristics of Nafion was developed, laying the foundation for the development of a completely novel membrane to

  9. Scale-up of osmotic membrane bioreactors by modeling salt accumulation and draw solution dilution using hollow-fiber membrane characteristics and operation conditions.

    PubMed

    Kim, Suhan

    2014-08-01

    A full-scale osmotic membrane bioreactor (OMBR) model was developed to simulate salt accumulation, draw solution (DS) dilution, and water flux over the hollow-fiber membrane length. The model uses the OMBR design parameters, DS properties, and forward osmosis (FO) membrane characteristics obtained from lab-scale tests. The modeling results revealed a tremendous water flux decline (10→0.82LMH) and short solids retention time (SRT: 5days) due to salt accumulation and DS dilution when OMBR is scaled up using commercially available DS and FO membrane. Simulated water flux is a result of interplay among reverse salt flux, internal and external concentration polarization (ICP and ECP). ECP adversely impacts water flux considerably in full-scale OMBR although it is often ignored in previous works. The OMBR model makes it possible to select better DS properties (higher flow rate and salt concentration) and FO membranes with higher water flux propensity in full-scale operation.

  10. Numerical simulation of proton exchange membrane fuel cells at high operating temperature

    NASA Astrophysics Data System (ADS)

    Peng, Jie; Lee, Seung Jae

    A three-dimensional, single-phase, non-isothermal numerical model for proton exchange membrane (PEM) fuel cell at high operating temperature (T ≥ 393 K) was developed and implemented into a computational fluid dynamic (CFD) code. The model accounts for convective and diffusive transport and allows predicting the concentration of species. The heat generated from electrochemical reactions, entropic heat and ohmic heat arising from the electrolyte ionic resistance were considered. The heat transport model was coupled with the electrochemical and mass transport models. The product water was assumed to be vaporous and treated as ideal gas. Water transportation across the membrane was ignored because of its low water electro-osmosis drag force in the polymer polybenzimidazole (PBI) membrane. The results show that the thermal effects strongly affect the fuel cell performance. The current density increases with the increasing of operating temperature. In addition, numerical prediction reveals that the width and distribution of gas channel and current collector land area are key optimization parameters for the cell performance improvement.

  11. R&D on an Ultra-Thin Composite Membrane for High-Temperature Operation in PEMFC. Final Report

    SciTech Connect

    Yuh, C.-Y.

    2003-10-06

    FuelCell Energy developed a novel high-temperature proton exchange membrane for PEM fuel cells for building applications. The laboratory PEM fuel cell successfully operated at 100-400{supdegree}C and low relative humidity to improve CO tolerance, mitigate water and thermal management challenges, and reduce membrane cost. The developed high-temperature membrane has successfully completed 500h 120C endurance testing.

  12. Membrane reactor for water detritiation: a parametric study on operating parameters

    SciTech Connect

    Mascarade, J.; Liger, K.; Troulay, M.; Perrais, C.

    2015-03-15

    This paper presents the results of a parametric study done on a single stage finger-type packed-bed membrane reactor (PBMR) used for heavy water vapor de-deuteration. Parametric studies have been done on 3 operating parameters which are: the membrane temperature, the total feed flow rate and the feed composition through D{sub 2}O content variations. Thanks to mass spectrometer analysis of streams leaving the PBMR, speciation of deuterated species was achieved. Measurement of the amounts of each molecular component allowed the calculation of reaction quotient at the packed-bed outlet. While temperature variation mainly influences permeation efficiency, feed flow rate perturbation reveals dependence of conversion and permeation properties to contact time between catalyst and reacting mixture. The study shows that isotopic exchange reactions occurring on the catalyst particles surface are not thermodynamically balanced. Moreover, the variation of the heavy water content in the feed exhibits competition between permeation and conversion kinetics.

  13. Molecular cloning and catalytic activity of a membrane-bound prenyl diphosphate phosphatase from Croton stellatopilosus Ohba.

    PubMed

    Nualkaew, Natsajee; Guennewich, Nils; Springob, Karin; Klamrak, Anuwatchakit; De-Eknamkul, Wanchai; Kutchan, Toni M

    2013-07-01

    Geranylgeraniol (GGOH), a bioactive acyclic diterpene with apoptotic induction activity, is the immediate precursor of the commercial anti-peptic, plaunotol (18-hydroxy geranylgeraniol), which is found in Croton stellatopilosus (Ohba). From this plant, a cDNA encoding a prenyl diphosphate phosphatase (CsPDP), which catalyses the dephosphorylation of geranylgeranyl diphosphate (GGPP) to GGOH, was isolated using a PCR approach. The full-length cDNA contained 888bp and encoded a 33.6 kDa protein (295 amino acids) that was phylogenetically grouped into the phosphatidic acid phosphatase (PAP) enzyme family. The deduced amino acid sequence showed 6 hydrophobic transmembrane regions with 57-85% homology to the sequences of other plant PAPs. The recombinant CsPDP and its 4 truncated constructs exhibited decreasing dephosphorylation activities relative to the lengths of the N-terminal deletions. While the full-length CsPDP successfully performed the two sequential monodephosphorylation steps on GGPP to form GGOH, the larger N-terminal deletion in the truncated enzymes appeared to specifically decrease the catalytic efficiency of the second monodephosphorylation step. The information presented here on the CsPDP cDNA and factors affecting the dephosphorylation activity of its recombinant protein may eventually lead to the discovery of the specific GGPP phosphatase gene and enzyme that are involved in the formation of GGOH in the biosynthetic pathway of plaunotol in C. stellatopilosus.

  14. Catalytic Conversion of Lipophilic Substrates by Phase constrained Enzymes in the Aqueous or in the Membrane Phase

    PubMed Central

    Cebula, Marcus; Turan, Ilke Simsek; Sjödin, Birgitta; Thulasingam, Madhuranayaki; Brock, Joseph; Chmyrov, Volodymyr; Widengren, Jerker; Abe, Hiroshi; Mannervik, Bengt; Haeggström, Jesper Z.; Rinaldo-Matthis, Agnes; Akkaya, Engin U.; Morgenstern, Ralf

    2016-01-01

    Both soluble and membrane-bound enzymes can catalyze the conversion of lipophilic substrates. The precise substrate access path, with regard to phase, has however, until now relied on conjecture from enzyme structural data only (certainly giving credible and valuable hypotheses). Alternative methods have been missing. To obtain the first experimental evidence directly determining the access paths (of lipophilic substrates) to phase constrained enzymes we here describe the application of a BODIPY-derived substrate (PS1). Using this tool, which is not accessible to cytosolic enzymes in the presence of detergent and, by contrast, not accessible to membrane embedded enzymes in the absence of detergent, we demonstrate that cytosolic and microsomal glutathione transferases (GSTs), both catalyzing the activation of PS1, do so only within their respective phases. This approach can serve as a guideline to experimentally validate substrate access paths, a fundamental property of phase restricted enzymes. Examples of other enzyme classes with members in both phases are xenobiotic-metabolizing sulphotransferases/UDP-glucuronosyl transferases or epoxide hydrolases. Since specific GSTs have been suggested to contribute to tumor drug resistance, PS1 can also be utilized as a tool to discriminate between phase constrained members of these enzymes by analyzing samples in the absence and presence of Triton X-100. PMID:27917951

  15. Effect of the catalytic ink preparation method on the performance of high temperature polymer electrolyte membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Lobato, J.; Rodrigo, M. A.; Linares, J. J.; Scott, K.

    Two methods of preparation of the membrane-electrode-assemblies based on polybenzimidazole membranes have been studied for high temperatures PEMFCs. One is called the "colloidal method" (using acetone as solvent), and the other is the "solution method" (using dimethylacetamide as solvent). Physical property studies (SEM micrographs and pore size distribution) and electrochemical analyses in half-cell (Electrochemical Impedance Spectroscopy, Polarization Curves for Oxygen Reduction and Cyclic Voltammetry) were carried out to characterise the structural and electrochemical behaviour of both methods. Finally, a cell performance investigation, using electrodes prepared by both methods was carried out at three different temperatures (125, 150, and 175 °C), in a single PEMFC setup. A better behaviour was obtained for the "solution method" at the two highest temperatures at intermediate current densities, whereas at 125 °C the best results were obtained with the "colloidal method" in all the current densities ranges. A discussion of the behaviours observed with the different characterisation techniques is made.

  16. Performance evaluation of microbial electrochemical systems operated with Nafion and supported ionic liquid membranes.

    PubMed

    Koók, László; Nemestóthy, Nándor; Bakonyi, Péter; Zhen, Guangyin; Kumar, Gopalakrishnan; Lu, Xueqin; Su, Lianghu; Saratale, Ganesh Dattatraya; Kim, Sang-Hyoun; Gubicza, László

    2017-05-01

    In this work, the performance of dual-chamber microbial fuel cells (MFCs) constructed either with commonly used Nafion(®) proton exchange membrane or supported ionic liquid membranes (SILMs) was assessed. The behavior of MFCs was followed and analyzed by taking the polarization curves and besides, their efficiency was characterized by measuring the electricity generation using various substrates such as acetate and glucose. By using the SILMs containing either [C6mim][PF6] or [Bmim][NTf2] ionic liquids, the energy production of these MFCs from glucose was comparable to that obtained with the MFC employing polymeric Nafion(®) and the same substrate. Furthermore, the MFC operated with [Bmim][NTf2]-based SILM demonstrated higher energy yield in case of low acetate loading (80.1 J g(-1) CODin m(-2) h(-1)) than the one with the polymeric Nafion(®) N115 (59 J g(-1) CODin m(-2) h(-1)). Significant difference was observed between the two SILM-MFCs, however, the characteristics of the system was similar based on the cell polarization measurements. The results suggest that membrane-engineering applying ionic liquids can be an interesting subject field for bioelectrochemical system research.

  17. 40 CFR 60.105a - Monitoring of emissions and operations for fluid catalytic cracking units (FCCU) and fluid coking...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... bags or filter media, or any other condition that may cause an increase in particulate emissions; (ii) Sealing off defective bags or filter media; (iii) Replacing defective bags or filter media or otherwise... for fluid catalytic cracking units (FCCU) and fluid coking units (FCU). 60.105a Section...

  18. 40 CFR Table 23 to Subpart Uuu of... - Operating Limits for Inorganic HAP Emission Limitations for Catalytic Reforming Units

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... established during the performance test. 2. Internal scrubbing system or no control device (e.g., hot regen... scrubbing liquid) exiting the internal scrubbing system must not fall below the limit established during the... existing catalytic reforming unit with this type of control device . . . You shall meet this...

  19. Evaluation of a long-term operation of a submerged nanofiltration membrane bioreactor (NF MBR) for advanced wastewater treatment.

    PubMed

    Choi, J H; Fukushi, K; Ng, H Y; Yamamoto, K

    2006-01-01

    Nanofiltration (NF) is considered as one of the most promising separation technologies to obtain a very good-quality permeate in water and wastewater treatment. A submerged NF membrane bioreactor (NF MBR) using polyamide membranes was tested for a long-term operation and the performance of the NF MBR was compared with that of a microfiltration MBR (MF MBR). Total organic carbon (TOC) concentration in the permeate of the NF MBR ranged from 0.5 to 2.0 mg/L, whereas that of the MF MBR showed an average of 5 mg/L. This could be explained by the tightness of the NF membrane. Although the concentration of organic matter in the supernatant of the NF MBR was higher than that in the permeate due to high rejection by the NF membrane, the NF MBR showed excellent treatment efficiency and satisfactory operational stability for a long-term operation.

  20. Assessment of energy-saving strategies and operational costs in full-scale membrane bioreactors.

    PubMed

    Gabarrón, S; Ferrero, G; Dalmau, M; Comas, J; Rodriguez-Roda, I

    2014-02-15

    The energy-saving strategies and operational costs of stand-alone, hybrid, and dual stream full-scale membrane bioreactors (MBRs) with capacities ranging from 1100 to 35,000 m(3) day(-1) have been assessed for seven municipal facilities located in Northeast Spain. Although hydraulic load was found to be the main determinant factor for the energy consumption rates, several optimisation strategies have shown to be effective in terms of energy reduction as well as fouling phenomenon minimization or preservation. Specifically, modifications of the biological process (installation of control systems for biological aeration) and of the filtration process (reduction of the flux or mixed liquor suspended solids concentration and installation of control systems for membrane air scouring) were applied in two stand-alone MBRs. After implementing these strategies, the yearly specific energy demand (SED) in flat-sheet (FS) and hollow-fibre (HF) stand-alone MBRs was reduced from 1.12 to 0.71 and from 1.54 to 1.12 kW h(-1) m(-3), respectively, regardless of their similar yearly averaged hydraulic loads. The strategies applied in the hybrid MBR, namely, buffering the influent flow and optimisation of both biological aeration and membrane air-scouring, reduced the SED values by 14%. These results illustrate that it is possible to apply energy-saving strategies to significantly reduce MBR operational costs, highlighting the need to optimise MBR facilities to reconsider them as an energy-competitive option.

  1. Advanced treatment of municipal wastewater by nanofiltration: Operational optimization and membrane fouling analysis.

    PubMed

    Li, Kun; Wang, Jianxing; Liu, Jibao; Wei, Yuansong; Chen, Meixue

    2016-05-01

    Municipal sewage from an oxidation ditch was treated for reuse by nanofiltration (NF) in this study. The NF performance was optimized, and its fouling characteristics after different operational durations (i.e., 48 and 169hr) were analyzed to investigate the applicability of nanofiltration for water reuse. The optimum performance was achieved when transmembrane pressure=12bar, pH=4 and flow rate=8L/min using a GE membrane. The permeate water quality could satisfy the requirements of water reclamation for different uses and local standards for water reuse in Beijing. Flux decline in the fouling experiments could be divided into a rapid flux decline and a quasi-steady state. The boundary flux theory was used to predict the evolution of permeate flux. The expected operational duration based on the 169-hr experiment was 392.6hr which is 175% longer than that of the 48-hr one. High molecular weight (MW) protein-like substances were suggested to be the dominant foulants after an extended period based on the MW distribution and the fluorescence characteristics. The analyses of infrared spectra and extracellular polymeric substances revealed that the roles of both humic- and polysaccharide-like substances were diminished, while that of protein-like substances were strengthened in the contribution of membrane fouling with time prolonged. Inorganic salts were found to have marginally influence on membrane fouling. Additionally, alkali washing was more efficient at removing organic foulants in the long term, and a combination of water flushing and alkali washing was appropriate for NF fouling control in municipal sewage treatment.

  2. Operational experience and evaluation of a dual-element stretched-membrane heliostat

    SciTech Connect

    Strachan, J.W.; Van Der Geest, J.

    1994-01-01

    A dual-element, stretched-membrane central receiver heliostat was designed and manufactured in 1989, by a private US company engaged in the development of commercial central receiver solar technology. The two-module collector, with a collection area of 97.5 m{sup 2}, extends stretched-membrane mirror technology on several fronts with face-down stow capability and a digital controller that integrates tracking and focusing control on a single programmable control board. The solar collector was installed at Sandia`s National Solar Thermal Test Facility in Albuquerque, New Mexico and evaluated over a three-and-a-half year period which ended in September 1993. The measured performance and the operational and maintenance characteristics of this commercial prototype are the subject of this report. The results of beam quality measurements, tracking repeatability tests, measurements of beam movement in elevated winds, performance tests of the focusing system, and all-day beam quality and tracking tests are presented, and the authors offer a detailed discussion of the knowledge gained through operation and maintenance and of the improvements made or suggested to the heliostat`s design.

  3. Effect of filtration flux on the development and operation of a dynamic membrane for anaerobic wastewater treatment.

    PubMed

    Saleem, Mubashir; Alibardi, Luca; Lavagnolo, Maria Cristina; Cossu, Raffaello; Spagni, Alessandro

    2016-09-15

    Dynamic membrane represents a cost effective alternative to conventional membranes by employing fouling as a means of solid-liquid separation. This study evaluated the effects of initial flux on both development rate of dynamic membrane and bioreactor performance during two consecutive experiments. The dynamic membrane was developed over a 200 μm mesh and the reactor was operated under anaerobic conditions. It was found that the effect of an initial higher applied flux on dynamic membrane development was more pronounced than mixed liquor suspended solid concentration inside the bioreactor. The development of the dynamic membrane was therefore positively associated with the applied flux. The rapid development of the dynamic membrane during the second experimental run at high initial fluxes and lower MLSS concentrations also affected the performance of the bioreactor in terms of more efficient COD removal and biogas production. A major shortcoming of applying higher initial applied flux was the formation of a denser and robust dynamic membrane layer that was resistant to applied hydraulic shear to control desired permeability and thus represented an obstacle in maintaining a long term operation with sustainable flux at lower transmembrane pressure (TMP).

  4. Evaluation of the importance of various operating and sludge property parameters to the fouling of membrane bioreactors.

    PubMed

    Sun, F Y; Li, X Y

    2011-01-01

    A single-fibre microfiltration system was employed to investigate the importance of various operating and sludge property parameters to the membrane fouling during sludge filtration. The sludge was obtained from a submerged membrane bioreactor (SMBR). A series of comparative and correlative filtration and fouling tests were conducted on the influence of the operating variables, sludge properties and the liquid-phase organic substances on the membrane fouling development. The test results were analysed statistically with Pearson's correlation coefficients and the stepwise multivariable linear regression. According to the statistical evaluation, the membrane fouling rate has a positive correlation with the biopolymer cluster (BPC) concentration, sludge concentration (mixed liquor suspended solids, MLSS), filtration flux and viscosity, a negative correlation with the cross-flow velocity, and a weak correlation with the extracellular polymeric substances and soluble microbial products. BPC appear to be the most important factor to membrane fouling development during the sludge filtration, followed by the filtration flux and MLSS concentration. The cross-flow rate also is important to the fouling control. It is argued that, during membrane filtration of SMBR sludge, BPC interact with sludge flocs at the membrane surface to facilitate the deposition of the sludge cake layer, leading to serious membrane fouling.

  5. Tube-side mass transfer for hollow fibre membrane contactors operated in the low Graetz range.

    PubMed

    Wang, C Y; Mercer, E; Kamranvand, F; Williams, L; Kolios, A; Parker, A; Tyrrel, S; Cartmell, E; McAdam, E J

    2017-02-01

    Transformation of the tube-side mass transfer coefficient derived in hollow fibre membrane contactors (HFMC) of different characteristic length scales (equivalent diameter and fibre length) has been studied when operated in the low Graetz range (Gz<10). Within the low Gz range, mass transfer is generally described by the Graetz problem (Sh=3.67) which assumes that the concentration profile comprises a constant shape over the fibre radius. In this study, it is experimentally evidenced that this assumption over predicts mass transfer within the low Graetz range. Furthermore, within the low Gz range (below 2), a proportional relationship between the experimentally determined mass transfer coefficient (Kov ) and the Graetz number has been identified. For Gz numbers below 2, the experimental Sh number approached unity, which suggests that mass transfer is strongly dependent upon diffusion. However, within this diffusion controlled region of mass transfer, tube-side fluid velocity remained important. For Gz numbers above 2, Sh could be satisfactorily described by extension to the Lévêque solution, which can be ascribed to the constrained growth of the concentration boundary layer adjacent to the fibre wall. Importantly this study demonstrates that whilst mass transfer in the low Graetz range does not explicitly conform to either the Graetz problem or classical Lévêque solution, it is possible to transform the experimentally derived overall mass transfer coefficient (Kov ) between characteristic length scales (dh and L). T h is was corroborated by comparison of the empirical relationship determined in this study (Sh=0.36Gz) with previously published studies operated in the low Gz range. This analysis provides important insight for process design when slow tube-side flows, or low Schmidt numbers (coincident with gases) constrain operation of hollow fibre membrane contactors to the low Gz range.

  6. Effect of operating conditions on the performances of multichannel ceramic UF membranes for textile mercerization wastewater treatment.

    PubMed

    Zebić Avdičević, Maja; Košutić, Krešimir; Dobrović, Slaven

    2017-01-01

    Textile wastewaters are rated as one of the most polluting in all industrial sectors, and membrane separation is the most promising technology for their treatment and reuse of auxiliary chemicals. This study evaluates the performance of three types of tubular ceramic ultrafiltration membranes differing by mean pore size (1, 2 and 500 kDa) treating textile mercerization wastewater from a textile mill at different operating conditions: cross-flow velocity (CFV) and temperature. Acceptable results were obtained with 1 kDa ceramic membrane, with rejection efficiencies 92% for suspended solids, 98% for turbidity, 98% for color and 53% for total organic carbon at 20°C and 3 m s(-1) CFV. Highest fouling effect was observed for 500 kDa membrane and lowest CFV. According to the observed results, 1 kDa membrane could be used for the treatment of wastewater from the textile mercerization process in terms of permeate quality.

  7. Catalytic oxidation for treatment of ECLSS and PMMS waste streams

    NASA Technical Reports Server (NTRS)

    Akse, James R.; Jolly, Clifford D.

    1991-01-01

    It is shown that catalytic oxidation is an effective technique for the removal of trace organic contaminants in a multifiltration potable processor's effluent. Essential elements of this technology are devices that deliver oxygen to the influent, and remove gaseous reaction byproducts from the effluent, via hollow-tube, gas-permeable membranes. Iodine, which poisons existing catalysis, is removed by a small deiodination bed prior to catalytic reactor entrance. The catalyst used is a mixture of Pt and Ru deposited on carbon, operating at 125-160 C and 39-90 psi pressures.

  8. Single-ion polymer electrolyte membranes enable lithium-ion batteries with a broad operating temperature range.

    PubMed

    Cai, Weiwei; Zhang, Yunfeng; Li, Jing; Sun, Yubao; Cheng, Hansong

    2014-04-01

    Conductive processes involving lithium ions are analyzed in detail from a mechanistic perspective, and demonstrate that single ion polymeric electrolyte (SIPE) membranes can be used in lithium-ion batteries with a wide operating temperature range (25-80 °C) through systematic optimization of electrodes and electrode/electrolyte interfaces, in sharp contrast to other batteries equipped with SIPE membranes that display appreciable operability only at elevated temperatures (>60 °C). The performance is comparable to that of batteries using liquid electrolyte of inorganic salt, and the batteries exhibit excellent cycle life and rate performance. This significant widening of battery operation temperatures coupled with the inherent flexibility and robustness of the SIPE membranes makes it possible to develop thin and flexible Li-ion batteries for a broad range of applications.

  9. Dual-Phase Oxygen Transport Membranes for Stable Operation in Environments Containing Carbon Dioxide and Sulfur Dioxide.

    PubMed

    Garcia-Fayos, Julio; Balaguer, María; Serra, José M

    2015-12-21

    Dual-phase membranes are appealing candidates for oxygen transport membranes owing to their unique combination of ambipolar electron-ion transport and endurance. However, O2 separation in industrial environments demands very high stability and effectiveness in the presence of CO2- and SO2-bearing process gases. Here, the composition of dual-phase membranes based on NiFe2O4-Ce(0.8) Tb(0.2)O(2-δ) (NFO-CTO) was optimized and the effective performance of catalytically-activated membranes was assessed in presence of CO2 and SO2. Further insight into the limiting mechanisms in the permeation was gained through electrical conductivity studies, permeation testing in several conditions and impedance spectroscopy analysis. The dual-phase membranes were prepared by one-pot sol-gel method and their permeability increases with increasing fluorite content. An O2 flux of 0.25 (ml min(-1)  cm(-2)) mm at 1000 °C was obtained for a thick self-standing membrane with 40:60 NFO/CTO composition. An in-depth study mimicking typical harsh conditions encountered in oxyfuel flue gases was performed on a 50:50 NFO/CTO membrane. CO2 content as well as SO2 presence in the sweep gas stream were evaluated in terms of O2 permeation. O2 fluxes of 0.13 and 0.09 mL min(-1)  cm(-2) at 850 °C were obtained for a 0.59 mm thick membrane under CO2 and 250 ppm SO2 in CO2 sweep conditions, respectively. Extended periods at work under CO2- and SO2-containing atmospheres revealed good permeation stability over time. Additionally, XRD, backscattered electrons detector (BSD)-SEM, and energy-dispersive X-ray spectroscopy (EDS) analysis of the spent membrane confirmed material stability upon prolonged exposure to SO2.

  10. Catalytic hydropyrolysis of microalgae: influence of operating variables on the formation and composition of bio-oil.

    PubMed

    Chang, Zhoufan; Duan, Peigao; Xu, Yuping

    2015-05-01

    Catalytic hydropyrolysis of microalgae has been studied by using a batch reactor. Nine different heterogenous catalysts of Pd/C, Pt/C, Ru/C, Rh/C, CoMo/γ-Al2O3, Mo2C, MoS2, and activated carbon were screened. Mo2C was identified as the most suitable catalyst. With Mo2C catalyst, influence of reaction conditions on the yield and properties of the hydropyrolysis oil (HPO) was examined. Temperature was the most influential factor affecting the yield and quality of the HPO. Higher temperature will produce HPO with higher C and H content and lower N and O content but at the cost of lowering the yield of HPO. Mo2C promoted the in situ deoxygenation and desulfurization of the HPO which has a HHVs varying between 35.3 and 39.3 MJ/kg. The highest energy recovery of 87.5% was achieved. Thus, this work shows that the catalytic hydropyrolysis is an effective way to produce high quality bio-oil from microalgae.

  11. Membrane-mirror-based autostereoscopic display for tele-operation and teleprescence applications

    NASA Astrophysics Data System (ADS)

    McKay, Stuart; Mair, Gordon M.; Mason, Steven; Revie, Kenneth

    2000-05-01

    An autostereoscopic display for telepresence and tele- operation applications has been developed at the University of Strathclyde in Glasgow, Scotland. The research is a collaborative effort between the Imaging Group and the Transparent Telepresence Research Group, both based at Strathclyde. A key component of the display is the directional screen; a 1.2-m diameter Stretchable Membrane Mirror is currently used. This patented technology enables large diameter, small f No., mirrors to be produced at a fraction of the cost of conventional optics. Another key element of the present system is an anthropomorphic and anthropometric stereo camera sensor platform. Thus, in addition to mirror development, research areas include sensor platform design focused on sight, hearing, research areas include sensor platform design focused on sight, hearing, and smell, telecommunications, display systems for all visual, aural and other senses, tele-operation, and augmented reality. The sensor platform is located at the remote site and transmits live video to the home location. Applications for this technology are as diverse as they are numerous, ranging from bomb disposal and other hazardous environment applications to tele-conferencing, sales, education and entertainment.

  12. POLYMER ELECTROLYTE MEMBRANE ELECTROLYZER OPERATION WITH VARYING INLET WATER FEED CONFIGURATIONS

    SciTech Connect

    Fox, E

    2008-09-12

    Proton Exchange Membrane (PEM) electrolysis is a potential alternative technology to crack water in specialty applications where a dry gas stream is needed, such as isotope production. One design proposal is to feed the cathode of the electrolyzer with vapor phase water. This feed configuration would allow isotopic water to be isolated on the cathode side of the electrolyzer and the isotope recovery system could be operated in a closed loop. Tests were performed to characterize the difference in the current-voltage behavior between a PEM electrolyzer operated with a cathode water vapor feed and with an anode liquid water feed. The cathode water vapor feed cell had a maximum limiting current density of 100 mA/cm2 at 70 C compared to a current density of 800 mA/cm2 for the anode liquid feed cell at 70 C. The limiting current densities for the cathode water vapor feed cell were approximately 3 times lower than predicted by a water mass transfer model. It is estimated that a cathode water vapor feed electrolyzer system will need to be between 8-14 times larger in active area or number of cells than an anode liquid feed system.

  13. Virus removal retention challenge tests performed at lab scale and pilot scale during operation of membrane units.

    PubMed

    Humbert, H; Machinal, C; Labaye, Ivan; Schrotter, J C

    2011-01-01

    The determination of the virus retention capabilities of UF units during operation is essential for the operators of drinking water treatment facilities in order to guarantee an efficient and stable removal of viruses through time. In previous studies, an effective method (MS2-phage challenge tests) was developed by the Water Research Center of Veolia Environnement for the measurement of the virus retention rates (Log Removal Rate, LRV) of commercially available hollow fiber membranes at lab scale. In the present work, the protocol for monitoring membrane performance was transferred from lab scale to pilot scale. Membrane performances were evaluated during pilot trial and compared to the results obtained at lab scale with fibers taken from the pilot plant modules. PFU culture method was compared to RT-PCR method for the calculation of LRV in both cases. Preliminary tests at lab scale showed that both methods can be used interchangeably. For tests conducted on virgin membrane, a good consistency was observed between lab and pilot scale results with the two analytical methods used. This work intends to show that a reliable determination of the membranes performances based on RT-PCR analytical method can be achieved during the operation of the UF units.

  14. 40 CFR Table 16 to Subpart Uuu of... - Operating Limits for Organic HAP Emissions From Catalytic Reforming Units

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... control device . . . You shall meet this operating limit during initial catalyst depressuring and purging... catalyst purging conditions that must be met prior to allowing uncontrolled purge releases....

  15. 40 CFR Table 16 to Subpart Uuu of... - Operating Limits for Organic HAP Emissions From Catalytic Reforming Units

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... control device . . . You shall meet this operating limit during initial catalyst depressuring and purging... catalyst purging conditions that must be met prior to allowing uncontrolled purge releases....

  16. Purification and properties of a shortened form of cytochrome P-450 2E1: deletion of the NH2-terminal membrane-insertion signal peptide does not alter the catalytic activities.

    PubMed Central

    Larson, J R; Coon, M J; Porter, T D

    1991-01-01

    As reported previously, alcohol-inducible cytochrome P-450 2E1 lacking the hydrophobic NH2-terminal segment is located primarily in the inner cell membrane when expressed in Escherichia coli and is active with a typical substrate. To study the catalytic properties in detail, we have purified the truncated P-450 lacking residues 3-29 to electrophoretic homogeneity from the solubilized bacterial membrane fraction in the presence of 4-methylpyrazole as a stabilizing agent. The resulting heme protein with a specific content of 15.8 nmol of P-450 per mg of protein has a reduced CO difference spectrum identical to that of the full-length enzyme, with a Soret maximum at 452 nm. The rates of catalysis of four reactions in the reconstituted enzyme system, including the oxygenation of ethanol to give acetaldehyde, the oxidative dealkylation of N-nitrosodiethylamine to give ethylene and acetaldehyde, and the ring hydroxylation of aniline and p-nitrophenol, are the same with the shortened and full-length enzymes. The apparent Km of p-nitrophenol is also the same, as is that for NADPH-cytochrome P-450 reductase and for cytochrome b5, which stimulates p-nitrocatechol formation about 3-fold. Moreover, the requirement for phosphatidylcholine for full catalytic activity is unchanged despite the absence of the NH2-terminal segment. Although this highly hydrophobic segment is believed to play a role in the intact cell as a membrane-insertion signal sequence, we conclude that it has no function in the catalytic activity of the cytochrome as an oxygenase, including interactions with the other components of the enzyme system. Images PMID:1656462

  17. Long term operation of high concentration powdered activated carbon membrane bio-reactor for advanced water treatment.

    PubMed

    Seo, G T; Moon, C D; Chang, S W; Lee, S H

    2004-01-01

    A pilot scale experiment was conducted to evaluate the performance of a membrane bioreactor filled with high concentration powdered activated carbon. This hybrid system has great potential to substitute for existing GAC or O3/BAC processes in the drinking water treatment train. The system was installed at a water treatment plant located downstream of the Nakdong river basin, Korea. Effluent of rapid sand filter was used as influent of the system which consists of PAC bio-reactor, submerged MF membrane module and air supply facility. PAC concentration of 20 g/L was maintained at the beginning of the experiment and it was increased to 40 g/L. The PAC has not been changed during the operational periods. The membrane was a hollow fiber type with pore sizes of 0.1 and 0.4 microm. It was apparent that the high PAC concentration could prevent membrane fouling. 40 g/L PAC was more effective to reduce the filtration resistance than 20 g/L. At the flux of 0.36 m/d, TMP was maintained less than 40 kPa for about 3 months by intermittent suction type operation (12 min suction/3 min idling). Adsorption was the dominant role to remove DOC at the initial operational period. However the biological effect was gradually increased after around 3 months operation. Constant DOC removal could be maintained at about 40% without any trouble and then a tremendous reduction of DBPs (HAA5 and THM) higher than 85% was achieved. Full nitrification was observed at the controlled influent ammonia nitrogen concentration of 3 and 7 mg/L. pH was an important parameter to keep stable ammonia oxidation. From almost two years of operation, it is clear that the PAC membrane bioreactor is highly applicable for advanced water treatment under the recent situation of more stringent DBPs regulation in Korea.

  18. 40 CFR Table 28 to Subpart Uuu of... - Continuous Compliance With Operating Limits for Inorganic HAP Emissions From Catalytic Reforming...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... operating limit . . . You shall demonstrate continuous compliance during coke burn-off and catalyst... concentration in the catalyst regenerator exhaust gas must not exceed the limit established during the... catalyst rejuvenation; implementing procedures in the operating and maintenance plan if the...

  19. A flexible all-inorganic fuel cell membrane with conductivity above Nafion, and durable operation at 150 °C

    NASA Astrophysics Data System (ADS)

    Ansari, Y.; Tucker, T. G.; Huang, W.; Klein, I. S.; Lee, S.-Y.; Yarger, J. L.; Angell, C. A.

    2016-01-01

    The search for fuel cell membranes has focused on carbon backbone polymers, among which Nafion seems to best survive the most severe of the degradation mechanisms - attack by peroxide radicals. Less attention has been given to inorganic membranes because of their generally inflexible nature and lower conductivity, though some SiO2-Nafion composites have shown improved properties. Nafion dominates, despite needing hydration, which then restricts operation to below 100 °C (so CO poisoning problems persist). Described herein is a low cost, flexible, and all-inorganic fiberglass reinforced gel membrane with conductivity exceeding that of Nafion at any temperature above 60 °C. Using Teflon fuel cells, maximum currents > 1 Acm-2 and OCV of 1.03 V at 150 °C are demonstrated. No detectable loss of cell potential was observed over 24 h during 50 mAcm-2 constant current operation at 120 °C while, at 150 °C and maximum power, the degradation rate is intermediate among other high conductivity H3PO4-PBI type membranes. The structure of the membrane is deduced, mainly from 29Si solid state-NMR. The -115 ppm resonance, which is extreme for Q4 Si(O) structures, identifies a zeolite-like SiO2 network, which is "floppy". 31P and 1H NMR establish nano-permeating H3PO4 as the source of the exceptional conductivity.

  20. Evolution of catalytic function

    NASA Technical Reports Server (NTRS)

    Joyce, G. F.

    1993-01-01

    An RNA-based evolution system was constructed in the laboratory and used to develop RNA enzymes with novel catalytic function. By controlling the nature of the catalytic task that the molecules must perform in order to survive, it is possible to direct the evolving population toward the expression of some desired catalytic behavior. More recently, this system has been coupled to an in vitro translation procedure, raising the possibility of evolving protein enzymes in the laboratory to produce novel proteins with desired catalytic properties. The aim of this line of research is to reduce darwinian evolution, the fundamental process of biology, to a laboratory procedure that can be made to operate in the service of organic synthesis.

  1. Stable closure of the cytoplasmic half-channel is required for efficient proton transport at physiological membrane potentials in the bacteriorhodopsin catalytic cycle.

    PubMed

    Wang, Ting; Oppawsky, Christoph; Duan, Yong; Tittor, Jörg; Oesterhelt, Dieter; Facciotti, Marc T

    2014-04-15

    The bacteriorhodopsin (BR) Asp96Gly/Phe171Cys/Phe219Leu triple mutant has been shown to translocate protons 66% as efficiently as the wild-type protein. Light-dependent ATP synthesis in haloarchaeal cells expressing the triple mutant is 85% that of the wild-type BR expressing cells. Therefore, the functional activity of BR seems to be largely preserved in the triple mutant despite the observations that its ground-state structure resembles that of the wild-type M state (i.e., the so-called cytoplasmically open state) and that the mutant shows no significant structural changes during its photocycle, in sharp contrast to what occurs in the wild-type protein in which a large structural opening and closing occurs on the cytoplasmic side. To resolve the contradiction between the apparent functional robustness of the triple mutant and the presumed importance of the opening and closing that occurs in the wild-type protein, we conducted additional experiments to compare the behavior of wild-type and mutant proteins under different operational loads. Specifically, we characterized the ability of the two proteins to generate light-driven proton currents against a range of membrane potentials. The wild-type protein showed maximal conductance between -150 and -50 mV, whereas the mutant showed maximal conductance at membrane potentials >+50 mV. Molecular dynamics (MD) simulations of the triple mutant were also conducted to characterize structural changes in the protein and in solvent accessibility that might help to functionally contextualize the current-voltage data. These simulations revealed that the cytoplasmic half-channel of the triple mutant is constitutively open and dynamically exchanges water with the bulk. Collectively, the data and simulations help to explain why this mutant BR does not mediate photosynthetic growth of haloarchaeal cells, and they suggest that the structural closing observed in the wild-type protein likely plays a key role in minimizing substrate

  2. Tympanic Membrane Perforation and Hearing Loss From Blast Overpressure in Operation Enduring Freedom and Operation Iraqi Freedom Wounded

    DTIC Science & Technology

    2007-10-01

    peripheral location of the defect have both been associated with lower rates of spontaneous healing.10 Most patients, in previous studies, were...5 19 Otorrhea 10 25 Tinnitus 21 50 Vertigo 3 8 Table 3 Grade of Tympanic Membrane Perforation, Size of Perforation, and Spontaneous Healing Rate Grade

  3. 40 CFR Table 23 to Subpart Uuu of... - Operating Limits for Inorganic HAP Emission Limitations for Catalytic Reforming Units

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... meet this operating limit during coke burn-off and catalyst rejuvenation . . . 1. Wet scrubber The... concentration in the catalyst regenerator exhaust gas must not exceed the limit established during...

  4. A comparison of low-pressure and supercharged operation of polymer electrolyte membrane fuel cell systems for aircraft applications

    NASA Astrophysics Data System (ADS)

    Werner, C.; Preiß, G.; Gores, F.; Griebenow, M.; Heitmann, S.

    2016-08-01

    Multifunctional fuel cell systems are competitive solutions aboard future generations of civil aircraft concerning energy consumption, environmental issues, and safety reasons. The present study compares low-pressure and supercharged operation of polymer electrolyte membrane fuel cells with respect to performance and efficiency criteria. This is motivated by the challenge of pressure-dependent fuel cell operation aboard aircraft with cabin pressure varying with operating altitude. Experimental investigations of low-pressure fuel cell operation use model-based design of experiments and are complemented by numerical investigations concerning supercharged fuel cell operation. It is demonstrated that a low-pressure operation is feasible with the fuel cell device under test, but that its range of stable operation changes between both operating modes. Including an external compressor, it can be shown that the power demand for supercharging the fuel cell is about the same as the loss in power output of the fuel cell due to low-pressure operation. Furthermore, the supercharged fuel cell operation appears to be more sensitive with respect to variations in the considered independent operating parameters load requirement, cathode stoichiometric ratio, and cooling temperature. The results indicate that a pressure-dependent self-humidification control might be able to exploit the potential of low-pressure fuel cell operation for aircraft applications to the best advantage.

  5. The significance of abrupt transitions in Lineweaver-Burk plots with particular reference to glutamate dehydrogenase. Negative and positive co-operativity in catalytic rate constants.

    PubMed

    Engel, P C; Ferdinand, W

    1973-01-01

    1. Lineweaver-Burk plots for glutamate dehydrogenase, glucose 6-phosphate dehydrogenase and several other enzymes show one or more abrupt transitions between apparently linear sections. These transitions correspond to abrupt increases in the apparent K(m) and V(max.) with increasing concentration of the varied substrate. 2. The generalized reciprocal initial-rate equation for a multi-site enzyme requires several restrictions to be put on it in order to generate such plots. These mathematical conditions are explored. 3. It is shown that the effective omission of a term in the denominator of the reciprocal initial-rate equation represents a minimal requirement for generation of abrupt transitions. This corresponds in physical terms to negative co-operativity followed by positive co-operativity affecting the catalytic rate constant for the reaction. 4. Previous models for glutamate dehydrogenase cannot adequately account for the results. On the other hand, the model based on both negative and positive co-operativity gives a good fit to the experimental points. 5. The conclusions are discussed in relation to current knowledge of the structure and mechanism of glutamate dehydrogenase.

  6. Clean catalytic combustor program

    NASA Technical Reports Server (NTRS)

    Ekstedt, E. E.; Lyon, T. F.; Sabla, P. E.; Dodds, W. J.

    1983-01-01

    A combustor program was conducted to evolve and to identify the technology needed for, and to establish the credibility of, using combustors with catalytic reactors in modern high-pressure-ratio aircraft turbine engines. Two selected catalytic combustor concepts were designed, fabricated, and evaluated. The combustors were sized for use in the NASA/General Electric Energy Efficient Engine (E3). One of the combustor designs was a basic parallel-staged double-annular combustor. The second design was also a parallel-staged combustor but employed reverse flow cannular catalytic reactors. Subcomponent tests of fuel injection systems and of catalytic reactors for use in the combustion system were also conducted. Very low-level pollutant emissions and excellent combustor performance were achieved. However, it was obvious from these tests that extensive development of fuel/air preparation systems and considerable advancement in the steady-state operating temperature capability of catalytic reactor materials will be required prior to the consideration of catalytic combustion systems for use in high-pressure-ratio aircraft turbine engines.

  7. 40 CFR Table 28 to Subpart Uuu of... - Continuous Compliance With Operating Limits for Inorganic HAP Emissions From Catalytic Reforming...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... catalyst rejuvenation by . . . 1. Wet scrubber a. The daily average pH or alkalinity of the water (or... Collecting the hourly and daily average pH or alkalinity monitoring data according to § 63.1572 1; and maintaining the daily average pH or alkalinity above the operating limit established during the...

  8. 40 CFR Table 23 to Subpart Uuu of... - Operating Limits for Inorganic HAP Emission Limitations for Catalytic Reforming Units

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Sulfur Recovery Units Pt. 63, Subpt. UUU, Table 23 Table 23 to Subpart UUU of Part 63—Operating Limits... recommended limit (1.35 weight percent for the Chlorsorb TM System); and the weekly average chloride level on... limit (1.8 weight percent for the Chlorsorb TM System)....

  9. 40 CFR Table 28 to Subpart Uuu of... - Continuous Compliance With Operating Limits for Inorganic HAP Emissions From Catalytic Reforming...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... HCl concentration below the applicable operating limit. 3. Internal scrubbing system meeting percent... exceed the design or manufacturer's recommended limit (1.35 weight percent for the Clorsorb TM Collecting... chloride concentration below the design or manufacturer's recommended limit (1.8 weight percent...

  10. 40 CFR Table 28 to Subpart Uuu of... - Continuous Compliance With Operating Limits for Inorganic HAP Emissions From Catalytic Reforming...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... HCl concentration below the applicable operating limit. 3. Internal scrubbing system meeting percent... exceed the design or manufacturer's recommended limit (1.35 weight percent for the Clorsorb TM Collecting... chloride concentration below the design or manufacturer's recommended limit (1.8 weight percent...

  11. Effect of operation parameters on the flux stabilization of gravity-driven membrane (GDM) filtration system for decentralized water supply.

    PubMed

    Tang, Xiaobin; Ding, An; Qu, Fangshu; Jia, Ruibao; Chang, Haiqing; Cheng, Xiaoxiang; Liu, Bin; Li, Guibai; Liang, Heng

    2016-08-01

    A pilot-scale gravity-driven membrane (GDM) filtration system under low gravitational pressure without any pre-treatment, backwash, flushing, or chemical cleaning was carried out to investigate the effect of operation parameters (including operation pressure, aeration mode, and intermittent filtration) on the effluent quality and permeability development. The results revealed that GDM system exhibited an efficient performance for the removal of suspended substances and organic compounds. The stabilization of flux occurred and the average values of stable flux were 6.6, 8.1, and 8.6 Lm(-2) h(-1) for pressures of 65, 120, and 200 mbar, respectively. In contrast, flux stabilization was not observed under continuous and intermittent aeration conditions. However, aeration (especially continuous aeration) was effective to improve flux and alleviate membrane fouling during 1-month operation. Moreover, intermittent filtration would influence the stabilization of permeate flux, resulting in a higher stable flux (ranging from 6 to 13 Lm(-2) h(-1)). The stable flux significantly improved with the increase of intermittent period. Additionally, GDM systems exhibited an efficient recovery of flux after simple physical cleaning and the analyses of resistance reversibility demonstrated that most of the total resistance was hydraulic reversible resistance (50-75 %). Therefore, it is expected that the results of this study can develop strategies to increase membrane permeability and reduce energy consumption in GDM systems for decentralized water supply.

  12. The installation and operation of a production scale membrane filtration system to treat and reuse waste water from a dyehouse

    SciTech Connect

    Brown, D.A.

    1997-11-01

    The waste water from the dyeing of cotton and poly-cotton blends is characterized by high levels of salts and color. The discharged salts are felt to contribute to effluent toxicity and the color is aesthetically unacceptable in the receiving streams. The system of selective membrane filtration offers a method to address both of these problems. By treating only the waste water having the most color and salt concentration, the expensive membrane equipment can be considerably downsized. The volume of the color to be removed is drastically reduced as filtrate material. At these low volumes of color more economical means of removal can be employed. The membranes are designed so that the color and other pollutant materials are rejected but the salt solution is allowed to pass through the membrane. This produces clean water containing the recovered salt suitable for reuse, greatly reducing the salt content of the effluent. After the successful completion of a small pilot scale system, the installation and operation of a production sized system was desired prior to the full incorporation of this technology.

  13. Degradation of a model azo dye in submerged anaerobic membrane bioreactor (SAMBR) operated with powdered activated carbon (PAC).

    PubMed

    Baêta, B E L; Luna, H J; Sanson, A L; Silva, S Q; Aquino, S F

    2013-10-15

    This work investigated the anaerobic degradation of the model azo dye Remazol Yellow Gold RNL in an upflow anaerobic sludge blanket reactor (UASB) and two submerged anaerobic membrane (SAMBR) bioreactors, one of which (SAMBR-1) was operated with powdered activated carbon (PAC) in its interior. The reactors were operated at 35 °C with a hydraulic retention time of 24 h in three operational phases, aimed to assess the effect of external sources of carbon (glucose) or redox mediator (yeast extract) on the removal or color and organic matter. The results showed that removal efficiencies of COD (73-94%) and color (90-94%) were higher for SAMBR-1 when compared to SAMBR-2 (operated without PAC) and UASB reactors. In addition, the presence of PAC in SAMBR-1 increased reactor stability, thereby leading to a lower accumulation of volatile fatty acids (VFA). The microfiltration membrane was responsible for an additional removal of ~50% of soluble residual COD in the form of VFA, thus improving permeate quality. On its turn, PAC exhibited the ability to adsorb byproducts (aromatic amines) of azo dye degradation as well as to act as source of immobilized redox mediator (quinone groups on its surface), thereby enhancing color removal.

  14. Dry gas operation of proton exchange membrane fuel cells with parallel channels: Non-porous versus porous plates

    NASA Astrophysics Data System (ADS)

    Litster, Shawn; Santiago, Juan G.

    We present a study of proton exchange membrane (PEM) fuel cells with parallel channel flow fields for the cathode, dry inlet gases, and ambient pressure at the outlets. The study compares the performance of two designs: a standard, non-porous graphite cathode plate design and a porous hydrophilic carbon plate version. The experimental study of the non-porous plate is a control case and highlights the significant challenges of operation with dry gases and non-porous, parallel channel cathodes. These challenges include significant transients in power density and severe performance loss due to flooding and electrolyte dry-out. Our experimental study shows that the porous plate yields significant improvements in performance and robustness of operation. We hypothesize that the porous plate distributes water throughout the cell area by capillary action; including pumping water upstream to normally dry inlet regions. The porous plate reduces membrane resistance and air pressure drop. Further, IR-free polarization curves confirm operation free of flooding. With an air stoichiometric ratio of 1.3, we obtain a maximum power density of 0.40 W cm -2, which is 3.5 times greater than that achieved with the non-porous plate at the same operating condition.

  15. Assemblies of protective anion exchange membrane on air electrode for its efficient operation in aqueous alkaline electrolyte

    NASA Astrophysics Data System (ADS)

    Bertolotti, Bruno; Chikh, Linda; Vancaeyzeele, Cédric; Alfonsi, Séverine; Fichet, Odile

    2015-01-01

    Aqueous alkaline metal-air batteries represent promising energy storage devices when supplied with atmospheric air. However, under this condition, the air electrode shows a very short life time (i.e. 50 h of operation in 5 M LiOH at -10 mA cm-2), mainly due to the precipitation of carbonates inside the electrode porosity. The air electrode can then be protected by an anion exchange membrane on the electrolyte side. In this paper, we demonstrate that the efficiency of this protective membrane depends on the assembly method on the electrode. When a modified poly(epichlorohydrin) (PECH) network is synthesized directly on the electrode, the polymer seeps inside the electrode porosity, and a suitable interface inducing negligible additional polarization in comparison with classical pressure-assembled membranes is obtained. This protected electrode shows improved stability of up to 160 h of operation in 5 M LiOH. This performance is improved to 350 h by adjusting the conductivity and the ionic exchange capacity. Finally, the interest of interpenetrating polymer network (IPN) architecture compared to a single network is confirmed. Indeed, an electrode protected with a PECH/poly(2-hydroxyethyl methacrylate) (PHEMA) IPN is stable for 650 h in 5 M LiOH. In addition, degradation process becomes reversible since the assembly can be regenerated, which is not possible for the bare electrode.

  16. FEA modeling of CMUT with membrane stand-off structures to enable selectable frequency-mode operation.

    PubMed

    Eames, Matthew D C; Reck, Theodore J; Kilroy, Joseph P; Hossack, John A

    2011-12-01

    A selectable, dual-frequency, capacitive micro- machined ultrasonic transducer (CMUT) designed for both high-frequency imaging and low-frequency therapeutic effect is presented. A validated finite element analysis (FEA) CMUT model was used to examine the performance of the proposed dual-frequency transducer. CMUT device simulations were used to design a hybrid device incorporating stand-off structures that divide a large, low-frequency membrane into smaller, high-frequency sub-membranes when the membrane is partially collapsed so that the stand-offs contact the substrate. In low-frequency operation, simulations indicated that the peak negative pressure achieved by the hybrid device, when biased by 30.0 VDC and excited by a 2-MHz signal with 30.0 V amplitude, exceeded 190 kPa, which is sufficient for microbubble rupture. Low-frequency mode bandwidth was 93% at a center frequency of 2.1 MHz. In the high-frequency mode of operation, the device was excited by 175 Vdc and 87.5 Vac, which generated a peak negative pressure of 247 kPa. Device center frequency was 44.1 MHz with a - 6-dB fractional bandwidth of 42%.

  17. Influence of membrane structure on the operating current densities of non-aqueous redox flow batteries: Organic-inorganic composite membranes based on a semi-interpenetrating polymer network

    NASA Astrophysics Data System (ADS)

    Shin, Sung-Hee; Kim, Yekyung; Yun, Sung-Hyun; Maurya, Sandip; Moon, Seung-Hyeon

    2015-11-01

    We develop three types of organic-inorganic composite membranes based on a semi-interpenetrating polymer network (SIPN) to explore the effects of membrane structure on the possible operating current densities of a non-aqueous redox flow battery (RFB) system. Poly(vinylidene fluoride) (PVdF) is selected as a supporting polymer matrix for improving the chemical and thermal stability of the organic-inorganic composite membranes. We also introduce silica nanoparticles (5 wt% of PVdF) into the membranes to ensure the low crossover of active species. The fabrication of SIPN through the addition of glycidyl methacrylate, 4-vinylpyridine, or N-vinylcarbazole enables control of the membrane structure. Depending on monomer type, the membrane structure is determined to be either aliphatic or aromatic in terms of chemical properties and either dense or porous in terms of physical properties. These chemical and physical structures affect the electrochemical properties that correspond to charge/discharge performance and to the range of possible operating current densities. An important requirement is to examine charge/discharge performance at the possible range of operating current densities by using various membrane structures. This requirement is discussed in relation to a proposed design strategy for non-aqueous RFB membranes.

  18. Transient catalytic combustor model

    NASA Technical Reports Server (NTRS)

    Tien, J. S.

    1981-01-01

    A quasi-steady gas phase and thermally thin substrate model is used to analyze the transient behavior of catalytic monolith combustors in fuel lean operation. The combustor response delay is due to the substrate thermal inertia. Fast response is favored by thin substrate, short catalytic bed length, high combustor inlet and final temperatures, and small gas channel diameters. The calculated gas and substrate temperature time history at different axial positions provides an understanding of how the catalytic combustor responds to an upstream condition change. The computed results also suggest that the gas residence times in the catalytic bed in the after bed space are correlatable with the nondimensional combustor response time. The model also performs steady state combustion calculations; and the computed steady state emission characteristics show agreement with available experimental data in the range of parameters covered. A catalytic combustor design for automotive gas turbine engine which has reasonably fast response ( 1 second) and can satisfy the emission goals in an acceptable total combustor length is possible.

  19. Transient catalytic combustor model

    NASA Astrophysics Data System (ADS)

    Tien, J. S.

    1981-05-01

    A quasi-steady gas phase and thermally thin substrate model is used to analyze the transient behavior of catalytic monolith combustors in fuel lean operation. The combustor response delay is due to the substrate thermal inertia. Fast response is favored by thin substrate, short catalytic bed length, high combustor inlet and final temperatures, and small gas channel diameters. The calculated gas and substrate temperature time history at different axial positions provides an understanding of how the catalytic combustor responds to an upstream condition change. The computed results also suggest that the gas residence times in the catalytic bed in the after bed space are correlatable with the nondimensional combustor response time. The model also performs steady state combustion calculations; and the computed steady state emission characteristics show agreement with available experimental data in the range of parameters covered. A catalytic combustor design for automotive gas turbine engine which has reasonably fast response ( 1 second) and can satisfy the emission goals in an acceptable total combustor length is possible.

  20. Zeolite membrane cascade for tritium extraction and recovery systems

    SciTech Connect

    Borisevich, O.; Demange, D.; Lefebvre, X.; Kind, M.

    2015-03-15

    Membrane separation by zeolite membranes has been proposed as a pre-concentration stage for the tritium extraction from the purge helium of the breeding blanket combined with a final recovery by the catalytic membrane reactor PERMCAT. This fully continuous operation improves the tritium management in fusion machines, minimizing the tritium inventory. For the first time, the permeation measurements for H{sub 2} - He mixtures through a MFI-alumina hollow fibre membrane has been measured for different compositions (0.1 - 20% H{sub 2}) and temperatures. Such a highly permeable membrane, although it shows a limited selectivity, appears attractive for tritium recovery in the blanket. This will imply its operation in a membrane cascade, for which simulation work is ongoing. Mathematically the process is modeled using mass balance equations that can be transformed into the matrix form and solved iteratively assuming a permeate concentration on the first step of iteration, until the separation requirements are fulfilled.

  1. A large-signal model for CMUT arrays with arbitrary membrane geometry operating in non-collapsed mode.

    PubMed

    Satir, Sarp; Zahorian, Jaime; Degertekin, F Levent

    2013-11-01

    A large-signal, transient model has been developed to predict the output characteristics of a CMUT array operated in the non-collapse mode. The model is based on separation of the nonlinear electrostatic voltage-to-force relation and the linear acoustic array response. For modeling of linear acoustic radiation and crosstalk effects, the boundary element method is used. The stiffness matrix in the vibroacoustics calculations is obtained using static finite element analysis of a single membrane which can have arbitrary geometry and boundary conditions. A lumped modeling approach is used to reduce the order of the system for modeling the transient nonlinear electrostatic actuation. To accurately capture the dynamics of the non-uniform electrostatic force distribution over the CMUT electrode during large deflections, the membrane electrode is divided into patches shaped to match higher order membrane modes, each introducing a variable to the system model. This reduced order nonlinear lumped model is solved in the time domain using commercial software. The model has two linear blocks to calculate the displacement profile of the electrode patches and the output pressure for a given force distribution over the array. The force-to-array-displacement block uses the linear acoustic model, and the Rayleigh integral is evaluated to calculate the pressure at any field point. Using the model, the time-domain transmitted pressure can be simulated for different large drive signal configurations. The acoustic model is verified by comparison to harmonic FEA in vacuum and fluid for high- and low-aspect-ratio membranes as well as mass-loaded membranes. The overall software model is verified by comparison to transient 3-D finite element analysis and experimental results for different large drive signals, and an example for a phased array simulation is given.

  2. A Large Signal Model for CMUT Arrays with Arbitrary Membrane Geometries Operating in Non-Collapsed Mode

    PubMed Central

    Satir, Sarp; Zahorian, Jaime; Degertekin, F. Levent

    2014-01-01

    A large signal, transient model has been developed to predict the output characteristics of a CMUT array operated in the non-collapse mode. The model is based on separation of the nonlinear electrostatic voltage-to-force relation and the linear acoustic array response. For linear acoustic radiation and crosstalk effects, the boundary element method is used. The stiffness matrix in the vibroacoustics calculations is obtained using static finite element analysis of a single membrane which can have arbitrary geometry and boundary conditions. A lumped modeling approach is used to reduce the order of the system for modeling the transient nonlinear electrostatic actuation. To accurately capture the dynamics of the non-uniform electrostatic force distribution over the CMUT electrode during large deflections, the membrane electrode is divided into patches shaped to match higher order membrane modes, each introducing a variable to the system model. This reduced order nonlinear lumped model is solved in the time domain using Simulink. The model has two linear blocks to calculate the displacement profile of the electrode patches and the output pressure for a given force distribution over the array, respectively. The force to array displacement block uses the linear acoustic model, and the Rayleigh integral is evaluated to calculate the pressure at any field point. Using the model, the transient transmitted pressure can be simulated for different large signal drive signal configurations. The acoustic model is verified by comparison to harmonic FEA in vacuum and fluid for high and low aspect ratio membranes as well as mass-loaded membranes. The overall Simulink model is verified by comparison to transient 3D FEA and experimental results for different large drive signals; and an example for a phased array simulation is given. PMID:24158297

  3. Mesoporous catalysts, supports and catalytic membranes based on MCM-41. Final report for the period January 15,2000 - January 14, 2001

    SciTech Connect

    Haller, Gary L.

    2001-07-01

    The research had two objectives: to understand the effect of pore size on the chemistry and activity of active sites, and to investigate both the pore size and anchoring effect of Me-MCM-41 on Pt clusters (where Me is a metal incorporated in silica-based MCM-41). The focus is not on the effect of pore size on transport of reactants and products, but on how the local radius of curvature might affect the properties of a foreign ion embedded in a silicon wall that acts as a catalytic site or anchor for the catalytic site. The mesoporous molecular sieve, MCM-41, allows the variation of pore size with constant composition and pore geometry so these new materials allow this scientific question to be addressed for the first time. For the anchoring effect, concentration was on Sn-MCM-41 to prepare Pt/Sn-MCM-41 catalysts, by characterizing these and by testing them with probe reforming reactions (dehydrogenation, isomerization and aromatization). Although this is a final report on activity January 15, 2000 - January 14, 2001, this was a continuation of work initiated in the three-year grant period January 15, 1997 - January 14, 2000, so the summary of progress for these three years is appended for completeness.

  4. Favorable effect of in-situ generated platinum in the membrane on fuel cell membrane durability

    NASA Astrophysics Data System (ADS)

    Macauley, Natalia; Wong, Ka Hung; Watson, Mark; Kjeang, Erik

    2015-12-01

    The overall lifetime of polymer electrolyte fuel cells is often determined by the membrane durability. Platinum, which may dissolve from the catalyst layers during fuel cell operation and deposit in the membrane, has been shown to have both positive and negative effects on membrane stability. In the present work, we analyze what specific conditions are required in order to reach a favorable, membrane stabilizing effect with the controlled use of platinum in the membrane. Using accelerated membrane durability testing, field operated membrane samples, and electron microscopy, we demonstrate that a high platinum concentration with specific particle shapes and sizes is essential for enhanced membrane stability. Specifically, star shaped and dendritic particles with high particle density and high surface area are shown to be preferable. These particles contain high levels of Pt(111) and are expected to have high catalytic activity toward peroxide quenching and crossover gas consumption, thereby mitigating chemical membrane degradation. On the other hand, small, dispersed cubic particles are found to have no effect or the opposite, negative effect on membrane stability.

  5. Operation of a breadboard liquid-sorbent/membrane-contactor system for removing carbon dioxide and water vapor from air

    NASA Technical Reports Server (NTRS)

    Mccray, Scott B.; Ray, Rod; Newbold, David D.; Millard, Douglas L.; Friesen, Dwayne T.; Foerg, Sandra

    1992-01-01

    Processes to remove and recover carbon dioxide (CO2) and water vapor from air are essential for successful long-duration space missions. This paper presents results of a developmental program focused on the use of a liquid-sorbent/membrane-contactor (LSMC) system for removal of CO2 and water vapor from air. In this system, air from the spacecraft cabin atmosphere is circulated through one side of a hollow-fiber membrane contactor. On the other side of the membrane contactor is flowed a liquid sorbent, which absorbs the CO2 and water vapor from the feed air. The liquid sorbent is then heated to desorb the CO2 and water vapor. The CO2 is subsequently removed from the system as a concentrated gas stream, whereas the water vapor is condensed, producing a water stream. A breadboard system based on this technology was designed and constructed. Tests showed that the LSMC breadboard system can produce a CO2 stream and a liquid-water stream. Details are presented on the operation of the system, as well as the effects on performance of variations in feed conditions.

  6. Ceramic oxygen transport membrane array reactor and reforming method

    DOEpatents

    Kelly, Sean M.; Christie, Gervase Maxwell; Robinson, Charles; Wilson, Jamie R.; Gonzalez, Javier E.; Doraswami, Uttam R.

    2016-11-08

    The invention relates to a commercially viable modular ceramic oxygen transport membrane reforming reactor configured using repeating assemblies of oxygen transport membrane tubes and catalytic reforming reactors.

  7. Impact of Nanostructure on Mechanical Properties of Norbornene-based Block Copolymers under Simulated Operating Conditions for Biobutanol Membranes.

    PubMed

    Ye, Changhuai; Takigawa, Tamami; Burtovvy, Oleksandr Sasha; Langsdorf, Leah; Jablonski, Dane; Bell, Andrew; Vogt, Bryan D

    2015-06-10

    The structure and mechanical properties of a novel block copolymer (BCP) system with T(g)'s for both segments exceeding 300 °C, poly(butylnorbornene)-block-poly(hydroxyhexafluoroisopropyl norbornene) (BuNB-b-HFANB), are investigated as a function of processing conditions used for solvent vapor annealing (SVA). Solvent selection impacts long-range order markedly, but unexpectedly vertical orientation of cylinders are preferred over a wide range of solubility parameters, as determined by atomic force microscopy and grazing incidence small-angle X-ray scattering. The mechanical properties (elastic modulus, fracture strength, and onset fracture strain) are dependent upon the long-range order induced during SVA and determined using the combination of surface wrinkling and cracking. The modulus and fracture strength of the films increase from 1.44 GPa and 12.1 MPa to 1.77 GPa and 17.5 MPa, respectively, whereas the onset fracture strain decreases from 1.6% to approximately 0.6% as the ordering is improved. The polarity difference in the segments of the BCP is attractive for membrane separations, especially butanol-water. For biobutanol recovery, the titers are typically <3 wt % butanol; exposure of the BCP membrane to aqueous 1 wt % butanol decreases the elastic modulus to approximately 0.90 GPa, irrespective of the morphology, despite the high T(g) of both segments and limited swelling (5.0 wt %). Correspondingly, the onset fracture strain of these swollen films is estimated to increase significantly to 6-7%. These results indicate that operating conditions impact the mechanical performance of BCP membranes more than their morphology despite the high T(g) of the neat copolymer. Wrinkling and cracking provide a facile route to test the mechanical properties of membranes under simulated operando conditions.

  8. Removal of organic micro-pollutants from solid waste landfill leachate in membrane bioreactor operated without excess sludge discharge.

    PubMed

    Boonyaroj, V; Chiemchaisri, C; Chiemchaisri, W; Yamamoto, K

    2012-01-01

    Two-stage membrane bioreactor (MBR) system was applied to the treatment of landfill leachate from a solid waste disposal site in Thailand. The first stage anoxic reactor was equipped with an inclined tube module for sludge separation. It was followed by an aerobic stage with a hollow fiber membrane module for solid liquid separation. Mixed liquor sludge from the aerobic reactor was re-circulated back to anoxic reactor in order to maintain constant mixed liquor suspended solids (MLSS) concentration in the aerobic reactor. The removal of micro-pollutants from landfill leachate along the treatment period of 300 days was monitored. The results indicated that two-stage MBRs could remove biochemical oxygen demand (BOD), chemical oxygen demand (COD) and NH(4)(+) by 97, 87 and 91% at steady operating condition. Meanwhile organic micro-pollutant removals were 50-76%. The removal efficiencies varied according to the hydrophobic characteristic of compounds but they were improved during long-term MBR operation without sludge discharge.

  9. The Kemp elimination in membrane mimetic reaction media. Probing catalytic properties of cationic vesicles formed from a double-tailed amphiphile and linear long-tailed alcohols or alkyl pyranosides.

    PubMed

    Klijn, Jaap E; Engberts, Jan B F N

    2004-06-21

    Vesicles formed from synthetic, double-tailed amphiphiles are often used as mimics for biological membranes. However, biological membranes are a complex mixture of various compounds. In the present paper we describe a first attempt to study the importance of additives on vesicular catalysis. The rate-determining deprotonation of 5-nitrobenzisoxazole (Kemp elimination) by hydroxide ion is efficiently catalysed by vesicles formed from dimethyldi-n-octadecylammonium chloride (C(18)C(18)(+)) as a result of (partial) dehydration of the reactants (especially the hydroxide ion) at the vesicular binding sites. Gradual addition of linear alcohols, such as n-decanol (C(10)OH), n-octadecanol (C(18)OH) and batyl alcohol (C(18)GlyOH) leads to a decrease in the observed catalysis. By contrast, gradual addition of oleyl alcohol, n-dodecyl-beta-glucoside (C(12)Glu) and n-dodecyl-beta-maltoside (C(12)Mal) leads to an increase in the observed catalysis. A detailed kinetic analysis, taking into account substrate binding site polarities, counterion binding percentages and binding affinity of the kinetic probe, suggests that the catalytic changes depend strongly on subtle changes in the structure of the additive. Whereas the C(12)Glu-induced effect can be explained by an increase in the vesicular rate constant, the effect of C(12)Mal can only be explained by an increase in the binding constant of the kinetic probe. However, for these pyranoside-containing vesicles others factors, such as a more extensive dehydration of the hydroxide ion, and micelle formation have to be considered. For the linear alcohols, besides a decrease in the counterion binding, changes in the vesicular rate constant and the binding constant should be taken into account. These two parameters change to a different extent for the different alcohols. The kinetic analysis is supported by differential scanning calorimetry (DSC), E(T)(30) absorbance data and Nile Red, Laurdan, ANS and pyrene fluorescence measurements

  10. Identification of the aspartic proteinases from human erythrocyte membranes and gastric mucosa (slow-moving proteinase) as catalytically equivalent to cathepsin E.

    PubMed Central

    Jupp, R A; Richards, A D; Kay, J; Dunn, B M; Wyckoff, J B; Samloff, I M; Yamamoto, K

    1988-01-01

    Three aspartic proteinases with similar Mr values (approx. 80,000) but from distinct sources (human gastric mucosa, human erythrocyte membranes and rat spleen) were shown to have immunological cross-reactivity and comparable mobilities when subjected to polyacrylamide-gel electrophoresis under non-denaturing conditions. Kinetic parameters (kcat, Km and Ki) were determined for the interactions of the three enzymes with two synthetic chromogenic substrates and five inhibitors (naturally occurring and synthetic). On this basis it would appear that all of the enzymes should be considered equivalent to cathepsin E. pH-activity measurements indicated that the aspartic proteinase that originated from the erythrocyte membranes retained activity at a higher pH value than either of its readily soluble counterparts. Images Fig. 1. Fig. 2. PMID:3058118

  11. Carbogenic molecular sieves for reaction and separation by design: A novel approach to shape selective super base, super acid and catalytic membranes. Final report

    SciTech Connect

    Foley, Henry C.

    2002-03-18

    This report details the findings of three years of research plus one year of a no-cost extension. Primary results are the work with supported nanoporous carbon membranes for separation and reaction as well as with cesium-nanoporous carbon catalysts. The work resulted in 17 plus 2 papers (2 are in progress) and partial or full support for five Ph.D. students. Two patents were filed based on this research.

  12. Association with the Plasma Membrane Is Sufficient for Potentiating Catalytic Activity of Regulators of G Protein Signaling (RGS) Proteins of the R7 Subfamily.

    PubMed

    Muntean, Brian S; Martemyanov, Kirill A

    2016-03-25

    Regulators of G protein Signaling (RGS) promote deactivation of heterotrimeric G proteins thus controlling the magnitude and kinetics of responses mediated by G protein-coupled receptors (GPCR). In the nervous system, RGS7 and RGS9-2 play essential role in vision, reward processing, and movement control. Both RGS7 and RGS9-2 belong to the R7 subfamily of RGS proteins that form macromolecular complexes with R7-binding protein (R7BP). R7BP targets RGS proteins to the plasma membrane and augments their GTPase-accelerating protein (GAP) activity, ultimately accelerating deactivation of G protein signaling. However, it remains unclear if R7BP serves exclusively as a membrane anchoring subunit or further modulates RGS proteins to increase their GAP activity. To directly answer this question, we utilized a rapidly reversible chemically induced protein dimerization system that enabled us to control RGS localization independent from R7BP in living cells. To monitor kinetics of Gα deactivation, we coupled this strategy with measuring changes in the GAP activity by bioluminescence resonance energy transfer-based assay in a cellular system containing μ-opioid receptor. This approach was used to correlate changes in RGS localization and activity in the presence or absence of R7BP. Strikingly, we observed that RGS activity is augmented by membrane recruitment, in an orientation independent manner with no additional contributions provided by R7BP. These findings argue that the association of R7 RGS proteins with the membrane environment provides a major direct contribution to modulation of their GAP activity.

  13. Chemogenetic E-MAP in Saccharomyces cerevisiae for Identification of Membrane Transporters Operating Lipid Flip Flop

    PubMed Central

    Vazquez, Hector M.; Vionnet, Christine; Roubaty, Carole; Mallela, Shamroop k.; Schneiter, Roger; Conzelmann, Andreas

    2016-01-01

    While most yeast enzymes for the biosynthesis of glycerophospholipids, sphingolipids and ergosterol are known, genes for several postulated transporters allowing the flopping of biosynthetic intermediates and newly made lipids from the cytosolic to the lumenal side of the membrane are still not identified. An E-MAP measuring the growth of 142'108 double mutants generated by systematically crossing 543 hypomorphic or deletion alleles in genes encoding multispan membrane proteins, both on media with or without an inhibitor of fatty acid synthesis, was generated. Flc proteins, represented by 4 homologous genes encoding presumed FAD or calcium transporters of the ER, have a severe depression of sphingolipid biosynthesis and elevated detergent sensitivity of the ER. FLC1, FLC2 and FLC3 are redundant in granting a common function, which remains essential even when the severe cell wall defect of flc mutants is compensated by osmotic support. Biochemical characterization of some other genetic interactions shows that Cst26 is the enzyme mainly responsible for the introduction of saturated very long chain fatty acids into phosphatidylinositol and that the GPI lipid remodelase Cwh43, responsible for introducing ceramides into GPI anchors having a C26:0 fatty acid in sn-2 of the glycerol moiety can also use lyso-GPI protein anchors and various base resistant lipids as substrates. Furthermore, we observe that adjacent deletions in several chromosomal regions show strong negative genetic interactions with a single gene on another chromosome suggesting the presence of undeclared suppressor mutations in certain chromosomal regions that need to be identified in order to yield meaningful E-map data. PMID:27462707

  14. DNA-Cu(II) poly(amine) complex membrane as novel catalytic layer for highly sensitive amperometric determination of hydrogen peroxide.

    PubMed

    Gu, Tingting; Hasebe, Yasushi

    2006-05-15

    A novel hydrogen peroxide biosensor was fabricated by using a DNA-Cu(II) complex as a novel electrocatalyst for the reduction of hydrogen peroxide (H2O2). A polyion complex (PIC) membrane composed of DNA and poly(allylamine) (PAA) functioned as a support matrix for immobilization of electrocatalytic element-copper ion. The circular dichroism (CD) spectrum of the DNA-Cu(II)/PAA membrane in wet state showed that the DNA exists in B-like form within the membrane. Electrochemical measurements of the DNA-Cu(II)/PAA membrane-modified glassy carbon (GC) electrode revealed that the copper ion embedded in the DNA/PAA layer exhibits good electrochemical behaviors, and the electrochemical rate constant between the immobilized copper ion and the GC electrode surface was estimated to be 26.4 s(-1). The resulting DNA-Cu(II)/PAA/GC electrode showed an excellent electrocatalytic activity for the H2O2 reduction. The sensitivity of the sensor for the determination of H2O2 was affected by the amount of each component, such as copper ion, DNA and PAA in the DNA-Cu(II)/PAA membrane. Effects of applied potential, pH, temperature, ionic strength and buffer concentrations upon the response currents of the sensor were also investigated for an optimum analytical performance. Even in the presence of dissolved oxygen, the sensor exhibited highly sensitive and rapid (response time, less than 5 s) response to H2O2. The steady-state cathodic current responses of the sensor obtained at -0.2 V versus Ag/AgCl in air-saturated 50 mM phosphate buffer (pH 5.0) increased linearly up to 135 microM with the detection limit of 50 nM. Interference by ascorbic acid and uric acid due to the reduction of Cu(II) was effectively cancelled by further modification of outermost layer of polyion complex film. In addition, the sensor exhibited good reproducibility and stability.

  15. High temperature ceramic membrane reactors for coal liquid upgrading

    SciTech Connect

    Tsotsis, T.T.

    1992-06-19

    Ceramic membranes are a new class of materials, which have shown promise in a variety of industrial applications. Their mechanical and chemical stability coupled with a wide range of operating temperatures and pressures make them suitable for environments found in coal liquid upgrading. In this project we will evaluate the performance of Sel-Gel alumina membranes in coal liquid upgrading processes under realistic temperature and pressure conditions and investigate the feasibility of using such membranes in a membrane reactor based coal liquid upgrading process. In addition, the development of novel ceramic membranes with enhanced catalytic activity for coal-liquid upgrading applications, such as carbon-coated alumina membranes, will be also investigated.

  16. High temperature ceramic membrane reactors for coal liquid upgrading

    SciTech Connect

    Tsotsis, T.T.

    1992-06-19

    Ceramic membranes are a new class of materials, which have shown promise in a variety of industrial applications. Their mechanical and chemical stability coupled with a wide range of operating temperatures and pressures make them suitable for environments found in coal liquid upgrading. In this project we will evaluate the performance of Sel-Gel alumina membranes in coal liquid upgrading processes under realistic temperature and pressure conditions and investigate the feasibility of using such membranes in a membrane reactor based coal liquid upgrading process. In addition, the development of novel ceramic membranes with enhanced catalytic activity for coal-liquid upgrading applications, such as carbon-coated alumina membranes, will also be investigated.

  17. Catalytic reforming

    SciTech Connect

    Aldag, A.W. Jr.

    1986-01-28

    This patent describes a process for the catalytic reforming of a feedstock which contains at least one reformable organic compound. The process consists of contacting the feedstock under suitable reforming conditions with a catalyst composition selected from the group consisting of a catalyst. The catalyst essentially consists of zinc oxide and a spinel structure alumina. Another catalyst consists essentially of a physical mixture of zinc titanate and a spinel structure alumina in the presence of sufficient added hydrogen to substantially prevent the formation of coke. Insufficient zinc is present in the catalyst composition for the formation of a bulk zinc aluminate.

  18. Effects of operating conditions on durability of polymer electrolyte membrane fuel cell Pt cathode catalyst layer

    NASA Astrophysics Data System (ADS)

    Ohyagi, Shinsuke; Matsuda, Toshihiko; Iseki, Yohei; Sasaki, Tatsuyoshi; Kaito, Chihiro

    In this study, we investigated the effects of humidity and oxygen reduction on the degradation of the catalyst of a polymer electrolyte membrane fuel cell (PEMFC) in a voltage cycling test. To elucidate the effect of humidity on the voltage cycling corrosion of a carbon-supported Pt catalyst with 3 nm Pt particles, voltage cycling tests based on 10,000 cycles were conducted using 100% relative humidity (RH) hydrogen as anode gas and nitrogen of varying humidities as cathode gas. The degradation rate of an electrochemical surface area (ECSA) was almost 50% under 189% RH nitrogen atmosphere and the Pt average particle diameter after 10,000 cycles under these conditions was about 2.3 times that of a particle of fresh catalyst because of the agglomeration of Pt particles. The oxygen reduction reaction (ORR) that facilitated Pt catalyst agglomeration when oxygen was employed as the cathode gas also demonstrated that Pt agglomeration was prominent in higher concentrations of oxygen. The ECSA degradation figure in 100% RH oxygen was similar to that in 189% RH nitrogen. It was concluded that liquid water, which was dropped under a supersaturated condition or generated by ORR, accelerated Pt agglomeration. In this paper, we suggest that the Pt agglomeration degradation occurs in a flooding area in a cell plane.

  19. Interlinkages between bacterial populations dynamics and the operational parameters in a moving bed membrane bioreactor treating urban sewage.

    PubMed

    Reboleiro-Rivas, P; Martín-Pascual, J; Morillo, J A; Juárez-Jiménez, B; Poyatos, J M; Rodelas, B; González-López, J

    2016-01-01

    Bacteria are key players in biological wastewater treatments (WWTs), thus a firm knowledge of the bacterial population dynamics is crucial to understand environmental/operational factors affecting the efficiency and stability of the biological depuration process. Unfortunately, little is known about the microbial ecology of the advanced biological WWTs combining suspended biomass (SB) and attached biofilms (AB). This study explored in depth the bacterial community structure and population dynamics in each biomass fraction from a pilot-scale moving bed membrane bioreactor (MBMBR) treating municipal sewage, by means of temperature-gradient gel electrophoresis (TGGE) and 454-pyrosequencing. Eight experimental phases were conducted, combining different carrier filling ratios, hydraulic retention times and concentrations of mixed liquor total suspended solids. The bacterial community, dominated by Proteobacteria (20.9-53.8%) and Actinobacteria (20.6-57.6%), was very similar in both biomass fractions and able to maintain its functional stability under all the operating conditions, ensuring a successful and steady depuration process. Multivariate statistical analysis demonstrated that solids concentration, carrier filling ratio, temperature and organic matter concentration in the influent were the significant factors explaining population dynamics. Bacterial diversity increased as carrier filling ratio increased (from 20% to 35%, v/v), and solids concentration was the main factor triggering the shifts of the community structure. These findings provide new insights on the influence of operational parameters on the biology of the innovative MBMBRs.

  20. Proton exchange membrane fuel cell reversible performance loss induced by carbon monoxide produced during operation

    NASA Astrophysics Data System (ADS)

    Decoopman, B.; Vincent, R.; Rosini, S.; Paganelli, G.; Thivel, P.-X.

    2016-08-01

    Cyclic voltammetry measurements at the anode have been carried out and reveal the presence of carbon monoxide in steady-state operation, with pure hydrogen. Experiments have been performed both in single cell and in stack to find out its origin. The contamination of the anode catalyst is partly due the reverse-water gas shift (RWGS) with carbon dioxide from the cathode. However, this study shows a temperature-activated and time-related corrosion mechanism which appears under humidified hydrogen. Due to this degradation mechanism, a reversible 25 mV-loss of performances is observed and can be recovered by oxidizing carbon monoxide on the anode.

  1. IN SITU DESTRUCTION OF CHLORINATED HYDROCARBON COMPOUNDS IN GROUNDWATER USING CATALYTIC REDUCTIVE REDUCTIVE DEHALOGENATION IN A REACTIVE WELL: TESTING AND OPERATIONAL EXPERIENCES. (R825421)

    EPA Science Inventory

    A groundwater treatment technology based on catalytic reductive
    dehalogenation has been developed to efficiently destroy chlorinated
    hydrocarbons in situ using a reactive well approach. The treatment process
    utilizes dissolved H2 as an electron donor, in...

  2. Catalytic ignition of hydrogen and oxygen propellants

    NASA Technical Reports Server (NTRS)

    Zurawski, Robert L.; Green, James M.

    1988-01-01

    An experimental program was conducted to evaluate the catalytic ignition of gaseous hydrogen and oxygen propellants. Shell 405 granular catalyst and a monolithic sponge catalyst were tested. Mixture ratio, mass flow rate, propellant temperature, and back pressure were varied parametrically in testing to determine the operational limits of the catalytic igniter. The test results show that the gaseous hydrogen and oxygen propellant combination can be ignited catalytically using Shell 405 catalyst over a wide range of mixture ratios, mass flow rates, and propellant injection temperatures. These operating conditions must be optimized to ensure reliable ignition for an extended period of time. A cyclic life of nearly 2000, 2 sec pulses at nominal operating conditions was demonstrated with the catalytic igniter. The results of the experimental program and the established operational limits for a catalytic igniter using the Shell 405 catalyst are presented.

  3. Catalytic ignition of hydrogen and oxygen propellants

    NASA Technical Reports Server (NTRS)

    Zurawski, Robert L.; Green, James M.

    1988-01-01

    An experimental program was conducted to evaluate the catalytic ignition of gaseous hydrogen and oxygen propellants. Shell 405 granular catalyst and a monolithic sponge catalyst were tested. Mixture ratio, mass flow rate, propellant temperature, and back pressure were varied parametrically in testing to determine the operational limits of the catalytic igniter. The test results show that the gaseous hydrogen and oxygen propellant combination can be ignited catalytically using Shell 405 catalyst over a wide range of mixture ratios, mass flow rates, and propellant injection temperatures. These operating conditions must be optimized to ensure reliable ignition for an extended period of time. A cyclic life of nearly 2000, 2 sec pulses at nominal operating conditions was demonstrated with the catalytic igniter. The results of the experimental program and the established operational limits for a catalytic igniter using the Shell 405 catalysts are presented.

  4. Intracellular calcium affects prestin's voltage operating point indirectly via turgor-induced membrane tension

    NASA Astrophysics Data System (ADS)

    Song, Lei; Santos-Sacchi, Joseph

    2015-12-01

    Recent identification of a calmodulin binding site within prestin's C-terminus indicates that calcium can significantly alter prestin's operating voltage range as gauged by the Boltzmann parameter Vh (Keller et al., J. Neuroscience, 2014). We reasoned that those experiments may have identified the molecular substrate for the protein's tension sensitivity. In an effort to understand how this may happen, we evaluated the effects of turgor pressure on such shifts produced by calcium. We find that the shifts are induced by calcium's ability to reduce turgor pressure during whole cell voltage clamp recording. Clamping turgor pressure to 1kPa, the cell's normal intracellular pressure, completely counters the calcium effect. Furthermore, following unrestrained shifts, collapsing the cells abolishes induced shifts. We conclude that calcium does not work by direct action on prestin's conformational state. The possibility remains that calcium interaction with prestin alters water movements within the cell, possibly via its anion transport function.

  5. Catalytic reactor

    SciTech Connect

    Aaron, Timothy Mark; Shah, Minish Mahendra; Jibb, Richard John

    2009-03-10

    A catalytic reactor is provided with one or more reaction zones each formed of set(s) of reaction tubes containing a catalyst to promote chemical reaction within a feed stream. The reaction tubes are of helical configuration and are arranged in a substantially coaxial relationship to form a coil-like structure. Heat exchangers and steam generators can be formed by similar tube arrangements. In such manner, the reaction zone(s) and hence, the reactor is compact and the pressure drop through components is minimized. The resultant compact form has improved heat transfer characteristics and is far easier to thermally insulate than prior art compact reactor designs. Various chemical reactions are contemplated within such coil-like structures such that as steam methane reforming followed by water-gas shift. The coil-like structures can be housed within annular chambers of a cylindrical housing that also provide flow paths for various heat exchange fluids to heat and cool components.

  6. High temperature ceramic membrane reactors for coal liquid upgrading

    SciTech Connect

    Tsotsis, T.T.

    1992-01-01

    In this project we intend to study a novel process concept, i.e, the use of ceramic membranes reactors in upgrading of coal derived liquids. Membrane reactors have been used in a number of catalytic reaction processes in order to overcome the limitations on conversion imposed by thermodynamic equilibrium. They have, furthermore, the inherent capability for combining reaction and separation in a single step. Thus they offer promise for improving and optimizing yield, selectivity and performance of processes involving complex liquids, as those typically found in coal liquid upgrading. Ceramic membranes are a new class of materials, which have shown promise in a variety of industrial applications. Their mechanical and chemical stability coupled with a wide range of operating temperatures and pressures make them suitable for environments found in coal liquid upgrading. In this project we will evaluate the performance of Sol-Gel alumina membranes in coal liquid upgrading processes under realistic temperature and pressure conditions and investigate the feasibility of using such membranes in a membrane reactor based coal liquid upgrading process. In addition, the development of novel ceramic membranes with enhanced catalytic activity for coal-liquid upgrading applications, such as carbon-coated alumina membranes, will be also investigated.

  7. High temperature ceramic membrane reactors for coal liquid upgrading

    SciTech Connect

    Tsotsis, T.T.

    1992-01-01

    In this project we intend to study a novel process concept, i.e.,the use of ceramic membranes reactors in upgrading of coal derived liquids. Membrane reactors have been used in a number of catalytic reaction processes in order to overcome the limitations on conversion imposed by thermodynamic equilibrium. They have, furthermore, the inherent capability for combining reaction and separation in a single step. Thus they offer promise for improving and optimizing yield, selectivity and performance of processes involving complex liquids, as those typically found in coal liquid upgrading. Ceramic membranes are a new class of materials, which have shown promise in a variety of industrial applications. Their mechanical and chemical stability coupled with a wide range of operating temperatures and pressures make them suitable for environments found in coal liquid upgrading. In this project we wig evaluate the performance of Sel-Gel alumina membranes in coal liquid upgrading processes under realistic temperature and pressure conditions and investigate the feasibility of using such membranes in a membrane reactor based coal liquid upgrading process. In addition, the development of novel ceramic membranes with enhanced catalytic activity for coal-liquid upgrading applications, such as carbon-coated alumina membranes, will be also investigated.

  8. Process feasibility, operational parameters and modeling of reverse osmosis membrane systems for the separation and concentration of hazardous, complex industrial wastes

    SciTech Connect

    Slater, C.S.

    1983-01-01

    Reverse osmosis (RO) was applied successfully to the renovation of complex and hazardous industrial wastewaters. Few others have had success in applying RO to the treatment of these high-strength wastewaters, including industrial landfill leachates. Because of the nature of these hazardous waste streams, difficulties are encountered if the RO treatment scheme is not designed or operated for the immediate purpose. The RO system consists of tubular cellulose acetate membranes that can operate in several process modes. The more functional process concentrates the feed, allowing the membrane to separate increments of

  9. The ReactorAFM: Non-contact atomic force microscope operating under high-pressure and high-temperature catalytic conditions

    SciTech Connect

    Roobol, S. B.; Cañas-Ventura, M. E.; Bergman, M.; Spronsen, M. A. van; Onderwaater, W. G.; Tuijn, P. C. van der; Koehler, R.; Frenken, J. W. M.; Ofitserov, A.; Baarle, G. J. C. van

    2015-03-15

    An Atomic Force Microscope (AFM) has been integrated in a miniature high-pressure flow reactor for in-situ observations of heterogeneous catalytic reactions under conditions similar to those of industrial processes. The AFM can image model catalysts such as those consisting of metal nanoparticles on flat oxide supports in a gas atmosphere up to 6 bar and at a temperature up to 600 K, while the catalytic activity can be measured using mass spectrometry. The high-pressure reactor is placed inside an Ultrahigh Vacuum (UHV) system to supplement it with standard UHV sample preparation and characterization techniques. To demonstrate that this instrument successfully bridges both the pressure gap and the materials gap, images have been recorded of supported palladium nanoparticles catalyzing the oxidation of carbon monoxide under high-pressure, high-temperature conditions.

  10. Catalytic ignition of hydrogen/oxygen

    NASA Technical Reports Server (NTRS)

    Green, James M.; Zurawski, Robert L.

    1988-01-01

    An experimental program was conducted to evaluate the catalytic ignition of gaseous hydrogen and oxygen. Shell 405 granular catalyst and a unique monolithic sponge catalyst were tested. Mixture ratio, mass flow rate, propellant inlet temperature, and back pressure were varied parametrically in testing to determine the operational limits of a catalytic igniter. The test results showed that the gaseous hydrogen/oxygen propellant combination can be ignited catalytically using Shell 405 catalyst over a wide range of mixture ratios, mass flow rates, and propellant injection temperatures. These operating conditions must be optimized to ensure reliable ignition for an extended period of time. The results of the experimental program and the established operational limits for a catalytic igniter using both the granular and monolithic catalysts are presented. The capabilities of a facility constructed to conduct the igniter testing and the advantages of a catalytic igniter over other ignition systems for gaseous hydrogen and oxygen are also discussed.

  11. Magnetic Membrane System

    DOEpatents

    McElfresh, Michael W.; ; Lucas, Matthew S.

    2004-12-30

    The present invention provides a membrane with magnetic particles. In one embodiment the membrane is created by mixing particles in a non-magnetic base. The membrane may act as an actuator, a sensor, a pump, a valve, or other device. A magnet is operatively connected to the membrane. The magnet acts on and changes the shape of the membrane.

  12. Membrane bioreactor (MBR) sludge inoculation in a hybrid process scheme concept to assist overloaded conventional activated sludge (CAS) process operations.

    PubMed

    Fenu, A; Roels, J; Van Damme, S; Wambecq, T; Weemaes, M; Thoeye, C; De Gueldre, G; Van De Steene, B

    2012-01-01

    This study analyzes the effect of inoculating membrane bioreactor (MBR) sludge in a parallel-operated overloaded conventional activated sludge (CAS) system. Modelling studies that showed the beneficial effect of this inoculation were confirmed though full scale tests. Total nitrogen (TN) removal in the CAS increased and higher nitrate formation rates were achieved. During MBR sludge inoculation, the TN removal in the CAS was proven to be dependent on MBR sludge loading. Special attention was given to the effect of inoculation on sludge quality. The MBR flocs, grown without selection pressure, were clearly distinct from the more compact flocs in the CAS system and also contained more filamentous bacteria. After inoculation the MBR flocs did not evolve into good-settling compact flocs, resulting in a decreasing sludge quality. During high flow conditions the effluent CAS contained more suspended solids. Sludge volume index, however, did not increase. Laboratory tests were held to determine the threshold volume of MBR sludge to be seeded into the CAS reactor. Above 16-30%, supernatant turbidity and scum formation increased markedly.

  13. High temperature ceramic membrane reactors for coal liquid upgrading

    SciTech Connect

    Tsotsis, T.T.

    1992-01-01

    Membrane reactors have been used in a number of catalytic reaction processes in order to overcome the limitations on conversion imposed by thermodynamic equilibrium. Having the inherent capability for combining reaction and separation in a single step, they offer promise for improving and optimizing yield, selectivity and performance of processes involving complex liquids, such as these typically found in coal liquid upgrading. Ceramic membranes are a new class of materials, which have shown promise in a variety of industrial applications. Their mechanical and chemical stability coupled with a wide range of operating temperatures and pressures make them suitable for environments found in coal liquid upgrading. This project will evaluate the performance of Sol-Gel alumina membranes in coal liquid upgrading processes under realistic temperature and pressure conditions and investigate the feasibility of using such membranes in a membrane reactor based coal liquid upgrading process. Development of novel ceramic membranes with enhanced catalytic activity for coal-liquid upgrading applications, such as carbon-coated alumina membranes, will be also investigated.

  14. Raney nickel catalytic device

    DOEpatents

    O'Hare, Stephen A.

    1978-01-01

    A catalytic device for use in a conventional coal gasification process which includes a tubular substrate having secured to its inside surface by expansion a catalytic material. The catalytic device is made by inserting a tubular catalytic element, such as a tubular element of a nickel-aluminum alloy, into a tubular substrate and heat-treating the resulting composite to cause the tubular catalytic element to irreversibly expand against the inside surface of the substrate.

  15. Performance of able-bodied subjects on a text-typing task using a head-operated device and expanded membrane cursor keys.

    PubMed

    Capilouto, Gilson J; McClenaghan, Bruce; Williams, Harriet G; Dickerson, John; Hussey, James R

    2004-02-01

    Children and adults with disabilities frequently rely on computers to complete written tasks. Those with significant motor limitations typically use alternative computer-input devices since the traditional keyboard and mouse are insufficient to accommodate their abilities. For persons unable to isolate their fingers, input devices controlled by movements of the head or whole hand or arm movements may be among the options considered. This study investigated the performance of a head-operated device and expanded membrane cursor keys for text entry. Data from 24 young adults indicated the head-operated device performed significantly faster given reduced cognitive demands for device operation, increased stimulus-response compatibility, and simplicity of movement. Use of the expanded membrane cursor keys resulted in significantly lower error rates. No significant differences in comfort or ease of use were reported for the two devices. The relative performance of device options for users sharing similar motor challenges provides rehabilitation specialists with important clinical information.

  16. Definition and validation of operating equations for poly(vinyl alcohol)-poly(lactide-co-glycolide) microfiltration membrane-scaffold bioreactors.

    PubMed

    Shipley, R J; Waters, S L; Ellis, M J

    2010-10-01

    The aim of this work is to provide operating data for biodegradable hollow fiber membrane bioreactors. The physicochemical cell culture environment can be controlled with the permeate flowrate, so this aim necessitates the provision of operating equations that enable end-users to set the pressures and feed flowrates to obtain their desired culture environment. In this paper, theoretical expressions for the pure water retentate and permeate flowrates, derived using lubrication theory, are compared against experimental data for a single fiber poly(vinyl alcohol)-poly(lactide-co-glycolide) crossflow module to give values for the membrane permeability and slip. Analysis of the width of the boundary layer region where slip effects are important, together with the sensitivity of the retentate and permeate equations to the slip parameter, show that slip is insignificant for these membranes, which have a mean pore diameter of 1.1 microm. The experimental data is used to determine a membrane permeability, of k = 1.86 x 10(-16) m(2), and to validate the model. It was concluded that the operating equation that relates the permeate to feed ratio, c, lumen inlet flowrate, Q (l,in), lumen outlet pressure, P (1), and ECS outlet pressure, P (0), is P(1) - P(0) = Q(l),in (Ac + B) where A and B are constants that depend on the membrane permeability and geometry (and are given explicitly). Finally, two worked examples are presented to demonstrate how a tissue engineer can use Equation (1) to specify operating conditions for their bioreactor.

  17. CATALYTIC OXIDATION OF GROUNDWATER STRIPPING EMISSIONS

    EPA Science Inventory

    The paper reviews the applicability of catalytic oxidation to control ground-water air stripping gaseous effluents, with special attention to system designs and case histories. The variety of contaminants and catalyst poisons encountered in stripping operations are also reviewed....

  18. Towards neat methanol operation of direct methanol fuel cells: a novel self-assembled proton exchange membrane.

    PubMed

    Li, Jing; Cai, Weiwei; Ma, Liying; Zhang, Yunfeng; Chen, Zhangxian; Cheng, Hansong

    2015-04-18

    We report here a novel proton exchange membrane with remarkably high methanol-permeation resistivity and excellent proton conductivity enabled by carefully designed self-assembled ionic conductive channels. A direct methanol fuel cell utilizing the membrane performs well with a 20 M methanol solution, very close to the concentration of neat methanol.

  19. Loss of autoinhibition of the plasma membrane Ca(2+) pump by substitution of aspartic 170 by asparagin. A ctivation of plasma membrane calcium ATPase 4 without disruption of the interaction between the catalytic core and the C-terminal regulatory domain.

    PubMed

    Bredeston, Luis M; Adamo, Hugo P

    2004-10-01

    The plasma membrane calcium ATPase (PMCA) actively transports Ca(2+) from the cytosol to the extra cellular space. The C-terminal segment of the PMCA functions as an inhibitory domain by interacting with the catalytic core. Ca(2+)-calmodulin binds to the C-terminal segment and stops inhibition. Here we showed that residue Asp(170), in the putative "A" domain of human PMCA isoform 4xb, plays a critical role in autoinhibition. In the absence of calmodulin a PMCA containing a site-specific mutation of D170N had 80% of the maximum activity of the calmodulin-activated PMCA and a similar high affinity for Ca(2+). The mutation did not change the activation of the PMCA by ATP. Deletion of the C-terminal segment further downstream of the calmodulin-binding site led to an additional increase in the maximal activity of the mutant, which suggests that the mutation did not affect the inhibition because of this portion of the C-terminal segment. The calmodulin-activated PMCA was more sensitive to vanadate inhibition than the autoinhibited enzyme. In contrast, inhibition of the D170N mutant required higher concentrations of vanadate and was not affected by calmodulin. Despite its higher basal activity, the mutant had an apparent affinity for calmodulin similar to that of the wild type enzyme, and its rate of proteolysis at the C-terminal segment was still calmodulin-dependent. Altogether these results suggest that activation by mutation D170N does not involve the displacement of the calmodulin-binding autoinhibitory domain from the catalytic core and may arise directly from changes in the accessibility to the calcium-binding residues of the pump.

  20. Catalytic distillation water recovery subsystem

    NASA Technical Reports Server (NTRS)

    Budininkas, P.; Rasouli, F.

    1985-01-01

    An integrated engineering breadboard subsystem for the recovery of potable water from untreated urine based on the vapor phase catalytic ammonia removal was designed, fabricated and tested. Unlike other evaporative methods, this process catalytically oxidizes ammonia and volatile hydrocarbons vaporizing with water to innocuous products; therefore, no pretreatment of urine is required. Since the subsystem is fabricated from commercially available components, its volume, weight and power requirements are not optimized; however, it is suitable for zero-g operation. The testing program consists of parametric tests, one month of daily tests and a continuous test of 168 hours duration. The recovered water is clear, odorless, low in ammonia and organic carbon, and requires only an adjustment of its pH to meet potable water standards. The obtained data indicate that the vapor phase catalytic ammonia removal process, if further developed, would also be competitive with other water recovery systems in weight, volume and power requirements.

  1. Membrane position control

    NASA Technical Reports Server (NTRS)

    Su, Ji (Inventor); Harrison, Joycelyn S. (Inventor)

    2004-01-01

    A membrane structure includes at least one electroactive bending actuator fixed to a supporting base. Each electroactive bending actuator is operatively connected to the membrane for controlling membrane position. Any displacement of each electroactive bending actuator effects displacement of the membrane. More specifically, the operative connection is provided by a guiding wheel assembly and a track, wherein displacement of the bending actuator effects translation of the wheel assembly along the track, thereby imparting movement to the membrane.

  2. Membranes from monopole operators in ABJM theory: Large angular momentum and M-theoretic AdS4/CFT3

    NASA Astrophysics Data System (ADS)

    Kovacs, Stefano; Sato, Yuki; Shimada, Hidehiko

    2014-09-01

    We study the duality between M-theory in AdS_4 × S^7/{Z}_k and the ABJM {N}=6 Chern-Simons-matter theory with gauge group U(N) × {U}(N) and level k, taking N large and k of order 1. In this M-theoretic regime the lack of an explicit formulation of M-theory in AdS_4 × S^7/{Z}_k makes the gravity side difficult, while the CFT is strongly coupled and the planar approximation is not applicable. We focus on states on the gravity side with large angular momentum J≫ 1 associated with a single plane of rotation in S^7 and identify their dual operators in the CFT. We show that natural approximation schemes arise on both sides thanks to the presence of the small parameter 1/J. On the AdS side, we use the matrix model of M-theory on the maximally supersymmetric pp-wave background with matrices of size J/k. A perturbative treatment of this matrix model provides a good approximation to M-theory in AdS_4 × S^7/{Z}_k when N^{1/3}≪ J≪ N^{1/2}. On the CFT side, we study the theory on S^2× {R} with magnetic flux J/k. A Born-Oppenheimer-type expansion arises naturally for large J in spite of the theory being strongly coupled. The energy spectra on the two sides agree at leading order. This provides a non-trivial test of the AdS_4/CFT_3 correspondence including near-BPS observables associated with membrane degrees of freedom, thus verifying the duality beyond the previously studied sectors corresponding to either BPS observables or the type IIA string regime.

  3. Dual-Electrode CMUT With Non-Uniform Membranes for High Electromechanical Coupling Coefficient and High Bandwidth Operation

    PubMed Central

    Guldiken, Rasim O.; Zahorian, Jaime; Yamaner, F. Y.; Degertekin, F. L.

    2010-01-01

    In this paper, we report measurement results on dual-electrode CMUT demonstrating electromechanical coupling coefficient (k2) of 0.82 at 90% of collapse voltage as well as 136% 3 dB one-way fractional bandwidth at the transducer surface around the design frequency of 8 MHz. These results are within 5% of the predictions of the finite element simulations. The large bandwidth is achieved mainly by utilizing a non-uniform membrane, introducing center mass to the design, whereas the dual-electrode structure provides high coupling coefficient in a large dc bias range without collapsing the membrane. In addition, the non-uniform membrane structure improves the transmit sensitivity of the dual-electrode CMUT by about 2dB as compared with a dual electrode CMUT with uniform membrane. PMID:19574135

  4. Dual-electrode CMUT with non-uniform membranes for high electromechanical coupling coefficient and high bandwidth operation.

    PubMed

    Guldiken, Rasim O; Zahorian, Jaime; Yamaner, F Y; Degertekin, F Levent

    2009-06-01

    In this paper, we report measurement results on dual-electrode CMUT demonstrating electromechanical coupling coefficient (k(2)) of 0.82 at 90% of collapse voltage as well as 136% 3 dB one-way fractional bandwidth at the transducer surface around the design frequency of 8 MHz. These results are within 5% of the predictions of the finite element simulations. The large bandwidth is achieved mainly by utilizing a non-uniform membrane, introducing center mass to the design, whereas the dual-electrode structure provides high coupling coefficient in a large dc bias range without collapsing the membrane. In addition, the non-uniform membrane structure improves the transmit sensitivity of the dual-electrode CMUT by about 2dB as compared with a dual electrode CMUT with uniform membrane.

  5. Membrane gas absorbers for H2S removal--design, operation and technology integration into existing odour treatment strategies.

    PubMed

    Jefferson, B; Nazareno, C; Georgaki, S; Gostelow, P; Stuetz, R M; Longhurst, P; Robinson, T

    2005-07-01

    A hollow fibre (HF) polypropylene membrane gas absorber was investigated for the removal of hydrogen sulphide (H2S) from gas streams. Gas concentrations between 25-2010 ppmV were fed into the shell side of a membrane module whilst water-NaOH solutions flowed counter-currently in the fibre lumens. The process was effective at removing the H2S (96% at G:L ratios up to 50 and pH 13) from the gas phase in a single pass through the membrane at all the concentrations of HaS investigated. Analysis of the mass transfer process revealed the rate of transfer to be controlled by the gas phase transfer coefficient with a value between 1 and 25 x 10(-4) m.s(-1). The possible integration of a membrane absorber system into existing odour treatment strategies was assessed by comparing the membrane system, based on the experimentally determined mass transfer coefficient, with existing full scale biofiltration plants. The membrane system became economically favourable at gas flow rates lower than 1630 m(3) x h(-1).

  6. Diesel engine catalytic combustor system. [aircraft engines

    NASA Technical Reports Server (NTRS)

    Ream, L. W. (Inventor)

    1984-01-01

    A low compression turbocharged diesel engine is provided in which the turbocharger can be operated independently of the engine to power auxiliary equipment. Fuel and air are burned in a catalytic combustor to drive the turbine wheel of turbine section which is initially caused to rotate by starter motor. By opening a flapper value, compressed air from the blower section is directed to catalytic combustor when it is heated and expanded, serving to drive the turbine wheel and also to heat the catalytic element. To start, engine valve is closed, combustion is terminated in catalytic combustor, and the valve is then opened to utilize air from the blower for the air driven motor. When the engine starts, the constituents in its exhaust gas react in the catalytic element and the heat generated provides additional energy for the turbine section.

  7. Operations

    ERIC Educational Resources Information Center

    Wilkins, Jesse L. M.; Norton, Anderson; Boyce, Steven J.

    2013-01-01

    Previous research has documented schemes and operations that undergird students' understanding of fractions. This prior research was based, in large part, on small-group teaching experiments. However, written assessments are needed in order for teachers and researchers to assess students' ways of operating on a whole-class scale. In this study,…

  8. Comparative study of the active cadmium efflux systems operating at the plasma membrane and tonoplast of cucumber root cells.

    PubMed

    Migocka, Magdalena; Papierniak, Anna; Kosatka, Ewelina; Klobus, Grazyna

    2011-10-01

    The strategies developed by plants to avoid the toxicity of cadmium (Cd) and other heavy metals involve active sequestration of metals into the apoplast and vacuoles. The protein systems excluding heavy metals from the cell cytosol localize to the plasma membrane and tonoplast and are energized either by ATP or by the electrochemical gradient generated by H(+)-ATPase or by V-ATPase and pyrophosphatase (PPase), respectively. In this work, a comparative study on the contribution of both the plasma membrane and tonoplast in the active detoxification of plant cells after treatment with Cd was performed. The studies using plants treated and untreated with Cd reveal that both, H(+)-coupled and MgATP-driven efflux of Cd across plasma membranes and tonoplast is markedly stimulated in the presence of Cd in the environment. Previous studies on plasma-membrane localized H(+)-coupled Cd efflux together with the present data demonstrating tonoplast H(+)/Cd(2+) antiport activity suggest that H(+)-coupled secondary transport of Cd displays a lower affinity for Cd when compared with Cd primary pumps driven by MgATP. In addition, it is shown that MgATP-energized Cd efflux across both membranes is significantly enhanced by cysteine, dithiothreitol, and glutathione. These results suggest that Cd is excluded from the cytosol through an energy-dependent system as a free ion as well as a complexed form. Although both membranes contribute in the active exclusion of ionized and complexed Cd from the cytosol, the overall calculation of Cd accumulation in the everted plasma membranes and vacuolar vesicles suggests that the tonoplast and vacuole have a major function in Cd efflux from the cytosol in the roots of cucumber subjected to Cd stress.

  9. 40 CFR 63.1567 - What are my requirements for inorganic HAP emissions from catalytic reforming units?

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... demonstrate continuous compliance with the percent reduction operating limit, calculate the HCl operating... permissible HCl concentration for the percent reduction operating limit, ppmv; %HCl ReductionLimit = Minimum... Pollutants for Petroleum Refineries: Catalytic Cracking Units, Catalytic Reforming Units, and Sulfur...

  10. 40 CFR 63.1567 - What are my requirements for inorganic HAP emissions from catalytic reforming units?

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... demonstrate continuous compliance with the percent reduction operating limit, calculate the HCl operating... permissible HCl concentration for the percent reduction operating limit, ppmv; %HCl ReductionLimit = Minimum... Pollutants for Petroleum Refineries: Catalytic Cracking Units, Catalytic Reforming Units, and Sulfur...

  11. Switchable catalytic DNA catenanes.

    PubMed

    Hu, Lianzhe; Lu, Chun-Hua; Willner, Itamar

    2015-03-11

    Two-ring interlocked DNA catenanes are synthesized and characterized. The supramolecular catenanes show switchable cyclic catalytic properties. In one system, the catenane structure is switched between a hemin/G-quadruplex catalytic structure and a catalytically inactive state. In the second catenane structure the catenane is switched between a catalytically active Mg(2+)-dependent DNAzyme-containing catenane and an inactive catenane state. In the third system, the interlocked catenane structure is switched between two distinct catalytic structures that include the Mg(2+)- and the Zn(2+)-dependent DNAzymes.

  12. Navigating environmental, economic, and technological trade-offs in the design and operation of submerged anaerobic membrane bioreactors (AnMBRs).

    PubMed

    Pretel, R; Shoener, B D; Ferrer, J; Guest, J S

    2015-12-15

    Anaerobic membrane bioreactors (AnMBRs) enable energy recovery from wastewater while simultaneously achieving high levels of treatment. The objective of this study was to elucidate how detailed design and operational decisions of submerged AnMBRs influence the technological, environmental, and economic sustainability of the system across its life cycle. Specific design and operational decisions evaluated included: solids retention time (SRT), mixed liquor suspended solids (MLSS) concentration, sludge recycling ratio (r), flux (J), and specific gas demand per membrane area (SGD). The possibility of methane recovery (both as biogas and as soluble methane in reactor effluent) and bioenergy production, nutrient recovery, and final destination of the sludge (land application, landfill, or incineration) were also evaluated. The implications of these design and operational decisions were characterized by leveraging a quantitative sustainable design (QSD) framework which integrated steady-state performance modeling across seasonal temperatures (using pilot-scale experimental data and the simulating software DESASS), life cycle cost (LCC) analysis, and life cycle assessment (LCA). Sensitivity and uncertainty analyses were used to characterize the relative importance of individual design decisions, and to navigate trade-offs across environmental, economic, and technological criteria. Based on this analysis, there are design and operational conditions under which submerged AnMBRs could be net energy positive and contribute to the pursuit of carbon negative wastewater treatment.

  13. Enhanced treatment performance of coking wastewater and reduced membrane fouling using a novel EMBR.

    PubMed

    Jiang, Bei; Du, Cong; Shi, Shengnan; Tan, Liang; Li, Meidi; Liu, Jiaxin; Xue, Lanlan; Ji, Xiangyu

    2017-04-01

    A novel EMBR (electric field applied in MBR) by placing stainless steel mesh cathode inside a flat membrane module and stainless steel mesh anode outside the module was built and operated to enhance the treatment performance of coking wastewater containing phenol, pyridine and quinoline and reduce the membrane fouling. The degradation rates of COD, phenol, pyridine and quinoline in EMBR with electric field (reactor A) were significantly higher than the sum of EMBR without electric field (reactor B) and only electro-catalytic degradation during the long-term treatment, confirming that a coupling effect was existed between biodegradation and electro-catalytic degradation process. Illumina sequencing data revealed that bacterial community was richer and more diverse in reactor A. Comamonas strain JB as the inoculums was the most dominant genus in each reactor and electric field applied in reactor A further improved the abundance of strain JB. The membrane fouling in reactor A was reduced.

  14. Catalytically enhanced packed tower scrubbing

    SciTech Connect

    Stitt, E.H.; Taylor, F.J.; Kelly, K.

    1996-12-31

    An enhanced wet scrubbing process for the treatment of gas streams containing odours and low level VOC`s is presented. It comprises essentially a single scrubbing column and a fixed bed catalytic reactor through which the dilute alkaline bleach scrubbing liquor is recirculated. The process has significant cost advantages over conventional chemical scrubbing technology, and copes well with peaks in odour levels. Traditional bleach scrubbing, and the improvements in process chemistry and the flowsheet afforded by inclusion of the catalyst, are discussed. The catalyst enables many of the well known problems associated with bleach scrubbing to be overcome, and facilitates odour removal efficiencies of greater than 99% in a single column. Pilot plant data from trials on sewage treatment works are presented. These show clearly the ability of the catalytically enhanced process to achieve sulphide and odour removals in excess of 99% in the single column. Case studies of some of the existing commercial installations are given, indicating the wide range of applications, industries and scale of the installed units. Comparative data are presented, measured on a commercial unit for the conventional operation of a bleach scrubber, and with the retrofitted catalyst in use. These data show clearly the benefits of the catalytic process in terms of removal efficiencies; and hence by inference also in equipment size and costs. The catalytic process is also shown to achieve very high removal efficiencies of organo-sulphides in a single column. 8 refs., 3 figs., 10 tabs.

  15. Main problems in the theory of modeling of catalytic processes

    SciTech Connect

    Pisarenko, V.N.

    1994-09-01

    This paper formulates the main problems in the theory of modeling of catalytic processes yet to be solved and describes the stages of modeling. Fundamental problems of model construction for the physico-chemical phenomena and processes taking place in a catalytic reactor are considered. New methods for determining the mechanism of a catalytic reaction and selecting a kinetic model for it are analyzed. The use of the results of specially controlled experiments for the construction of models of a catalyst grain and a catalytic reactor is discussed. Algorithms are presented for determining the muliplicity of stationary states in the operation of a catalyst grain and a catalytic reactor.

  16. VOC Destruction by Catalytic Combustion Microturbine

    SciTech Connect

    Tom Barton

    2009-03-10

    This project concerned the application of a catalytic combustion system that has been married to a micro-turbine device. The catalytic combustion system decomposes the VOC's and transmits these gases to the gas turbine. The turbine has been altered to operate on very low-level BTU fuels equivalent to 1.5% methane in air. The performance of the micro-turbine for VOC elimination has some flexibility with respect to operating conditions, and the system is adaptable to multiple industrial applications. The VOC source that was been chosen for examination was the emissions from coal upgrading operations. The overall goal of the project was to examine the effectiveness of a catalytic combustion based system for elimination of VOCs while simultaneously producing electrical power for local consumption. Project specific objectives included assessment of the feasibility for using a Flex-Microturbine that generates power from natural gas while it consumes VOCs generated from site operations; development of an engineering plan for installation of the Flex-Microturbine system; operation of the micro-turbine through various changes in site and operation conditions; measurement of the VOC destruction quantitatively; and determination of the required improvements for further studies. The micro-turbine with the catalytic bed worked effectively to produce power on levels of fuel much lower than the original turbine design. The ability of the device to add or subtract supplemental fuel to augment the amount of VOC's in the inlet air flow made the device an effective replacement for a traditional flare. Concerns about particulates in the inlet flow and the presence of high sulfur concentrations with the VOC mixtures was identified as a drawback with the current catalytic design. A new microturbine design was developed based on this research that incorporates a thermal oxidizer in place of the catalytic bed for applications where particulates or contamination would limit the lifetime of

  17. Local potential evolutions during proton exchange membrane fuel cell operation with dead-ended anode - Part II: Aging mitigation strategies based on water management and nitrogen crossover

    NASA Astrophysics Data System (ADS)

    Abbou, S.; Dillet, J.; Maranzana, G.; Didierjean, S.; Lottin, O.

    2017-02-01

    Proton exchange membrane (PEM) fuel cells operate with dead-ended anode in order to reduce system cost and complexity when compared with hydrogen re-circulation systems. In the first part of this work, we showed that localized fuel starvation events may occur, because of water and nitrogen accumulation in the anode side, which could be particularly damaging to the cell performance. To prevent these degradations, the anode compartment must be purged which may lead to an overall system efficiency decrease because of significant hydrogen waste. In the second part, we present several purge strategies in order to minimize both hydrogen waste and membrane-electrode assembly degradations during dead-ended anode operation. A linear segmented cell with reference electrodes was used to monitor simultaneously the current density distribution along the gas channel and the time evolution of local anode and cathode potentials. To asses MEA damages, Platinum ElectroChemical Surface Area (ECSA) and cell performance were periodically measured. The results showed that dead-end mode operation with an anode plate maintained at a temperature 5 °C hotter than the cathode plate limits water accumulation in the anode side, reducing significantly purge frequency (and thus hydrogen losses) as well as MEA damages. As nitrogen contribution to hydrogen starvation is predominant in this thermal configuration, we also tested a microleakage solution to discharge continuously most the nitrogen accumulating in the anode side while ensuring low hydrogen losses and minimum ECSA losses provided the right microleakage flow rate is chosen.

  18. Development of membrane electrode assembly for high temperature proton exchange membrane fuel cell by catalyst coating membrane method

    NASA Astrophysics Data System (ADS)

    Liang, Huagen; Su, Huaneng; Pollet, Bruno G.; Pasupathi, Sivakumar

    2015-08-01

    Membrane electrode assembly (MEA), which contains cathode and anode catalytic layer, gas diffusion layers (GDL) and electrolyte membrane, is the key unit of a PEMFC. An attempt to develop MEA for ABPBI membrane based high temperature (HT) PEMFC is conducted in this work by catalyst coating membrane (CCM) method. The structure and performance of the MEA are examined by scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS) and I-V curve. Effects of the CCM preparation method, Pt loading and binder type are investigated for the optimization of the single cell performance. Under 160 °C and atmospheric pressure, the peak power density of the MEA, with Pt loading of 0.5 mg cm-2 and 0.3 mg cm-2 for the cathode and the anode, can reach 277 mW cm-2, while a current density of 620 A cm-2 is delivered at the working voltage of 0.4 V. The MEA prepared by CCM method shows good stability operating in a short term durability test: the cell voltage maintained at ∼0.45 V without obvious drop when operated at a constant current density of 300 mA cm-2 and 160 °C under ambient pressure for 140 h.

  19. Rich catalytic injection

    DOEpatents

    Veninger, Albert

    2008-12-30

    A gas turbine engine includes a compressor, a rich catalytic injector, a combustor, and a turbine. The rich catalytic injector includes a rich catalytic device, a mixing zone, and an injection assembly. The injection assembly provides an interface between the mixing zone and the combustor. The injection assembly can inject diffusion fuel into the combustor, provides flame aerodynamic stabilization in the combustor, and may include an ignition device.

  20. Local potential evolutions during proton exchange membrane fuel cell operation with dead-ended anode - Part I: Impact of water diffusion and nitrogen crossover

    NASA Astrophysics Data System (ADS)

    Abbou, S.; Dillet, J.; Maranzana, G.; Didierjean, S.; Lottin, O.

    2017-02-01

    Operating a PEMFC with a dead-ended anode may lead to local fuel-starvation because of water and possibly nitrogen accumulation in the anode compartment. In previous works, we used a segmented linear cell with reference electrodes to monitor simultaneously the local potentials and current densities during dead-ended anode operation. The results indicated that water transport as well as nitrogen crossover through the membrane were most probably the two key factors governing fuel starvation. In this first from a set of two papers, we evaluated with more details the contributions of nitrogen crossover and water transport to hydrogen starvation. To assess nitrogen contribution, the fuel cell cathode compartment was first supplied with pure oxygen instead of air. The results showed that in the absence of nitrogen (in the cathode side) the fuel starvation was much slower than with air, suggesting that nitrogen contribution cannot be neglected. On the other hand, the contribution of water flooding to hydrogen starvation was investigated by using different cooling temperature on the cathode and anode sides in order to drive water toward the colder plate. The results showed that with a colder anode side, fuel starvation was faster. In the opposite case of a hotter anode plate, water accumulation in the anode compartment was limited, nitrogen crossover through the membrane was the main reason for hydrogen starvation in this case. To fully assess the impact of the thermal configurations on membrane-electrode assembly (MEA) degradation, aging protocols with a dead-ended anode and a fixed closing time were also performed. The results showed that operation with a hotter anode could help to limit significantly cathode ElectroChemical Surface Area (ECSA) losses along the cell area and performance degradation induced by hydrogen starvation.

  1. Two stage catalytic combustor

    NASA Technical Reports Server (NTRS)

    Alvin, Mary Anne (Inventor); Bachovchin, Dennis (Inventor); Smeltzer, Eugene E. (Inventor); Lippert, Thomas E. (Inventor); Bruck, Gerald J. (Inventor)

    2010-01-01

    A catalytic combustor (14) includes a first catalytic stage (30), a second catalytic stage (40), and an oxidation completion stage (49). The first catalytic stage receives an oxidizer (e.g., 20) and a fuel (26) and discharges a partially oxidized fuel/oxidizer mixture (36). The second catalytic stage receives the partially oxidized fuel/oxidizer mixture and further oxidizes the mixture. The second catalytic stage may include a passageway (47) for conducting a bypass portion (46) of the mixture past a catalyst (e.g., 41) disposed therein. The second catalytic stage may have an outlet temperature elevated sufficiently to complete oxidation of the mixture without using a separate ignition source. The oxidation completion stage is disposed downstream of the second catalytic stage and may recombine the bypass portion with a catalyst exposed portion (48) of the mixture and complete oxidation of the mixture. The second catalytic stage may also include a reticulated foam support (50), a honeycomb support, a tube support or a plate support.

  2. Performance of a novel baffled osmotic membrane bioreactor-microfiltration hybrid system under continuous operation for simultaneous nutrient removal and mitigation of brine discharge.

    PubMed

    Pathak, Nirenkumar; Chekli, Laura; Wang, Jin; Kim, Youngjin; Phuntsho, Sherub; Li, Sheng; Ghaffour, Noreddine; Leiknes, TorOve; Shon, Hokyong

    2017-03-14

    The present study investigated the performance of an integrated osmotic and microfiltration membrane bioreactor system for wastewater treatment employing baffles in the reactor. Thus, this reactor design enables both aerobic and anoxic processes in an attempt to reduce the process footprint and energy costs associated with continuous aeration. The process performance was evaluated in terms of water flux, salinity build up in the bioreactor, organic and nutrient removal and microbial activity using synthetic reverse osmosis (RO) brine as draw solution (DS). The incorporation of MF membrane was effective in maintaining a reasonable salinity level (612-1434mg/L) in the reactor which resulted in a much lower flux decline (i.e. 11.48-6.98LMH) as compared to previous studies. The stable operation of the osmotic membrane bioreactor-forward osmosis (OMBR-FO) process resulted in an effective removal of both organic matter (97.84%) and nutrient (phosphate 87.36% and total nitrogen 94.28%), respectively.

  3. High temperature ceramic membrane reactors for coal liquid upgrading. Quarterly report No. 2, December 21, 1989--March 20, 1990

    SciTech Connect

    Tsotsis, T.T.

    1992-06-19

    Ceramic membranes are a new class of materials, which have shown promise in a variety of industrial applications. Their mechanical and chemical stability coupled with a wide range of operating temperatures and pressures make them suitable for environments found in coal liquid upgrading. In this project we will evaluate the performance of Sel-Gel alumina membranes in coal liquid upgrading processes under realistic temperature and pressure conditions and investigate the feasibility of using such membranes in a membrane reactor based coal liquid upgrading process. In addition, the development of novel ceramic membranes with enhanced catalytic activity for coal-liquid upgrading applications, such as carbon-coated alumina membranes, will be also investigated.

  4. High temperature ceramic membrane reactors for coal liquid upgrading. Quarterly report No. 8, June 21, 1991--September 20, 1991

    SciTech Connect

    Tsotsis, T.T.

    1992-06-19

    Ceramic membranes are a new class of materials, which have shown promise in a variety of industrial applications. Their mechanical and chemical stability coupled with a wide range of operating temperatures and pressures make them suitable for environments found in coal liquid upgrading. In this project we will evaluate the performance of Sel-Gel alumina membranes in coal liquid upgrading processes under realistic temperature and pressure conditions and investigate the feasibility of using such membranes in a membrane reactor based coal liquid upgrading process. In addition, the development of novel ceramic membranes with enhanced catalytic activity for coal-liquid upgrading applications, such as carbon-coated alumina membranes, will also be investigated.

  5. High temperature ceramic membrane reactors for coal liquid upgrading. Quarterly report No. 7, March 21, 1991--June 20, 1991

    SciTech Connect

    Tsotsis, T.T.

    1992-06-19

    Ceramic membranes are a new class of materials, which have shown promise in a variety of industrial applications. Their mechanical and chemical stability coupled with a wide range of operating temperatures and pressures make them suitable for environments found in coal liquid upgrading. In this project we will evaluate the performance of Sel-Gel alumina membranes in coal liquid upgrading processes under realistic temperature and pressure conditions and investigate the feasibility of using such membranes in a membrane reactor based coal liquid upgrading process. In addition, the development of novel ceramic membranes with enhanced catalytic activity for coal-liquid upgrading applications, such as carbon-coated alumina membranes, will be also investigated.

  6. Degradation effects in polymer electrolyte membrane fuel cell stacks by sub-zero operation-An in situ and ex situ analysis

    NASA Astrophysics Data System (ADS)

    Alink, R.; Gerteisen, D.; Oszcipok, M.

    The effect of low temperatures down to -40 °C on the performance and component properties of a polymer electrolyte membrane (PEM) fuel cell stack was investigated. By analyzing the temperature-dependent high-frequency resistance, the mechanism of ice formation within the stack was investigated during freeze/thaw (F/T) cycling while the stack was not operating and during a cold start-up. A step-like change in conductivity at 0 °C indicates that the membranes are dehydrated at sub-zero temperatures due to a change in capillary pressure at the interface membrane/catalyst. Furthermore, it was found that the stack shows little degradation when it is dried out before cooling down. Freezing in a wet state and additional cold start-ups resulted in performance degradation which was mainly attributed to changes in wetting properties. Ex situ environmental scanning electron microscope (ESEM) investigations showed distinct damage and increasing porosity of the electrode in the wet frozen stack, which was most likely the reason for the change in wetting properties. Inductively coupled plasma (ICP) mass spectroscopy showed distinct concentrations of platinum in the exhaust gas of the dry cycled stack, but no additional platinum was found when the stack was cycled in a wet state. Additional ex situ F/T investigations of gas diffusion layers (GDLs) and membrane electrode assemblies (MEAs) within an ESEM confirmed the results, found by in situ investigations of the fuel cell stacks. Serious detachment of electrode material was found without the compressive force applied to an assembly.

  7. Catalytic distillation structure

    DOEpatents

    Smith, Jr., Lawrence A.

    1984-01-01

    Catalytic distillation structure for use in reaction distillation columns, a providing reaction sites and distillation structure and consisting of a catalyst component and a resilient component intimately associated therewith. The resilient component has at least about 70 volume % open space and being present with the catalyst component in an amount such that the catalytic distillation structure consist of at least 10 volume % open space.

  8. Dual gas-diffusion membrane- and mediatorless dihydrogen/air-breathing biofuel cell operating at room temperature

    NASA Astrophysics Data System (ADS)

    Xia, Hong-qi; So, Keisei; Kitazumi, Yuki; Shirai, Osamu; Nishikawa, Koji; Higuchi, Yoshiki; Kano, Kenji

    2016-12-01

    A membraneless direct electron transfer (DET)-type dihydrogen (H2)/air-breathing biofuel cell without any mediator was constructed wherein bilirubin oxidase from Myrothecium verrucaria (BOD) and membrane-bound [NiFe] hydrogenase from Desulfovibrio vulgaris Miyazaki F (MBH) were used as biocatalysts for the cathode and the anode, respectively, and Ketjen black-modified water proof carbon paper (KB/WPCC) was used as an electrode material. The KB/WPCC surface was modified with 2-aminobenzoic acid and p-phenylenediamine, respectively, to face the positively charged electron-accepting site of BOD and the negatively charged electron-donating site of MBH to the electrode surface. A gas-diffusion system was employed for the electrodes to realize high-speed substrate supply. As result, great improvement in the current density of O2 reduction with BOD and H2 reduction with MBH were realized at negatively and postively charged surfaces, respectively. Gas diffusion system also suppressed the oxidative inactivation of MBH at high electrode potentials. Finally, based on the improved bioanode and biocathode, a dual gas-diffusion membrane- and mediatorless H2/air-breathing biofuel cell was constructed. The maximum power density reached 6.1 mW cm-2 (at 0.72 V), and the open circuit voltage was 1.12 V using 1 atm of H2 gas as a fuel at room temperature and under passive and quiescent conditions.

  9. Investigations on transfer of water and vanadium ions across Nafion membrane in an operating vanadium redox flow battery

    NASA Astrophysics Data System (ADS)

    Sun, Chenxi; Chen, Jian; Zhang, Huamin; Han, Xi; Luo, Qingtao

    Diffusion coefficients of the vanadium ions across Nafion 115 (Dupont) in a vanadium redox flow battery (VRFB) are measured and found to be in the order of V 2+ > VO 2+ > VO 2 + > V 3+. It is found that both in self-discharge process and charge-discharge cycles, the concentration difference of vanadium ions between the positive electrolyte (+ve) and negative electrolyte (-ve) is the main reason causing the transfer of vanadium ions across the membrane. In self-discharge process, the transfer of water includes the transfer of vanadium ions with the bound water and the corresponding transfer of protons with the dragged water to balance the charges, and the transfer of water driven by osmosis. In this case, about 75% of the net transfer of water is caused by osmosis. In charge-discharge cycles, except those as mentioned in the case of self-discharge, the transfer of protons with the dragged water across the membrane during the electrode reaction for the formation of internal electric circuit plays the key role in the water transfer. But in the long-term cycles of charge-discharge, the net transfer of water towards +ve is caused by the transfer of vanadium ions with the bound water and the transfer of water driven by osmosis.

  10. Optimum structural properties for an anode current collector used in a polymer electrolyte membrane water electrolyzer operated at the boiling point of water

    NASA Astrophysics Data System (ADS)

    Li, Hua; Fujigaya, Tsuyohiko; Nakajima, Hironori; Inada, Akiko; Ito, Kohei

    2016-11-01

    This study attempts to optimize the properties of the anode current collector of a polymer electrolyte membrane water electrolyzer at high temperatures, particularly at the boiling point of water. Different titanium meshes (4 commercial ones and 4 modified ones) with various properties are experimentally examined by operating a cell with each mesh under different conditions. The average pore diameter, thickness, and contact angle of the anode current collector are controlled in the ranges of 10-35 μm, 0.2-0.3 mm, and 0-120°, respectively. These results showed that increasing the temperature from the conventional temperature of 80 °C to the boiling point could reduce both the open circuit voltage and the overvoltages to a large extent without notable dehydration of the membrane. These results also showed that decreasing the contact angle and the thickness suppresses the electrolysis overvoltage largely by decreasing the concentration overvoltage. The effect of the average pore diameter was not evident until the temperature reached the boiling point. Using operating conditions of 100 °C and 2 A/cm2, the electrolysis voltage is minimized to 1.69 V with a hydrophilic titanium mesh with an average pore diameter of 21 μm and a thickness of 0.2 mm.

  11. Bioelectricity generation in an integrated system combining microbial fuel cell and tubular membrane reactor: effects of operation parameters performing a microbial fuel cell-based biosensor for tubular membrane bioreactor.

    PubMed

    Wang, Jie; Zheng, Yawen; Jia, Hui; Zhang, Hongwei

    2014-10-01

    A bio-cathode microbial fuel cell (MFC) with tubular membrane was integrated to construct a microbial fuel cell-tubular membrane bioreactor (MFC-TMBR) system, in which the bio-cathode MFC was developed as a biosensor for COD real-time monitoring in TMBR and the performance was analyzed in terms of its current variation caused by operation parameters. With a constant anode potential, the effect of HRT demonstrated that higher rate of mass transport increased the response of the system. The system was further explored an inverse relationship between TMP and current peak by using EPS concentration under the different MLSS concentration. The sensor output had a linear relationship with COD up to 1000mg/L (regression coefficient, R(2)=0.97) and MLSS (regression coefficient, R(2)=0.94). The simple and compact bio-cathode MFC biosensor for TMBR using MFC-TMBR integrated system showed promising potential for direct and economical COD online monitoring, and provided an opportunity to widen the application of MFC-based biosensor.

  12. A study on naphtha catalytic reforming reactor simulation and analysis.

    PubMed

    Liang, Ke-min; Guo, Hai-yan; Pan, Shi-wei

    2005-06-01

    A naphtha catalytic reforming unit with four reactors in series is analyzed. A physical model is proposed to describe the catalytic reforming radial flow reactor. Kinetics and thermodynamics equations are selected to describe the naphtha catalytic reforming reactions characteristics based on idealizing the complex naphtha mixture by representing the paraffin, naphthene, and aromatic groups by single compounds. The simulation results based above models agree very well with actual operation unit data.

  13. A study on naphtha catalytic reforming reactor simulation and analysis

    PubMed Central

    Liang, Ke-min; Guo, Hai-yan; Pan, Shi-wei

    2005-01-01

    A naphtha catalytic reforming unit with four reactors in series is analyzed. A physical model is proposed to describe the catalytic reforming radial flow reactor. Kinetics and thermodynamics equations are selected to describe the naphtha catalytic reforming reactions characteristics based on idealizing the complex naphtha mixture by representing the paraffin, naphthene, and aromatic groups by single compounds. The simulation results based above models agree very well with actual operation unit data. PMID:15909350

  14. Preparation of Pd-Loaded Hierarchical FAU Membranes and Testing in Acetophenone Hydrogenation.

    PubMed

    Molinari, Raffaele; Lavorato, Cristina; Mastropietro, Teresa F; Argurio, Pietro; Drioli, Enrico; Poerio, Teresa

    2016-03-22

    Pd-loaded hierarchical FAU (Pd-FAU) membranes, containing an intrinsic secondary non-zeolitic (meso)porosity, were prepared and tested in the catalytic transfer hydrogenation of acetophenone (AP) to produce phenylethanol (PE), an industrially relevant product. The best operating conditions were preliminarily identified by testing different solvents and organic hydrogen donors in a batch hydrogenation process where micron-sized FAU seeds were employed as catalyst support. Water as solvent and formic acid as hydrogen source resulted to be the best choice in terms of conversion for the catalytic hydrogenation of AP, providing the basis for the design of a green and sustainable process. The best experimental conditions were selected and applied to the Pd-loaded FAU membrane finding enhanced catalytic performance such as a five-fold higher productivity than with the unsupported Pd-FAU crystals (11.0 vs. 2.2 mgproduct gcat(-1)·h(-1)). The catalytic performance of the membrane on the alumina support was also tested in a tangential flow system obtaining a productivity higher than that of the batch system (22.0 vs. 11.0 mgproduct gcat(-1)·h(-1)).

  15. Modelling of operation of a lithium-air battery with ambient air and oxygen-selective membrane

    NASA Astrophysics Data System (ADS)

    Sahapatsombut, Ukrit; Cheng, Hua; Scott, Keith

    2014-03-01

    A macro-homogeneous model has been developed to evaluate the impact of replacing pure oxygen with ambient air on the performance of a rechargeable non-aqueous Li-air battery. The model exhibits a significant reduction in discharge capacity, e.g. from 1240 to 226 mAh gcarbon-1 at 0.05 mA cm-2 when using ambient air rather than pure oxygen. The model correlates the relationship between the performance and electrolyte decomposition and formation of discharge products (such as Li2O2 and Li2CO3) under ambient air conditions. The model predicts a great benefit of using an oxygen-selective membrane on increasing capacity. The results indicate a good agreement between the experimental data and the model.

  16. Enzymatic membrane reactor for full saccharification of ionic liquid-pretreated microcrystalline cellulose.

    PubMed

    Lozano, Pedro; Bernal, Berenice; Jara, Antonio G; Belleville, Marie-Pierre

    2014-01-01

    Ultrafiltration reactors based on polymeric or ceramic membranes were shown to be suitable catalytic systems for fast enzymatic saccharification of cellulose, allowing the full recovery and reuse of enzymes. By pre-treating cellulose with the IL 1-butyl-3-methylimidazolium chloride, the suitability of this substrate for enzymatic saccharification in a reactor based on polymeric ultrafiltration membranes was demonstrated, leading to 95% cellulose hydrolysis in 4h at 50°C. The filtration process gave a clear glucose solution (up to 113 mM) at constant permeate flow (24.7 L h(-1) m(-2)), allowing the enzyme to be reused for 9 operation cycles under semi-continuous operation, without any loss of enzyme activity. Under continuous operation mode and using ceramic ultrafiltration membranes at different residence times, the enzymatic reactor showed constant profiles in both the permeate flow rate and the glucose concentration, demonstrating the excellent suitability of the proposed approach for the saccharification of cellulose.

  17. Amorphous Alloy Membranes for High Temperature Hydrogen Separation

    SciTech Connect

    Coulter, K

    2013-09-30

    At the beginning of this project, thin film amorphous alloy membranes were considered a nascent but promising new technology for industrial-scale hydrogen gas separations from coal- derived syngas. This project used a combination of theoretical modeling, advanced physical vapor deposition fabricating, and laboratory and gasifier testing to develop amorphous alloy membranes that had the potential to meet Department of Energy (DOE) targets in the testing strategies outlined in the NETL Membrane Test Protocol. The project is complete with Southwest Research Institute® (SwRI®), Georgia Institute of Technology (GT), and Western Research Institute (WRI) having all operated independently and concurrently. GT studied the hydrogen transport properties of several amorphous alloys and found that ZrCu and ZrCuTi were the most promising candidates. GT also evaluated the hydrogen transport properties of V, Nb and Ta membranes coated with different transition-metal carbides (TMCs) (TM = Ti, Hf, Zr) catalytic layers by employing first-principles calculations together with statistical mechanics methods and determined that TiC was the most promising material to provide catalytic hydrogen dissociation. SwRI developed magnetron coating techniques to deposit a range of amorphous alloys onto both porous discs and tubular substrates. Unfortunately none of the amorphous alloys could be deposited without pinhole defects that undermined the selectivity of the membranes. WRI tested the thermal properties of the ZrCu and ZrNi alloys and found that under reducing environments the upper temperature limit of operation without recrystallization is ~250 °C. There were four publications generated from this project with two additional manuscripts in progress and six presentations were made at national and international technical conferences. The combination of the pinhole defects and the lack of high temperature stability make the theoretically identified most promising candidate amorphous alloys

  18. High temperature ceramic membrane reactors for coal liquid upgrading. Quarterly report No. 12, June 21, 1992--September 20, 1992

    SciTech Connect

    Tsotsis, T.T.

    1992-12-31

    In this project we intend to study a novel process concept, i.e.,the use of ceramic membranes reactors in upgrading of coal derived liquids. Membrane reactors have been used in a number of catalytic reaction processes in order to overcome the limitations on conversion imposed by thermodynamic equilibrium. They have, furthermore, the inherent capability for combining reaction and separation in a single step. Thus they offer promise for improving and optimizing yield, selectivity and performance of processes involving complex liquids, as those typically found in coal liquid upgrading. Ceramic membranes are a new class of materials, which have shown promise in a variety of industrial applications. Their mechanical and chemical stability coupled with a wide range of operating temperatures and pressures make them suitable for environments found in coal liquid upgrading. In this project we wig evaluate the performance of Sel-Gel alumina membranes in coal liquid upgrading processes under realistic temperature and pressure conditions and investigate the feasibility of using such membranes in a membrane reactor based coal liquid upgrading process. In addition, the development of novel ceramic membranes with enhanced catalytic activity for coal-liquid upgrading applications, such as carbon-coated alumina membranes, will be also investigated.

  19. High temperature ceramic membrane reactors for coal liquid upgrading. Quarter report No. 9, September 21, 1991--December 20, 1991

    SciTech Connect

    Tsotsis, T.T.

    1992-07-01

    In this project we intend to study a novel process concept, i.e, the use of ceramic membranes reactors in upgrading of coal derived liquids. Membrane reactors have been used in a number of catalytic reaction processes in order to overcome the limitations on conversion imposed by thermodynamic equilibrium. They have, furthermore, the inherent capability for combining reaction and separation in a single step. Thus they offer promise for improving and optimizing yield, selectivity and performance of processes involving complex liquids, as those typically found in coal liquid upgrading. Ceramic membranes are a new class of materials, which have shown promise in a variety of industrial applications. Their mechanical and chemical stability coupled with a wide range of operating temperatures and pressures make them suitable for environments found in coal liquid upgrading. In this project we will evaluate the performance of Sol-Gel alumina membranes in coal liquid upgrading processes under realistic temperature and pressure conditions and investigate the feasibility of using such membranes in a membrane reactor based coal liquid upgrading process. In addition, the development of novel ceramic membranes with enhanced catalytic activity for coal-liquid upgrading applications, such as carbon-coated alumina membranes, will be also investigated.

  20. Membrane reactor microstructure for polymer grade olefin production and hydrogen cogeneration.

    PubMed

    Ziaka, Zoe D; Navrozidou, Anna; Paraschopoulou, Louisa; Vasileiadis, Savvas P

    2010-09-01

    The current communication describes research work on effective membrane reactor nanostructures and nanoreaction-nanoseparation technology for polymer grade olefin production via catalytic paraffin dehydrogenation reactions. Emphasis is given in systems of permreactors and permeators to perform the described reactive and separative operations. We elaborate on new membrane microstructure designs for paraffin dehydrogenations including the design of experiments, operation, and best parameter selection and optimization of such systems. The described processes are of current significance in the area of new microreactor design and operation including hydrocarbon processing and conversion to valuable fuels and chemicals such as hydrogen, olefins, and polyolefins. These improved results are because of the unique design characteristics of the examined microreactor systems to perform accurate multiphase and heterogeneous functions into one unit operation. A number of membrane reactor configurations were made and tested on stream for the catalytic propane dehydrogenation reaction to propylene with successful results. Some of the results are discussed below which show the better performance of nanostructured membrane reactors for the specific dehydrogenation.

  1. Membrane technology as a promising alternative in biodiesel production: a review.

    PubMed

    Shuit, Siew Hoong; Ong, Yit Thai; Lee, Keat Teong; Subhash, Bhatia; Tan, Soon Huat

    2012-01-01

    In recent years, environmental problems caused by the use of fossil fuels and the depletion of petroleum reserves have driven the world to adopt biodiesel as an alternative energy source to replace conventional petroleum-derived fuels because of biodiesel's clean and renewable nature. Biodiesel is conventionally produced in homogeneous, heterogeneous, and enzymatic catalysed processes, as well as by supercritical technology. All of these processes have their own limitations, such as wastewater generation and high energy consumption. In this context, the membrane reactor appears to be the perfect candidate to produce biodiesel because of its ability to overcome the limitations encountered by conventional production methods. Thus, the aim of this paper is to review the production of biodiesel with a membrane reactor by examining the fundamental concepts of the membrane reactor, its operating principles and the combination of membrane and catalyst in the catalytic membrane. In addition, the potential of functionalised carbon nanotubes to serve as catalysts while being incorporated into the membrane for transesterification is discussed. Furthermore, this paper will also discuss the effects of process parameters for transesterification in a membrane reactor and the advantages offered by membrane reactors for biodiesel production. This discussion is followed by some limitations faced in membrane technology. Nevertheless, based on the findings presented in this review, it is clear that the membrane reactor has the potential to be a breakthrough technology for the biodiesel industry.

  2. Catalytic Microtube Rocket Igniter

    NASA Technical Reports Server (NTRS)

    Schneider, Steven J.; Deans, Matthew C.

    2011-01-01

    Devices that generate both high energy and high temperature are required to ignite reliably the propellant mixtures in combustion chambers like those present in rockets and other combustion systems. This catalytic microtube rocket igniter generates these conditions with a small, catalysis-based torch. While traditional spark plug systems can require anywhere from 50 W to multiple kW of power in different applications, this system has demonstrated ignition at less than 25 W. Reactants are fed to the igniter from the same tanks that feed the reactants to the rest of the rocket or combustion system. While this specific igniter was originally designed for liquid methane and liquid oxygen rockets, it can be easily operated with gaseous propellants or modified for hydrogen use in commercial combustion devices. For the present cryogenic propellant rocket case, the main propellant tanks liquid oxygen and liquid methane, respectively are regulated and split into different systems for the individual stages of the rocket and igniter. As the catalyst requires a gas phase for reaction, either the stored boil-off of the tanks can be used directly or one stream each of fuel and oxidizer can go through a heat exchanger/vaporizer that turns the liquid propellants into a gaseous form. For commercial applications, where the reactants are stored as gases, the system is simplified. The resulting gas-phase streams of fuel and oxidizer are then further divided for the individual components of the igniter. One stream each of the fuel and oxidizer is introduced to a mixing bottle/apparatus where they are mixed to a fuel-rich composition with an O/F mass-based mixture ratio of under 1.0. This premixed flow then feeds into the catalytic microtube device. The total flow is on the order of 0.01 g/s. The microtube device is composed of a pair of sub-millimeter diameter platinum tubes connected only at the outlet so that the two outlet flows are parallel to each other. The tubes are each

  3. A sustainable catalytic pyrrole synthesis

    NASA Astrophysics Data System (ADS)

    Michlik, Stefan; Kempe, Rhett

    2013-02-01

    The pyrrole heterocycle is a prominent chemical motif and is found widely in natural products, drugs, catalysts and advanced materials. Here we introduce a sustainable iridium-catalysed pyrrole synthesis in which secondary alcohols and amino alcohols are deoxygenated and linked selectively via the formation of C-N and C-C bonds. Two equivalents of hydrogen gas are eliminated in the course of the reaction, and alcohols based entirely on renewable resources can be used as starting materials. The catalytic synthesis protocol tolerates a large variety of functional groups, which includes olefins, chlorides, bromides, organometallic moieties, amines and hydroxyl groups. We have developed a catalyst that operates efficiently under mild conditions.

  4. Double-Side Co-Catalytic Activation of Anodic TiO2 Nanotube Membranes with Sputter-Coated Pt for Photocatalytic H2 Generation from Water/Methanol Mixtures.

    PubMed

    Cha, Gihoon; Altomare, Marco; Truong Nguyen, Nhat; Taccardi, Nicola; Lee, Kiyoung; Schmuki, Patrik

    2017-02-01

    Self-standing TiO2 nanotube layers in the form of membranes are fabricated by self-organizing anodization of Ti metal and a potential shock technique. The membranes are then decorated by sputtering different Pt amounts i) only at the top, ii) only at the bottom or iii) at both top and bottom of the tube layers. The Pt-decorated membranes are transferred either in tube top-up or in tube top-down configuration onto FTO slides and are investigated, after crystallization, as photocatalysts for H2 generation using either front or back-side light irradiation. Double-side Pt-decoration of the tube membranes leads to higher H2 generation rates (independently of tube and light-irradiation configuration) compared to membranes decorated at only one side with similar overall Pt amounts. The results suggest that this effect cannot be only ascribed to the overall amount of Pt co-catalyst as such but also to its distribution at both tube extremities. This leads to optimized light absorption and electron diffusion/transfer dynamics: the central part of the membranes acts as light-harvesting zone and electrons therein generated can diffuse towards the Pt/TiO2 active zones (tube extremities) where they can react with the environment and generate H2 .

  5. Catalytic distillation process

    DOEpatents

    Smith, L.A. Jr.

    1982-06-22

    A method is described for conducting chemical reactions and fractionation of the reaction mixture comprising feeding reactants to a distillation column reactor into a feed zone and concurrently contacting the reactants with a fixed bed catalytic packing to concurrently carry out the reaction and fractionate the reaction mixture. For example, a method for preparing methyl tertiary butyl ether in high purity from a mixed feed stream of isobutene and normal butene comprising feeding the mixed feed stream to a distillation column reactor into a feed zone at the lower end of a distillation reaction zone, and methanol into the upper end of said distillation reaction zone, which is packed with a properly supported cationic ion exchange resin, contacting the C[sub 4] feed and methanol with the catalytic distillation packing to react methanol and isobutene, and concurrently fractionating the ether from the column below the catalytic zone and removing normal butene overhead above the catalytic zone.

  6. Catalytic distillation process

    DOEpatents

    Smith, Jr., Lawrence A.

    1982-01-01

    A method for conducting chemical reactions and fractionation of the reaction mixture comprising feeding reactants to a distillation column reactor into a feed zone and concurrently contacting the reactants with a fixed bed catalytic packing to concurrently carry out the reaction and fractionate the reaction mixture. For example, a method for preparing methyl tertiary butyl ether in high purity from a mixed feed stream of isobutene and normal butene comprising feeding the mixed feed stream to a distillation column reactor into a feed zone at the lower end of a distillation reaction zone, and methanol into the upper end of said distillation reaction zone, which is packed with a properly supported cationic ion exchange resin, contacting the C.sub.4 feed and methanol with the catalytic distillation packing to react methanol and isobutene, and concurrently fractionating the ether from the column below the catalytic zone and removing normal butene overhead above the catalytic zone.

  7. Catalytic distillation structure

    DOEpatents

    Smith, L.A. Jr.

    1984-04-17

    Catalytic distillation structure is described for use in reaction distillation columns, and provides reaction sites and distillation structure consisting of a catalyst component and a resilient component intimately associated therewith. The resilient component has at least about 70 volume % open space and is present with the catalyst component in an amount such that the catalytic distillation structure consists of at least 10 volume % open space. 10 figs.

  8. Proton exchange membrane fuel cells with chromium nitridenanocrystals as electrocatalysts

    SciTech Connect

    Zhong, Hexiang; Chen, Xiaobo; Zhang, Huamin; Wang, Meiri; Mao,Samuel S.

    2007-07-01

    Polymer electrolyte membrane fuel cells (PEMFCs) are energy conversion devices that produce electricity from a supply of fuel, such as hydrogen. One of the major challenges in achieving efficient energy conversion is the development of cost-effective materials that can act as electrocatalysts for PEMFCs. In this letter, we demonstrate that, instead of conventional noble metals, such as platinum, chromium nitride nanocrystals of fcc structure exhibit attractive catalytic activity for PEMFCs. Device testing indicates good stability of nitride nanocrystals in low temperature fuel cell operational environment.

  9. Reactor process using metal oxide ceramic membranes

    DOEpatents

    Anderson, Marc A.

    1994-01-01

    A reaction vessel for use in photoelectrochemical reactions includes as its reactive surface a metal oxide porous ceramic membrane of a catalytic metal such as titanium. The reaction vessel includes a light source and a counter electrode. A provision for applying an electrical bias between the membrane and the counter electrode permits the Fermi levels of potential reaction to be favored so that certain reactions may be favored in the vessel. The electrical biasing is also useful for the cleaning of the catalytic membrane. Also disclosed is a method regenerating a porous metal oxide ceramic membrane used in a photoelectrochemical catalytic process by periodically removing the reactants and regenerating the membrane using a variety of chemical, thermal, and electrical techniques.

  10. Reactor process using metal oxide ceramic membranes

    DOEpatents

    Anderson, M.A.

    1994-05-03

    A reaction vessel for use in photoelectrochemical reactions includes as its reactive surface a metal oxide porous ceramic membrane of a catalytic metal such as titanium. The reaction vessel includes a light source and a counter electrode. A provision for applying an electrical bias between the membrane and the counter electrode permits the Fermi levels of potential reaction to be favored so that certain reactions may be favored in the vessel. The electrical biasing is also useful for the cleaning of the catalytic membrane. Also disclosed is a method regenerating a porous metal oxide ceramic membrane used in a photoelectrochemical catalytic process by periodically removing the reactants and regenerating the membrane using a variety of chemical, thermal, and electrical techniques. 2 figures.

  11. Porous media for catalytic renewable energy conversion

    NASA Astrophysics Data System (ADS)

    Hotz, Nico

    2012-05-01

    A novel flow-based method is presented to place catalytic nanoparticles into a reactor by sol-gelation of a porous ceramic consisting of copper-based nanoparticles, silica sand, ceramic binder, and a gelation agent. This method allows for the placement of a liquid precursor containing the catalyst into the final reactor geometry without the need of impregnating or coating of a substrate with the catalytic material. The so generated foam-like porous ceramic shows properties highly appropriate for use as catalytic reactor material, e.g., reasonable pressure drop due to its porosity, high thermal and catalytic stability, and excellent catalytic behavior. The catalytic activity of micro-reactors containing this foam-like ceramic is tested in terms of their ability to convert alcoholic biofuel (e.g. methanol) to a hydrogen-rich gas mixture with low concentrations of carbon monoxide (up to 75% hydrogen content and less than 0.2% CO, for the case of methanol). This gas mixture is subsequently used in a low-temperature fuel cell, converting the hydrogen directly to electricity. A low concentration of CO is crucial to avoid poisoning of the fuel cell catalyst. Since conventional Polymer Electrolyte Membrane (PEM) fuel cells require CO concentrations far below 100 ppm and since most methods to reduce the mole fraction of CO (such as Preferential Oxidation or PROX) have CO conversions of up to 99%, the alcohol fuel reformer has to achieve initial CO mole fractions significantly below 1%. The catalyst and the porous ceramic reactor of the present study can successfully fulfill this requirement.

  12. Functional nanofibers and membranes by electrospinning

    NASA Astrophysics Data System (ADS)

    Formo, Eric Victor

    This research focuses on advances in the fabrication of functional membranes through the process of electrospinning to either alter the arrangement or composition of nanofiber arrays. To control nanofiber arrangement, easily reconfigurable collectors were constructed that could direct the deposition over large areas (>50 cm2) and pattern the membranes into various designs, including parallel, fan-out, and spiral arrays. Subsequently, the composition of electrospun membranes was modified using the sol-gel method to yield fibers composed of TiO2 (anatase and rutile) and ZrO 2 (tetragonal) phases. Implementing the polyol reduction method, these nanofiber surfaces were coated with Pt, Pd, and Rh nanoparticles of 2-5 nm or Pt nanowires with lengths up to 125 nm. Interestingly, by calcining the ZrO2 at a lower temperature, the nanofibers could mediate the growth of Pt nanostars or Pt nanowires by adjusting the Pt precursor concentration in the polyol reduction bath. The anatase membranes could also be modified through the self-assembly of various silanes to give either thiol or amine surface groups. The functionalized membranes were then tested for a number of applications associated with the catalysis field. Specifically, anatase fiber membranes coated with Pt and Pd nanoparticles were used as catalysts in a continuous flow reactor for either hydrogenation or cross-coupling reactions, respectively, which was proven to operate with a high yield, a rapid flow rate, and were readily recyclable. The effects of both the coverage and morphology of the Pt-decorated anatase fibers on the methanol oxidation reaction were then studied. Nanofibers with a submonolayer of Pt nanoparticles or Pt nanowires were found to display improved catalytic durability over commercial Pt/C as determined by chronoamperometry. Further, by utilizing the oxygen reduction reaction, results showed that the Pt nanostars had superior electrochemical properties in comparison to Pt black. Finally, the

  13. Microbial community structure and dynamics in a pilot-scale submerged membrane bioreactor aerobically treating domestic wastewater under real operation conditions.

    PubMed

    Molina-Muñoz, M; Poyatos, J M; Sánchez-Peinado, M; Hontoria, E; González-López, J; Rodelas, B

    2009-06-15

    A pilot scale submerged ultra-filtration membrane bioreactor (MBR) was used for the aerobic treatment of domestic wastewater over 9 months of year 2006 (28th March to 21st December). The MBR was installed at a municipal wastewater facility (EMASAGRA, Granada, Spain) and was fed with real wastewater. The experimental work was divided in 4 stages run under different sets of operation conditions. Operation parameters (total and volatile suspended solids, dissolved oxygen concentration) and environmental variables (temperature, pH, COD and BOD(5) of influent water) were daily monitored. In all the experiments conducted, the MBR generated an effluent of optimal quality complying with the requirements of the European Law (91/271/CEE 1991). A cultivation-independent approach (polymerase chain reaction-temperature gradient gel electrophoresis, PCR-TGGE) was used to analyze changes in the structure of the bacterial communities in the sludge. Cluster analysis of TGGE profiles demonstrated significant differences in community structure related to variations of the operation parameters and environmental factors. Canonical correspondence analysis (CCA) suggested that temperature, hydraulic retention time and concentration of volatile suspended solids were the factors mostly influencing community structure. 23 prominent TGGE bands were successfully reamplified and sequenced, allowing gaining insight into the identities of predominantly present bacterial populations in the sludge. Retrieved partial 16S-rRNA gene sequences were mostly related to the alpha-Proteobacteria, beta-Proteobacteria and gamma-Proteobacteria classes. The community established in the MBR in each of the four stages of operation significantly differed in species composition and the sludge generated displayed dissimilar rates of mineralization, but these differences did not influence the performance of the bioreactor (quality of the permeate). These data indicate that the flexibility of the bacterial community

  14. Towards Enhanced Gas Sensor Performance with Fluoropolymer Membranes

    PubMed Central

    Graunke, Thorsten; Schmitt, Katrin; Raible, Stefan; Wöllenstein, Jürgen

    2016-01-01

    In this paper we report on how to increase the selectivity of gas sensors by using fluoropolymer membranes. The mass transport of polar and non-polar gases through a polymer membrane matrix was studied by systematic selection of polymers with different degrees of fluorination, as well as polymers whose monomers have ether groups (-O-) in addition to fluorine groups (-F). For the study, a set of application-relevant gases including H2, CO, CO2, NO2, methane, ethanol, acetone, and acetaldehyde as well as various concentrations of relative humidity were used. These gases have different functional groups and polarities, yet have a similar kinetic diameter and are therefore typically difficult to separate. The concentrations of the gases were chosen according to international indicative limit values (TWA, STEL). To measure the concentration in the feed and permeate, we used tin-dioxide-based metal oxide gas sensors with palladium catalyst (SnO2:Pd), catalytic sensors (also SnO2:Pd-based) and thermal conductivity sensors. This allows a close examination of the interdependence of diffusion and physicochemical operating principle of the sensor. Our goal is to increase the selectivity of gas sensors by using inexpensive fluoropolymer membranes. The measurements showed that through membranes with low polarity, preferably non-polar gases are transported. Furthermore, the degree of crystallization influences the permeability and selectivity of a polymer membrane. Basically the polar polymers showed a higher permeability to water vapor and polar substances than non-polar polymer membranes. PMID:27690045

  15. Efficient process for previous metal recovery from cell membrane electrode assemblies

    DOEpatents

    Shore, Lawrence; Matlin, Ramail; Heinz, Robert

    2010-05-04

    A method is provided for recovering a catalytic element from a fuel cell membrane electrode assembly. The method includes grinding the membrane electrode assembly into a powder, extracting the catalytic element by forming a slurry comprising the powder and an acid leachate adapted to dissolve the catalytic element into a soluble salt, and separating the slurry into a depleted powder and a supernatant containing the catalytic element salt. The depleted powder is washed to remove any catalytic element salt retained within pores in the depleted powder and the catalytic element is purified from the salt.

  16. High temperature ceramic membrane reactors for coal liquid upgrading. Quarterly report No. 11, March 21, 1992--June 20, 1992

    SciTech Connect

    Tsotsis, T.T.

    1992-12-31

    Membrane reactors have been used in a number of catalytic reaction processes in order to overcome the limitations on conversion imposed by thermodynamic equilibrium. Having the inherent capability for combining reaction and separation in a single step, they offer promise for improving and optimizing yield, selectivity and performance of processes involving complex liquids, such as these typically found in coal liquid upgrading. Ceramic membranes are a new class of materials, which have shown promise in a variety of industrial applications. Their mechanical and chemical stability coupled with a wide range of operating temperatures and pressures make them suitable for environments found in coal liquid upgrading. This project will evaluate the performance of Sol-Gel alumina membranes in coal liquid upgrading processes under realistic temperature and pressure conditions and investigate the feasibility of using such membranes in a membrane reactor based coal liquid upgrading process. Development of novel ceramic membranes with enhanced catalytic activity for coal-liquid upgrading applications, such as carbon-coated alumina membranes, will be also investigated.

  17. Transient analysis of gas transport in anode channel of a polymer electrolyte membrane fuel cell with dead-ended anode under pressure swing operation

    NASA Astrophysics Data System (ADS)

    Ichikawa, Yasushi; Oshima, Nobuyuki; Tabuchi, Yuichiro; Ikezoe, Keigo

    2014-12-01

    Further cost reduction is a critical issue for commercialization of fuel-cell electric vehicles (FCEVs) based on polymer electrolyte fuel cells (PEFCs). The cost of the fuel-cell system is driven by the multiple parts required to maximize stack performance and maintain durability and robustness. The fuel-cell system of the FCEV must be simplified while maintaining functionality. The dead-ended anode is considered as a means of simplification in this study. Generally, if hydrogen is supplied under constant pressure during dead-ended operation, stable power generation is impossible because of accumulation of liquid water produced by power generation and of nitrogen via leakage from the cathode through the membrane. Herein, pressure oscillation is applied to address this issue. Empirical and CFD data are employed to elucidate the mechanism of stable power generation using the pressure swing supply. Simultaneous and time-continuous measurements of the current distribution and gas concentration distribution are also conducted. The results demonstrate that the nitrogen concentration in the anode channel under pressure constant operation differs from that under pressure swing supply conditions. The transient two-dimensional CFD results indicate that oscillatory flow is generated by pressure swing supply, which periodically sweeps out nitrogen from the active area, resulting in stable power generation.

  18. Prevalence of Nitrosomonas cluster 7 populations in the ammonia-oxidizing community of a submerged membrane bioreactor treating urban wastewater under different operation conditions.

    PubMed

    Cerrone, F; Poyatos, J M; Molina-Muñoz, M; Cortés-Lorenzo, C; González-López, J; Rodelas, B

    2013-07-01

    A pilot-scale ultrafiltration membrane bioreactor (MBR) was used for the aerobic treatment of urban wastewater in four experimental stages influenced by seasonal temperature and different sets of operation conditions. The structure of the ammonia-oxidizing bacteria (AOB) community was profiled by temperature gradient gel electrophoresis (TGGE), based on the amplification and separation of partial ammonia-monoxygenase subunit A (amoA) genes. Canonical correspondence analysis revealed that temperature, hydraulic retention time and percentage of ammonia removal had a significant effect on the fingerprints of AOB communities. Phylogenetic analysis conducted on amoA/AmoA sequences of reamplified TGGE bands showed, however, that closely related ammonia-oxidizing populations inhabited the sludge of the MBR in all experimental stages. Nitrosomonas cluster 7 populations (N. europaea-N. eutropha cluster) prevailed under all conditions tested, even when the MBR was operated under complete biomass retention or at low temperatures, suggesting that the high ammonia concentrations in the system were determinant to select r-strategist AOB.

  19. Application of an automation system and a supervisory control and data acquisition (SCADA) system for the optimal operation of a membrane adsorption hybrid system.

    PubMed

    Smith, P J; Vigneswaran, S; Ngo, H H; Nguyen, H T; Ben-Aim, R

    2006-01-01

    The application of automation and supervisory control and data acquisition (SCADA) systems to municipal water and wastewater treatment plants is rapidly increasing. However, the application of these systems is less frequent in the research and development phases of emerging treatment technologies used in these industries. This study involved the implementation of automation and a SCADA system to the submerged membrane adsorption hybrid system for use in a semi-pilot scale research project. An incremental approach was used in the development of the automation and SCADA systems, leading to the development of two new control systems. The first system developed involved closed loop control of the backwash initiation, based upon a pressure increase, leading to productivity improvements as the backwash is only activated when required, not at a fixed time. This system resulted in a 40% reduction in the number of backwashes required and also enabled optimised operations under unsteady concentrations of wastewater. The second system developed involved closed loop control of the backwash duration, whereby the backwash was terminated when the pressure reached a steady state. This system resulted in a reduction of the duration of the backwash of up to 25% and enabled optimised operations as the foulant build-up within the reactor increased.

  20. SOFC system with integrated catalytic fuel processing

    NASA Astrophysics Data System (ADS)

    Finnerty, Caine; Tompsett, Geoff. A.; Kendall, Kevin; Ormerod, R. Mark

    In recent years, there has been much interest in the development of solid oxide fuel cell technology operating directly on hydrocarbon fuels. The development of a catalytic fuel processing system, which is integrated with the solid oxide fuel cell (SOFC) power source is outlined here. The catalytic device utilises a novel three-way catalytic system consisting of an in situ pre-reformer catalyst, the fuel cell anode catalyst and a platinum-based combustion catalyst. The three individual catalytic stages have been tested in a model catalytic microreactor. Both temperature-programmed and isothermal reaction techniques have been applied. Results from these experiments were used to design the demonstration SOFC unit. The apparatus used for catalytic characterisation can also perform in situ electrochemical measurements as described in previous papers [C.M. Finnerty, R.H. Cunningham, K. Kendall, R.M. Ormerod, Chem. Commun. (1998) 915-916; C.M. Finnerty, N.J. Coe, R.H. Cunningham, R.M. Ormerod, Catal. Today 46 (1998) 137-145]. This enabled the performance of the SOFC to be determined at a range of temperatures and reaction conditions, with current output of 290 mA cm -2 at 0.5 V, being recorded. Methane and butane have been evaluated as fuels. Thus, optimisation of the in situ partial oxidation pre-reforming catalyst was essential, with catalysts producing high H 2/CO ratios at reaction temperatures between 873 K and 1173 K being chosen. These included Ru and Ni/Mo-based catalysts. Hydrocarbon fuels were directly injected into the catalytic SOFC system. Microreactor measurements revealed the reaction mechanisms as the fuel was transported through the three-catalyst device. The demonstration system showed that the fuel processing could be successfully integrated with the SOFC stack.

  1. Catalytic hydrotreating process

    DOEpatents

    Karr, Jr., Clarence; McCaskill, Kenneth B.

    1978-01-01

    Carbonaceous liquids boiling above about 300.degree. C such as tars, petroleum residuals, shale oils and coal-derived liquids are catalytically hydrotreated by introducing the carbonaceous liquid into a reaction zone at a temperature in the range of 300.degree. to 450.degree. C and a pressure in the range of 300 to 4000 psig for effecting contact between the carbonaceous liquid and a catalytic transition metal sulfide in the reaction zone as a layer on a hydrogen permeable transition metal substrate and then introducing hydrogen into the reaction zone by diffusing the hydrogen through the substrate to effect the hydrogenation of the carbonaceous liquid in the presence of the catalytic sulfide layer.

  2. Synergize fuel and petrochemical processing plans with catalytic reforming

    SciTech Connect

    1997-03-01

    Depending on the market, refiner`s plans to produce clean fuels and higher value petrochemicals will weigh heavily on the catalytic reformer`s flexibility. It seems that as soon as a timely article related to catalytic reforming operations is published, a new {open_quotes}boutique{close_quotes} gasoline fuel specification is slapped on to existing fuel standards, affecting reformer operations and processing objectives. Just as importantly, the petrochemical market (such as aromatics) that refiners are targeting, can be very fickle. That`s why process engineers have endeavored to maintain an awareness of the flexibility that technology suppliers are building into modern catalytic reformers.

  3. Evolution of catalytic RNA in the laboratory

    NASA Technical Reports Server (NTRS)

    Joyce, Gerald F.

    1992-01-01

    We are interested in the biochemistry of existing RNA enzymes and in the development of RNA enzymes with novel catalytic function. The focal point of our research program has been the design and operation of a laboratory system for the controlled evolution of catalytic RNA. This system serves as working model of RNA-based life and can be used to explore the catalytic potential of RNA. Evolution requires the integration of three chemical processes: amplification, mutation, and selection. Amplification results in additional copies of the genetic material. Mutation operates at the level of genotype to introduce variability, this variability in turn being expressed as a range of phenotypes. Selection operates at the level of phenotype to reduce variability by excluding those individuals that do not conform to the prevailing fitness criteria. These three processes must be linked so that only the selected individuals are amplified, subject to mutational error, to produce a progeny distribution of mutant individuals. We devised techniques for the amplification, mutation, and selection of catalytic RNA, all of which can be performed rapidly in vitro within a single reaction vessel. We integrated these techniques in such a way that they can be performed iteratively and routinely. This allowed us to conduct evolution experiments in response to artificially-imposed selection constraints. Our objective was to develop novel RNA enzymes by altering the selection constraints in a controlled manner. In this way we were able to expand the catalytic repertoire of RNA. Our long-range objective is to develop an RNA enzyme with RNA replicase activity. If such an enzyme had the ability to produce additional copies of itself, then RNA evolution would operate autonomously and the origin of life will have been realized in the laboratory.

  4. Synthesis of UV-absorbing and fluorescent carrier ampholyte mixtures and their application for the determination of the operational pH values of buffering membranes used in isoelectric trapping separations.

    PubMed

    North, Robert; Hwang, Ann; Lalwani, Sanjiv; Shave, Evan; Vigh, Gyula

    2006-10-20

    Success in isoelectric trapping separations critically depends on the knowledge of the accurate operational pH value of the buffering membranes used. Currently, due to a lack of easy, rapid, accurate methods that can be used for the post-synthesis determination of the operational pH value of a buffering membrane, only nominal pH values calculated from the amounts of the reagents used in the synthesis of the membranes and their acid-base dissociation constants are available. To rectify this problem, UV-absorbing and fluorescent carrier ampholyte mixtures were prepared by alkylating pentaethylenehexamine with a chromophore and a fluorophore, followed by Michael addition of acrylic acid and itaconic acid to the resulting oligoamine. Carrier ampholyte mixtures, with evenly distributed absorbance values across the 3membrane to be characterized. The pI value of the most basic UV-absorbing or fluorescent carrier ampholyte collected in the anodic separation compartment, determined by full-column imaging capillary isoelectric focusing analysis, indicates the operational pH value of the separation membrane.

  5. Catalytic Combustor for Fuel-Flexible Turbine

    SciTech Connect

    W. R. Laster; E. Anoshkina

    2008-01-31

    Under the sponsorship of the U. S. Department of Energy's National Energy Technology Laboratory, Siemens Westinghouse has conducted a three-year program to develop an ultra low NOx, fuel flexible catalytic combustor for gas turbine application in IGCC. The program is defined in three phases: Phase 1 - Implementation Plan, Phase 2 - Validation Testing and Phase 3 - Field Testing. Both Phase 1 and Phase 2 of the program have been completed. In IGCC power plants, the gas turbine must be capable of operating on syngas as a primary fuel and an available back-up fuel such as natural gas. In this program the Rich Catalytic Lean (RCLTM) technology is being developed as an ultra low NOx combustor. In this concept, ultra low NOx is achieved by stabilizing a lean premix combustion process by using a catalytic reactor to oxidize a portion of the fuel, increasing the temperature of fuel/air mixture prior to the main combustion zone. In Phase 1, the feasibility of the catalytic concept for syngas application has been evaluated and the key technology issues identified. In Phase II the technology necessary for the application of the catalytic concept to IGCC fuels was developed through detailed design and subscale testing. Phase III (currently not funded) will consist of full-scale combustor basket testing on natural gas and syngas.

  6. Catalytic Combustor for Fuel-Flexible Turbine

    SciTech Connect

    Laster, W. R.; Anoshkina, E.

    2008-01-31

    Under the sponsorship of the U. S. Department of Energy’s National Energy Technology Laboratory, Siemens Westinghouse has conducted a three-year program to develop an ultra low NOx, fuel flexible catalytic combustor for gas turbine application in IGCC. The program is defined in three phases: Phase 1- Implementation Plan, Phase 2- Validation Testing and Phase 3 – Field Testing. Both Phase 1 and Phase 2 of the program have been completed. In IGCC power plants, the gas turbine must be capable of operating on syngas as a primary fuel and an available back-up fuel such as natural gas. In this program the Rich Catalytic Lean (RCLTM) technology is being developed as an ultra low NOx combustor. In this concept, ultra low NOx is achieved by stabilizing a lean premix combustion process by using a catalytic reactor to oxidize a portion of the fuel, increasing the temperature of fuel/air mixture prior to the main combustion zone. In Phase 1, the feasibility of the catalytic concept for syngas application has been evaluated and the key technology issues identified. In Phase II the technology necessary for the application of the catalytic concept to IGCC fuels was developed through detailed design and subscale testing. Phase III (currently not funded) will consist of full-scale combustor basket testing on natural gas and syngas.

  7. Catalytic Combustor for Fuel-Flexible Turbine

    SciTech Connect

    W. R. Laster; E. Anoshkina; P. Szedlacsek

    2006-03-31

    Under the sponsorship of the U.S. Department of Energy's National Energy Technology Laboratory, Siemens Westinghouse is conducting a three-year program to develop an ultra low NOx, fuel flexible catalytic combustor for gas turbine application in IGCC. The program is defined in three phases: Phase 1-Implementation Plan, Phase 2-Validation Testing and Phase 3-Field Testing. The Phase 1 program has been completed. Phase II was initiated in October 2004. In IGCC power plants, the gas turbine must be capable of operating on syngas as a primary fuel and an available back-up fuel such as natural gas. In this program the Rich Catalytic Lean (RCL{trademark}) technology is being developed as an ultra low NOx combustor. In this concept, ultra low NOx is achieved by stabilizing a lean premix combustion process by using a catalytic reactor to react part of the fuel, increasing the fuel/air mixture temperature. In Phase 1, the feasibility of the catalytic concept for syngas application has been evaluated and the key technology issues identified. In Phase II the catalytic concept will be demonstrated through subscale testing. Phase III will consist of full-scale combustor basket testing on natural gas and syngas.

  8. Steam reformer with catalytic combustor

    NASA Technical Reports Server (NTRS)

    Voecks, Gerald E. (Inventor)

    1990-01-01

    A steam reformer is disclosed having an annular steam reforming catalyst bed formed by concentric cylinders and having a catalytic combustor located at the center of the innermost cylinder. Fuel is fed into the interior of the catalytic combustor and air is directed at the top of the combustor, creating a catalytic reaction which provides sufficient heat so as to maintain the catalytic reaction in the steam reforming catalyst bed. Alternatively, air is fed into the interior of the catalytic combustor and a fuel mixture is directed at the top. The catalytic combustor provides enhanced radiant and convective heat transfer to the reformer catalyst bed.

  9. Steam reformer with catalytic combustor

    DOEpatents

    Voecks, Gerald E.

    1990-03-20

    A steam reformer is disclosed having an annular steam reforming catalyst bed formed by concentric cylinders and having a catalytic combustor located at the center of the innermost cylinder. Fuel is fed into the interior of the catalytic combustor and air is directed at the top of the combustor, creating a catalytic reaction which provides sufficient heat so as to maintain the catalytic reaction in the steam reforming catalyst bed. Alternatively, air is fed into the interior of the catalytic combustor and a fuel mixture is directed at the top. The catalytic combustor provides enhanced radiant and convective heat transfer to the reformer catalyst bed.

  10. Reactor vessel using metal oxide ceramic membranes

    DOEpatents

    Anderson, Marc A.; Zeltner, Walter A.

    1992-08-11

    A reaction vessel for use in photoelectrochemical reactions includes as its reactive surface a metal oxide porous ceramic membrane of a catalytic metal such as titanium. The reaction vessel includes a light source and a counter electrode. A provision for applying an electrical bias between the membrane and the counter electrode permits the Fermi levels of potential reaction to be favored so that certain reactions may be favored in the vessel. The electrical biasing is also useful for the cleaning of the catalytic membrane.

  11. Architecture and function of metallopeptidase catalytic domains

    PubMed Central

    Cerdà-Costa, Núria; Gomis-Rüth, Francesc Xavier

    2014-01-01

    The cleavage of peptide bonds by metallopeptidases (MPs) is essential for life. These ubiquitous enzymes participate in all major physiological processes, and so their deregulation leads to diseases ranging from cancer and metastasis, inflammation, and microbial infection to neurological insults and cardiovascular disorders. MPs cleave their substrates without a covalent intermediate in a single-step reaction involving a solvent molecule, a general base/acid, and a mono-or dinuclear catalytic metal site. Most monometallic MPs comprise a short metal-binding motif (HEXXH), which includes two metal-binding histidines and a general base/acid glutamate, and they are grouped into the zincin tribe of MPs. The latter divides mainly into the gluzincin and metzincin clans. Metzincins consist of globular ∼130–270-residue catalytic domains, which are usually preceded by N-terminal pro-segments, typically required for folding and latency maintenance. The catalytic domains are often followed by C-terminal domains for substrate recognition and other protein–protein interactions, anchoring to membranes, oligomerization, and compartmentalization. Metzincin catalytic domains consist of a structurally conserved N-terminal subdomain spanning a five-stranded β-sheet, a backing helix, and an active-site helix. The latter contains most of the metal-binding motif, which is here characteristically extended to HEXXHXXGXX(H,D). Downstream C-terminal subdomains are generally shorter, differ more among metzincins, and mainly share a conserved loop—the Met-turn—and a C-terminal helix. The accumulated structural data from more than 300 deposited structures of the 12 currently characterized metzincin families reviewed here provide detailed knowledge of the molecular features of their catalytic domains, help in our understanding of their working mechanisms, and form the basis for the design of novel drugs. PMID:24596965

  12. High temperature ceramic membrane reactors for coal liquid upgrading

    SciTech Connect

    Tsotsis, T.T.

    1992-06-19

    In this project we well evaluate the performance of Sel-Gel alumina membranes in coal liquid upgrading processes under realistic temperature and pressure conditions and investigate the feasibility of using such membranes in a membrane reactor based coal liquid upgrading process. In addition, the development of novel ceramic membranes with enhanced catalytic activity for coal-liquid upgrading applications, such as carbon-coated alumina membranes, will be also investigated. (VC)

  13. Catalytic efficiency of designed catalytic proteins

    PubMed Central

    Korendovych, Ivan V; DeGrado, William F

    2014-01-01

    The de novo design of catalysts that mimic the affinity and specificity of natural enzymes remains one of the Holy Grails of chemistry. Despite decades of concerted effort we are still unable to design catalysts as efficient as enzymes. Here we critically evaluate approaches to (re)design of novel catalytic function in proteins using two test cases: Kemp elimination and ester hydrolysis. We show that the degree of success thus far has been modest when the rate enhancements seen for the designed proteins are compared with the rate enhancements by small molecule catalysts in solvents with properties similar to the active site. Nevertheless, there are reasons for optimism: the design methods are ever improving and the resulting catalyst can be efficiently improved using directed evolution. PMID:25048695

  14. Catalytic coal liquefaction process

    DOEpatents

    Garg, D.; Sunder, S.

    1986-12-02

    An improved process for catalytic solvent refining or hydroliquefaction of non-anthracitic coal at elevated temperatures under hydrogen pressure in a solvent comprises using as catalyst a mixture of a 1,2- or 1,4-quinone and an alkaline compound, selected from ammonium, alkali metal, and alkaline earth metal oxides, hydroxides or salts of weak acids. 1 fig.

  15. Catalytic coal liquefaction process

    DOEpatents

    Garg, Diwakar; Sunder, Swaminathan

    1986-01-01

    An improved process for catalytic solvent refining or hydroliquefaction of non-anthracitic coal at elevated temperatures under hydrogen pressure in a solvent comprises using as catalyst a mixture of a 1,2- or 1,4-quinone and an alkaline compound, selected from ammonium, alkali metal, and alkaline earth metal oxides, hydroxides or salts of weak acids.

  16. Viral membrane fusion.

    PubMed

    Harrison, Stephen C

    2015-05-01

    Membrane fusion is an essential step when enveloped viruses enter cells. Lipid bilayer fusion requires catalysis to overcome a high kinetic barrier; viral fusion proteins are the agents that fulfill this catalytic function. Despite a variety of molecular architectures, these proteins facilitate fusion by essentially the same generic mechanism. Stimulated by a signal associated with arrival at the cell to be infected (e.g., receptor or co-receptor binding, proton binding in an endosome), they undergo a series of conformational changes. A hydrophobic segment (a "fusion loop" or "fusion peptide") engages the target-cell membrane and collapse of the bridging intermediate thus formed draws the two membranes (virus and cell) together. We know of three structural classes for viral fusion proteins. Structures for both pre- and postfusion conformations of illustrate the beginning and end points of a process that can be probed by single-virion measurements of fusion kinetics.

  17. Viral membrane fusion

    PubMed Central

    Harrison, Stephen C.

    2015-01-01

    Membrane fusion is an essential step when enveloped viruses enter cells. Lipid bilayer fusion requires catalysis to overcome a high kinetic barrier; viral fusion proteins are the agents that fulfill this catalytic function. Despite a variety of molecular architectures, these proteins facilitate fusion by essentially the same generic mechanism. Stimulated by a signal associated with arrival at the cell to be infected (e.g., receptor or co-receptor binding, proton binding in an endosome), they undergo a series of conformational changes. A hydrophobic segment (a “fusion loop” or “fusion peptide”) engages the target-cell membrane and collapse of the bridging intermediate thus formed draws the two membranes (virus and cell) together. We know of three structural classes for viral fusion proteins. Structures for both pre- and postfusion conformations of illustrate the beginning and end points of a process that can be probed by single-virion measurements of fusion kinetics. PMID:25866377

  18. Transport in a Microfluidic Catalytic Reactor

    SciTech Connect

    Park, H G; Chung, J; Grigoropoulos, C P; Greif, R; Havstad, M; Morse, J D

    2003-04-30

    A study of the heat and mass transfer, flow, and thermodynamics of the reacting flow in a catalytic microreactor is presented. Methanol reforming is utilized in the fuel processing system driving a micro-scale proton exchange membrane fuel cell. Understanding the flow and thermal transport phenomena as well as the reaction mechanisms is essential for improving the efficiency of the reforming process as well as the quality of the processed fuel. Numerical studies have been carried out to characterize the transport in a silicon microfabricated reactor system. On the basis of these results, optimized conditions for fuel processing are determined.

  19. Possible involvement of membrane lipids peroxidation and oxidation of catalytically essential thiols of the cerebral transmembrane sodium pump as component mechanisms of iron-mediated oxidative stress-linked dysfunction of the pump's activity.

    PubMed

    Omotayo, T I; Akinyemi, G S; Omololu, P A; Ajayi, B O; Akindahunsi, A A; Rocha, J B T; Kade, I J

    2015-01-01

    The precise molecular events defining the complex role of oxidative stress in the inactivation of the cerebral sodium pump in radical-induced neurodegenerative diseases is yet to be fully clarified and thus still open. Herein we investigated the modulation of the activity of the cerebral transmembrane electrogenic enzyme in Fe(2+)-mediated in vitro oxidative stress model. The results show that Fe(2+) inhibited the transmembrane enzyme in a concentration dependent manner and this effect was accompanied by a biphasic generation of aldehydic product of lipid peroxidation. While dithiothreitol prevented both Fe(2+) inhibitory effect on the pump and lipid peroxidation, vitamin E prevented only lipid peroxidation but not inhibition of the pump. Besides, malondialdehyde (MDA) inhibited the pump by a mechanism not related to oxidation of its critical thiols. Apparently, the low activity of the pump in degenerative diseases mediated by Fe(2+) may involve complex multi-component mechanisms which may partly involve an initial oxidation of the critical thiols of the enzyme directly mediated by Fe(2+) and during severe progression of such diseases; aldehydic products of lipid peroxidation such as MDA may further exacerbate this inhibitory effect by a mechanism that is likely not related to the oxidation of the catalytically essential thiols of the ouabain-sensitive cerebral electrogenic pump.

  20. Demonstration of catalytic combustion with residual fuel

    NASA Technical Reports Server (NTRS)

    Dodds, W. J.; Ekstedt, E. E.

    1981-01-01

    An experimental program was conducted to demonstrate catalytic combustion of a residual fuel oil. Three catalytic reactors, including a baseline configuration and two backup configurations based on baseline test results, were operated on No. 6 fuel oil. All reactors were multielement configurations consisting of ceramic honeycomb catalyzed with palladium on stabilized alumina. Stable operation on residual oil was demonstrated with the baseline configuration at a reactor inlet temperature of about 825 K (1025 F). At low inlet temperature, operation was precluded by apparent plugging of the catalytic reactor with residual oil. Reduced plugging tendency was demonstrated in the backup reactors by increasing the size of the catalyst channels at the reactor inlet, but plugging still occurred at inlet temperature below 725 K (845 F). Operation at the original design inlet temperature of 589 K (600 F) could not be demonstrated. Combustion efficiency above 99.5% was obtained with less than 5% reactor pressure drop. Thermally formed NO sub x levels were very low (less than 0.5 g NO2/kg fuel) but nearly 100% conversion of fuel-bound nitrogen to NO sub x was observed.

  1. Highly Selective H2 Separation Zeolite Membranes for Coal Gasification Membrane Reactor Applications

    SciTech Connect

    Mei Hong; Richard D. Noble; John L. Falconer

    2006-09-24

    Zeolite membranes are thermally, chemically, and mechanically stable. They also have tunable molecular sieving and catalytic ability. These unique properties make zeolite membrane an excellent candidate for use in catalytic membrane reactor applications related to coal conversion and gasification, which need high temperature and high pressure range separation in chemically challenging environment where existing technologies are inefficient or unable to operate. Small pore, good quality, and thin zeolite membranes are needed for highly selective H{sub 2} separation from other light gases (CO{sub 2}, CH{sub 4}, CO). However, zeolite membranes have not been successful for H{sub 2} separation from light gases because the zeolite pores are either too big or the membranes have a large number of defects. The objective of this study is to develop zeolite membranes that are more suitable for H{sub 2} separation. In an effort to tune the size of zeolite pores and/or to decrease the number of defects, medium-pore zeolite B-ZSM-5 (MFI) membranes were synthesized and silylated. Silylation on B-ZSM-5 crystals reduced MFI-zeolite pore volume, but had little effect on CO{sub 2} and CH{sub 4} adsorption. Silylation on B-ZSM-5 membranes increased H{sub 2} selectivity both in single component and in mixtures with CO{sub 2}CO{sub 2}, CH{sub 4}, or N2. Single gas and binary mixtures of H{sub 2}/CO{sub 2} and H{sub 2}/CH{sub 4} were separated through silylated B-ZSM-5 membranes at feed pressures up to 1.7 MPa and temperatures up to 773 K. For one BZSM-5 membrane after silylation, the H2/CO{sub 2} separation selectivity at 473 K increased from 1.4 to 37, whereas the H{sub 2}/CH{sub 4} separation selectivity increased from 1.6 to 33. Hydrogen permeance through a silylated B-ZSM-5 membrane was activated, but the CO{sub 2} and CH4 permeances decreased slightly with temperature in both single gas and in mixtures. Therefore, the H{sub 2} permeance and H{sub 2}/CO{sub 2} and H{sup 2} /CH{sub 4

  2. Proteins causing membrane fouling in membrane bioreactors.

    PubMed

    Miyoshi, Taro; Nagai, Yuhei; Aizawa, Tomoyasu; Kimura, Katsuki; Watanabe, Yoshimasa

    2015-01-01

    In this study, the details of proteins causing membrane fouling in membrane bioreactors (MBRs) treating real municipal wastewater were investigated. Two separate pilot-scale MBRs were continuously operated under significantly different operating conditions; one MBR was a submerged type whereas the other was a side-stream type. The submerged and side-stream MBRs were operated for 20 and 10 days, respectively. At the end of continuous operation, the foulants were extracted from the fouled membranes. The proteins contained in the extracted foulants were enriched by using the combination of crude concentration with an ultrafiltration membrane and trichloroacetic acid precipitation, and then separated by two-dimensional polyacrylamide gel electrophoresis (2D-PAGE). The N-terminal amino acid sequencing analysis of the proteins which formed intensive spots on the 2D-PAGE gels allowed us to partially identify one protein (OmpA family protein originated from genus Brevundimonas or Riemerella anatipestifer) from the foulant obtained from the submerged MBR, and two proteins (OprD and OprF originated from genus Pseudomonas) from that obtained from the side-stream MBR. Despite the significant difference in operating conditions of the two MBRs, all proteins identified in this study belong to β-barrel protein. These findings strongly suggest the importance of β-barrel proteins in developing membrane fouling in MBRs.

  3. Water Membrane Evaporator

    NASA Technical Reports Server (NTRS)

    Ungar, Eugene K.; Almlie, Jay C.

    2010-01-01

    A water membrane evaporator (WME) has been conceived and tested as an alternative to the contamination-sensitive and corrosion-prone evaporators currently used for dissipating heat from space vehicles. The WME consists mainly of the following components: An outer stainless-steel screen that provides structural support for the components mentioned next; Inside and in contact with the stainless-steel screen, a hydrophobic membrane that is permeable to water vapor; Inside and in contact with the hydrophobic membrane, a hydrophilic membrane that transports the liquid feedwater to the inner surface of the hydrophobic membrane; Inside and in contact with the hydrophilic membrane, an annular array of tubes through which flows the spacecraft coolant carrying the heat to be dissipated; and An inner exclusion tube that limits the volume of feedwater in the WME. In operation, a pressurized feedwater reservoir is connected to the volume between the exclusion tube and the coolant tubes. Feedwater fills the volume, saturates the hydrophilic membrane, and is retained by the hydrophobic membrane. The outside of the WME is exposed to space vacuum. Heat from the spacecraft coolant is conducted through the tube walls and the water-saturated hydrophilic membrane to the liquid/vapor interface at the hydrophobic membrane, causing water to evaporate to space. Makeup water flows into the hydrophilic membrane through gaps between the coolant tubes.

  4. Membrane stabilizer

    DOEpatents

    Mingenbach, William A.

    1988-01-01

    A device is provided for stabilizing a flexible membrane secured within a frame, wherein a plurality of elongated arms are disposed radially from a central hub which penetrates the membrane, said arms imposing alternately against opposite sides of the membrane, thus warping and tensioning the membrane into a condition of improved stability. The membrane may be an opaque or translucent sheet or other material.

  5. Catalytic, hollow, refractory spheres

    NASA Technical Reports Server (NTRS)

    Wang, Taylor G. (Inventor); Elleman, Daniel D. (Inventor); Lee, Mark C. (Inventor); Kendall, Jr., James M. (Inventor)

    1987-01-01

    Improved, heterogeneous, refractory catalysts are in the form of gas-impervious, hollow, thin-walled spheres (10) suitable formed of a shell (12) of refractory such as alumina having a cavity (14) containing a gas at a pressure greater than atmospheric pressure. The wall material may be itself catalytic or a catalytically active material coated onto the sphere as a layer (16), suitably platinum or iron, which may be further coated with a layer (18) of activator or promoter. The density of the spheres (30) can be uniformly controlled to a preselected value within .+-.10 percent of the density of the fluid reactant such that the spheres either remain suspended or slowly fall or rise through the liquid reactant.

  6. Catalytic thermal barrier coatings

    DOEpatents

    Kulkarni, Anand A.; Campbell, Christian X.; Subramanian, Ramesh

    2009-06-02

    A catalyst element (30) for high temperature applications such as a gas turbine engine. The catalyst element includes a metal substrate such as a tube (32) having a layer of ceramic thermal barrier coating material (34) disposed on the substrate for thermally insulating the metal substrate from a high temperature fuel/air mixture. The ceramic thermal barrier coating material is formed of a crystal structure populated with base elements but with selected sites of the crystal structure being populated by substitute ions selected to allow the ceramic thermal barrier coating material to catalytically react the fuel-air mixture at a higher rate than would the base compound without the ionic substitutions. Precious metal crystallites may be disposed within the crystal structure to allow the ceramic thermal barrier coating material to catalytically react the fuel-air mixture at a lower light-off temperature than would the ceramic thermal barrier coating material without the precious metal crystallites.

  7. Catalytic reforming catalyst

    SciTech Connect

    Buss, W.C.; Kluksdahl, H.E.

    1980-12-09

    An improved catalyst, having a reduced fouling rate when used in a catalytic reforming process, said catalyst comprising platinum disposed on an alumina support wherein the alumina support is obtained by removing water from aluminum hydroxide produced as a by-product from a ziegler higher alcohol synthesis reaction, and wherein the alumina is calcined at a temperature of 1100-1400/sup 0/F so as to have a surface area of 165 to 215 square meters per gram.

  8. Quenched catalytic cracking process

    SciTech Connect

    Krambeck, F.J.; Penick, J.E.; Schipper, P.H.

    1990-12-18

    This paper describes improvement in a fluidized catalytic cracking process wherein a fluidizable catalyst cracking catalyst and a hydrocarbon feed are charged to a reactor riser at catalytic riser cracking conditions to form catalytically cracked vapor product and spent catalyst which are discharged into a reactor vessel having a volume via a riser reactor outlet equipped with a separation means to produce a catalyst lean phase. It comprises: a majority of the cracked product, and a catalyst rich phase comprising a majority of the spend catalyst. The the catalyst rich phase is discharged into a dense bed of catalyst maintained below the riser outlet and the catalyst lean phase is discharged into the vessel for a time, and at a temperature, which cause unselective thermal cracking of the cracked product in the reactor volume before product is withdrawn from the vessel via a vessel outlet. The improvement comprises: addition, after riser cracking is completed, and after separation of cracked products from catalyst, of a quenching stream into the vessel above the dense bed of catalyst, via a quench stream addition point which allows the quench stream to contact at least a majority of the volume of the vessel above the dense bed.

  9. Membrane reactors at Degussa.

    PubMed

    Wöltinger, Jens; Karau, Andreas; Leuchtenberger, Wolfgang; Drauz, Karlheinz

    2005-01-01

    The review covers the development of membrane reactor technologies at Degussa for the synthesis of fine chemicals. The operation of fed-batch or continuous biocatalytic processes in the enzyme membrane reactor (EMR) is well established at Degussa. Degussa has experience of running EMRs from laboratory gram scale up to a production scale of several hundreds of tons per year. The transfer of the enzyme membrane reactor from biocatalysis to chemical catalysis in the chemzyme membrane reactor (CMR) is discussed. Various homogeneous catalysts have been investigated in the CMR, and the scope and limitation of this new technique is discussed.

  10. Anion exchange membrane

    DOEpatents

    Verkade, John G; Wadhwa, Kuldeep; Kong, Xueqian; Schmidt-Rohr, Klaus

    2013-05-07

    An anion exchange membrane and fuel cell incorporating the anion exchange membrane are detailed in which proazaphosphatrane and azaphosphatrane cations are covalently bonded to a sulfonated fluoropolymer support along with anionic counterions. A positive charge is dispersed in the aforementioned cations which are buried in the support to reduce the cation-anion interactions and increase the mobility of hydroxide ions, for example, across the membrane. The anion exchange membrane has the ability to operate at high temperatures and in highly alkaline environments with high conductivity and low resistance.

  11. 40 CFR 63.1564 - What are my requirements for metal HAP emissions from catalytic cracking units?

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... permissible hourly average Ni operating limit, percent-acfm-ppmw, i.e., your site-specific Ni operating limit....009 Where: Ni operating limit2 = Maximum permissible hourly average Ni operating limit, percent-ppmw... Petroleum Refineries: Catalytic Cracking Units, Catalytic Reforming Units, and Sulfur Recovery...

  12. Viral membrane fusion

    SciTech Connect

    Harrison, Stephen C.

    2015-05-15

    Membrane fusion is an essential step when enveloped viruses enter cells. Lipid bilayer fusion requires catalysis to overcome a high kinetic barrier; viral fusion proteins are the agents that fulfill this catalytic function. Despite a variety of molecular architectures, these proteins facilitate fusion by essentially the same generic mechanism. Stimulated by a signal associated with arrival at the cell to be infected (e.g., receptor or co-receptor binding, proton binding in an endosome), they undergo a series of conformational changes. A hydrophobic segment (a “fusion loop” or “fusion peptide”) engages the target-cell membrane and collapse of the bridging intermediate thus formed draws the two membranes (virus and cell) together. We know of three structural classes for viral fusion proteins. Structures for both pre- and postfusion conformations of illustrate the beginning and end points of a process that can be probed by single-virion measurements of fusion kinetics. - Highlights: • Viral fusion proteins overcome the high energy barrier to lipid bilayer merger. • Different molecular structures but the same catalytic mechanism. • Review describes properties of three known fusion-protein structural classes. • Single-virion fusion experiments elucidate mechanism.

  13. IFP solutions for revamping catalytic reforming units

    SciTech Connect

    Gendler, J.L.; Domergue, B.; Mank, L.

    1996-12-01

    The decision-making process for the refiner considering a revamp of a catalytic reforming unit comprises many factors. These may be grouped in two broad areas: technical and economic. This paper presents the results of a study performed by IFP that illustrates catalytic reforming unit revamp options. Three IFP processes are described and operating conditions, expected yields, and economic data are presented. The following options are discussed: base case Conventional, fixed-bed, semi-regenerative catalytic reformer; Case 1--revamp using IFP Dualforming technology; Case 2--revamp using IFP Dualforming Plus technology; and Case 3--revamp to IFP Octanizing technology. The study illustrates various options for the refiner to balance unit performance improvements with equipment, site, and economic constraints. The study was performed assuming design feedrate of 98.2 tons/hour (20,000 BPSD) in all cases. Because of the increased need for octane in many refineries, the study assumed that operating severity was set at a design value of 100 research octane number clear (RON). In all of the cases in this study, it was assumed that the existing recycle compressor was reused. Operating pressure differences between the cases is discussed separately. Also, in all cases, a booster compressor was included in order to return export hydrogen pressure to that of the conventional unit.

  14. Purification of reformer streams by catalytic hydrogenation

    SciTech Connect

    Polanek, P.J.; Hooper, H.M.; Mueller, J.; Walter, M.; Emmrich, G.

    1996-12-01

    Catalytic Reforming is one of the most important processes to produce high grade motor gasolines. Feedstocks are mainly gasoline and naphtha streams from the crude oil distillation boiling in the range of 212 F to 350 F. By catalytic reforming the octane number of these gasoline components is increased from 40--60 RON to 95--100 RON. Besides isomerization and dehydrocyclization reactions mainly formation of aromatics by dehydrogenation of naphthenes occur. Thus, catalytic reformers within refineries are an important source of BTX--aromatics (benzene, toluene, xylenes). Frequently, high purity aromatics are recovered from these streams using modern extractive distillation or liquid extraction processes, e.g. the Krupp-Koppers MORPHYLANE{reg_sign} process. Aromatics product specifications, notably bromine index and acid wash color, have obligated producers to utilize clay treatment to remove trace impurities of diolefins and/or olefins. The conventional clay treatment is a multiple vessel batch process which periodically requires disposal of the spent clay in a suitable environmental manner. BASF, in close cooperation with Krupp-Koppers, has developed a continuous Selective Catalytic Hydrogenation Process (SCHP) as an alternative to clay treatment which is very efficient, cost effective and environmentally compatible. In the following the main process aspects including the process scheme catalyst and operating conditions is described.

  15. Membrane projection lithography

    DOEpatents

    Burckel, David Bruce; Davids, Paul S; Resnick, Paul J; Draper, Bruce L

    2015-03-17

    The various technologies presented herein relate to a three dimensional manufacturing technique for application with semiconductor technologies. A membrane layer can be formed over a cavity. An opening can be formed in the membrane such that the membrane can act as a mask layer to the underlying wall surfaces and bottom surface of the cavity. A beam to facilitate an operation comprising any of implantation, etching or deposition can be directed through the opening onto the underlying surface, with the opening acting as a mask to control the area of the underlying surfaces on which any of implantation occurs, material is removed, and/or material is deposited. The membrane can be removed, a new membrane placed over the cavity and a new opening formed to facilitate another implantation, etching, or deposition operation. By changing the direction of the beam different wall/bottom surfaces can be utilized to form a plurality of structures.

  16. Zeolite membrane application in hydrocarbon processing

    SciTech Connect

    Suzuki, H.

    1988-06-01

    Zeolites are of great importance in hydrocarbon processing either as adsorbents or catalysts. This paper presents a research since 1973 about the transformation of zeolite into membrane zeolite, that dramatically contributes to the free world of peace and prosperity. Commercial and organic membranes are of two categories: anisotropic membrane, e.g. cellulose acetate, and composite membrane, e.g. plasma {und in}-{und situ} polymerization on polysulfone support. Zeolite membrane belongs to the latter category, zeolite {und in}-{und situ} hydrothermalization on porous glass. Basically zeolite membrane is consisted of three groups: (1) eight-oxygen ring window, zeolite A, (2) ten-oxygen ring window, Pentasil, and (3) twelve-oxygen ring window, Faujasite. The technology of zeolite membrane synthesis and subsequent treatment is almost transferred from the one applied to powder zeolites. Zeolite membrane is expected to play a major role in the field of hydrocarbon processing, that is, PSA, Distillation/Extraction, and Catalytic Reactions.

  17. Catalytic converter with thermoelectric generator

    SciTech Connect

    Parise, R.J.

    1998-07-01

    The unique design of an electrically heated catalyst (EHC) and the inclusion of an ECO valve in the exhaust of an internal combustion engine will meet the strict new emission requirements, especially at vehicle cold start, adopted by several states in this country as well as in Europe and Japan. The catalytic converter (CC) has been a most useful tool in pollution abatement for the automobile. But the emission requirements are becoming more stringent and, along with other improvements, the CC must be improved to meet these new standards. Coupled with the ECO valve, the EHC can meet these new emission limits. In an internal combustion engine vehicle (ICEV), approximately 80% of the energy consumed leaves the vehicle as waste heat: out the tail pipe, through the radiator, or convected/radiated off the engine. Included with the waste heat out the tail pipe are the products of combustion which must meet strict emission requirements. The design of a new CC is presented here. This is an automobile CC that has the capability of producing electrical power and reducing the quantity of emissions at vehicle cold start, the Thermoelectric Catalytic Power Generator. The CC utilizes the energy of the exothermic reactions that take place in the catalysis substrate to produce electrical energy with a thermoelectric generator. On vehicle cold start, the thermoelectric generator is used as a heat pump to heat the catalyst substrate to reduce the time to catalyst light-off. Thus an electrically heated catalyst (EHC) will be used to augment the abatement of tail pipe emissions. Included with the EHC in the exhaust stream of the automobile is the ECO valve. This valve restricts the flow of pollutants out the tail pipe of the vehicle for a specified amount of time until the EHC comes up to operating temperature. Then the ECO valve opens and allows the full exhaust, now treated by the EHC, to leave the vehicle.

  18. Low and medium heating value coal gas catalytic combustor characterization

    NASA Technical Reports Server (NTRS)

    Schwab, J. A.

    1982-01-01

    Catalytic combustion with both low and medium heating value coal gases obtained from an operating gasifier was demonstrated. A practical operating range for efficient operation was determined, and also to identify potential problem areas were identified for consideration during stationary gas turbine engine design. The test rig consists of fuel injectors, a fuel-air premixing section, a catalytic reactor with thermocouple instrumentation and a single point, water cooled sample probe. The test rig included inlet and outlet transition pieces and was designed for installation into an existing test loop.

  19. Polyethersulfone hollow fiber modified with poly(styrenesulfonate) and Pd nanoparticles for catalytic reaction

    NASA Astrophysics Data System (ADS)

    Emin, C.; Gu, Y.; Remigy, J.-C.; Lahitte, J.-F.

    2015-07-01

    The aim of this work is the synthesis of polymer-stabilized Pd nanoparticles (PdNP) inside a functionalized polymeric porous membrane in order to develop hybrid catalytic membrane reactors and to test them in model metal-catalyzed organic reactions. For this goal, a polymeric membrane support (Polyethersulfone hollow fiber-shaped) was firstly functionalized with an ionogenic polymer (i.e. poly(styrenesulfonate) capable to retain PdNP precursors using an UV photo-grafting method. PdNP were then generated inside the polymeric matrix by chemical reduction of precursor salts (intermatrix synthesis). The catalytic performance of the PdNP catalytic membranes was evaluated using reduction of nitrophenol by sodium borohydride (NaBH4) in water.

  20. Ammonia-treated Ordered Mesoporous Carbons as Catalytic Materials for Oxygen Reduction Reaction

    SciTech Connect

    Wang, Xiqing; Lee, Je Seung; Zhu, Qing; Liu, Jun; Wang, Yong; Dai, Sheng

    2010-04-13

    Polymer electrolyte membrane fuel cells (PEMFCs) have been considered as promising alternative power sources for many mobile and stationary applications. Compared to the fast hydrogen oxidation at the anode, the sluggish oxygen reduction reaction (ORR) at the cathode requires high-performance catalysts. Currently, platium (Pt) nanoparticles supported on high surface area carbons remain the best catalysts for ORR. However, both instability and high cost of Pt-based catalysts represent two main obstacles limiting the commercial applications of PEMFCs. The instability of supported Pt catalysts is mainly due to the corrosion of carbon support under operation conditions and the agglomation and detachment of Pt particles, leading to a decrease in catalytic surface areas. Development of corrosion resistant supports and enhancement of the interactions between Pt and supports are two strategies to improve the cathode long-term activity.

  1. Catalytic reforming process

    SciTech Connect

    Absil, R.P.; Huss, A. Jr.; McHale, W.D.; Partridge, R.D.

    1989-06-13

    This patent describes a catalytic reforming process which comprises contacting a naphtha range feed with a low acidity extrudate comprising an intermediate and/or a large pore acidic zeolite bound with a low acidity refractory oxide under reforming conditions to provide a reaction product of increased aromatic content, the extrudate having been prepared with at least an extrusion-facilitating amount of a low acidity refractory oxide in colloidal form and containing at least one metal species selected from the platinum group metals.

  2. MEMBRANE SYSTEM FOR RECOVERY OF VOLATILE ORGANIC COMPOUNDS FROM REMEDIATION OFF-GASES

    SciTech Connect

    J.G. Wijmans

    2003-11-17

    In situ vacuum extraction, air or steam sparging, and vitrification are widely used to remediate soil contaminated with volatile organic compounds (VOCs). All of these processes produce a VOC-laden air stream from which the VOC must be removed before the air can be discharged or recycled to the generating process. Treatment of these off-gases is often a major portion of the cost of the remediation project. Currently, carbon adsorption and catalytic incineration are the most common methods of treating these gas streams. Membrane Technology and Research, Inc. (MTR) proposed an alternative treatment technology based on selective membranes that separate the organic components from the gas stream, producing a VOC-free air stream. This technology can be applied to off-gases produced by various remediation activities and the systems can be skid-mounted and automated for easy transportation and unattended operation. The target performance for the membrane systems is to produce clean air (less than 10 ppmv VOC) for discharge or recycle, dischargeable water (less than 1 ppmw VOC), and a concentrated liquid VOC phase. This report contains the results obtained during Phase II of a two-phase project. In Phase I, laboratory experiments were carried out to demonstrate the feasibility of the proposed approach. In the subsequent Phase II project, a demonstration system was built and operated at the McClellan Air Force Base near Sacramento, California. The membrane system was fed with off-gas from a Soil Vacuum Extraction (SVE) system. The work performed in Phase II demonstrated that the membrane system can reduce the VOC concentration in remediation off-gas to 10 ppmv, while producing a concentrated VOC phase and dischargeable water containing less than 1 ppmw VOC. However, the tests showed that the presence of 1 to 3% carbon dioxide in the SVE off-gas reduced the treatment capacity of the system by a factor of three to four. In an economic analysis, treatment costs of the membrane

  3. Membrane stabilizer

    DOEpatents

    Mingenbach, W.A.

    1988-02-09

    A device is provided for stabilizing a flexible membrane secured within a frame, wherein a plurality of elongated arms are disposed radially from a central hub which penetrates the membrane, said arms imposing alternately against opposite sides of the membrane, thus warping and tensioning the membrane into a condition of improved stability. The membrane may be an opaque or translucent sheet or other material. 10 figs.

  4. Durability aspects of polymer electrolyte membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Sethuraman, Vijay Anand

    In order for the successful adoption of proton exchange membrane (PEM) fuel cell technology, it is imperative that durability is understood, quantified and improved. A number of mechanisms are known to contribute to PEMFC membrane electrode assembly (MEA) performance degradation. In this dissertation, we show, via experiments, some of the various processes that degrade the proton exchange membrane in a PEM fuel cell; and catalyst poisoning due to hydrogen sulfide (H2S) and siloxane. The effect of humidity on the chemical stability of two types of membranes, [i.e., perfluorosulfonic acid type (PFSA, NafionRTM 112) and biphenyl sulfone hydrocarbon type, (BPSH-35)] was studied by subjecting the MEAs to open-circuit voltage (OCV) decay and potential cycling tests at elevated temperatures and low inlet gas relative humidities. The BPSH-35 membranes showed poor chemical stability in ex situ Fenton tests compared to that of NafionRTM membranes. However, under fuel cell conditions, BPSH-35 MEAs outperformed NafionRTM 112 MEAs in both the OCV decay and potential cycling tests. For both membranes, (i) at a given temperature, membrane degradation was more pronounced at lower humidities and (ii) at a given relative humidity operation, increasing the cell temperature accelerated membrane degradation. Mechanical stability of these two types of membranes was also studied using relative humidity (RH) cycling. Hydrogen peroxide (H2O2) formation rates in a proton exchange membrane (PEM) fuel cell were estimated by studying the oxygen reduction reaction (ORR) on a rotating ring disc electrode (RRDE). Fuel cell conditions were replicated by depositing a film of Pt/Vulcan XC-72 catalyst onto the disk and by varying the temperature, dissolved O2 concentration and the acidity levels in HClO4. The HClO4 acidity was correlated to ionomer water activity and hence fuel cell humidity. H 2O2 formation rates showed a linear dependence on oxygen concentration and square dependence on water

  5. Recent Advances in Pd-Based Membranes for Membrane Reactors.

    PubMed

    Arratibel Plazaola, Alba; Pacheco Tanaka, David Alfredo; Van Sint Annaland, Martin; Gallucci, Fausto

    2017-01-01

    Palladium-based membranes for hydrogen separation have been studied by several research groups during the last 40 years. Much effort has been dedicated to improving the hydrogen flux of these membranes employing different alloys, supports, deposition/production techniques, etc. High flux and cheap membranes, yet stable at different operating conditions are required for their exploitation at industrial scale. The integration of membranes in multifunctional reactors (membrane reactors) poses additional demands on the membranes as interactions at different levels between the catalyst and the membrane surface can occur. Particularly, when employing the membranes in fluidized bed reactors, the selective layer should be resistant to or protected against erosion. In this review we will also describe a novel kind of membranes, the pore-filled type membranes prepared by Pacheco Tanaka and coworkers that represent a possible solution to integrate thin selective membranes into membrane reactors while protecting the selective layer. This work is focused on recent advances on metallic supports, materials used as an intermetallic diffusion layer when metallic supports are used and the most recent advances on Pd-based composite membranes. Particular attention is paid to improvements on sulfur resistance of Pd based membranes, resistance to hydrogen embrittlement and stability at high temperature.

  6. Highly Selective H2 Separation Zeolite Membranes for Coal Gasification Membrane Reactor Applications

    SciTech Connect

    Mei Hong; Richard Noble; John Falconer

    2007-09-24

    Zeolite membranes are thermally, chemically, and mechanically stable. They also have tunable molecular sieving and catalytic ability. These unique properties make zeolite membrane an excellent candidate for use in catalytic membrane reactor applications related to coal conversion and gasification, which need high temperature and high pressure range separation in chemically challenging environment where existing technologies are inefficient or unable to operate. Small pore, good quality, and thin zeolite membranes are needed for highly selective H2 separation from other light gases (CO2, CH4, CO). However, current zeolite membranes have either too big zeolite pores or a large number of defects and have not been successful for H2 separation from light gases. The objective of this study is to develop zeolite membranes that are more suitable for H2 separation. In an effort to tune the size of zeolite pores and/or to decrease the number of defects, medium-pore zeolite B-ZSM-5 (MFI) membranes were synthesized and silylated. Silylation on B-ZSM-5 crystals reduced MFI-zeolite pore volume, but had little effect on CO2 and CH4 adsorption. Silylation on B-ZSM-5 membranes increased H2 selectivity both in single component and in mixtures with CO2, CH4, or N2. Single gas and binary mixtures of H2/CO2 and H2/CH4 were permeated through silylated B-ZSM-5 membranes at feed pressures up to 1.7 MPa and temperatures up to 773 K. For one B-ZSM-5 membrane after silylation, the H2/CO2 separation selectivity at 473 K increased from 1.4 to 37, whereas the H2/CH4 separation selectivity increased from 1.6 to 33. Hydrogen permeance through a silylated BZSM-5 membrane was activated with activation energy of {approx}10 kJ/mol, but the CO2 and CH4 permeances decreased slightly with temperature in both single gas and in mixtures. Therefore, the H2 permeance and H2/CO2 and H2/CH4 separation selectivities increased with temperature. At 673 K, the H2 permeance was 1.0x10-7 mol{center_dot}m-2{center

  7. Method and apparatus for monitoring a hydrocarbon-selective catalytic reduction device

    DOEpatents

    Schmieg, Steven J; Viola, Michael B; Cheng, Shi-Wai S; Mulawa, Patricia A; Hilden, David L; Sloane, Thompson M; Lee, Jong H

    2014-05-06

    A method for monitoring a hydrocarbon-selective catalytic reactor device of an exhaust aftertreatment system of an internal combustion engine operating lean of stoichiometry includes injecting a reductant into an exhaust gas feedstream upstream of the hydrocarbon-selective catalytic reactor device at a predetermined mass flowrate of the reductant, and determining a space velocity associated with a predetermined forward portion of the hydrocarbon-selective catalytic reactor device. When the space velocity exceeds a predetermined threshold space velocity, a temperature differential across the predetermined forward portion of the hydrocarbon-selective catalytic reactor device is determined, and a threshold temperature as a function of the space velocity and the mass flowrate of the reductant is determined. If the temperature differential across the predetermined forward portion of the hydrocarbon-selective catalytic reactor device is below the threshold temperature, operation of the engine is controlled to regenerate the hydrocarbon-selective catalytic reactor device.

  8. Revolutionary systems for catalytic combustion and diesel catalytic particulate traps.

    SciTech Connect

    Stuecker, John Nicholas; Witze, Peter O.; Ferrizz, Robert Matthew; Cesarano, Joseph, III; Miller, James Edward

    2004-12-01

    This report is a summary of an LDRD project completed for the development of materials and structures conducive to advancing the state of the art for catalyst supports and diesel particulate traps. An ancillary development for bio-medical bone scaffolding was also realized. Traditionally, a low-pressure drop catalyst support, such as a ceramic honeycomb monolith, is used for catalytic reactions that require high flow rates of gases at high-temperatures. A drawback to the traditional honeycomb monoliths under these operating conditions is poor mass transfer to the catalyst surface in the straight-through channels. ''Robocasting'' is a unique process developed at Sandia National Laboratories that can be used to manufacture ceramic monoliths with alternative 3-dimensional geometries, providing tortuous pathways to increase mass transfer while maintaining low-pressure drops. These alternative 3-dimensional geometries may also provide a foundation for the development of self-regenerating supports capable of trapping and combusting soot particles from a diesel engine exhaust stream. This report describes the structures developed and characterizes the improved catalytic performance that can result. The results show that, relative to honeycomb monolith supports, considerable improvement in mass transfer efficiency is observed for robocast samples synthesized using an FCC-like geometry of alternating rods. Also, there is clearly a trade-off between enhanced mass transfer and increased pressure drop, which can be optimized depending on the particular demands of a given application. Practical applications include the combustion of natural gas for power generation, production of syngas, and hydrogen reforming reactions. The robocast lattice structures also show practicality for diesel particulate trapping. Preliminary results for trapping efficiency are reported as well as the development of electrically resistive lattices that can regenerate the structure by combusting the

  9. Catalytic cracking of hydrocarbons

    SciTech Connect

    Absil, R.P.L.; Bowes, E.; Green, G.J.; Marler, D.O.; Shihabi, D.S.; Socha, R.F.

    1992-02-04

    This patent describes an improvement in a catalytic cracking process in which a hydrocarbon feed is cracked in a cracking zone in the absence of added hydrogen and in the presence of a circulating inventory of solid acidic cracking a catalyst which acquires a deposit of coke that contains chemically bound nitrogen while the cracking catalyst is in the cracking zone, the coke catalyst being circulated to t regeneration zone to convert the coke catalyst to a regenerated catalyst with the formation of a flue gas comprising nitrogen oxides: the improvement comprises incorporating into the circulating catalyst inventory an amount of additive particles comprising a synthetic porous crystalline material containing copper metal or cations, to reduce the content of nitrogen oxides in the flue gas.

  10. Catalytic hollow spheres

    NASA Technical Reports Server (NTRS)

    Wang, Taylor G. (Inventor); Elleman, Daniel D. (Inventor); Lee, Mark C. (Inventor); Kendall, Jr., James M. (Inventor)

    1986-01-01

    The improved, heterogeneous catalysts are in the form of gas-impervious, hollow, thin-walled spheres (10) suitably formed of a shell (12) of metal such as aluminum having a cavity (14) containing a gas at a pressure greater than atmospheric pressure. The wall material may be, itself, catalytic or the catalyst can be coated onto the sphere as a layer (16), suitably platinum or iron, which may be further coated with a layer (18) of activator or promoter. The density of the spheres (30) can be uniformly controlled to a preselected value within .+-.10 percent of the density of the fluid reactant such that the spheres either remain suspended or slowly fall or rise through the liquid reactant.

  11. Catalytic hollow spheres

    NASA Technical Reports Server (NTRS)

    Wang, Taylor G. (Inventor); Elleman, Daniel D. (Inventor); Lee, Mark C. (Inventor); Kendall, Jr., James M. (Inventor)

    1989-01-01

    The improved, heterogeneous catalysts are in the form of gas-impervious, hollow, thin-walled spheres (10) suitably formed of a shell (12) of metal such as aluminum having a cavity (14) containing a gas at a pressure greater than atmospheric pressure. The wall material may be, itself, catalytic or the catalyst can be coated onto the sphere as a layer (16), suitably platinum or iron, which may be further coated with a layer (18) of activator or promoter. The density of the spheres (30) can be uniformly controlled to a preselected value within .+-.10 percent of the density of the fluid reactant such that the spheres either remain suspended or slowly fall or rise through the liquid reactant.

  12. Bifunctional catalytic electrode

    NASA Technical Reports Server (NTRS)

    Cisar, Alan (Inventor); Murphy, Oliver J. (Inventor); Clarke, Eric (Inventor)

    2005-01-01

    The present invention relates to an oxygen electrode for a unitized regenerative hydrogen-oxygen fuel cell and the unitized regenerative fuel cell having the oxygen electrode. The oxygen electrode contains components electrocatalytically active for the evolution of oxygen from water and the reduction of oxygen to water, and has a structure that supports the flow of both water and gases between the catalytically active surface and a flow field or electrode chamber for bulk flow of the fluids. The electrode has an electrocatalyst layer and a diffusion backing layer interspersed with hydrophilic and hydrophobic regions. The diffusion backing layer consists of a metal core having gas diffusion structures bonded to the metal core.

  13. Upgrading of Intermediate Bio-Oil Produced by Catalytic Pyrolysis

    SciTech Connect

    Abdullah, Zia; Chadwell, Brad; Taha, Rachid; Hindin, Barry; Ralston, Kevin

    2015-06-30

    The objectives of this project were to (1) develop a process to upgrade catalytic pyrolysis bio-oil, (2) investigate new upgrading catalysts suited for upgrading catalytic pyrolysis bio-oil, (3) demonstrate upgrading system operation for more than 1,000 hours using a single catalyst charge, and (4) produce a final upgraded product that can be blended to 30 percent by weight with petroleum fuels or that is compatible with existing petroleum refining operations. This project has, to the best of our knowledge, for the first time enabled a commercially viable bio-oil hydrotreatment process to produce renewable blend stock for transportation fuels.

  14. Cyclic membrane separation process

    DOEpatents

    Bowser, John

    2004-04-13

    A cyclic process for controlling environmental emissions of volatile organic compounds (VOC) from vapor recovery in storage and dispensing operations of liquids maintains a vacuum in the storage tank ullage. In one of a two-part cyclic process ullage vapor is discharged through a vapor recovery system in which VOC are stripped from vented gas with a selectively gas permeable membrane. In the other part, the membrane is inoperative while gas pressure rises in the ullage. Ambient air is charged to the membrane separation unit during the latter part of the cycle.

  15. Cyclic membrane separation process

    DOEpatents

    Nemser, Stuart M.

    2005-05-03

    A cyclic process for controlling environmental emissions of volatile organic compounds (VOC) from vapor recovery in storage and dispensing operations of liquids maintains a vacuum in the storage tank ullage. In the first part of a two-part cyclic process ullage vapor is discharged through a vapor recovery system in which VOC are stripped from vented gas with a selectively gas permeable membrane. In the second part, the membrane is inoperative while gas pressure rises in the ullage. In one aspect of this invention, a vacuum is drawn in the membrane separation unit thus reducing overall VOC emissions.

  16. Ultra Low NOx Catalytic Combustion for IGCC Power Plants

    SciTech Connect

    Shahrokh Etemad; Benjamin Baird; Sandeep Alavandi; William Pfefferle

    2008-03-31

    In order to meet DOE's goals of developing low-emissions coal-based power systems, PCI has further developed and adapted it's Rich-Catalytic Lean-burn (RCL{reg_sign}) catalytic reactor to a combustion system operating on syngas as a fuel. The technology offers ultra-low emissions without the cost of exhaust after-treatment, with high efficiency (avoidance of after-treatment losses and reduced diluent requirements), and with catalytically stabilized combustion which extends the lower Btu limit for syngas operation. Tests were performed in PCI's sub-scale high-pressure (10 atm) test rig, using a two-stage (catalytic then gas-phase) combustion process for syngas fuel. In this process, the first stage consists of a fuel-rich mixture reacting on a catalyst with final and excess combustion air used to cool the catalyst. The second stage is a gas-phase combustor, where the air used for cooling the catalyst mixes with the catalytic reactor effluent to provide for final gas-phase burnout and dilution to fuel-lean combustion products. During testing, operating with a simulated Tampa Electric's Polk Power Station syngas, the NOx emissions program goal of less than 0.03 lbs/MMBtu (6 ppm at 15% O{sub 2}) was met. NOx emissions were generally near 0.01 lbs/MMBtu (2 ppm at 15% O{sub 2}) (PCI's target) over a range on engine firing temperatures. In addition, low emissions were shown for alternative fuels including high hydrogen content refinery fuel gas and low BTU content Blast Furnace Gas (BFG). For the refinery fuel gas increased resistance to combustor flashback was achieved through preferential consumption of hydrogen in the catalytic bed. In the case of BFG, stable combustion for fuels as low as 88 BTU/ft{sup 3} was established and maintained without the need for using co-firing. This was achieved based on the upstream catalytic reaction delivering a hotter (and thus more reactive) product to the flame zone. The PCI catalytic reactor was also shown to be active in ammonia

  17. Vapor-Driven Propulsion of Catalytic Micromotors

    NASA Astrophysics Data System (ADS)

    Dong, Renfeng; Li, Jinxing; Rozen, Isaac; Ezhilan, Barath; Xu, Tailin; Christianson, Caleb; Gao, Wei; Saintillan, David; Ren, Biye; Wang, Joseph

    2015-08-01

    Chemically-powered micromotors offer exciting opportunities in diverse fields, including therapeutic delivery, environmental remediation, and nanoscale manufacturing. However, these nanovehicles require direct addition of high concentration of chemical fuel to the motor solution for their propulsion. We report the efficient vapor-powered propulsion of catalytic micromotors without direct addition of fuel to the micromotor solution. Diffusion of hydrazine vapor from the surrounding atmosphere into the sample solution is instead used to trigger rapid movement of iridium-gold Janus microsphere motors. Such operation creates a new type of remotely-triggered and powered catalytic micro/nanomotors that are responsive to their surrounding environment. This new propulsion mechanism is accompanied by unique phenomena, such as the distinct off-on response to the presence of fuel in the surrounding atmosphere, and spatio-temporal dependence of the motor speed borne out of the concentration gradient evolution within the motor solution. The relationship between the motor speed and the variables affecting the fuel concentration distribution is examined using a theoretical model for hydrazine transport, which is in turn used to explain the observed phenomena. The vapor-powered catalytic micro/nanomotors offer new opportunities in gas sensing, threat detection, and environmental monitoring, and open the door for a new class of environmentally-triggered micromotors.

  18. Vapor-Driven Propulsion of Catalytic Micromotors

    PubMed Central

    Dong, Renfeng; Li, Jinxing; Rozen, Isaac; Ezhilan, Barath; Xu, Tailin; Christianson, Caleb; Gao, Wei; Saintillan, David; Ren, Biye; Wang, Joseph

    2015-01-01

    Chemically-powered micromotors offer exciting opportunities in diverse fields, including therapeutic delivery, environmental remediation, and nanoscale manufacturing. However, these nanovehicles require direct addition of high concentration of chemical fuel to the motor solution for their propulsion. We report the efficient vapor-powered propulsion of catalytic micromotors without direct addition of fuel to the micromotor solution. Diffusion of hydrazine vapor from the surrounding atmosphere into the sample solution is instead used to trigger rapid movement of iridium-gold Janus microsphere motors. Such operation creates a new type of remotely-triggered and powered catalytic micro/nanomotors that are responsive to their surrounding environment. This new propulsion mechanism is accompanied by unique phenomena, such as the distinct off-on response to the presence of fuel in the surrounding atmosphere, and spatio-temporal dependence of the motor speed borne out of the concentration gradient evolution within the motor solution. The relationship between the motor speed and the variables affecting the fuel concentration distribution is examined using a theoretical model for hydrazine transport, which is in turn used to explain the observed phenomena. The vapor-powered catalytic micro/nanomotors offer new opportunities in gas sensing, threat detection, and environmental monitoring, and open the door for a new class of environmentally-triggered micromotors. PMID:26285032

  19. Plant uses membrane separation

    SciTech Connect

    Yamashiro, H.; Hirajo, M.; Maitland, C.F.; Schell, W.J.

    1985-02-01

    Cellulose acetate membranes exhibit long-time stability in refinery H/sub 2/ recovery applications even under harsh operating conditions. High performance has been achieved at temperatures as great as 82/sup 0/ C while in the presence of benzene, toluene, xylene and other heavy hydrocarbons. In addition, constant values for selectivity and permeation rate have been obtained under a variety of pressure ratios and flowrates. Successful operation of this system demonstrates the commercial capability of such membranes for hydrogen recovery applications. One of the most practical applications for membranes is in recovery and purification of hydrogen from fuel gases. As hydrogen is an expensive chemical feedstock in hydrogen refining, the attendant reduction in hydrogen supply needs from outside sources is of considerable interest. In addition, installation of a membrane system can satisfy increasing need for more hydrogen as more sour and heavy crude oils are processed. Commercial use of cellulose acetate membranes for this application has been demonstrated on a reformer off-gas stream in the Chiba Refinery of the Cosmo Oil Co. in Japan. The system has been operating since October 1983, processing approximately 1,000 Nm/sup 3//h of 80% H/sub 2/ off-gas. Operating conditions are very severe due to the presence of aromatic hydrocarbons in the gas stream, thus successful testing is particularly noteworthy.

  20. Catalytic combustion with incompletely vaporized residual fuel

    NASA Technical Reports Server (NTRS)

    Rosfjord, T. J.

    1981-01-01

    Catalytic combustion of fuel lean mixtures of incompletely vaporized residual fuel and air was investigated. The 7.6 cm diameter, graded cell reactor was constructed from zirconia spinel substrate and catalyzed with a noble metal catalyst. Streams of luminous particles exited the rector as a result of fuel deposition and carbonization on the substrate. Similar results were obtained with blends of No. 6 and No. 2 oil. Blends of shale residual oil and No. 2 oil resulted in stable operation. In shale oil blends the combustor performance degraded with a reduced degree of fuel vaporization. In tests performed with No. 2 oil a similar effect was observed.

  1. CENTRIFUGAL MEMBRANE FILTRATION

    SciTech Connect

    Daniel J. Stepan; Bradley G. Stevens; Melanie D. Hetland

    1999-10-01

    The overall project consists of several integrated research phases related to the applicability, continued development, demonstration, and commercialization of the SpinTek centrifugal membrane filtration process. Work performed during this reporting period consisted of Phase 2 evaluation of the SpinTek centrifugal membrane filtration technology and Phase 3, Technology Partnering. During Phase 1 testing conducted at the EERC using the SpinTek ST-IIL unit operating on a surrogate tank waste, a solids cake developed on the membrane surface. The solids cake was observed where linear membrane velocities were less than 17.5 ft/s and reduced the unobstructed membrane surface area up to 25%, reducing overall filtration performance. The primary goal of the Phase 2 research effort was to enhance filtration performance through the development and testing of alternative turbulence promoter designs. The turbulence promoters were designed to generate a shear force across the entire membrane surface sufficient to maintain a self-cleaning membrane capability and improve filtration efficiency and long-term performance. Specific Phase 2 research activities included the following: System modifications to accommodate an 11-in.-diameter, two-disk rotating membrane assembly; Development and fabrication of alternative turbulence promoter designs; Testing and evaluation of the existing and alternative turbulence promoters under selected operating conditions using a statistically designed test matrix; and Data reduction and analysis; The objective of Phase 3 research was to demonstrate the effectiveness of SpinTek's centrifugal membrane filtration as a pretreatment to remove suspended solids from a liquid waste upstream of 3M's WWL cartridge technology for the selective removal of technetium (Tc).

  2. Membrane electrode assembly for a fuel cell

    NASA Technical Reports Server (NTRS)

    Prakash, Surya (Inventor); Narayanan, Sekharipuram R. (Inventor); Atti, Anthony (Inventor); Olah, George (Inventor); Smart, Marshall C. (Inventor)

    2006-01-01

    A catalyst ink for a fuel cell including a catalytic material and poly(vinylidene fluoride). The ink may be applied to a substrate to form an electrode, or bonded with other electrode layers to form a membrane electrode assembly (MEA).

  3. Hybrid Amyloid Membranes for Continuous Flow Catalysis.

    PubMed

    Bolisetty, Sreenath; Arcari, Mario; Adamcik, Jozef; Mezzenga, Raffaele

    2015-12-29

    Amyloid fibrils are promising nanomaterials for technological applications such as biosensors, tissue engineering, drug delivery, and optoelectronics. Here we show that amyloid-metal nanoparticle hybrids can be used both as efficient active materials for wet catalysis and as membranes for continuous flow catalysis applications. Initially, amyloid fibrils generated in vitro from the nontoxic β-lactoglobulin protein act as templates for the synthesis of gold and palladium metal nanoparticles from salt precursors. The resulting hybrids possess catalytic features as demonstrated by evaluating their activity in a model catalytic reaction in water, e.g., the reduction of 4-nitrophenol into 4-aminophenol, with the rate constant of the reduction increasing with the concentration of amyloid-nanoparticle hybrids. Importantly, the same nanoparticles adsorbed onto fibrils surface show improved catalytic efficiency compared to the same unattached particles, pointing at the important role played by the amyloid fibril templates. Then, filter membranes are prepared from the metal nanoparticle-decorated amyloid fibrils by vacuum filtration. The resulting membranes serve as efficient flow catalysis active materials, with a complete catalytic conversion achieved within a single flow passage of a feeding solution through the membrane.

  4. Catalytic gasification of biomass

    NASA Astrophysics Data System (ADS)

    Robertus, R. J.; Mudge, L. K.; Sealock, L. J., Jr.; Mitchell, D. H.; Weber, S. L.

    1981-12-01

    Methane and methanol synthesis gas can be produced by steam gasification of biomass in the presence of appropriate catalysts. This concept is to use catalysts in a fluidized bed reactor which is heated indirectly. The objective is to determine the technical and economic feasibility of the concept. Technically the concept has been demonstrated on a 50 lb per hr scale. Potential advantages over conventional processes include: no oxygen plant is needed, little tar is produced so gas and water treatment are simplified, and yields and efficiencies are greater than obtained by conventional gasification. Economic studies for a plant processing 2000 T/per day dry wood show that the cost of methanol from wood by catalytic gasification is competitive with the current price of methanol. Similar studies show the cost of methane from wood is competitive with projected future costs of synthetic natural gas. When the plant capacity is decreased to 200 T per day dry wood, neither product is very attractive in today's market.

  5. Fundamental studies of the mechanism of catalytic reactions with catalysts effective in the gasification of carbon solids and the oxidative coupling of methane. Quarterly report, April 1, 1994--June 30, 1994

    SciTech Connect

    Iglesia, E.; Perry, D.L.; Heinemann, H.

    1994-06-01

    Catalytic gasification work has been completed and no other work is planned in the general area of catalytic gasification of coals and chars has operated without a post-doctoral fellow because of budget limitations during the first two quarters of FY1994. Dr. S. Sundararajan joined the group in April 1994 and will be assigned to the project throughout the remaining of the fiscal year. Results published by Hamakawa, et al. in The Journal of the Electrochemical Society have confirmed the concept of methane coupling via a membrane reactor. These findings confirm our previous conclusion that thinner membranes and increased surface activity for C-H bond activation at low temperatures are required in order to reach commercially attractive rates of reaction. The initial analysis of a theoretical model comparing the membrane and cyclic processes has been completed. The results indicate that perovskite membranes on the order of 50 microns will be needed for the membrane operation to be superior to a cyclic one. Two techniques, laser ablation and spin-coating/sol-gel chemistry are being tried to prepare the thin membranes described above. Studies of the magnetochemical properties of the calcium-nickel-potassium oxide powdered catalysts have been concluded and a manuscript describing the work has been completed. Synchrotron x-ray fluorescence microprobe data for calcium-nickel-potassium films have been analyzed and an abstract of the results has been submitted for presentation at the Fall Meeting of the Materials Research Society. Initial films of strontium-zirconium oxide, using yttria-stabilized zirconia as a buffer layer, have been fabricated using pulsed laser deposition. X-ray diffraction data have been obtained for several of the strontium-zirconium-yttrium oxide films.

  6. Blood coagulation reactions on nanoscale membrane surfaces

    NASA Astrophysics Data System (ADS)

    Pureza, Vincent S.

    Blood coagulation requires the assembly of several membrane-bound protein complexes composed of regulatory and catalytic subunits. The biomembranes involved in these reactions not only provide a platform for these procoagulant proteins, but can also affect their function. Increased exposure of acidic phospholipids on the outer leaflet of the plasma membrane can dramatically modulate the catalytic efficiencies of such membrane-bound enzymes. Under physiologic conditions, however, these phospholipids spontaneously cluster into a patchwork of membrane microdomains upon which membrane binding proteins may preferentially assemble. As a result, the membrane composition surrounding these proteins is largely unknown. Through the development and use of a nanometer-scale bilayer system that provides rigorous control of the phospholipid membrane environment, I investigated the role of phosphatidylserine, an acidic phospholipid, in the direct vicinity (within nanometers) of two critical membrane-bound procoagulant protein complexes and their respective natural substrates. Here, I present how the assembly and function of the tissue factor˙factor VIIa and factor Va˙factor Xa complexes, the first and final cofactor˙enzyme complexes of the blood clotting cascade, respectively, are mediated by changes in their immediate phospholipid environments.

  7. Alternative energy efficient membrane bioreactor using reciprocating submerged membrane.

    PubMed

    Ho, J; Smith, S; Roh, H K

    2014-01-01

    A novel membrane bioreactor (MBR) pilot system, using membrane reciprocation instead of air scouring, was operated at constant high flux and daily fluctuating flux to demonstrate its application under peak and diurnal flow conditions. Low and stable transmembrane pressure was achieved at 40 l/m(2)/h (LMH) by use of repetitive membrane reciprocation. The results reveal that the inertial forces acting on the membrane fibers effectively propel foulants from the membrane surface. Reciprocation of the hollow fiber membrane is beneficial for the constant removal of solids that may build up on the membrane surface and inside the membrane bundle. The membrane reciprocation in the reciprocating MBR pilot consumed less energy than coarse air scouring used in conventional MBR systems. Specific energy consumption for the membrane reciprocation was 0.072 kWh/m(3) permeate produced at 40 LMH flux, which is 75% less than for a conventional air scouring system as reported in literature without consideration of energy consumption for biological aeration (0.29 kWh/m(3)). The daily fluctuating flux test confirmed that the membrane reciprocation is effective to handle fluctuating flux up to 50 LMH. The pilot-scale reciprocating MBR system successfully demonstrated that fouling can be controlled via 0.43 Hz membrane reciprocation with 44 mm or higher amplitude.

  8. Membrane bioreactors for water reclamation.

    PubMed

    Tao, G; Kekre, K; Wei, Z; Lee, T C; Viswanath, B; Seah, H

    2005-01-01

    Singapore has been using dual membrane technology (MF/UF RO) to produce high-grade water (NEWater) from secondary treated sewage. Membrane bioreactor (MBR) has very high potential and will lead to the further improvement of the productivity and quality of high-grade water. This study was focused on the technical feasibility of MBR system for water reclamation in Singapore, making a comparison between various membrane systems available and to get operational experience in terms of membrane cleaning and other issues. Three MBR plants were built at Bedok Water Reclamation Plant with a design flow of 300 m3/day each. They were commissioned in March 2003. Three different types of submerged membranes were tested. They are Membrane A, plate sheet membrane with pore size of 0.4 microm; Membrane B, hollow fibre membrane with pore size of 0.4 microm; and Membrane C, hollow fibre membrane with pore size of 0.035 microm. The permeate quality of all the three MBR Systems were found equivalent to or better than that of the conventional tertiary treatment by ultrafiltration. MBR permeate TOC was about 2 mg/l lower than UF permeate TOC. GC-MS, GC-ECD and HPLC scan results show that trace organic contaminants in MBR permeate and UF permeate were in the same range. MBR power consumption can be less than 1 kwh/m3. Gel layer or dynamic membrane generated on the submerged membrane surface played an important role for the lower MBR permeate TOC than the supernatant TOC in the membrane tank. Intensive chemical cleaning can temporarily remove this layer. During normal operation conditions, the formation of dynamic membrane may need one day to obtain the steady low TOC levels in MBR permeate.

  9. Hydrogen-oxygen catalytic ignition and thruster investigation. Volume 1: Catalytic ignition and low pressure thruster evaluations

    NASA Technical Reports Server (NTRS)

    Johnson, R. J.

    1972-01-01

    An experimental and analytical program was conducted to evaluate catalytic igniter operational limits, igniter scaling criteria, and delivered performance of cooled, flightweight gaseous hydrogen-oxygen reaction control thrusters. Specific goals were to: (1) establish operating life and environmental effects for both Shell 405-ABSG and Engelhard MFSA catalysts, (2) provide generalized igniter design guidelines for high response without flashback, and (3) to determine overall performance of thrusters at chamber pressures of 15 and 300 psia (103 and 2068 kN/sq m) and thrust levels of 30 and 1500 lbf, respectively. The experimental results have demonstrated the feasibility of reliable, high response catalytic ignition and the effectiveness of ducted chamber cooling for a high performance flightweight thruster. This volume presents the results of the catalytic igniter and low pressure thruster evaluations are presented.

  10. Control of industrial VOC (volatile organic compound) emissions by catalytic incineration. volume 5. catalytic incinerator performance at industrial site c-3. Final report, May 1982-August 1983

    SciTech Connect

    Blacksmith, J.R.; Randall, J.L.

    1984-07-01

    The report is part of a two-phase EPA effort to assess the performance, suitability, and costs of various technologies to control emissions of volatile organic compounds (VOCs). In Phase 1, information was assembled from the literature on the use and cost of using catalytic incineration for VOC control. Results included: (1) a review of current and developing catalytic incineration technology, (2) an assessment of the overall performance of catalytic incinerators, (3) a review of applications where catalytic incinerators are used, (4) a comparative analysis of catalytic incineration with other competing VOC controls, (5) an examination of available methods for emission testing catalytic incinerators, and (6) an assessment of the need for additional performance test data. Phase 2 was a test program designed to increase the catalytic incinerator performance data base. It resulted in reports documenting the performance of eight catalytic incinerators at six industrial sites. The incinerators were used to control VOC emissions from solvent evaporation processes at can coating, coil coating, magnet wire, and graphic arts printing plants. Performance was measured at several process conditions at each site. Incinerator performance was characterized in terms of destruction efficiency, outlet solvent concentration, and energy usage. Design and operating data were collected. This report preseents test resultls and data evaluation for the testing conducted at the third test site, which involved the testing of two catalytic incinerators at Plant C-3, a graphic arts printing establishment.

  11. Catalytic reforming of naphtha fractions

    SciTech Connect

    Bishop, K.C.; Vorhis, F.H.

    1980-09-16

    Production of motor gasoline and a btx-enriched reformate by fractionating a naphtha feedstock into a mid-boiling btxprecursor fraction, a relatively high-boiling fraction and a relatively low-boiling fraction; catalytically reforming the btxprecursor fraction in a first reforming zone; combining the relatively high-boiling and low-boiling fractions and catalytically reforming the combined fractions in a second reforming zone.

  12. Advanced catalytic combustors for low pollutant emissions, phase 1

    NASA Technical Reports Server (NTRS)

    Dodds, W. J.

    1979-01-01

    The feasibility of employing the known attractive and distinguishing features of catalytic combustion technology to reduce nitric oxide emissions from gas turbine engines during subsonic, stratospheric cruise operation was investigated. Six conceptual combustor designs employing catalytic combustion were defined and evaluated for their potential to meet specific emissions and performance goals. Based on these evaluations, two parallel-staged, fixed-geometry designs were identified as the most promising concepts. Additional design studies were conducted to produce detailed preliminary designs of these two combustors. Results indicate that cruise nitric oxide emissions can be reduced by an order of magnitude relative to current technology levels by the use of catalytic combustion. Also, these combustors have the potential for operating over the EPA landing-takeoff cycle and at cruise with a low pressure drop, high combustion efficiency and with a very low overall level of emission pollutants. The use of catalytic combustion, however, requires advanced technology generation in order to obtain the time-temperature catalytic reactor performance and durability required for practical aircraft engine combustors.

  13. Mixed ionic and electronic conducting ceramic membranes for hydrocarbon processing

    DOEpatents

    Van Calcar, Pamela; Mackay, Richard; Sammells, Anthony F.

    2002-01-01

    The invention relates to mixed phase materials for the preparation of catalytic membranes which exhibit ionic and electronic conduction and which exhibit improved mechanical strength compared to single phase ionic and electronic conducting materials. The mixed phase materials are useful for forming gas impermeable membranes either as dense ceramic membranes or as dense thin films coated onto porous substrates. The membranes and materials of this invention are useful in catalytic membrane reactors in a variety of applications including synthesis gas production. One or more crystalline second phases are present in the mixed phase material at a level sufficient to enhance the mechanical strength of the mixture to provide membranes for practical application in CMRs.

  14. DESTRUCTION OF VOLATILE ORGANIC COMPOUNDS USING CATALYTIC OXIDATION

    EPA Science Inventory

    The paper discusses the application of catalytic oxidation to four types of air emission sources: (1) groundwater stripping operations, (2) graphic arts facilities, (3) f1exographic printing plants, and (4) latex monomer production. Characteristics of each of these emissions are ...

  15. Multicomponent membranes

    DOEpatents

    Kulprathipanja, Santi; Kulkarni, Sudhir S.; Funk, Edward W.

    1988-01-01

    A multicomponent membrane which may be used for separating various components which are present in a fluid feed mixture comprises a mixture of a plasticizer such as a glycol and an organic polymer cast upon a porous organic polymer support. The membrane may be prepared by casting an emulsion or a solution of the plasticizer and polymer on the porous support, evaporating the solvent and recovering the membrane after curing.

  16. Lowering the platinum loading of high temperature polymer electrolyte membrane fuel cells with acid doped polybenzimidazole membranes

    NASA Astrophysics Data System (ADS)

    Martin, S.; Li, Q.; Jensen, J. O.

    2015-10-01

    Membrane electrode assemblies (MEAs) with ultra-low Pt loading electrodes were prepared for high temperature polymer electrolyte membrane fuel cells (HT-PEMFCs) based on acid doped polybenzimidazole. With no electrode binders or ionomers, the triple phase boundary of the catalyst layer was established by the acid transfer from the acid doped membrane to the electrodes and can therefore be tailored by using catalysts with varied Pt to C ratios. With a loading of ca. 0.1 mgPtcm-2 on each electrode the best performance was obtained with electrodes prepared from 10 wt.% Pt/C due to the improved Pt dispersion, extended triple phase boundary upon the acid transfer and the alleviated acid flooding of the catalytic layer. The MEA delivered a peak power density of 482 mW cm-2 for H2/O2 and 321 mW cm-2 for H2/air, corresponding to an overall Pt utilization of 2.5 and 1.7 kW gPt-1, respectively. The durability test revealed no net voltage decay during more than 1700 h of uninterrupted operation at 200 mA cm-2 and 160 °C.

  17. Membrane device and process for mass exchange, separation, and filtration

    DOEpatents

    Liu, Wei; Canfield, Nathan L.

    2016-11-15

    A membrane device and processes for fabrication and for using are disclosed. The membrane device may include a number of porous metal membranes that provide a high membrane surface area per unit volume. The membrane device provides various operation modes that enhance throughput and selectivity for mass exchange, mass transfer, separation, and/or filtration applications between feed flow streams and permeate flow streams.

  18. Catalytic reforming of heart cut fcc naphthas

    SciTech Connect

    Gerritsen, L.A.

    1985-03-01

    The anticipated lead phasedown in the USA and the growing demand for unleaded gasoline will require a higher gasoline pool octane number. One of the possibilities to achieve this increase of pool octane will be catalytic reforming of FCC naphtha. In this paper we evaluate the effects of FCC naphtha reforming on the reformer operation and gasoline pool volume for various lead phasedown scenarios. High-stability reforming catalysts, like TPR-8/CK-522 TRILOBE catalyst, will be required to maintain acceptable cycle lengths at the more severe reformer operating conditions. The properties and octane distribution of FCC naphtha are discussed, as well as its hydrotreating with high-active NiMo catalysts.

  19. Biofuel from fast pyrolysis and catalytic hydrodeoxygenation.

    SciTech Connect

    Elliott, Douglas C.

    2015-09-04

    This review addresses recent developments in biomass fast pyrolysis bio-oil upgrading by catalytic hydrotreating. The research in the field has expanded dramatically in the past few years with numerous new research groups entering the field while existing efforts from others expand. The issues revolve around the catalyst formulation and operating conditions. Much work in batch reactor tests with precious metal catalysts needs further validation to verify long-term operability in continuous flow systems. The effect of the low level of sulfur in bio-oil needs more study to be better understood. Utilization of the upgraded bio-oil for feedstock to finished fuels is still in an early stage of understanding.

  20. Graphene oxide based ultrafiltration membranes for photocatalytic degradation of organic pollutants in salty water.

    PubMed

    Pastrana-Martínez, Luisa M; Morales-Torres, Sergio; Figueiredo, José L; Faria, Joaquim L; Silva, Adrián M T

    2015-06-15

    Flat sheet ultrafiltration (UF) membranes with photocatalytic properties were prepared with lab-made TiO2 and graphene oxide-TiO2 (GOT), and also with a reference TiO2 photocatalyst from Evonik (P25). These membranes were tested in continuous operation mode for the degradation and mineralization of a pharmaceutical compound, diphenhydramine (DP), and an organic dye, methyl orange (MO), under both near-UV/Vis and visible light irradiation. The effect of NaCl was investigated considering simulated brackish water (NaCl 0.5 g L(-1)) and simulated seawater (NaCl 35 g L(-1)). The results indicated that the membranes prepared with the GOT composite (M-GOT) exhibited the highest photocatalytic activity, outperforming those prepared with bare TiO2 (M-TiO2) and P25 (M-P25), both inactive under visible light illumination. The best performance of M-GOT may be due to the lower band-gap energy (2.9 eV) of GOT. In general, the permeate flux was also higher for M-GOT probably due to a combined effect of its highest photocatalytic activity, highest hydrophilicity (contact angles of 11°, 17° and 18° for M-GOT, M-TiO2 and M-P25, respectively) and higher porosity (71%). The presence of NaCl had a detrimental effect on the efficiency of the membranes, since chloride anions can act as hole and hydroxyl radical scavengers, but it did not affect the catalytic stability of these membranes. A hierarchically ordered membrane was also prepared by intercalating a freestanding GO membrane in the structure of the M-GOT membrane (M-GO/GOT). The results showed considerably higher pollutant removal in darkness and good photocatalytic activity under near-UV/Vis and visible light irradiation in continuous mode experiments.

  1. Effect of membrane polymeric materials on relationship between surface pore size and membrane fouling in membrane bioreactors

    NASA Astrophysics Data System (ADS)

    Miyoshi, Taro; Yuasa, Kotaku; Ishigami, Toru; Rajabzadeh, Saeid; Kamio, Eiji; Ohmukai, Yoshikage; Saeki, Daisuke; Ni, Jinren; Matsuyama, Hideto

    2015-03-01

    We investigated the effect of different membrane polymeric materials on the relationship between membrane pore size and development of membrane fouling in a membrane bioreactor (MBR). Membranes with different pore sizes were prepared using three different polymeric materials, cellulose acetate butyrate (CAB), polyvinyl butyral (PVB), and polyvinylidene fluoride (PVDF), and the development of membrane fouling in each membrane was evaluated by batch filtration tests using a mixed liquor suspension obtained from a laboratory-scale MBR. The results revealed that the optimal membrane pore size to mitigate membrane fouling differed depending on membrane polymeric material. For PVDF membranes, the degree of membrane fouling decreased as membrane pore size increased. In contrast, CAB membranes with smaller pores had less fouling propensity than those with larger ones. Such difference can be attributed to the difference in major membrane foulants in each membrane; in PVDF, they were small colloids or dissolved organics in which proteins are abundant, and in CAB, microbial flocs. The results obtained in this study strongly suggested that optimum operating conditions of MBRs differ depending on the characteristics of the used membrane.

  2. Membrane-electrode assemblies for electrochemical cells

    DOEpatents

    Swathirajan, Sundararajan; Mikhail, Youssef M.

    1993-01-01

    A combination, unitary, membrane and electrode assembly with a solid polymer electrolyte membrane, and first and second electrodes at least partially embedded in opposed surfaces of the membrane. The electrodes each comprise a respective group of finely divided carbon particles, very finely divided catalytic particles supported on internal and external surfaces of the carbon particles and a proton conductive material intermingled with the catalytic and carbon particles. A first group of finely divided carbon particles forming the first electrode has greater water attraction and retention properties, and is more hydrophilic than a second group of carbon particles forming the second electrode. In a preferred method, the membrane electrode assembly of the invention is prepared by forming a slurry of proton conductive material and at least one group of the carbon and catalyst particles. The slurry is applied to the opposed surfaces of the membrane and heated while being pressed to the membrane for a time and at a temperature and compressive load sufficient to embed at least a portion of the particles into the membrane.

  3. Catalytic gasification of automotive shredder residues with hydrogen generation

    NASA Astrophysics Data System (ADS)

    Lin, Kuen-Song; Chowdhury, Sujan; Wang, Ze-Ping

    Hydrogen is a clean and new energy carrier to generate power through the Proton exchange membrane fuel cell (PEMFC) system. Hydrogen can be effectively turned out through the catalytic gasification of organic material such as automotive shredder residues (ASR). The main objective of this manuscript is to present an analysis of the catalytic gasification of ASR for the generation of high-purity hydrogen in a lab-scale fixed-bed downdraft gasifier using 15 wt.% NiO/Al 2O 3 catalysts at 760-900 K. In the catalytic gasification process, reduction of Ni(II) catalyst into Ni(0) has been confirmed through XANES spectra and consequently EXAFS data shows that the central Ni atoms have Ni-O and Ni-Ni bonds with bond distances of 2.03 ± 0.05 and 2.46 ± 0.05 Å, respectively. ASR is partially oxidized and ultimately converts into hydrogen rich syngas (CO and H 2) and increases of the reaction temperature are favored the generation of hydrogen with decomposition of the CO. As well, approximately 220 kg h -1 of ASR would be catalytically gasified at 760-900 K and 46.2 atm with the reactor volume 0.27 m 3 to obtain approximately 3.42 × 10 5 kcal h -1 of thermal energy during over 87% syngas generation with the generation of 100 kW electric powers.

  4. Catalytic combustion with steam injection

    NASA Technical Reports Server (NTRS)

    Anderson, D. N.; Tacina, R. R.

    1982-01-01

    The effects of steam injection on (1) catalytic combustion performance, and (2) the tendency of residual fuel to burn in the premixing duct upstream of the catalytic reactor were determined. A petroleum residual, no. 2 diesel, and a blend of middle and heavy distillate coal derived fuels were tested. Fuel and steam were injected together into the preheated airflow entering a 12 cm diameter catalytic combustion test section. The inlet air velocity and pressure were constant at 10 m/s and 600 kPa, respectively. Steam flow rates were varied from 24 percent to 52 percent of the air flow rate. The resulting steam air mixture temperatures varied from 630 to 740 K. Combustion temperatures were in the range of 1200 to 1400 K. The steam had little effect on combustion efficiency or emissions. It was concluded that the steam acts as a diluent which has no adverse effect on catalytic combustion performance for no. 2 diesel and coal derived liquid fuels. Tests with the residual fuel showed that upstream burning could be eliminated with steam injection rates greater than 30 percent of the air flow rate, but inlet mixture temperatures were too low to permit stable catalytic combustion of this fuel.

  5. Develpment of Higher Temperature Membrane and Electrode Assembly (MEA) for Proton Exchange Membrane Fuel Cell Devices

    SciTech Connect

    Susan Agro, Anthony DeCarmine, Shari Williams

    2005-12-30

    Our work will fucus on developing higher temperature MEAs based on SPEKK polymer blends. Thse MEAs will be designed to operatre at 120 degrees C Higher temperatures, up to 200 degrees C will also be explored. This project will develop Nafion-free MEAs using only SPEKK blends in both membrane and catalytic layers.

  6. Expression studies of catalytic antibodies

    SciTech Connect

    Ulrich, H.D.; Patten, P.A.; Yang, P.L.

    1995-12-05

    We have examined the positive influence of human constant regions on the folding and bacterial expression of active soluble mouse immunoglobulin variable domains derived form a number of catalytic antibodies. Expression yields of eight hybridoma-and myeloma-derived chimeric Fab fragments are compared in both shake flasks and high-density fermentation. In addition the usefulness of this system for the generation of in vivo expression libraries is examined by constructing and expressing combinations of heavy and light chain variable regions that were not selected as a pair during an immune response. A mutagenesis study of one of the recombinant catalytic Fab fragments reveals that single amino acid substitutions can have dramatic effects on the expression yield. This system should be generally applicable to the production of Fab fragments of catalytic and other hybridoma-derived antibodies for crystallographic and structure-function studies. 41 refs., 4 figs., 1 tab.

  7. Consider nanofiltration for membrane separations

    SciTech Connect

    Raman, L.P. ); Cheryna, M.; Rajagopalan, N. )

    1994-03-01

    The best known liquid-phase membrane processes are reverse osmosis (RO), ultrafiltration (UF), microfiltration (MF), dialysis, and electrodialysis (ED). However, over the past few years, a new membrane process called nanofiltration (NF) has emerged that promises to significantly widen the application of membranes in liquid-phase separations. This paper discusses the following: NF operating range, membrane properties, and the following applications: demineralizing water, cleaning up contaminated groundwater, ultrapure water, effluents containing heavy metals, offshore oil platforms, yeast production, pulp and paper mills, textile production, electroless copper plating, and cheese whey production.

  8. Molecular-Level Modeling of the Structure and Proton Transport within the Membrane Electrode Assembly of Hydrogen Proton Exchange Membrane Fuel Cells

    NASA Astrophysics Data System (ADS)

    Selvan, Myvizhi Esai; Keffer, David J.

    The creation of proton exchange membrane fuel cells (PEMFCs) in the early 1960's attracted great interest with the prospect of serving as a highly efficient and eco-friendly power source. This nascent technology found a broad range of applications spanning from spacecrafts to automobiles and electronic devices. The PEMFC in its simplest form consists of an anode, where the hydrogen fuel is catalytically electro-oxidized (dissociated into protons and electrons), a cathode, where oxygen is catalytically electro-reduced (combined with protons to form water) and a polymer electrolyte membrane, which serves as the structural framework of the cell and transports protons from anode to cathode, while the electrons are forced through the external circuit generating electricity. Today, fuel cell remains one of the most promising means of generating energy from alternative fuels, with tremendous potential to reduce oil dependence and carbon emissions. However, current PEMFCs have a relatively narrow operational range and a high cost of production, thus requiring significant experimental and theoretical research to develop a thorough understanding of this technology (at both the molecular and macroscopic scale), which will ultimately render the fuel cell as an economically viable option.

  9. Inorganic membranes and solid state sciences

    NASA Astrophysics Data System (ADS)

    Cot, Louis; Ayral, André; Durand, Jean; Guizard, Christian; Hovnanian, Nadine; Julbe, Anne; Larbot, André

    2000-05-01

    The latest developments in inorganic membranes are closely related to recent advances in solid state science. Sol-gel processing, plasma-enhanced chemical vapor deposition and hydrothermal synthesis are methods that can be used for inorganic membrane preparation. Innovative concepts from material science (templating effect, nanophase materials, growing of continuous zeolite layers, hybrid organic-inorganic materials) have been applied by our group to the preparation of inorganic membrane materials. Sol-gel-derived nanophase ceramic membranes are presented with current applications in nanofiltration and catalytic membrane reactors. Silica membranes with an ordered porosity, due to liquid crystal phase templating effect, are described with potential application in pervaporation. Defect-free and thermally stable zeolite membranes can be obtained through an original synthesis method, in which zeolite crystals are grown inside the pores of a support. Hybrid organic-inorganic materials with permselective properties for gas separation and facilitated transport of solutes in liquid media, have been successfully adapted to membrane applications. Potential membrane developments offered by CVD deposition techniques are also illustrated through several examples related to the preparation of purely inorganic and hybrid organic-inorganic membrane materials.

  10. Poisoning of bubble propelled catalytic micromotors: the chemical environment matters.

    PubMed

    Zhao, Guanjia; Sanchez, Samuel; Schmidt, Oliver G; Pumera, Martin

    2013-04-07

    Self-propelled catalytic microjets have attracted considerable attention in recent years and these devices have exhibited the ability to move in complex media. The mechanism of propulsion is via the Pt catalysed decomposition of H2O2 and it is understood that the Pt surface is highly susceptible to poisoning by sulphur-containing molecules. Here, we show that important extracellular thiols as well as basic organic molecules can significantly hamper the motion of catalytic microjet engines. This is due to two different mechanisms: (i) molecules such as dimethyl sulfoxide can quench the hydroxyl radicals produced at Pt surfaces and reduce the amount of oxygen gas generated and (ii) molecules containing -SH, -SSR, and -SCH3 moieties can poison the catalytically active platinum surface, inhibiting the motion of the jet engines. It is essential that the presence of such molecules in the environment be taken into consideration for future design and operation of catalytic microjet engines. We show this effect on catalytic micromotors prepared by both rolled-up and electrodeposition approaches, demonstrating that such poisoning is universal for Pt catalyzed micromotors. We believe that our findings will contribute significantly to this field to develop alternative systems or catalysts for self-propulsion when practical applications in the real environment are considered.

  11. Poisoning of bubble propelled catalytic micromotors: the chemical environment matters

    NASA Astrophysics Data System (ADS)

    Zhao, Guanjia; Sanchez, Samuel; Schmidt, Oliver G.; Pumera, Martin

    2013-03-01

    Self-propelled catalytic microjets have attracted considerable attention in recent years and these devices have exhibited the ability to move in complex media. The mechanism of propulsion is via the Pt catalysed decomposition of H2O2 and it is understood that the Pt surface is highly susceptible to poisoning by sulphur-containing molecules. Here, we show that important extracellular thiols as well as basic organic molecules can significantly hamper the motion of catalytic microjet engines. This is due to two different mechanisms: (i) molecules such as dimethyl sulfoxide can quench the hydroxyl radicals produced at Pt surfaces and reduce the amount of oxygen gas generated and (ii) molecules containing -SH, -SSR, and -SCH3 moieties can poison the catalytically active platinum surface, inhibiting the motion of the jet engines. It is essential that the presence of such molecules in the environment be taken into consideration for future design and operation of catalytic microjet engines. We show this effect on catalytic micromotors prepared by both rolled-up and electrodeposition approaches, demonstrating that such poisoning is universal for Pt catalyzed micromotors. We believe that our findings will contribute significantly to this field to develop alternative systems or catalysts for self-propulsion when practical applications in the real environment are considered.

  12. Fuel Flexible, Low Emission Catalytic Combustor for Opportunity Fuel Applications

    SciTech Connect

    Eteman, Shahrokh

    2013-06-30

    Limited fuel resources, increasing energy demand and stringent emission regulations are drivers to evaluate process off-gases or process waste streams as fuels for power generation. Often these process waste streams have low energy content and/or highly reactive components. Operability of low energy content fuels in gas turbines leads to issues such as unstable and incomplete combustion. On the other hand, fuels containing higher-order hydrocarbons lead to flashback and auto-ignition issues. Due to above reasons, these fuels cannot be used directly without modifications or efficiency penalties in gas turbine engines. To enable the use of these wide variety of fuels in gas turbine engines a rich catalytic lean burn (RCL®) combustion system was developed and tested in a subscale high pressure (10 atm.) rig. The RCL® injector provided stability and extended turndown to low Btu fuels due to catalytic pre-reaction. Previous work has shown promise with fuels such as blast furnace gas (BFG) with LHV of 85 Btu/ft3 successfully combusted. This program extends on this work by further modifying the combustor to achieve greater catalytic stability enhancement. Fuels containing low energy content such as weak natural gas with a Lower Heating Value (LHV) of 6.5 MJ/m3 (180 Btu/ft3 to natural gas fuels containing higher hydrocarbon (e.g ethane) with LHV of 37.6 MJ/m3 (1010 Btu/ft3) were demonstrated with improved combustion stability; an extended turndown (defined as the difference between catalytic and non-catalytic lean blow out) of greater than 250oF was achieved with CO and NOx emissions lower than 5 ppm corrected to 15% O2. In addition, for highly reactive fuels the catalytic region preferentially pre-reacted the higher order hydrocarbons with no events of flashback or auto-ignition allowing a stable and safe operation with low NOx and CO emissions.

  13. Perfluoropolyalkylether decomposition on catalytic aluminas

    NASA Technical Reports Server (NTRS)

    Morales, Wilfredo

    1994-01-01

    The decomposition of Fomblin Z25, a commercial perfluoropolyalkylether liquid lubricant, was studied using the Penn State Micro-oxidation Test, and a thermal gravimetric/differential scanning calorimetry unit. The micro-oxidation test was conducted using 440C stainless steel and pure iron metal catalyst specimens, whereas the thermal gravimetric/differential scanning calorimetry tests were conducted using catalytic alumina pellets. Analysis of the thermal data, high pressure liquid chromatography data, and x-ray photoelectron spectroscopy data support evidence that there are two different decomposition mechanisms for Fomblin Z25, and that reductive sites on the catalytic surfaces are responsible for the decomposition of Fomblin Z25.

  14. Catalytic combustion of actual low and medium heating value gases

    NASA Technical Reports Server (NTRS)

    Bulzan, D. L.

    1982-01-01

    Catalytic combustion of both low and medium heating value gases using actual coal derived gases obtained from operating gasifiers was demonstrated. A fixed bed gasifier with a complete product gas cleanup system was operated in an air blown mode to produce low heating value gas. A fluidized bed gasifier with a water quench product gas cleanup system was operated in both an air enriched and an oxygen blown mode to produce low and medium, heating value gas. Noble metal catalytic reactors were evaluated in 12 cm flow diameter test rigs on both low and medium heating value gases. Combustion efficiencies greater than 99.5% were obtained with all coal derived gaseous fuels. The NOx emissions ranged from 0.2 to 4 g NO2 kg fuel.

  15. Crystalline Membranes

    NASA Technical Reports Server (NTRS)

    Tsapatsis, Michael (Inventor); Lai, Zhiping (Inventor)

    2008-01-01

    In certain aspects, the invention features methods for forming crystalline membranes (e.g., a membrane of a framework material, such as a zeolite) by inducing secondary growth in a layer of oriented seed crystals. The rate of growth of the seed crystals in the plane of the substrate is controlled to be comparable to the rate of growth out of the plane. As a result, a crystalline membrane can form a substantially continuous layer including grains of uniform crystallographic orientation that extend through the depth of the layer.

  16. High temperature size selective membranes

    SciTech Connect

    Yates, S.F.; Swamikannu, A.X.

    1993-09-01

    The high temperature membrane, capable of operation above 550{degree}C, is designed to be a composite membrane composed of a thin layer of a size selective membrane supported by a microporous ceramic support. The kinetic diameters of H{sub 2} and CO{sub 2} are 2.96 {Angstrom} and 4.00 {Angstrom}. The thin layer will be made from CMS whose pore size will be controlled to be less than 4 {Angstrom}. The membrane will be truly size selective and be impermeable to carbon dioxide. The membrane will have higher selectivity than membranes which operate on Knudsen diffusion mechanism. The ceramic support will be fabricated from Allied Signal`s proprietary Blackglas{trademark} resin. The ceramic material, noted for its high thermal and oxidative resistance, has a coefficient of thermal expansion which matches closely that of CMS. The close match will insure mechanical integrity when the membrane is subjected to thermal cycles. The CMS layer will be produced by controlled pyrolysis of polymeric precursors. Pore size will be suitably modified by post-treatments to the carbon. The composite membrane will be tested for its permeation properties at 550{degree}C or higher. Thermal, mechanical and chemical stability of the membrane will be assessed. We have produced several samples of CMS from polymeric precursors. We have initiated work also on the preparation of microporous supports from Blackglas{trademark} resin. We have completed the design of the high temperature membrane pilot plant. The membrane cell was fabricated out of two kinds of stainless steel. The inner parts are made of SS 316 and the outer ring made of SS 420. The greater thermal expansion of the SS 316 will help obtain a leak free seal at the operating temperatures.

  17. Comparison of treatment efficiency of submerged nanofiltration membrane bioreactors using cellulose triacetate and polyamide membrane.

    PubMed

    Choi, J H; Fukushi, K; Yamamoto, K

    2005-01-01

    This study evaluates the performance of nanofiltration membrane bioreactor (NF MBR) systems using cellulose triacetate (CA) and polyamide (PA) membranes. The results indicated that both NF membranes could produce high quality permeate in the submerged NF MBR system. In addition, hollow fiber CA membranes exhibited the capability of higher permeate productivity than PA membranes. However, to obtain high quality permeate for a long-term operation, CA membranes should be maintained using an appropriate method, such as chlorine disinfection, in order to control the membrane biodegradation. The results demonstrated that PA membranes were capable of producing higher quality permeate for a long period than CA membranes. In order to enhance the practicability of PA membranes in submerged NF MBR systems, it is required that the membranes should have the lowest possible intrinsic salt rejection.

  18. SEPARATION OF HYDROGEN AND CARBON DIOXIDE USING A NOVEL MEMBRANE REACTOR IN ADVANCED FOSSIL ENERGY CONVERSION PROCESS

    SciTech Connect

    Shamsuddin Ilias

    2001-06-25

    Inorganic membrane reactors offer the possibility of combining reaction and separation in a single operation at high temperatures to overcome the equilibrium limitations experienced in conventional reactor configurations. Such attractive features can be advantageously utilized in a number of potential commercial opportunities, which include dehydrogenation, hydrogenation, oxidative dehydrogenation, oxidation and catalytic decomposition reactions. However, to be cost effective, significant technological advances and improvements will be required to solve several key issues which include: (a) permselective thin solid film, (b) thermal, chemical and mechanical stability of the film at high temperatures, and (c) reactor engineering and module development in relation to the development of effective seals at high temperature and high pressure. In this project, we are working on the development and application of palladium and palladium-silver alloy thin-film composite membranes in membrane reactor-separator configuration for simultaneous production and separation of hydrogen and carbon dioxide at high temperature. From our research on Pd-composite membrane, we have demonstrated that the new membrane has significantly higher hydrogen flux with very high perm-selectivity than any of the membranes commercially available. The steam reforming of methane by equilibrium shift in Pd-composite membrane reactor is being studied to demonstrate the potential application this new development. To have better understanding of the membrane reactor, during this reporting period, we developed a two-dimensional pseudo-homogeneous reactor model for steam reforming of methane by equilibrium shift in a tubular membrane reactor. In numerical solution of the reactor model equations, numerical difficulties were encountered and we seeking alternative solution techniques to overcome the problem.

  19. Catalytic reforming process

    SciTech Connect

    Swan, G.A.

    1982-09-07

    A process, or procedure, is disclosed for the start-up of reforming units, particularly those employing highly active sulfur-sensitive polymetallic, promoted noble metal containing catalysts. On start -up of a reforming unit, a sulfur-containing naphtha feed is fed at reforming conditions over a platinum-catalyst containing lead reactor of a series while bypassing subsequent reactors of the series, the product therefrom is separated into hydrogen-containing gas and C5+ liquid fractions, the hydrogen-containing gas fraction is desulfurized and dried and recycled to the platinum-catalyst containing lead reactor and, after sufficient hydrogen has been generated for operation of a hydrofiner which is used to hydrodesulfurize the naphtha feed for the reformer, product from the platinum-catalyst containing lead reactor is fed to subsequent reactors of the series which contain the more sulfur-sensitive catalysts.

  20. Carbon Cloth Supports Catalytic Electrodes

    NASA Technical Reports Server (NTRS)

    Lu, W. T. P.; Ammon, R. L.

    1983-01-01

    Carbon cloth is starting material for promising new catalytic electrodes. Carbon-cloth electrodes are more efficient than sintered-carbon configuration previously used. Are also chemically stable and require less catalyst--an important economic advantage when catalyst is metal such as platinum.

  1. Catalytic oxidation of waste materials

    NASA Technical Reports Server (NTRS)

    Jagow, R. B.

    1977-01-01

    Aqueous stream of human waste is mixed with soluble ruthenium salts and is introduced into reactor at temperature where ruthenium black catalyst forms on internal surfaces of reactor. This provides catalytically active surface to convert oxidizable wastes into breakdown products such as water and carbon dioxide.

  2. Simple, Chemoselective, Catalytic Olefin Isomerization

    PubMed Central

    2015-01-01

    Catalytic amounts of Co(SaltBu,tBu)Cl and organosilane irreversibly isomerize terminal alkenes by one position. The same catalysts effect cycloisomerization of dienes and retrocycloisomerization of strained rings. Strong Lewis bases like amines and imidazoles, and labile functionalities like epoxides, are tolerated. PMID:25398144

  3. Catalytic Asymmetric Bromocyclization of Polyenes.

    PubMed

    Samanta, Ramesh C; Yamamoto, Hisashi

    2017-02-01

    The first catalytic asymmetric bromonium ion-induced polyene cyclization has been achieved by using a chiral BINOL-derived thiophosphoramide catalyst and 1,3-dibromo-5,5-dimethylhydantoin as an electrophilic bromine source. Bromocyclization products are obtained in high yields, with good enantiomeric ratios and high diastereoselectivity, and are abundantly found as scaffolds in natural products.

  4. Process for Coating Substrates with Catalytic Materials

    NASA Technical Reports Server (NTRS)

    Klelin, Ric J. (Inventor); Upchurch, Billy T. (Inventor); Schryer, David R. (Inventor)

    2004-01-01

    A process for forming catalysts by coating substrates with two or more catalytic components, which comprises the following sequence of steps. First, the substrate is infused with an adequate amount of solution having a starting material comprising a catalytic component precursor, wherein the thermal decomposition product of the catalytic component precursor is a catalytic component. Second, the excess of the solution is removed from the substrate. thereby leaving a coating of the catalytic component precursor on the surface of the substrate. Third, the coating of the catalytic component precursor is converted to the catalytic component by thermal decomposition. Finally, the coated substance is etched to increase the surface area. The list three steps are then repeated for at least a second catalytic component. This process is ideally suited for application in producing efficient low temperature oxidation catalysts.

  5. Biological membranes

    PubMed Central

    Watson, Helen

    2015-01-01

    Biological membranes allow life as we know it to exist. They form cells and enable separation between the inside and outside of an organism, controlling by means of their selective permeability which substances enter and leave. By allowing gradients of ions to be created across them, membranes also enable living organisms to generate energy. In addition, they control the flow of messages between cells by sending, receiving and processing information in the form of chemical and electrical signals. This essay summarizes the structure and function of membranes and the proteins within them, and describes their role in trafficking and transport, and their involvement in health and disease. Techniques for studying membranes are also discussed. PMID:26504250

  6. Importance of Membrane Structural Integrity for RPE65 Retinoid Isomerization Activity

    SciTech Connect

    Golczak, Marcin; Kiser, Philip D.; Lodowski, David T.; Maeda, Akiko; Palczewski, Krzysztof

    2010-04-05

    Regeneration of visual chromophore in the vertebrate visual cycle involves the retinal pigment epithelium-specific protein RPE65, the key enzyme catalyzing the cleavage and isomerization of all-trans-retinyl fatty acid esters to 11-cis-retinol. Although RPE65 has no predicted membrane spanning domains, this protein predominantly associates with microsomal fractions isolated from bovine retinal pigment epithelium (RPE). We have re-examined the nature of RPE65 interactions with native microsomal membranes by using extraction and phase separation experiments. We observe that hydrophobic interactions are the dominant forces that promote RPE65 association with these membranes. These results are consistent with the crystallographic model of RPE65, which features a large lipophilic surface that surrounds the entrance to the catalytic site of this enzyme and likely interacts with the hydrophobic core of the endoplasmic reticulum membrane. Moreover, we report a critical role for phospholipid membranes in preserving the retinoid isomerization activity and physical properties of RPE65. Isomerase activity measured in bovine RPE was highly sensitive to phospholipase A{sup 2} treatment, but the observed decline in 11-cis-retinol production did not directly reflect inhibition by products of lipid hydrolysis. Instead, a direct correlation between the kinetics of phospholipid hydrolysis and retinoid isomerization suggests that the lipid membrane structure is critical for RPE65 enzymatic activity. We also provide evidence that RPE65 operates in a multiprotein complex with retinol dehydrogenase 5 and retinal G protein-coupled receptor in RPE microsomes. Modifications in the phospholipid environment affecting interactions with these protein components may be responsible for the alterations in retinoid metabolism observed in phospholipid-depleted RPE microsomes. Thus, our results indicate that the enzymatic activity of native RPE65 strongly depends on its membrane binding and

  7. Method for low temperature catalytic production of hydrogen

    DOEpatents

    Mahajan, Devinder

    2003-07-22

    The invention provides a process for the catalytic production of a hydrogen feed by exposing a hydrogen feed to a catalyst which promotes a base-catalyzed water-gas-shift reaction in a liquid phase. The hydrogen feed can be provided by any process known in the art of making hydrogen gas. It is preferably provided by a process that can produce a hydrogen feed for use in proton exchange membrane fuel cells. The step of exposing the hydrogen feed takes place preferably from about 80.degree. C. to about 150.degree. C.

  8. Exergy and Economic Analysis of Catalytic Coal Gasifiers Coupled With Solid Oxide Fuel Cells

    SciTech Connect

    Siefert, Nicholas; Litster, Shawn

    2011-01-01

    The National Energy Technology Laboratory (NETL) has undertaken a review of coal gasification technologies that integrate with solid oxide fuel cells (SOFC) to achieve system efficiencies near 60% while capturing and sequestering >90% of the carbon dioxide. One way to achieve an overall system efficiency of greater than 60% is in a power plant in which a catalytic coal gasifier produces a syngas with a methane composition of roughly 25% on a dry volume basis and this is sent to a SOFC, with CO{sub 2} capture occurring either before or after the SOFC. Integration of a catalytic gasifier with a SOFC, as opposed to a conventional entrained flow gasifier, is improved due to (a) decreased exergy destruction inside a catalytic, steam-coal gasifier producing a high-methane content syngas, and (b) decreased exergy destruction in the SOFC due to the ability to operate at lower air stoichiometric flow ratios. For example, thermal management of the SOFC is greatly improved due to the steam-methane reforming in the anode of the fuel cell. This paper has two main goals. First, we converted the levelized cost of electricity (LCOE) estimates of various research groups into an average internal rate of return on investment (IRR) in order to make comparisons between their results, and to underscore the increased rate of return on investment for advanced integrated gasification fuel cell systems with carbon capture & sequestration (IGFC-CCS) compared with conventional integrated gasification combined cycle (IGCC-CCS) systems and pulverized coal combustion (PCC-CCS) systems. Using capital, labor, and fuel costs from previous researchers and using an average price of baseload electricity generation of $61.50 / MW-hr, we calculated inflation-adjusted IRR values of up to 13%/yr for catalytic gasification with pressurized fuel cell and carbon dioxide capture and storage (CCS), whereas we calculate an IRR of ~4%/yr and ~2%/yr for new, conventional IGCC-CCS and PCC-CCS, respectively. If the

  9. CENTRIFUGAL MEMBRANE FILTRATION

    SciTech Connect

    William A. Greene; Patricia A. Kirk; Richard Hayes; Joshua Riley

    2005-10-28

    SpinTek Membrane Systems, Inc., the developer of a centrifugal membrane filtration technology, has engineered and developed a system for use within the U.S. Department of Energy (DOE) Environmental Management (EM) Program. The technology uses supported microporous membranes rotating at high rpm, under pressure, to separate suspended and colloidal solids from liquid streams, yielding a solids-free permeate stream and a highly concentrated solids stream. This is a crosscutting technology that falls under the Efficient Separations and Processing Crosscutting Program, with potential application to tank wastes, contaminated groundwater, landfill leachate, and secondary liquid waste streams from other remediation processes, including decontamination and decommissioning systems. SpinTek II High Shear Rotary Membrane Filtration System is a unique compact crossflow membrane system that has large, demonstrable advantages in performance and cost compared to currently available systems: (1) High fluid shear prevents membrane fouling even with very high solids content; hazardous and radioactive components can be concentrated to the consistency of a pasty slurry without fouling. (2) Induced turbulence and shear across the membrane increases membrane flux by a factor of ten over existing systems and allows operation on fluids not otherwise treatable. (3) Innovative ceramic membrane and mechanical sealing technology eliminates compatibility problems with aggressive DOE waste streams. (4) System design allows rapid, simple disassembly for inspection or complete decontamination. (5) Produces colloidal- and suspended-solids-free filtrate without the addition of chemicals. The first phase of this project (PRDA maturity stage 5) completed the physical scale-up of the SpinTek unit and verified successful scale-up with surrogate materials. Given successful scale-up and DOE concurrence, the second phase of this project (PRDA maturity stage 6) will provide for the installation and

  10. Catalytic liquefaction of biomass

    SciTech Connect

    Davis, H.; Figueroa, C.; Karatas, C.; Kloden, D.; Schaleger, L.; Yaghoubzadeh, N.

    1981-10-01

    The bench-scale continuous liquefaction unit or CLU is in operation as a back-mixed reactor. Its capabilities include temperatures up to 370/sup 0/C, reaction times of about 10 to 30 minutes and pressures up to 4000 PSIG. It is in use exploring a factorial experiment in temperature, time, slurry pH, gas to slurry feed ratio and other variables. From early runs at times of about 20 minutes, temperatures of 350/sup 0/C or higher and slurry pH's above 8 are desirable. The reactor has been used only on Douglas fir wood slurries. However, it is available for a wide range of biomass or even fossil feedstocks. New methods of characterizing oil and water-soluble products have been developed and applied to CLU products. Conditions under which formate ion, probable intermediate in both water gas shift reaction and reduction of biomass oxygen by CO, is formed in large quantities have been found. Raw wood chips have been shown to undergo solvolysis - total dissolution - when mixed with wood liquefaction oil and heated under certain conditions. This phenomenon must occur to some degree in the initial stages of the PERC process. Solvolysis is suggested as a possible way to get the benefits of oil recycle without the uneconomicaly high recycle ratios of the PERC process.

  11. Catalytic Hydrothermal Gasification

    SciTech Connect

    Elliott, Douglas C.

    2015-05-31

    The term “hydrothermal” used here refers to the processing of biomass in water slurries at elevated temperature and pressure to facilitate the chemical conversion of the organic structures in biomass into useful fuels. The process is meant to provide a means for treating wet biomass materials without drying and to access ionic reaction conditions by maintaining a liquid water processing medium. Typical hydrothermal processing conditions are 523-647K of temperature and operating pressures from 4-22 MPa of pressure. The temperature is sufficient to initiate pyrolytic mechanisms in the biopolymers while the pressure is sufficient to maintain a liquid water processing phase. Hydrothermal gasification is accomplished at the upper end of the process temperature range. It can be considered an extension of the hydrothermal liquefaction mechanisms that begin at the lowest hydrothermal conditions with subsequent decomposition of biopolymer fragments formed in liquefaction to smaller molecules and eventually to gas. Typically, hydrothermal gasification requires an active catalyst to accomplish reasonable rates of gas formation from biomass.

  12. Techno-economic assessment of catalytic gasification of biomass powders for methanol production.

    PubMed

    Carvalho, Lara; Furusjö, Erik; Kirtania, Kawnish; Wetterlund, Elisabeth; Lundgren, Joakim; Anheden, Marie; Wolf, Jens

    2017-02-08

    This study evaluated the techno-economic performance and potential benefits of methanol production through catalytic gasification of forest residues and lignin. The results showed that while catalytic gasification enables increased cold gas efficiencies and methanol yields compared to non-catalytic gasification, the additional pre-treatment energy and loss of electricity production result in small or no system efficiency improvements. The resulting required methanol selling prices (90-130€/MWh) are comparable with production costs for other biofuels. It is concluded that catalytic gasification of forest residues can be an attractive option as it provides operational advantages at production costs comparable to non-catalytic gasification. The addition of lignin would require lignin costs below 25€/MWh to be economically beneficial.

  13. High temperature ceramic membrane reactors for coal liquid upgrading. Quarterly report No. 1, September 21, 1989--December 20, 1989

    SciTech Connect

    Tsotsis, T.T.

    1992-06-19

    In this project we well evaluate the performance of Sel-Gel alumina membranes in coal liquid upgrading processes under realistic temperature and pressure conditions and investigate the feasibility of using such membranes in a membrane reactor based coal liquid upgrading process. In addition, the development of novel ceramic membranes with enhanced catalytic activity for coal-liquid upgrading applications, such as carbon-coated alumina membranes, will be also investigated. (VC)

  14. Applicability of dynamic membrane technology in anaerobic membrane bioreactors.

    PubMed

    Ersahin, Mustafa Evren; Ozgun, Hale; Tao, Yu; van Lier, Jules B

    2014-01-01

    This study investigated the applicability of dynamic membrane technology in anaerobic membrane bioreactors for the treatment of high strength wastewaters. A monofilament woven fabric was used as support material for dynamic membrane formation. An anaerobic dynamic membrane bioreactor (AnDMBR) was operated under a variety of operational conditions, including different sludge retention times (SRTs) of 20 and 40 days in order to determine the effect of SRT on both biological performance and dynamic membrane filtration characteristics. High COD removal efficiencies exceeding 99% were achieved during the operation at both SRTs. Higher filtration resistances were measured during the operation at SRT of 40 days in comparison to SRT of 20 days, applying a stable flux of 2.6 L/m(2) h. The higher filtration resistances coincided with lower extracellular polymeric substances concentration in the bulk sludge at SRT of 40 days, likely resulting in a decreased particle flocculation. Results showed that dynamic membrane technology achieved a stable and high quality permeate and AnDMBRs can be used as a reliable and satisfactory technology for treatment of high strength wastewaters.

  15. Catalytic activity of human carbonic anhydrase isoform IX is displayed both extra- and intracellularly.

    PubMed

    Klier, Michael; Jamali, Somayeh; Ames, Samantha; Schneider, Hans-Peter; Becker, Holger M; Deitmer, Joachim W

    2016-01-01

    Most carbonic anhydrases catalyse the reversible conversion of carbon dioxide to protons and bicarbonate, either as soluble cytosolic enzymes, in or at intracellular organelles, or at the extracellular face of the cell membrane as membrane-anchored proteins. Carbonic anhydrase isoform IX (CA IX), a membrane-bound enzyme with catalytic activity at the extracellular membrane surface, has come to prominence in recent years because of its association with hypoxic tissue, particularly tumours, often indicating poor prognosis. We have evaluated the catalytic activity of CA IX heterologously expressed in Xenopus laevis oocytes by measuring the amplitude and rate of cytosolic pH changes as well as pH changes at the outer membrane surface (pHs ) during addition and removal of 5% CO2 /25 mm HCO3-, and by mass spectrometry. Our results indicate both extracellular and intracellular catalytic activity of CA IX. Reduced rates of CO2 -dependent intracellular pH changes after knockdown of CA IX confirmed these findings in two breast cancer cell lines: MCF-7 and MDA-MB-231. Our results demonstrate a new function of CA IX that may be important in the search for therapeutic cancer drugs targeting CA IX.

  16. Gas Separations using Ceramic Membranes

    SciTech Connect

    Paul KT Liu

    2005-01-13

    This project has been oriented toward the development of a commercially viable ceramic membrane for high temperature gas separations. A technically and commercially viable high temperature gas separation membrane and process has been developed under this project. The lab and field tests have demonstrated the operational stability, both performance and material, of the gas separation thin film, deposited upon the ceramic membrane developed. This performance reliability is built upon the ceramic membrane developed under this project as a substrate for elevated temperature operation. A comprehensive product development approach has been taken to produce an economically viable ceramic substrate, gas selective thin film and the module required to house the innovative membranes for the elevated temperature operation. Field tests have been performed to demonstrate the technical and commercial viability for (i) energy and water recovery from boiler flue gases, and (ii) hydrogen recovery from refinery waste streams using the membrane/module product developed under this project. Active commercializations effort teaming with key industrial OEMs and end users is currently underway for these applications. In addition, the gas separation membrane developed under this project has demonstrated its economical viability for the CO2 removal from subquality natural gas and landfill gas, although performance stability at the elevated temperature remains to be confirmed in the field.

  17. Voltage-dependent motion of the catalytic region of voltage-sensing phosphatase monitored by a fluorescent amino acid

    PubMed Central

    Sakata, Souhei; Jinno, Yuka; Kawanabe, Akira; Okamura, Yasushi

    2016-01-01

    The cytoplasmic region of voltage-sensing phosphatase (VSP) derives the voltage dependence of its catalytic activity from coupling to a voltage sensor homologous to that of voltage-gated ion channels. To assess the conformational changes in the cytoplasmic region upon activation of the voltage sensor, we genetically incorporated a fluorescent unnatural amino acid, 3-(6-acetylnaphthalen-2-ylamino)-2-aminopropanoic acid (Anap), into the catalytic region of Ciona intestinalis VSP (Ci-VSP). Measurements of Anap fluorescence under voltage clamp in Xenopus oocytes revealed that the catalytic region assumes distinct conformations dependent on the degree of voltage-sensor activation. FRET analysis showed that the catalytic region remains situated beneath the plasma membrane, irrespective of the voltage level. Moreover, Anap fluorescence from a membrane-facing loop in the C2 domain showed a pattern reflecting substrate turnover. These results indicate that the voltage sensor regulates Ci-VSP catalytic activity by causing conformational changes in the entire catalytic region, without changing their distance from the plasma membrane. PMID:27330112

  18. Membrane fouling and wetting in membrane distillation and their mitigation by novel membranes with special wettability.

    PubMed

    Wang, Zhangxin; Lin, Shihong

    2017-04-01

    Membrane distillation (MD) has been identified as a promising technology to desalinate the hypersaline wastewaters from fracking and other industries. However, conventional hydrophobic MD membranes are highly susceptible to fouling and/or wetting by the hydrophobic and/or amphiphilic constituents in these wastewaters of complex compositions. This study systematically investigates the impact of the surface wetting properties on the membrane wetting and/or fouling behaviors in MD. Specifically, we compare the wetting and fouling resistance of three types of membranes of different wetting properties, including hydrophobic and omniphobic membranes as well as composite membranes with a hydrophobic substrate and a superhydrophilic top surface. We challenged the MD membranes with hypersaline feed solutions that contained a relatively high concentration of crude oil with and without added synthetic surfactants, Triton X-100. We found that the composite membranes with superhydrophilic top surface were robustly resistant to oil fouling in the absence of Triton X-100, but were subject to pore wetting in the presence of Triton X-100. On the other hand, the omniphobic membranes were easily fouled by oil-in-water emulsion without Triton X-100, but successfully sustained stable MD performance with Triton X-100 stabilized oil-in-water emulsion as the feed solution. In contrast, the conventional hydrophobic membranes failed readily regardless whether Triton X-100 was present, although via different mechanisms. These findings are corroborated by contact angle measures as well as oil-probe force spectroscopy. This study provides a holistic picture regarding how a hydrophobic membrane fails in MD and how we can leverage membranes with special wettability to prevent membrane failure in MD operations.

  19. Hydrogen production from methane through catalytic partial oxidation reactions

    NASA Astrophysics Data System (ADS)

    Freni, S.; Calogero, G.; Cavallaro, S.

    This paper reviews recent developments in syn-gas production processes used for partial methane oxidation with and/or without steam. In particular, we examined different process charts (fixed bed, fluidised bed, membrane, etc.), kinds of catalysts (powders, foams, monoliths, etc.) and catalytically active phases (Ni, Pt, Rh, etc.). The explanation of the various suggested technical solutions accounted for the reaction mechanism that may selectively lead to calibrated mixtures of CO and H 2 or to the unwanted formation of products of total oxidation (CO 2 and H 2O) and pyrolysis (coke). Moreover, the new classes of catalysts allow the use of small reactors to treat large amounts of methane (monoliths) or separate hydrogen in situ from the other reaction products (membrane). This leads to higher conversions and selectivity than could have been expected thermodynamically. Although catalysts based on Rh are extremely expensive, they can be used to minimise H 2O formation by maximising H 2 yield.

  20. Industrial Gas Turbine Engine Catalytic Pilot Combustor-Prototype Testing

    SciTech Connect

    Etemad, Shahrokh; Baird, Benjamin; Alavandi, Sandeep; Pfefferle, William

    2010-04-01

    PCI has developed and demonstrated its Rich Catalytic Lean-burn (RCL®) technology for industrial and utility gas turbines to meet DOE's goals of low single digit emissions. The technology offers stable combustion with extended turndown allowing ultra-low emissions without the cost of exhaust after-treatment and further increasing overall efficiency (avoidance of after-treatment losses). The objective of the work was to develop and demonstrate emission benefits of the catalytic technology to meet strict emissions regulations. Two different applications of the RCL® concept were demonstrated: RCL® catalytic pilot and Full RCL®. The RCL® catalytic pilot was designed to replace the existing pilot (a typical source of high NOx production) in the existing Dry Low NOx (DLN) injector, providing benefit of catalytic combustion while minimizing engine modification. This report discusses the development and single injector and engine testing of a set of T70 injectors equipped with RCL® pilots for natural gas applications. The overall (catalytic pilot plus main injector) program NOx target of less than 5 ppm (corrected to 15% oxygen) was achieved in the T70 engine for the complete set of conditions with engine CO emissions less than 10 ppm. Combustor acoustics were low (at or below 0.1 psi RMS) during testing. The RCL® catalytic pilot supported engine startup and shutdown process without major modification of existing engine controls. During high pressure testing, the catalytic pilot showed no incidence of flashback or autoignition while operating over a wide range of flame temperatures. In applications where lower NOx production is required (i.e. less than 3 ppm), in parallel, a Full RCL® combustor was developed that replaces the existing DLN injector providing potential for maximum emissions reduction. This concept was tested at industrial gas turbine conditions in a Solar Turbines, Incorporated high-pressure (17 atm.) combustion rig and in a modified Solar Turbines

  1. Vapor Phase Catalytic Ammonia Reduction

    NASA Technical Reports Server (NTRS)

    Flynn, Michael T.; Harper, Lynn D. (Technical Monitor)

    1994-01-01

    This paper discusses the development of a Vapor Phase Catalytic Ammonia Reduction (VPCAR) teststand and the results of an experimental program designed to evaluate the potential of the technology as a water purification process. In the experimental program the technology is evaluated based upon product water purity, water recovery rate, and power consumption. The experimental work demonstrates that the technology produces high purity product water and attains high water recovery rates at a relatively high specific power consumption. The experimental program was conducted in 3 phases. In phase I an Igepon(TM) soap and water mixture was used to evaluate the performance of an innovative Wiped-Film Rotating-Disk evaporator and associated demister. In phase II a phenol-water solution was used to evaluate the performance of the high temperature catalytic oxidation reactor. In phase III a urine analog was used to evaluate the performance of the combined distillation/oxidation functions of the processor.

  2. A model-based parametric analysis of a direct ethanol polymer electrolyte membrane fuel cell performance

    NASA Astrophysics Data System (ADS)

    Andreadis, G. M.; Podias, A. K. M.; Tsiakaras, P. E.

    In the present work, a model-based parametric analysis of the performance of a direct ethanol polymer electrolyte membrane fuel cell (DE-PEMFC) is conducted with the purpose to investigate the effect of several parameters on the cell's operation. The analysis is based on a previously validated one-dimensional mathematical model that describes the operation of a DE-PEMFC in steady state. More precisely, the effect of several operational and structural parameters on (i) the ethanol crossover rate from the anode to the cathode side of the cell, (ii) the parasitic current generation (mixed potential formation) and (iii) the total cell performance is investigated. According to the model predictions it was found that the increase of the ethanol feed concentration leads to higher ethanol crossover rates, higher parasitic currents and higher mixed potential values resulting in the decrease of the cell's power density. However there is an optimum ethanol feed concentration (approximately 1.0 mol L -1) for which the cell power density reaches its highest value. The platinum (Pt) loading of the anode and the cathode catalytic layers affects strongly the cell performance. Higher values of Pt loading of the catalytic layers increase the specific reaction surface area resulting in higher cell power densities. An increase of the anode catalyst loading compared to an equal one of the cathode catalyst loading has greater impact on the cell's power density. Another interesting finding is that increasing the diffusion layers' porosity up to a certain extent, improves the cell power density despite the fact that the parasitic current increases. This is explained by the fact that the reactants' concentrations over the catalysts are increased, leading to lower activation overpotential values, which are the main source of the total cell overpotentials. Moreover, the use of a thicker membrane leads to lower ethanol crossover rate, lower parasitic current and lower mixed potential values

  3. Catalytic σ-Bond Metathesis

    NASA Astrophysics Data System (ADS)

    Reznichenko, Alexander L.; Hultzsch, Kai C.

    This account summarizes information on recently reported applications of organo-rare-earth metal complexes in various catalytic transformations of small molecules. The σ-bond metathesis at d0rare-earth metal centers plays a pivotal role in carbon-carbon and carbon-heteroatom bond forming processes. Relevant mechanistic details are discussed and the focus of the review lies in practical applications of organo-rare-earth metal complexes.

  4. Production of Hydrogen Using Nuclear Energy and Inorganic Membranes

    SciTech Connect

    Bischoff, Brian L.; Trowbridge, Lee D.; Mansur, Louis K.; Forsberg, Charles W.

    2004-07-01

    The sulfur family of thermochemical processes are the leading candidates worldwide for production of hydrogen (H{sub 2}) using nuclear energy. These processes thermo-catalytically crack water yielding hydrogen and oxygen. The processes consist of a series of chemical reactions where all the chemicals are recycled in the process except for water. The processes are potentially efficient, scalable to large sizes, and use no expensive chemical reagents; however, these processes have one major disadvantage: high operating temperatures (800 to 900 deg. C). The high-temperature chemical reaction common to all of these cycles is the equilibrium thermal decomposition of sulfuric acid. There is a potential to lower the peak temperature by 200+ deg. C if the high-temperature decomposition products of sulfuric acid, O{sub 2}, H{sub 2}O, and SO{sub 2}, can be separated from SO{sub 3} using an inorganic membrane. The goal of this project is to conduct proof-of-principle experiments and associated analysis to demonstrate the potential for inorganic membranes to dramatically improve the sulfur family of thermochemical processes. We will present preliminary data of the separation efficiency of the product gases from SO{sub 3}. (authors)

  5. Characterization of a hybrid powdered activated carbon-dynamic membrane bioreactor (PAC-DMBR) process with high flux by gravity flow: Operational performance and sludge properties.

    PubMed

    Hu, Yisong; Wang, Xiaochang C; Sun, Qiyuan; Ngo, Huu Hao; Yu, Zhenzhen; Tang, Jialing; Zhang, Qionghua

    2017-01-01

    Three PAC-DMBRs were developed for wastewater treatment under different PAC dosages with biomass concentrations averaged at 2.5, 3.5 and 5.0g/L. The DMBRs could be continuously operated at 40-100L/m(2)h, while higher fluxes were obtained within the PAC-DMBRs with hydraulic retention times varying in 4-10h. A dose of 1g/L PAC brought about obvious improvement in the sludge particle size distribution, settling, flocculating and dewatering properties due to the formation of biological PAC, and the sludge properties were further improved at a higher PAC dose (3g/L). The addition of PAC notably shortened the DM formation time after air backwashing and enhanced pollutant removal. Moreover, under a long solid retention time (approximately 150d), the concentrations of both soluble and bound extracellular polymeric substances (EPS) decreased substantially because of the adsorption and biodegradation effects of the biological PAC. No obvious impact on biomass activity was observed with PAC addition.

  6. Thermodynamics of catalytic nanoparticle morphology

    NASA Astrophysics Data System (ADS)

    Zwolak, Michael; Sharma, Renu; Lin, Pin Ann

    Metallic nanoparticles are an important class of industrial catalysts. The variability of their properties and the environment in which they act, from their chemical nature & surface modification to their dispersion and support, allows their performance to be optimized for many chemical processes useful in, e.g., energy applications and other areas. Their large surface area to volume ratio, as well as varying sizes and faceting, in particular, makes them an efficient source for catalytically active sites. These characteristics of nanoparticles - i.e., their morphology - can often display intriguing behavior as a catalytic process progresses. We develop a thermodynamic model of nanoparticle morphology, one that captures the competition of surface energy with other interactions, to predict structural changes during catalytic processes. Comparing the model to environmental transmission electron microscope images of nickel nanoparticles during carbon nanotube (and other product) growth demonstrates that nickel deformation in response to the nanotube growth is due to a favorable interaction with carbon. Moreover, this deformation is halted due to insufficient volume of the particles. We will discuss the factors that influence morphology and also how the model can be used to extract interaction strengths from experimental observations.

  7. Tubular hydrogen permeable metal foil membrane and method of fabrication

    DOEpatents

    Paglieri, Stephen N.; Birdsell, Stephen A.; Barbero, Robert S.; Snow, Ronny C.; Smith, Frank M.

    2006-04-04

    A tubular hydrogen permeable metal membrane and fabrication process comprises obtaining a metal alloy foil having two surfaces, coating the surfaces with a metal or metal alloy catalytic layer to produce a hydrogen permeable metal membrane, sizing the membrane into a sheet with two long edges, wrapping the membrane around an elongated expandable rod with the two long edges aligned and overlapping to facilitate welding of the two together, placing the foil wrapped rod into a surrounding fixture housing with the two aligned and overlapping foil edges accessible through an elongated aperture in the surrounding fixture housing, expanding the elongated expandable rod within the surrounding fixture housing to tighten the foil about the expanded rod, welding the two long overlapping foil edges to one another generating a tubular membrane, and removing the tubular membrane from within the surrounding fixture housing and the expandable rod from with the tubular membrane.

  8. Metamaterial membranes

    NASA Astrophysics Data System (ADS)

    Restrepo-Flórez, Juan Manuel; Maldovan, Martin

    2017-01-01

    We introduce a new class of metamaterial device to achieve separation of compounds by using coordinate transformations and metamaterial theory. By rationally designing the spatial anisotropy for mass diffusion, we simultaneously concentrate different compounds in different spatial locations, leading to separation of mixtures across a metamaterial membrane. The separation of mixtures into their constituent compounds is critically important in biophysics, biomedical, and chemical applications. We present a practical case where a mixture of oxygen and nitrogen diffusing through a polymeric planar matrix is separated. This work opens doors to new paradigms in membrane separations via coordinate transformations and metamaterials by introducing novel properties and unconventional mass diffusion phenomena.

  9. Hybrid lean premixing catalytic combustion system for gas turbines

    DOEpatents

    Critchley, Ian L.

    2003-12-09

    A system and method of combusting a hydrocarbon fuel is disclosed. The system combines the accuracy and controllability of an air staging system with the ultra-low emissions achieved by catalytic combustion systems without the need for a pre-heater. The result is a system and method that is mechanically simple and offers ultra-low emissions over a wide range of power levels, fuel properties and ambient operating conditions.

  10. Catalytically active nanomaterials: a promising candidate for artificial enzymes.

    PubMed

    Lin, Youhui; Ren, Jinsong; Qu, Xiaogang

    2014-04-15

    Natural enzymes, exquisite biocatalysts mediating every biological process in living organisms, are able to accelerate the rate of chemical reactions up to 10(19) times for specific substrates and reactions. However, the practical application of enzymes is often hampered by their intrinsic drawbacks, such as low operational stability, sensitivity of catalytic activity to environmental conditions, and high costs in preparation and purification. Therefore, the discovery and development of artificial enzymes is highly desired. Recently, the merging of nanotechnology with biology has ignited extensive research efforts for designing functional nanomaterials that exhibit various properties intrinsic to enzymes. As a promising candidate for artificial enzymes, catalytically active nanomaterials (nanozymes) show several advantages over natural enzymes, such as controlled synthesis in low cost, tunability in catalytic activities, as well as high stability against stringent conditions. In this Account, we focus on our recent progress in exploring and constructing such nanoparticulate artificial enzymes, including graphene oxide, graphene-hemin nanocomposites, carbon nanotubes, carbon nanodots, mesoporous silica-encapsulated gold nanoparticles, gold nanoclusters, and nanoceria. According to their structural characteristics, these enzyme mimics are categorized into three classes: carbon-, metal-, and metal-oxide-based nanomaterials. We aim to highlight the important role of catalytic nanomaterials in the fields of biomimetics. First, we provide a practical introduction to the identification of these nanozymes, the source of the enzyme-like activities, and the enhancement of activities via rational design and engineering. Then we briefly describe new or enhanced applications of certain nanozymes in biomedical diagnosis, environmental monitoring, and therapeutics. For instance, we have successfully used these biomimetic catalysts as colorimetric probes for the detection of

  11. Membrane technology comes of age

    SciTech Connect

    Dietrich, J.A.

    1995-07-01

    Membrane technology has come of age for industry, paralleling the increased pressures to recover products, recycle wastewater and minimize the volume, costs and liability associated with waste disposal. But, the conventional microfiltration/ultrafiltration/nanofiltration/reverse-osmosis breakout is only a starting point in determining whether membrane technology is a viable alternative in any given application. Membranes are distinguished not only by their pore size and molecular weight break-off points, but by their configurations and materials of construction. The efficiency of a particular membrane design relies, first and foremost, on an accurate understanding of the goals and objectives of the system. As waste disposal becomes an increasingly difficult and costly operation, the search for ways to recover usable products, recycle process liquids, and reduce the amounts of waste requiring disposal intensifies. For many of those goals, membrane technology offers options that are effective, dependable and increasingly cost-effective.

  12. Thermal performance of a catalytic/oxidizer for the Space Station Freedom

    NASA Technical Reports Server (NTRS)

    Wedel, R. K.; Djordjevic, N.; Faulkner, F.

    1993-01-01

    Thermal analysis and testing have been performed for the High Temperature Catalytic/Oxidizer (HTCO) for the Space Station Freedom (SSF) Trace Contaminant Control Subassembly (TCCS). The HTCO consists of a counterflow, plate-fin heat exchanger, a resistance heater, and a charcoal catalytic oxidizer bed. The unit removes various inorganics and hydrocarbons from the SSF cabin air. A thermal model of the unit was developed which was used to design the HEX and catalytic bed. The model has been used to predict both steady state and transient results. Accurate predictions of ground test data have led to confidence in proper operation of the unit in the SSF.

  13. Refinery hydrogen recovery with sepharex membrane systems

    SciTech Connect

    Schnell, W.J.; Houston, C.D.

    1985-03-01

    Gas separation by membranes is discussed, and presented to be an economically viable process. Commercial installation of membrane systems has been made for hydrogen recovery in refineries and ammonia plants and for CO/sub 2/ removal from various gas streams. The process described in this paper utilizes a flat-sheet cellulose acetate membrane fabricated into a spiral wound element configuration. An illustration of the membrane, named Separex, is provided. These membranes exhibit long-time stability in refinery H/sub 2/ recovery applications even under harsh operating conditions. The successful operation of this system demonstrates the commercial capability of Separex membranes. A comparison with PSA for hydrogen purification shows that membrane systems offer a substantially lower hydrogen production cost and an increase in hydrogen recovery.

  14. Ternary structure reveals mechanism of a membrane diacylglycerol kinase

    SciTech Connect

    Li, Dianfan; Stansfeld, Phillip J.; Sansom, Mark S. P.; Keogh, Aaron; Vogeley, Lutz; Howe, Nicole; Lyons, Joseph A.; Aragao, David; Fromme, Petra; Fromme, Raimund; Basu, Shibom; Grotjohann, Ingo; Kupitz, Christopher; Rendek, Kimberley; Weierstall, Uwe; Zatsepin, Nadia A.; Cherezov, Vadim; Liu, Wei; Bandaru, Sateesh; English, Niall J.; Gati, Cornelius; Barty, Anton; Yefanov, Oleksandr; Chapman, Henry N.; Diederichs, Kay; Messerschmidt, Marc; Boutet, Sébastien; Williams, Garth J.; Marvin Seibert, M.; Caffrey, Martin

    2015-12-17

    Diacylglycerol kinase catalyses the ATP-dependent conversion of diacylglycerol to phosphatidic acid in the plasma membrane of Escherichia coli. The small size of this integral membrane trimer, which has 121 residues per subunit, means that available protein must be used economically to craft three catalytic and substrate-binding sites centred about the membrane/cytosol interface. How nature has accomplished this extraordinary feat is revealed here in a crystal structure of the kinase captured as a ternary complex with bound lipid substrate and an ATP analogue. Residues, identified as essential for activity by mutagenesis, decorate the active site and are rationalized by the ternary structure. The γ-phosphate of the ATP analogue is positioned for direct transfer to the primary hydroxyl of the lipid whose acyl chain is in the membrane. A catalytic mechanism for this unique enzyme is proposed. As a result, the active site architecture shows clear evidence of having arisen by convergent evolution.

  15. Ternary structure reveals mechanism of a membrane diacylglycerol kinase

    NASA Astrophysics Data System (ADS)

    Li, Dianfan; Stansfeld, Phillip J.; Sansom, Mark S. P.; Keogh, Aaron; Vogeley, Lutz; Howe, Nicole; Lyons, Joseph A.; Aragao, David; Fromme, Petra; Fromme, Raimund; Basu, Shibom; Grotjohann, Ingo; Kupitz, Christopher; Rendek, Kimberley; Weierstall, Uwe; Zatsepin, Nadia A.; Cherezov, Vadim; Liu, Wei; Bandaru, Sateesh; English, Niall J.; Gati, Cornelius; Barty, Anton; Yefanov, Oleksandr; Chapman, Henry N.; Diederichs, Kay; Messerschmidt, Marc; Boutet, Sébastien; Williams, Garth J.; Marvin Seibert, M.; Caffrey, Martin

    2015-12-01

    Diacylglycerol kinase catalyses the ATP-dependent conversion of diacylglycerol to phosphatidic acid in the plasma membrane of Escherichia coli. The small size of this integral membrane trimer, which has 121 residues per subunit, means that available protein must be used economically to craft three catalytic and substrate-binding sites centred about the membrane/cytosol interface. How nature has accomplished this extraordinary feat is revealed here in a crystal structure of the kinase captured as a ternary complex with bound lipid substrate and an ATP analogue. Residues, identified as essential for activity by mutagenesis, decorate the active site and are rationalized by the ternary structure. The γ-phosphate of the ATP analogue is positioned for direct transfer to the primary hydroxyl of the lipid whose acyl chain is in the membrane. A catalytic mechanism for this unique enzyme is proposed. The active site architecture shows clear evidence of having arisen by convergent evolution.

  16. Ternary structure reveals mechanism of a membrane diacylglycerol kinase

    PubMed Central

    Li, Dianfan; Stansfeld, Phillip J.; Sansom, Mark S. P.; Keogh, Aaron; Vogeley, Lutz; Howe, Nicole; Lyons, Joseph A.; Aragao, David; Fromme, Petra; Fromme, Raimund; Basu, Shibom; Grotjohann, Ingo; Kupitz, Christopher; Rendek, Kimberley; Weierstall, Uwe; Zatsepin, Nadia A.; Cherezov, Vadim; Liu, Wei; Bandaru, Sateesh; English, Niall J.; Gati, Cornelius; Barty, Anton; Yefanov, Oleksandr; Chapman, Henry N.; Diederichs, Kay; Messerschmidt, Marc; Boutet, Sébastien; Williams, Garth J.; Marvin Seibert, M.; Caffrey, Martin

    2015-01-01

    Diacylglycerol kinase catalyses the ATP-dependent conversion of diacylglycerol to phosphatidic acid in the plasma membrane of Escherichia coli. The small size of this integral membrane trimer, which has 121 residues per subunit, means that available protein must be used economically to craft three catalytic and substrate-binding sites centred about the membrane/cytosol interface. How nature has accomplished this extraordinary feat is revealed here in a crystal structure of the kinase captured as a ternary complex with bound lipid substrate and an ATP analogue. Residues, identified as essential for activity by mutagenesis, decorate the active site and are rationalized by the ternary structure. The γ-phosphate of the ATP analogue is positioned for direct transfer to the primary hydroxyl of the lipid whose acyl chain is in the membrane. A catalytic mechanism for this unique enzyme is proposed. The active site architecture shows clear evidence of having arisen by convergent evolution. PMID:26673816

  17. Catalytic oxidation of volatile organic compounds (VOCs) - A review

    NASA Astrophysics Data System (ADS)

    Kamal, Muhammad Shahzad; Razzak, Shaikh A.; Hossain, Mohammad M.

    2016-09-01

    Emission of volatile organic compounds (VOCs) is one of the major contributors to air pollution. The main sources of VOCs are petroleum refineries, fuel combustions, chemical industries, decomposition in the biosphere and biomass, pharmaceutical plants, automobile industries, textile manufacturers, solvents processes, cleaning products, printing presses, insulating materials, office supplies, printers etc. The most common VOCs are halogenated compounds, aldehydes, alcohols, ketones, aromatic compounds, and ethers. High concentrations of these VOCs can cause irritations, nausea, dizziness, and headaches. Some VOCs are also carcinogenic for both humans and animals. Therefore, it is crucial to minimize the emission of VOCs. Among the available technologies, the catalytic oxidation of VOCs is the most popular because of its versatility of handling a range of organic emissions under mild operating conditions. Due to that fact, there are numerous research initiatives focused on developing advanced technologies for the catalytic destruction of VOCs. This review discusses recent developments in catalytic systems for the destruction of VOCs. Review also describes various VOCs and their sources of emission, mechanisms of catalytic destruction, the causes of catalyst deactivation, and catalyst regeneration methods.

  18. ULTRA LOW NOx CATALYTIC COMBUSTION FOR IGCC POWER PLANTS

    SciTech Connect

    Lance L. Smith

    2004-03-01

    Tests were performed in PCI's sub-scale high-pressure (10 atm) test rig, using PCI's two-stage (catalytic / gas-phase) combustion process for syngas fuel. In this process, the first stage is a Rich-Catalytic Lean-burn (RCL{trademark}) catalytic reactor, wherein a fuel-rich mixture contacts the catalyst and reacts while final and excess combustion air cool the catalyst. The second stage is a gas-phase combustor, wherein the catalyst cooling air mixes with the catalytic reactor effluent to provide for final gas-phase burnout and dilution to fuel-lean combustion products. During the reporting period, PCI successfully achieved NOx = 0.011 lbs/MMBtu at 10 atm pressure (corresponding to 2.0 ppm NOx corrected to 15% O{sub 2} dry) with near-zero CO emissions, surpassing the project goal of < 0.03 lbs/MMBtu NOx. These emissions levels were achieved at scaled (10 atm, sub-scale) baseload conditions corresponding to Tampa Electric's Polk Power Station operation on 100% syngas (no co-firing of natural gas).

  19. Catalytic two-stage coal hydrogenation and hydroconversion process

    DOEpatents

    MacArthur, James B.; McLean, Joseph B.; Comolli, Alfred G.

    1989-01-01

    A process for two-stage catalytic hydrogenation and liquefaction of coal to produce increased yields of low-boiling hydrocarbon liquid and gas products. In the process, the particulate coal is slurried with a process-derived liquid solvent and fed at temperature below about 650.degree. F. into a first stage catalytic reaction zone operated at conditions which promote controlled rate liquefaction of the coal, while simultaneously hydrogenating the hydrocarbon recycle oils at conditions favoring hydrogenation reactions. The first stage reactor is maintained at 650.degree.-800.degree. F. temperature, 1000-4000 psig hydrogen partial pressure, and 10-60 lb coal/hr/ft.sup.3 reactor space velocity. The partially hydrogenated material from the first stage reaction zone is passed directly to the close-coupled second stage catalytic reaction zone maintained at a temperature at least about 25.degree. F. higher than for the first stage reactor and within a range of 750.degree.-875.degree. F. temperature for further hydrogenation and thermal hydroconversion reactions. By this process, the coal feed is successively catalytically hydrogenated and hydroconverted at selected conditions, which results in significantly increased yields of desirable low-boiling hydrocarbon liquid products and minimal production of undesirable residuum and unconverted coal and hydrocarbon gases, with use of less energy to obtain the low molecular weight products, while catalyst life is substantially increased.

  20. Membrane magic

    SciTech Connect

    Buecker, B.

    2005-09-01

    The Kansas Power and Light Co.'s La Cyne generating station has found success with membrane filtration water pretreatment technology. The article recounts the process followed in late 2004 to install a Pall Aria 4 microfilter in Unit 1 makeup water system at the plant to produce cleaner water for reverse osmosis feed. 2 figs., 2 photos.

  1. Membranes for Environmentally Friendly Energy Processes

    PubMed Central

    He, Xuezhong; Hägg, May-Britt

    2012-01-01

    Membrane separation systems require no or very little chemicals compared to standard unit operations. They are also easy to scale up, energy efficient, and already widely used in various gas and liquid separation processes. Different types of membranes such as common polymers, microporous organic polymers, fixed-site-carrier membranes, mixed matrix membranes, carbon membranes as well as inorganic membranes have been investigated for CO2 capture/removal and other energy processes in the last two decades. The aim of this work is to review the membrane systems applied in different energy processes, such as post-combustion, pre-combustion, oxyfuel combustion, natural gas sweetening, biogas upgrading, hydrogen production, volatile organic compounds (VOC) recovery and pressure retarded osmosis for power generation. Although different membranes could probably be used in a specific separation process, choosing a suitable membrane material will mainly depend on the membrane permeance and selectivity, process conditions (e.g., operating pressure, temperature) and the impurities in a gas stream (such as SO2, NOx, H2S, etc.). Moreover, process design and the challenges relevant to a membrane system are also being discussed to illustrate the membrane process feasibility for a specific application based on process simulation and economic cost estimation. PMID:24958426

  2. High flux and antifouling properties of negatively charged membrane for dyeing wastewater treatment by membrane distillation.

    PubMed

    An, Alicia Kyoungjin; Guo, Jiaxin; Jeong, Sanghyun; Lee, Eui-Jong; Tabatabai, S Assiyeh Alizadeh; Leiknes, TorOve

    2016-10-15

    This study investigated the applicability of membrane distillation (MD) to treat dyeing wastewater discharged by the textile industry. Four different dyes containing methylene blue (MB), crystal violet (CV), acid red 18 (AR18), and acid yellow 36 (AY36) were tested. Two types of hydrophobic membranes made of polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PVDF) were used. The membranes were characterized by testing against each dye (foulant-foulant) and the membrane-dye (membrane-foulant) interfacial interactions and their mechanisms were identified. The MD membranes possessed negative charges, which facilitated the treatment of acid and azo dyes of the same charge and showed higher fluxes. In addition, PTFE membrane reduced the wettability with higher hydrophobicity of the membrane surface. The PTFE membrane evidenced especially its resistant to dye absorption, as its strong negative charge and chemical structure caused a flake-like (loose) dye-dye structure to form on the membrane surface rather than in the membrane pores. This also enabled the recovery of flux and membrane properties by water flushing (WF), thereby direct-contact MD with PTFE membrane treating 100 mg/L of dye mixtures showed stable flux and superior color removal during five days operation. Thus, MD shows a potential for stable long-term operation in conjunction with a simple membrane cleaning process, and its suitability in dyeing wastewater treatment.

  3. Advanced Low-Emissions Catalytic-Combustor Program, phase 1. [aircraft gas turbine engines

    NASA Technical Reports Server (NTRS)

    Sturgess, G. J.

    1981-01-01

    Six catalytic combustor concepts were defined, analyzed, and evaluated. Major design considerations included low emissions, performance, safety, durability, installations, operations and development. On the basis of these considerations the two most promising concepts were selected. Refined analysis and preliminary design work was conducted on these two concepts. The selected concepts were required to fit within the combustor chamber dimensions of the reference engine. This is achieved by using a dump diffuser discharging into a plenum chamber between the compressor discharge and the turbine inlet, with the combustors overlaying the prediffuser and the rear of the compressor. To enhance maintainability, the outer combustor case for each concept is designed to translate forward for accessibility to the catalytic reactor, liners and high pressure turbine area. The catalytic reactor is self-contained with air-cooled canning on a resilient mounting. Both selected concepts employed integrated engine-starting approaches to raise the catalytic reactor up to operating conditions. Advanced liner schemes are used to minimize required cooling air. The two selected concepts respectively employ fuel-rich initial thermal reaction followed by rapid quench and subsequent fuel-lean catalytic reaction of carbon monoxide, and, fuel-lean thermal reaction of some fuel in a continuously operating pilot combustor with fuel-lean catalytic reaction of remaining fuel in a radially-staged main combustor.

  4. Catalytic cracking of bio-oil to organic liquid product (OLP).

    PubMed

    Hew, K L; Tamidi, A M; Yusup, S; Lee, K T; Ahmad, M M

    2010-11-01

    The main objective of this paper is to find the optimum operating condition to upgrade the EFB-derived pyrolysis oil (bio-oil) to liquid fuel, mainly gasoline using Taguchi Method. From the analysis that has been done, it is found that the optimum operating condition for heterogeneous catalytic cracking process is at 400 degrees C, 15min of reaction time using 30g of catalyst weight where operating at this condition produced the highest yield of gasoline fraction which is 91.67 wt.%. This observation proves that EFB-derived pyrolysis oil could be upgraded via heterogeneous catalytic cracking to produce gasoline.

  5. Catalytic Combustion for Ultra-Low NOx Hydrogen Turbines

    SciTech Connect

    Etemad, Shahrokh; Baird, Benjamin; Alavandi, Sandeep

    2011-06-30

    Precision Combustion, Inc., (PCI) in close collaboration with Solar Turbines, Incorporated, has developed and demonstrated a combustion system for hydrogen fueled turbines that reduces NOx to low single digit level while maintaining or improving current levels of efficiency and eliminating emissions of carbon dioxide. Full scale Rich Catalytic Hydrogen (RCH1) injector was developed and successfully tested at Solar Turbines, Incorporated high pressure test facility demonstrating low single digit NOx emissions for hydrogen fuel in the range of 2200F-2750F. This development work was based on initial subscale development for faster turnaround and reduced cost. Subscale testing provided promising results for 42% and 52% H2 with NOx emissions of less than 2 ppm with improved flame stability. In addition, catalytic reactor element testing for substrate oxidation, thermal cyclic injector testing to simulate start-stop operation in a gas turbine environment, and steady state 15 atm. operation testing were performed successfully. The testing demonstrated stable and robust catalytic element component life for gas turbine conditions. The benefit of the catalytic hydrogen combustor technology includes capability of delivering near-zero NOx without costly post-combustion controls and without requirement for added sulfur control. In addition, reduced acoustics increase gas turbine component life. These advantages advances Department of Energy (DOE’s) objectives for achievement of low single digit NOx emissions, improvement in efficiency vs. postcombustion controls, fuel flexibility, a significant net reduction in Integrated Gasification Combined Cycle (IGCC) system net capital and operating costs, and a route to commercialization across the power generation field from micro turbines to industrial and utility turbines.

  6. Ultrathin self-assembled polyelectrolyte multilayer membranes

    NASA Astrophysics Data System (ADS)

    Tieke, B.; van Ackern, F.; Krasemann, L.; Toutianoush, A.

    The paper is concerned with ultrathin membranes prepared upon alternating layer-by-layer adsorption of cationic and anionic polyelectrolytes on a porous substructure. The formation of the polyelectrolyte multilayer membranes is characterised and the transport of gases, liquid mixtures and ions across the membranes is studied. In particular, the use of the membranes for alcohol/water separation under pervaporation conditions, and for the separation of mono- and divalent ions is described. It is demonstrated that upon a suitable choice of polyelectrolytes and substructures, and a careful optimisation of preparation and operation conditions, membranes can be tailored exhibiting an excellent separation capability.

  7. OXIDATIVE COUPLING OF METHANE USING INORGANIC MEMBRANE REACTORS

    SciTech Connect

    Dr. Y.H. Ma; Dr. W.R. Moser; Dr. A.G. Dixon; Dr. A.M. Ramachandra; Dr. Y. Lu; C. Binkerd

    1998-04-01

    The objective of this research is to study the oxidative coupling of methane in catalytic inorganic membrane reactors. A specific target is to achieve conversion of methane to C{sub 2} hydrocarbons at very high selectivity and higher yields than in conventional non-porous, co-feed, fixed bed reactors by controlling the oxygen supply through the membrane. A membrane reactor has the advantage of precisely controlling the rate of delivery of oxygen to the catalyst. This facility permits balancing the rate of oxidation and reduction of the catalyst. In addition, membrane reactors minimize the concentration of gas phase oxygen thus reducing non selective gas phase reactions, which are believed to be a main route for the formation of CO{sub x} products. Such gas phase reactions are a cause of decreased selectivity in the oxidative coupling of methane in conventional flow reactors. Membrane reactors could also produce higher product yields by providing better distribution of the reactant gases over the catalyst than the conventional plug flow reactors. Membrane reactor technology also offers the potential for modifying the membranes both to improve catalytic properties as well as to regulate the rate of the permeation/diffusion of reactants through the membrane to minimize by-product generation. Other benefits also exist with membrane reactors, such as the mitigation of thermal hot-spots for highly exothermic reactions such as the oxidative coupling of methane. The application of catalytically active inorganic membranes has potential for drastically increasing the yield of reactions which are currently limited by either thermodynamic equilibria, product inhibition, or kinetic selectivity.

  8. Catalytic combustion of alcohols for microburner applications

    NASA Astrophysics Data System (ADS)

    Behrens, Douglas A.; Lee, Ivan C.; Waits, C. Michael

    The combustion of energy dense liquid fuels in a catalytic micro-combustor, whose temperatures can be used in energy conversion devices, is an attractive alternative to cumbersome batteries. To miniaturize the reactor, an evaporation model was developed to calculate the minimum distance required for complete droplet vaporization. By increasing the ambient temperature from 298 to 350 K, the distance required for complete evaporation of a 6.5 μm droplet decreases from 3.5 to 0.15 cm. A platinum mesh acted as a preliminary measurement and demonstrated 75% conversion of ethanol. We then selected a more active rhodium-coated alumina foam with a larger surface area and attained 100% conversion of ethanol and 95% conversion of 1-butanol under fuel lean conditions. Effluent post-combustion gas analysis showed that varying the equivalence ratio results in three possible modes of operation. A regime of high carbon selectivity for CO 2 occurs at low equivalence ratios and corresponds to complete combustion with a typical temperature of 775 K that is ideal for PbTe thermoelectric energy conversion devices. Conversely for equivalence ratios greater than 1, carbon selectivity for CO 2 decreases as hydrogen, olefin and paraffin production increases. By tuning the equivalence ratio, we have shown that a single device can combust completely for thermoelectric applications, operate as a fuel reformer to produce hydrogen gas for fuel cells or perform as a bio-refinery for paraffin and olefin synthesis.

  9. Evaluation of catalytic combustion of actual coal-derived gas

    NASA Technical Reports Server (NTRS)

    Blanton, J. C.; Shisler, R. A.

    1982-01-01

    The combustion characteristics of a Pt-Pl catalytic reactor burning coal-derived, low-Btu gas were investigated. A large matrix of test conditions was explored involving variations in fuel/air inlet temperature and velocity, reactor pressure, and combustor exit temperature. Other data recorded included fuel gas composition, reactor temperatures, and exhaust emissions. Operating experience with the reactor was satisfactory. Combustion efficiencies were quite high (over 95 percent) over most of the operating range. Emissions of NOx were quite high (up to 500 ppm V and greater), owing to the high ammonia content of the fuel gas.

  10. An update on catalytic reforming

    SciTech Connect

    Wei, D.H.; Moser, M.D.; Haizmann, R.S.

    1996-10-01

    The UOP Platforming process is a catalytic reforming process in widespread use throughout the petroleum and petrochemical industries. Since the first unit went onstream in 1949, the process has become a standard feature in refineries worldwide. Over the years, significant improvements have been made in process catalysts and process design. The most recent improvement is the combination of a catalyst called R-72 with a new patented flow scheme, R-72 staged loading, which gives significantly higher yields and provides increased catalyst stability. In this article, the authors describe two types of Platforming processes and the new R-72 staged loading scheme.

  11. Catalytic cracking of heavy oils

    SciTech Connect

    Otterstedt, J.E.; Gevert, B.; Sterte, J. )

    1987-08-01

    Of the many factors which influence product yields in a fluid catalytic cracker, the feed stock quality and the catalyst composition are of particular interest as they can be controlled only to a limited extent by the refiner. In the past decade there has been a trend towards using heavier feedstocks in the FCC-unit, which is expected to continue in the foreseeable future. It is therefore important to study how molecular types, characteristic not only of heavy petroleum oil but also of e.g. coal liquid, shale oil and biomass oil, respond to cracking over catalysts of different compositions.

  12. Molecular catalytic coal liquid conversion

    SciTech Connect

    Stock, L.M.; Yang, Shiyong

    1995-12-31

    This research, which is relevant to the development of new catalytic systems for the improvement of the quality of coal liquids by the addition of dihydrogen, is divided into two tasks. Task 1 centers on the activation of dihydrogen by molecular basic reagents such as hydroxide ion to convert it into a reactive adduct (OH{center_dot}H{sub 2}){sup {minus}} that can reduce organic molecules. Such species should be robust withstanding severe conditions and chemical poisons. Task 2 is focused on an entirely different approach that exploits molecular catalysts, derived from organometallic compounds that are capable of reducing monocyclic aromatic compounds under very mild conditions. Accomplishments and conclusions are discussed.

  13. Adaptive Model Predictive Control of Diesel Engine Selective Catalytic Reduction (SCR) Systems

    ERIC Educational Resources Information Center

    McKinley, Thomas L.

    2009-01-01

    Selective catalytic reduction or SCR is coming into worldwide use for diesel engine emissions reduction for on- and off-highway vehicles. These applications are characterized by broad operating range as well as rapid and unpredictable changes in operating conditions. Significant nonlinearity, input and output constraints, and stringent performance…

  14. Mechanisms and Kinetics of Catalytic Reactions

    DTIC Science & Technology

    1990-08-01

    CHEMICAL RESEARCH, r- DEVELOPMENT 5 N ENGINEERING CRDE-R-084 "" CENTER CENER(GC-TR-1728-008) ’ 04 N MECHANISMS AND KINETICS OF CATALYTIC REACTIONS Q...and Kinetics of Catalytic Reactions &AUTHOR(S) Garlick, Stephanie M. 7. PERFORMING ORGANIZATION NAME(S) AND ADORESS(ES) . PERFORMING ORGANIZATION...Tables........................87 vi MECHANISMS AND KINETICS OF CATALYTIC REACTIONS 1. INTRODUCTION The hydrolysis of phosphate esters in microemulsion

  15. Influence of membrane properties on physically reversible and irreversible fouling in membrane bioreactors.

    PubMed

    Tsuyuhara, T; Hanamoto, Y; Miyoshi, T; Kimura, K; Watanabe, Y

    2010-01-01

    This study aimed to examine the impact of membrane properties on membrane fouling in membrane bioreactor (MBR). Membrane fouling was divided into two categories: physically reversible and irreversible fouling. Membrane properties related to each type of membrane fouling were investigated separately. Five microfiltration (MF) and one ultrafiltration (UF) membranes with different properties (pore size, contact angle, roughness, zeta potential, and pure water permeability) were examined with a laboratory-scale MBR, fed with synthetic wastewater. Two separate experiments were conducted: the first to examine physically reversible fouling, and the second to examine physically irreversible fouling. The correlation between the degree of each type of fouling and membrane properties was studied. High correlation was observed between the degree of physically reversible fouling and roughness (R(2)=0.96). In contrast, with regard to physically irreversible fouling, strong correlation between roughness and degree of membrane fouling can only be found in the case of MF membranes. Except for the membrane with the highest roughness, the degree of physically irreversible fouling can be well correlated with pure water permeability (lower pure water permeability results in higher degree of physically irreversible fouling) including UF membrane. On the basis of the results obtained in this study, it can be concluded that roughness is an important factor in determination of physically reversible fouling regardless of the types of membrane (i.e. MF or UF membranes) and evolutions of physically irreversible fouling can be mitigated when an MBR is operated with membranes with smooth surface and high pure water permeability.

  16. High Flux Metallic Membranes for Hydrogen Recovery and Membrane Reactors

    SciTech Connect

    Buxbaum, Robert

    2010-06-30

    We made and tested over 250 new alloys for use as lower cost, higher flux hydrogen extraction membrane materials. Most of these were intermetallic, or contained significant intermetallic content, particularly based on B2 alloy compositions with at least one refractory component; B2 intermetallics resemble BCC alloys, in structure, but the atoms have relatively fixed positions, with one atom at the corners of the cube, the other at the centers. The target materals we were looking for would contain little or no expensive elements, no strongly toxic or radioactive elements, would have high flux to hydrogen, while being fabricable, brazable, and relatively immune to hydrogen embrittlement and corrosion in operation. The best combination of properties of the membrane materials we developed was, in my opinion, a Pd-coated membrane consisting of V -9 atomic % Pd. This material was relatively cheap, had 5 times the flux of Pd under the same pressure differential, was reasonably easy to fabricate and braze, and not bad in terms of embrittlement. Based on all these factors we project, about 1/3 the cost of Pd, on an area basis for a membrane designed to last 20 years, or 1/15 the cost on a flux basis. Alternatives to this membrane replaced significant fractions of the Pd with Ni and or Co. The cost for these membranes was lower, but so was the flux. We produced successful brazed products from the membrane materials, and made them into flat sheets. We tested, unsuccessfully, several means of fabricating thematerials into tubes, and eventually built a membrane reactor using a new, flat-plate design: a disc and doughnut arrangement, a design that seems well- suited to clean hydrogen production from coal. The membranes and reactor were tested successfully at Western Research. A larger equipment company (Chart Industries) produced similar results using a different flat-plate reactor design. Cost projections of the membrane are shown to be attractive.

  17. Catalytic microrotor driven by geometrical asymmetry.

    PubMed

    Yang, Mingcheng; Ripoll, Marisol; Chen, Ke

    2015-02-07

    An asymmetric gear with homogeneous surface properties is, here, presented as a prototype to fabricate catalytic microrotors. The driving torque arises from the diffusiophoretic effect induced by the concentration gradients generated by catalytic chemical reactions at the gear surface. This torque produces a spontaneous and unidirectional rotation of the asymmetric gear. By means of mesoscopic simulations, we prove and characterize this scenario. The gear rotational velocity is determined by the gear-solvent interactions, the gear geometry, the solvent viscosity, and the catalytic reaction ratio. Our work presents a simple way to design self-propelled microrotors, alternative to existing catalytic bi-component, or thermophoretic ones.

  18. Catalytic microrotor driven by geometrical asymmetry

    NASA Astrophysics Data System (ADS)

    Yang, Mingcheng; Ripoll, Marisol; Chen, Ke

    2015-02-01

    An asymmetric gear with homogeneous surface properties is, here, presented as a prototype to fabricate catalytic microrotors. The driving torque arises from the diffusiophoretic effect induced by the concentration gradients generated by catalytic chemical reactions at the gear surface. This torque produces a spontaneous and unidirectional rotation of the asymmetric gear. By means of mesoscopic simulations, we prove and characterize this scenario. The gear rotational velocity is determined by the gear-solvent interactions, the gear geometry, the solvent viscosity, and the catalytic reaction ratio. Our work presents a simple way to design self-propelled microrotors, alternative to existing catalytic bi-component, or thermophoretic ones.

  19. Heterogeneous kinetic modeling of the catalytic conversion of cycloparaffins

    NASA Astrophysics Data System (ADS)

    Al-Sabawi, Mustafa N.

    The limited availability of high value light hydrocarbon feedstocks along with the rise in crude prices has resulted in the international recognition of the vast potential of Canada's oil sands. With the recent expansion of Canadian bitumen production come, however, many technical challenges, one of which is the significant presence of aromatics and cycloparaffins in bitumen-derived feedstocks. In addition to their negative environmental impact, aromatics limit fluid catalytic cracking (FCC) feedstock conversion, decrease the yield and quality of valuable products such as gasoline and middle distillates, increase levels of polyaromatic hydrocarbons prone to form coke on the catalyst, and ultimately compromise the FCC unit performance. Although cycloparaffins do not have such negative impacts, they are precursors of aromatics as they frequently undergo hydrogen transfer reactions. However, cycloparaffin cracking chemistry involves other competing reactions that are complex and need much investigation. This dissertation provides insights and understanding of the fundamentals of the catalytic cracking of cycloparaffins using carefully selected model compounds such as methylcyclohexane (MCH) and decalin. Thermal and catalytic cracking of these cycloparaffins on FCC-type catalysts are carried out using the CREC Riser Simulator under operating conditions similar to those of the industrial FCC units in terms of temperature, reaction time, reactant partial pressure and catalyst-to-hydrocarbon ratio. The crystallite size of the supported zeolites is varied between 0.4 and 0.9 microns, with both activity and selectivity being monitored. Catalytic conversions ranged between 4 to 16 wt% for MCH and between 8 to 27 wt% for decalin. Reaction pathways of cycloparaffins are determined, and these include ring-opening, protolytic cracking, isomerization, hydrogen transfer and transalkylation. The yields and selectivities of over 60 and 140 products, formed during MCH and decalin

  20. Characterization of a Membrane-active Peptide from the Bordetella pertussis CyaA Toxin*

    PubMed Central

    Subrini, Orso; Sotomayor-Pérez, Ana-Cristina; Hessel, Audrey; Spiaczka-Karst, Johanna; Selwa, Edithe; Sapay, Nicolas; Veneziano, Rémi; Pansieri, Jonathan; Chopineau, Joel; Ladant, Daniel; Chenal, Alexandre

    2013-01-01

    Bordetella pertussis, the pathogenic bacteria responsible for whooping cough, secretes several virulence factors, among which is the adenylate cyclase toxin (CyaA) that plays a crucial role in the early stages of human respiratory tract colonization. CyaA invades target cells by translocating its catalytic domain directly across the plasma membrane and overproduces cAMP, leading to cell death. The molecular process leading to the translocation of the catalytic domain remains largely unknown. We have previously shown that the catalytic domain per se, AC384, encompassing residues 1–384 of CyaA, did not interact with lipid bilayer, whereas a longer polypeptide, AC489, spanning residues 1–489, binds to membranes and permeabilizes vesicles. Moreover, deletion of residues 375–485 within CyaA abrogated the translocation of the catalytic domain into target cells. Here, we further identified within this region a peptidic segment that exhibits membrane interaction properties. A synthetic peptide, P454, corresponding to this sequence (residues 454–485 of CyaA) was characterized by various biophysical approaches. We found that P454 (i) binds to membranes containing anionic lipids, (ii) adopts an α-helical structure oriented in plane with respect to the lipid bilayer, and (iii) permeabilizes vesicles. We propose that the region encompassing the helix 454–485 of CyaA may insert into target cell membrane and induce a local destabilization of the lipid bilayer, thus favoring the translocation of the catalytic domain across the plasma membrane. PMID:24064217

  1. Catalytic conversion of light alkanes

    SciTech Connect

    Lyons, J.E.

    1992-06-30

    The second Quarterly Report of 1992 on the Catalytic Conversion of Light Alkanes reviews the work done between April 1, 1992 and June 31, 1992 on the Cooperative Agreement. The mission of this work is to devise a new catalyst which can be used in a simple economic process to convert the light alkanes in natural gas to oxygenate products that can either be used as clean-burning, high octane liquid fuels, as fuel components or as precursors to liquid hydrocarbon uwspomdon fuel. During the past quarter we have continued to design, prepare, characterize and test novel catalysts for the mild selective reaction of light hydrocarbons with air or oxygen to produce alcohols directly. These catalysts are designed to form active metal oxo (MO) species and to be uniquely active for the homolytic cleavage of the carbon-hydrogen bonds in light alkanes producing intermediates which can form alcohols. We continue to investigate three molecular environments for the active catalytic species that we are trying to generate: electron-deficient macrocycles (PHASE I), polyoxometallates (PHASE II), and regular oxidic lattices including zeolites and related structures as well as other molecular surface structures having metal oxo groups (PHASE I).

  2. Evolution of a Catalytic Mechanism

    PubMed Central

    Rauwerdink, Alissa; Lunzer, Mark; Devamani, Titu; Jones, Bryan; Mooney, Joanna; Zhang, Zhi-Jun; Xu, Jian-He; Kazlauskas, Romas J.; Dean, Antony M.

    2016-01-01

    The means by which superfamilies of specialized enzymes arise by gene duplication and functional divergence are poorly understood. The escape from adaptive conflict hypothesis, which posits multiple copies of a gene encoding a primitive inefficient and highly promiscuous generalist ancestor, receives support from experiments showing that resurrected ancestral enzymes are indeed more substrate-promiscuous than their modern descendants. Here, we provide evidence in support of an alternative model, the innovation–amplification–divergence hypothesis, which posits a single-copied ancestor as efficient and specific as any modern enzyme. We argue that the catalytic mechanisms of plant esterases and descendent acetone cyanohydrin lyases are incompatible with each other (e.g., the reactive substrate carbonyl must bind in opposite orientations in the active site). We then show that resurrected ancestral plant esterases are as catalytically specific as modern esterases, that the ancestor of modern acetone cyanohydrin lyases was itself only very weakly promiscuous, and that improvements in lyase activity came at the expense of esterase activity. These observations support the innovation–amplification–divergence hypothesis, in which an ancestor gains a weak promiscuous activity that is improved by selection at the expense of the ancestral activity, and not the escape from adaptive conflict in which an inefficient generalist ancestral enzyme steadily loses promiscuity throughout the transition to a highly active specialized modern enzyme. PMID:26681154

  3. Preparing two-dimensional nano-catalytic combustion patterns using direct inkjet printing

    NASA Astrophysics Data System (ADS)

    Luo, Xi; Zeng, Zhigang; Wang, Xiaohong; Xiao, Jinhua; Gan, Zhongxue; Wu, Hao; Hu, Zhiyu

    2014-12-01

    Two-dimensional catalytic combustion patterns, which can be used as heat source in micro-nano scale MEMS devices such as gas sensor and micro-generator, are fabricated by inkjet printing (IJP). The performances of the catalytic patterns are evaluated by both traditional catalytic activity measurement and infrared thermography (IR) camera. Results show that ultra-low (0.014 mg cm-2) loading and high utilizing (34,710 mW mg-1) of Pt catalysts can be achieved by inkjet printing method. Spontaneous combustion is also observed for the printed Pt/Al2O3 powder membrane at rather low initiation temperature and small scale. The IR camera analysis indicates the uniform temperature distribution and rapid temperature response of the micro-patterned catalyst surface. With the advantages of the inkjet printing, this new direct-write method would, in principle, open up possibilities of these special catalyst patterns serving as micro energy sources for MEMS applications.

  4. Catalytic wet air oxidation of high concentration pharmaceutical wastewater.

    PubMed

    Zhan, Wei; Wang, Xiaocong; Li, Daosheng; Ren, Yongzheng; Liu, Dongqi; Kang, Jianxiong

    2013-01-01

    In this study, we investigated the pretreatment of a high concentration pharmaceutical wastewater by catalytic wet air oxidation (CWAO) process. Different experiments were conducted to investigate the effects of the catalyst type, operating temperature, initial system pH, and oxygen partial pressure on the oxidation of the wastewater. Results show that the catalysts prepared by the co-precipitation method have better catalytic activity compared to others. Chemical oxygen demand (COD) conversion increased with the increase in temperature from 160 to 220 °C and decreased with the increase in pH. Moreover, the effect of the oxygen partial pressure on the COD conversion was significant only during the first 20 min of the reaction. Furthermore, the biodegradability of the wastewater improved greatly after CWAO, the ratio of BOD5/COD increased less than 0.1-0.75 when treated at 220 °C (BOD: biochemical oxygen demand).

  5. Catalytic wet hydrogen peroxide oxidation of a petrochemical wastewater.

    PubMed

    Pariente, M I; Melero, J A; Martínez, F; Botas, J A; Gallego, A I

    2010-01-01

    Continuous Catalytic Wet Hydrogen Peroxide Oxidation (CWHPO) for the treatment of a petrochemical industry wastewater has been studied on a pilot plant scale process. The installation, based on a catalytic fixed bed reactor (FBR) coupled with a stirred tank reactor (STR), shows an interesting alternative for the intensification of a continuous CWHPO treatment. Agglomerated SBA-15 silica-supported iron oxide (Fe(2)O(3)/SBA-15) was used as Fenton-like catalyst. Several variables such as the temperature and hydrogen peroxide concentration, as well as the capacity of the pilot plant for the treatment of inlet polluted streams with different dilution degrees were studied. Remarkable results in terms of TOC reduction and increased biodegradability were achieved using 160 degrees C and moderate hydrogen peroxide initial concentration. Additionally, a good stability of the catalyst was evidenced for 8 hours of treatment with low iron leaching (less than 1 mg/L) under the best operating conditions.

  6. Catalytic gasification of wet biomass in supercritical water

    SciTech Connect

    Antal, M.J. Jr.; Matsumura, Yukihiko; Xu, Xiaodong

    1995-12-01

    A pressurized catalytic gasification process, operated at 600{degrees}C, 34.5 MPa, efficiently produces a hydrogen rich synthesis gas from high-moisture content biomass. Glucose was selected as a model compound for catalytic biomass gasification. A proprietary heterogeneous catalyst X was extremely effective for the gasification of both the model compound and whole biomass feeds. The effect of temperature, pressure, reactant concentration on the gasification of glucose with catalyst X were investigated. Complete conversion of glucose (22% by weight in water) to gas was obtained at a weight hourly space velocity of 22.2 (g/h)/g in supercritical water at 600{degrees}C, 34.5 MPa. Complete conversion of whole biomass feeds including water hyacinth, depithed bagasse liquid extract, sewage sludge, and paper sludge was also achieved at the same temperature and pressure. The propriety catalyst X is inexpensive and extremely effective.

  7. Enhanced heterogeneous catalytic conversion of furfuryl alcohol into butyl levulinate.

    PubMed

    Demma Carà, Piera; Ciriminna, Rosaria; Shiju, N R; Rothenberg, Gadi; Pagliaro, Mario

    2014-03-01

    We study the catalytic condensation of furfuryl alcohol with 1-butanol to butyl levulinate. A screening of several commercial and as-synthesized solid acid catalysts shows that propylsulfonic acid-functionalized mesoporous silica outperforms the state-of-the-art phosphotungstate acid catalysts. The catalyst is prepared via template-assisted sol-gel polycondensation of TEOS and MPTMS. It gives 96 % yield (and 100 % selectivity) of butyl levulinate in 4 h at 110 °C. Reaction profiles before and after a hot filtration test confirm that the active catalytic species do not leach into the solution. The catalyst synthesis, characterization, and mode of operation are presented and discussed.

  8. Modulated mechanism of phosphatidylserine on the catalytic activity of Naja naja atra phospholipase A2 and Notechis scutatus scutatus notexin.

    PubMed

    Chiou, Yi-Ling; Lin, Shinne-Ren; Hu, Wan-Ping; Chang, Long-Sen

    2014-12-15

    Phosphatidylserine (PS) externalization is a hallmark for apoptotic death of cells. Previous studies showed that Naja naja atra phospholipase A2 (NnaPLA2) and Notechis scutatus scutatus notexin induced apoptosis of human cancer cells. However, NnaPLA2 and notexin did not markedly disrupt the integrity of cellular membrane as evidenced by membrane permeability of propidium iodide. These findings reflected that the ability of NnaPLA2 and notexin to hydrolyze membrane phospholipids may be affected by PS externalization. To address that question, this study investigated the membrane-interacted mode and catalytic activity of NnaPLA2 and notexin toward outer leaflet (phosphatidylcholine/sphingomyelin/cholesterol, PC/SM/Chol) and inner leaflet (phosphatidylserine/phosphatidylethanolamine/cholesterol, PS/PE/Chol) of plasma membrane-mimicking vesicles. PS incorporation promoted enzymatic activity of NnaPLA2 and notexin on PC and PC/SM vesicles, but suppressed NnaPLA2 and notexin activity on PC/SM/Chol and PE/Chol vesicles. PS incorporation increased the membrane fluidity of PC vesicles but reduced membrane fluidity of PC/SM, PC/SM/Chol and PE/Chol vesicles. PS increased the phospholipid order of all the tested vesicles. Moreover, PS incorporation did not greatly alter the binding affinity of notexin and NnaPLA2 with phospholipid vesicles. Acrylamide quenching studies and trinitrophenylation of Lys residues revealed that membrane-bound mode of notexin and NnaPLA2 varied with the targeted membrane compositions. The fine structure of catalytic site in NnaPLA2 and notexin in all the tested vesicles showed different changes. Collectively, the present data suggest that membrane-inserted PS modulates PLA2 interfacial activity via its effects on membrane structure and membrane-bound mode of NnaPLA2 and notexin, and membrane compositions determine the effect of PS on PLA2 activity.

  9. Coal conversion wastewater treatment by catalytic oxidation in supercritical water

    SciTech Connect

    Phillip E. Savage

    1999-10-20

    rate of formation of phenoxy radicals, which then react in the fluid phase by the same mechanism operative for non-catalytic SCWO of phenol. The rates of phenol disappearance and CO{sub 2} formation are sensitive to the phenol and O{sub 2} concentrations, but independent of the water density. Power-law rate expressions were developed to correlate the catalytic kinetics. The catalytic kinetics were also consistent with a Langmuir-Hinshelwood rate law derived from a dual-site mechanism comprising the following steps: reversible adsorption of phenol on one type of catalytic site, reversible dissociative adsorption of oxygen on a different type of site, and irreversible, rate-determining surface reaction between adsorbed phenol and adsorbed oxygen.

  10. COAL CONVERSION WASTEWATER TREATMENT BY CATALYTIC OXIDATION IN SUPERCRITICAL WATER

    SciTech Connect

    Phillip E. Savage

    1999-10-18

    phenoxy radicals, which then react in the fluid phase by the same mechanism operative for non-catalytic SCWO of phenol. The rates of phenol disappearance and CO{sub 2} formation are sensitive to the phenol and O{sub 2} concentrations, but independent of the water density. Power-law rate expressions were developed to correlate the catalytic kinetics. The catalytic kinetics were also consistent with a Langmuir-Hinshelwood rate law derived from a dual-site mechanism comprising the following steps: reversible adsorption of phenol on one type of catalytic site, reversible dissociative adsorption of oxygen on a different type of site, and irreversible, rate-determining surface reaction between adsorbed phenol and adsorbed oxygen.

  11. The effect of catalyst length and downstream reactor distance on catalytic combustor performance

    NASA Technical Reports Server (NTRS)

    Anderson, D.

    1980-01-01

    A study was made to determine the effects on catalytic combustor performance which resulted from independently varying the length of a catalytic reactor and the length available for gas-phase reactions downstream of the catalyst. Monolithic combustion catalysts from three manufacturers were tested in a combustion test rig with no. 2 diesel fuel. Catalytic reactor lengths of 2.5 and 5.4 cm, and downstream gas-phase reaction distances of 7.3, 12.4, 17.5, and 22.5 cm were evaluated. Measurements of carbon monoxide, unburned hydrocarbons, nitrogen oxides, and pressure drop were made. The catalytic-reactor pressure drop was less than 1 percent of the upstream total pressure for all test configurations and test conditions. Nitrogen oxides and unburned hydrocarbons emissions were less than 0.25 g NO2/kg fuel and 0.6 g HC/kg fuel, respectively. The minimum operating temperature (defined as the adiabatic combustion temperature required to obtain carbon monoxide emissions below a reference level of 13.6 g CO/kg fuel) ranged from 1230 K to 1500 K for the various conditions and configurations tested. The minimum operating temperature decreased with increasing total (catalytic-reactor-plus-downstream-gas-phase-reactor-zone) residence time but was independent of the relative times spent in each region when the catalytic-reactor residence time was greater than or equal to 1.4 ms.

  12. Catalytic multi-stage process for hydroconversion and refining hydrocarbon feeds

    DOEpatents

    Comolli, Alfred G.; Lee, Lap-Keung

    2001-01-01

    A multi-stage catalytic hydrogenation and hydroconversion process for heavy hydrocarbon feed materials such as coal, heavy petroleum fractions, and plastic waste materials. In the process, the feedstock is reacted in a first-stage, back-mixed catalytic reactor with a highly dispersed iron-based catalyst having a powder, gel or liquid form. The reactor effluent is pressure-reduced, vapors and light distillate fractions are removed overhead, and the heavier liquid fraction is fed to a second stage back-mixed catalytic reactor. The first and second stage catalytic reactors are operated at 700-850.degree. F. temperature, 1000-3500 psig hydrogen partial pressure and 20-80 lb./hr per ft.sup.3 reactor space velocity. The vapor and light distillates liquid fractions removed from both the first and second stage reactor effluent streams are combined and passed to an in-line, fixed-bed catalytic hydrotreater for heteroatom removal and for producing high quality naphtha and mid-distillate or a full-range distillate product. The remaining separator bottoms liquid fractions are distilled at successive atmospheric and vacuum pressures, low and intermediate-boiling hydrocarbon liquid products are withdrawn, and heavier distillate fractions are recycled and further upgraded to provide additional low-boiling hydrocarbon liquid products. This catalytic multistage hydrogenation process provides improved flexibility for hydroprocessing the various carbonaceous feedstocks and adjusting to desired product structures and for improved economy of operations.

  13. Unique behaviour of dinitrogen-bridged dimolybdenum complexes bearing pincer ligand towards catalytic formation of ammonia

    PubMed Central

    Tanaka, Hiromasa; Arashiba, Kazuya; Kuriyama, Shogo; Sasada, Akira; Nakajima, Kazunari; Yoshizawa, Kazunari; Nishibayashi, Yoshiaki

    2014-01-01

    It is vital to design effective nitrogen fixation systems that operate under mild conditions, and to this end we recently reported an example of the catalytic formation of ammonia using a dinitrogen-bridged dimolybdenum complex bearing a pincer ligand, where up to twenty three equivalents of ammonia were produced based on the catalyst. Here we study the origin of the catalytic behaviour of the dinitrogen-bridged dimolybdenum complex bearing the pincer ligand with density functional theory calculations, based on stoichiometric and catalytic formation of ammonia from molecular dinitrogen under ambient conditions. Comparison of di- and mono-molybdenum systems shows that the dinitrogen-bridged dimolybdenum core structure plays a critical role in the protonation of the coordinated molecular dinitrogen in the catalytic cycle. PMID:24769530

  14. Alumina-based monopropellant microthruster with integrated heater, catalytic bed and temperature sensors

    NASA Astrophysics Data System (ADS)

    Khaji, Zahra; Klintberg, Lena; Barbade, Dhananjay; Palmer, Kristoffer; Thornell, Greger

    2016-10-01

    A liquid propellant alumina microthruster with an integrated heater, catalytic bed and two temperature sensors has been developed and tested using 30 wt.% hydrogen peroxide. The temperature sensors and the catalytic bed were screen-printed using platinum paste on tapes of alumina that was stacked and laminated before sintering. In order to increase the surface of the catalytic bed, the platinum paste was mixed with a sacrificial paste that disappeared during sintering, leaving behind a porous and rough layer. Complete evaporation and combustion, resulting in only gas coming from the outlet, was achieved with powers above 3.7 W for a propellant flow of 50 μl/min. At this power, the catalytic bed reached a maximum temperature of 147°C. The component was successfully operated up to a temperature of 307°C, where it cracked.

  15. Membranes for corrosive oxidations. Final CRADA report.

    SciTech Connect

    Snyder, S. W.; Energy Systems

    2010-02-01

    The objective of this project is to develop porous hydrophilic membranes that are highly resistant to oxidative and corrosive conditions and to deploy them for recovery and purification of high tonnage chemicals such as hydrogen peroxide and other oxychemicals. The research team patented a process for membrane-based separation of hydrogen peroxide (US Patent No. 5,662,878). The process is based on using a hydrophilic membrane to separate hydrogen peroxide from the organic working solution. To enable this process, a new method for producing hydrophilic membrane materials (Patent No.6,464,880) was reported. We investigated methods of producing these hydrophilic materials and evaluated separations performance in comparison to membrane stability. It was determined that at the required membrane flux, membrane stability was not sufficient to design a commercial process. This work was published (Hestekin et al., J. Membrane Science 2006). To meet the performance needs of the process, we developed a membrane contactor method to extract the hydrogen peroxide, then we surveyed several commercial and pre-commercial membrane materials. We identified pre-commercial hydrophilic membranes with the required selectivity, flux, and stability to meet the needs of the process. In addition, we invented a novel reaction/separations format that greatly increases the performance of the process. To test the performance of the membranes and the new formats we procured and integrated reactor/membrane separations unit that enables controlled mixing, flow, temperature control, pressure control, and sampling. The results were used to file a US non-provisional patent application (ANL-INV 03-12). Hydrogen peroxide is widely used in pulp and paper applications, environmental treatment, and other industries. Virtually all hydrogen peroxide production is now based on a process featuring catalytic hydrogenation followed by auto-oxidation of suitable organic carrier molecules. This process has several

  16. Omniphobic Membrane for Robust Membrane Distillation

    SciTech Connect

    Lin, SH; Nejati, S; Boo, C; Hu, YX; Osuji, CO; Ehmelech, M

    2014-11-01

    In this work, we fabricate an omniphobic microporous membrane for membrane distillation (MD) by modifying a hydrophilic glass fiber membrane with silica nanoparticles followed by surface fluorination and polymer coating. The modified glass fiber membrane exhibits an anti-wetting property not only against water but also against low surface tension organic solvents that easily wet a hydrophobic polytetrafluoroethylene (PTFE) membrane that is commonly used in MD applications. By comparing the performance of the PTFE and omniphobic membranes in direct contact MD experiments in the presence of a surfactant (sodium dodecyl sulfate, SDS), we show that SDS wets the hydrophobic PTFE membrane but not the omniphobic membrane. Our results suggest that omniphobic membranes are critical for MD applications with feed waters containing surface active species, such as oil and gas produced water, to prevent membrane pore wetting.

  17. Catalytic Leadership: Strategies for an Interconnected World.

    ERIC Educational Resources Information Center

    Luke, Jeffrey S.

    A catalytic leader brings together diverse individuals from multiple agencies to address intractable public problems. Strategies for promoting catalytic leadership are explored. The book opens with a review of the problems facing public leaders, emphasizing the complexity and interconnectedness of problems in the public sphere. The book highlights…

  18. Novel selective surface flow (SSF{sup TM}) membranes for the recovery of hydrogren from waste gas streams. Final report

    SciTech Connect

    Anand, M.

    1995-08-01

    The waste streams are off-gas streams from various chemical/refinery operations. In Phase I, the architecture of the membrane and the separation device were defined and demonstrated. The system consists of a shell-and-tube separator in which the gas to be separated is fed to the tube side, the product is collected as high pressure effluent and the permeate constitutes the waste/fuel stream. Each tube, which has the membrane coated on the interior, does the separation. A multi- tube separator device containing 1 ft{sup 2} membrane area was built and tested. The engineering data were used for designing a process for hydrogen recovery from a fluid catalytic cracker off-gas stream. First-pass economics showed that overall cost for hydrogen production is reduced by 35% vs on-purpose production of hydrogen by steam- methane reforming. The hydrogen recovery process using the SSF membrane results in at least 15% energy reduction and significant decrease in CO{sub 2} and NO{sub x} emissions.

  19. Thin membranes of new hard/soft segment copolymers

    SciTech Connect

    Ho, W.S.; Sartori, G.; Thaler, W.A.

    1996-12-31

    Thin membranes of new hard/soft segment copolymers have been synthesized for the separation of aromatics from saturates through high temperature pervaporation. In the membranes, hard segments provide temperature stability and solvent resistance, while soft segments govern aromatic/saturate selectivity and flux. We have synthesized new chlorinated polyurethane/polyester and polyimide/polyester copolymers. Based on a polyimide copolymer membrane, a new technology has been developed recently to separate heavy catalytically cracked naphtha into an aromatics-rich permeate and an aromatics-lean retentate.

  20. Electrospun superhydrophobic membranes with unique structures for membrane distillation.

    PubMed

    Liao, Yuan; Loh, Chun-Heng; Wang, Rong; Fane, Anthony G

    2014-09-24

    With modest temperature demand, low operating pressure, and high solute rejection, membrane distillation (MD) is an attractive option for desalination, waste treatment, and food and pharmaceutical processing. However, large-scale practical applications of MD are still hindered by the absence of effective membranes with high hydrophobicity, high porosity, and adequate mechanical strength, which are important properties for MD permeation fluxes, stable long-term performance, and effective packing in modules without damage. This study describes novel design strategies for highly robust superhydrophobic dual-layer membranes for MD via electrospinning. One of the newly developed membranes comprises a durable and ultrathin 3-dimensional (3D) superhydrophobic skin and porous nanofibrous support whereas another was fabricated by electrospinning 3D superhydrophobic layers on a nonwoven support. These membranes exhibit superhydrophobicity toward distilled water, salty water, oil-in-water emulsion, and beverages, which enables them to be used not only for desalination but also for other processes. The superhydrophobic dual-layer membrane #3S-N with nanofibrous support has a competitive permeation flux of 24.6 ± 1.2 kg m(-2) h(-1) in MD (feed and permeate temperate were set as 333 and 293 K, respectively) due to the higher porosity of the nanofibrous scaffold. Meanwhile, the membranes with the nonwoven support exhibit greater mechanical strength due to this support combined with better long-term performance because of the thicker 3D superhydrophobic layers. The morphology, pore size, porosity, mechanical properties, and liquid enter pressure of water of these superhydrophobic composite membranes with two different structures are reported and compared with commercial polyvinylidene fluoride membranes.

  1. Multilayered semiconductor membranes for nanopore ionic conductance modulation.

    PubMed

    Gracheva, Maria E; Melnikov, Dmitriy V; Leburton, Jean-Pierre

    2008-11-25

    We explore the possibility of using thin layered semiconductor membranes for electrical control of the ion current flow through a nanopore, thereby operating like tunable ionic transistors. While single layer semiconductor membranes can be voltage tuned to operate as ionic filters or "switches", double layered membranes can rectify the ion current flowing through the nanopore in addition to ion filtering. Triple layer membranes exhibit enhanced functionality with characteristics similar to those of the single and double layer membranes in addition to bidirectional current blocking and switching, thereby operating similar to tunable ionic transistors.

  2. Electrochemical promotion of catalytic reactions

    NASA Astrophysics Data System (ADS)

    Imbihl, R.

    2010-05-01

    The electrochemical promotion of heterogeneously catalyzed reactions (EPOC) became feasible through the use of porous metal electrodes interfaced to a solid electrolyte. With the O 2- conducting yttrium stabilized zirconia (YSZ), the Na + conducting β″-Al 2O 3 (β-alumina), and several other types of solid electrolytes the EPOC effect has been demonstrated for about 100 reaction systems in studies conducted mainly in the mbar range. Surface science investigations showed that the physical basis for the EPOC effect lies in the electrochemically induced spillover of oxygen and alkali metal, respectively, onto the surface of the metal electrodes. For the catalytic promotion effect general concepts and mechanistic schemes were proposed but these concepts and schemes are largely speculative. Applying surface analytical tools to EPOC systems the proposed mechanistic schemes can be verified or invalidated. This report summarizes the progress which has been achieved in the mechanistic understanding of the EPOC effect.

  3. Non-catalytic recuperative reformer

    SciTech Connect

    Khinkis, Mark J.; Kozlov, Aleksandr P.; Kurek, Harry

    2015-12-22

    A non-catalytic recuperative reformer has a flue gas flow path for conducting hot flue gas from a thermal process and a reforming mixture flow path for conducting a reforming mixture. At least a portion of the reforming mixture flow path is embedded in the flue gas flow path to permit heat transfer from the hot flue gas to the reforming mixture. The reforming mixture flow path contains substantially no material commonly used as a catalyst for reforming hydrocarbon fuel (e.g., nickel oxide, platinum group elements or rhenium), but instead the reforming mixture is reformed into a higher calorific fuel via reactions due to the heat transfer and residence time. In a preferred embodiment, extended surfaces of metal material such as stainless steel or metal alloy that are high in nickel content are included within at least a portion of the reforming mixture flow path.

  4. APPARATUS FOR CATALYTICALLY COMBINING GASES

    DOEpatents

    Busey, H.M.

    1958-08-12

    A convection type recombiner is described for catalytically recombining hydrogen and oxygen which have been radiolytically decomposed in an aqueous homogeneous nuclear reactor. The device is so designed that the energy of recombination is used to circulate the gas mixture over the catalyst. The device consists of a vertical cylinder having baffles at its lower enda above these coarse screens having platinum and alumina pellets cemented thereon, and an annular passage for the return of recombined, condensed water to the reactor moderator system. This devicea having no moving parts, provides a simple and efficient means of removing the danger of accumulated hot radioactive, explosive gases, and restoring them to the moderator system for reuse.

  5. Catalytic cartridge SO3 decomposer

    SciTech Connect

    Galloway, T.R.

    1982-05-25

    A catalytic cartridge surrounding a heat pipe driven by a heat source is utilized as a SO3 decomposer for thermochemical hydrogen production. The cartridge has two embodiments, a crossflow cartridge and an axial flow cartridge. In the cross-flow cartridge, SO3 gas is flowed through a chamber and incident normally to a catalyst coated tube extending through the chamber, the catalyst coated tube surrounding the heat pipe. In the axialflow cartridge, so3 gas is flowed through the annular space between concentric inner and outer cylindrical walls, the inner cylindrical wall being coated by a catalyst and surrounding the heat pipe. The modular cartridge decomposer provides high thermal efficiency, high conversion efficiency, and increased safety.

  6. Catalytic reactor with improved burner

    DOEpatents

    Faitani, Joseph J.; Austin, George W.; Chase, Terry J.; Suljak, George T.; Misage, Robert J.

    1981-01-01

    To more uniformly distribute heat to the plurality of catalyst tubes in a catalytic reaction furnace, the burner disposed in the furnace above the tops of the tubes includes concentric primary and secondary annular fuel and air outlets. The fuel-air mixture from the primary outlet is directed towards the tubes adjacent the furnace wall, and the burning secondary fuel-air mixture is directed horizontally from the secondary outlet and a portion thereof is deflected downwardly by a slotted baffle toward the tubes in the center of the furnace while the remaining portion passes through the slotted baffle to another baffle disposed radially outwardly therefrom which deflects it downwardly in the vicinity of the tubes between those in the center and those near the wall of the furnace.

  7. Method of fabricating a catalytic structure

    DOEpatents

    Rollins, Harry W.; Petkovic, Lucia M.; Ginosar, Daniel M.

    2009-09-22

    A precursor to a catalytic structure comprising zinc oxide and copper oxide. The zinc oxide has a sheet-like morphology or a spherical morphology and the copper oxide comprises particles of copper oxide. The copper oxide is reduced to copper, producing the catalytic structure. The catalytic structure is fabricated by a hydrothermal process. A reaction mixture comprising a zinc salt, a copper salt, a hydroxyl ion source, and a structure-directing agent is formed. The reaction mixture is heated under confined volume conditions to produce the precursor. The copper oxide in the precursor is reduced to copper. A method of hydrogenating a carbon oxide using the catalytic structure is also disclosed, as is a system that includes the catalytic structure.

  8. Silver nanocluster catalytic microreactors for water purification

    NASA Astrophysics Data System (ADS)

    Da Silva, B.; Habibi, M.; Ognier, S.; Schelcher, G.; Mostafavi-Amjad, J.; Khalesifard, H. R. M.; Tatoulian, M.; Bonn, D.

    2016-07-01

    A new method for the elaboration of a novel type of catalytic microsystem with a high specific area catalyst is developed. A silver nanocluster catalytic microreactor was elaborated by doping a soda-lime glass with a silver salt. By applying a high power laser beam to the glass, silver nanoclusters are obtained at one of the surfaces which were characterized by BET measurements and AFM. A microfluidic chip was obtained by sealing the silver coated glass with a NOA 81 microchannel. The catalytic activity of the silver nanoclusters was then tested for the efficiency of water purification by using catalytic ozonation to oxidize an organic pollutant. The silver nanoclusters were found to be very stable in the microreactor and efficiently oxidized the pollutant, in spite of the very short residence times in the microchannel. This opens the way to study catalytic reactions in microchannels without the need of introducing the catalyst as a powder or manufacturing complex packed bed microreactors.

  9. Geometry of membrane fission.

    PubMed

    Frolov, Vadim A; Escalada, Artur; Akimov, Sergey A; Shnyrova, Anna V

    2015-01-01

    Cellular membranes define the functional geometry of intracellular space. Formation of new membrane compartments and maintenance of complex organelles require division and disconnection of cellular membranes, a process termed membrane fission. Peripheral membrane proteins generally control membrane remodeling during fission. Local membrane stresses, reflecting molecular geometry of membrane-interacting parts of these proteins, sum up to produce the key membrane geometries of fission: the saddle-shaped neck and hour-glass hemifission intermediate. Here, we review the fundamental principles behind the translation of molecular geometry into membrane shape and topology during fission. We emphasize the central role the membrane insertion of specialized protein domains plays in orchestrating fission in vitro and in cells. We further compare individual to synergistic action of the membrane insertion during fission mediated by individual protein species, proteins complexes or membrane domains. Finally, we describe how local geometry of fission intermediates defines the functional design of the protein complexes catalyzing fission of cellular membranes.

  10. Liquid membrane purification of biogas

    SciTech Connect

    Majumdar, S.; Guha, A.K.; Lee, Y.T.; Papadopoulos, T.; Khare, S. . Dept. of Chemistry and Chemical Engineering)

    1991-03-01

    Conventional gas purification technologies are highly energy intensive. They are not suitable for economic removal of CO{sub 2} from methane obtained in biogas due to the small scale of gas production. Membrane separation techniques on the other hand are ideally suited for low gas production rate applications due to their modular nature. Although liquid membranes possess a high species permeability and selectivity, they have not been used for industrial applications due to the problems of membrane stability, membrane flooding and poor operational flexibility, etc. A new hollow-fiber-contained liquid membrane (HFCLM) technique has been developed recently. This technique overcomes the shortcomings of the traditional immobilized liquid membrane technology. A new technique uses two sets of hydrophobic, microporous hollow fine fibers, packed tightly in a permeator shell. The inter-fiber space is filled with an aqueous liquid acting as the membrane. The feed gas mixture is separated by selective permeation of a species through the liquid from one fiber set to the other. The second fiber set carries a sweep stream, gas or liquid, or simply the permeated gas stream. The objectives (which were met) of the present investigation were as follows. To study the selective removal of CO{sub 2} from a model biogas mixture containing 40% CO{sub 2} (the rest being N{sub 2} or CH{sub 4}) using a HFCLM permeator under various operating modes that include sweep gas, sweep liquid, vacuum and conventional permeation; to develop a mathematical model for each mode of operation; to build a large-scale purification loop and large-scale permeators for model biogas separation and to show stable performance over a period of one month.

  11. Fabrication and characterization of a flow-through nanoporous gold nanowire/AAO composite membrane

    NASA Astrophysics Data System (ADS)

    Liu, L.; Lee, W.; Huang, Z.; Scholz, R.; Gösele, U.

    2008-08-01

    The fabrication of a composite membrane of nanoporous gold nanowires and anodic aluminum oxide (AAO) is demonstrated by the electrodeposition of Au-Ag alloy nanowires into an AAO membrane, followed by selective etching of silver from the alloy nanowires. This composite membrane is advantageous for flow-through type catalytic reactions. The morphology evolution of the nanoporous gold nanowires as a function of the diameter of the Au-Ag nanowire 'precursors' is also investigated.

  12. Polymer nanocomposite membranes with hierarchically structured catalysts for high throughput dehalogenation

    NASA Astrophysics Data System (ADS)

    Crock, Christopher A.

    Halogenated organics are categorized as primary pollutants by the Environmental Protection Agency. Trichloroethylene (TCE), which had broad industrial use in the past, shows persistence in the environment because of its chemical stability. The large scale use and poor control of TCE resulted in its prolonged release into the environment before the carcinogenic risk associated with TCE was fully understood. TCE pollution stemmed from industrial effluents and improper disposal of solvent waste. Membrane reactors are promising technology for treating TCE polluted groundwater because of the high throughput, relatively low cost of membrane fabrication and facile retrofitting of existing membrane based water treatment facilities with catalytic membrane reactors. Compared to catalytic fluidized or fixed bed reactors, catalytic membrane reactors feature minimal diffusional limitation. Additionally, embedding catalyst within the membrane avoids the need for catalyst recovery and can prevent aggregation of catalytic nanoparticles. In this work, Pd/xGnP, Pd-Au/xGnP, and commercial Pd/Al2O3 nanoparticles were employed in batch and flow-through membrane reactors to catalyze the dehalogenation of TCE in the presence of dissolved H2. Bimetallic Pd-Au/xGnP catalysts were shown to be more active than monometallic Pd/xGnP or commercial Pd/Al 2O3 catalysts. In addition to synthesizing nanocomposite membranes for high-throughput TCE dehalogenation, the membrane based dehalogenation process was designed to minimize the detrimental impact of common catalyst poisons (S2-, HS-, and H2S -) by concurrent oxidation of sulfide species to gypsum in the presence of Ca2+ and removal of gypsum through membrane filtration. The engineered membrane dehalogenation process demonstrated that bimetallic Pd-Au/xGnP catalysts resisted deactivation by residual sulfide species after oxidation, and showed complete removal of gypsum during membrane filtration.

  13. Large hybrid membrane mirrors

    NASA Astrophysics Data System (ADS)

    Sohn, Erika; Ruiz Schneider, Elfego; Ferreira, Alejandra

    2003-01-01

    The trend to minimize the thickness in optical mirrors has led to several practical limits in their fabrication and operation. The design of a flexible membrane mirror segment, which overcomes most of these limitations and can be conformed to giant segmented primary mirrors, is presented. The segment consists of a lightweight multi-layer hybrid structure, which will permit precise active control of the reflecting surface by means of a continuous elastic medium interface with embedded pneumatic actuators. Conceptual designs, finite element analysis model simulations and experimental results are included.

  14. Proton Exchange Membranes for Fuel Cells

    SciTech Connect

    Devanathan, Ramaswami

    2010-11-01

    Proton exchange membrane, also known as polymer electrolyte membrane, fuel cells (PEMFCs) offer the promise of efficient conversion of chemical energy of fuel, such as hydrogen or methanol, into electricity with minimal pollution. Their widespread use to power zero-emission automobiles as part of a hydrogen economy can contribute to enhanced energy security and reduction in greenhouse gas emissions. However, the commercial viability of PEMFC technology is hindered by high cost associated with the membrane electrode assembly (MEA) and poor membrane durability under prolonged operation at elevated temperature. Membranes for automotive fuel cell applications need to perform well over a period comparable to the life of an automotive engine and under heavy load cycling including start-stop cycling under sub-freezing conditions. The combination of elevated temperature, changes in humidity levels, physical stresses and harsh chemical environment contribute to membrane degradation. Perfluorinated sulfonic acid (PFSA)-based membranes, such as Nafion®, have been the mainstay of PEMFC technology. Their limitations, in terms of cost and poor conductivity at low hydration, have led to continuing research into membranes that have good proton conductivity at elevated temperatures above 120 °C and under low humidity conditions. Such membranes have the potential to avoid catalyst poisoning, simplify fuel cell design and reduce the cost of fuel cells. Hydrocarbon-based membranes are being developed as alternatives to PFSA membranes, but concerns about chemical and mechanical stability and durability remain. Novel anhydrous membranes based on polymer gels infused with protic ionic liquids have also been recently proposed, but considerable fundamental research is needed to understand proton transport in novel membranes and evaluate durability under fuel cell operating conditions. In order to advance this promising technology, it is essential to rationally design the next generation

  15. Membrane fouling control using a rotary disk in a submerged anaerobic membrane sponge bioreactor.

    PubMed

    Kim, Jungmin; Shin, Jaewon; Kim, Hyemin; Lee, Jung-Yeol; Yoon, Min-Hyuk; Won, Seyeon; Lee, Byung-Chan; Song, Kyung Guen

    2014-11-01

    Despite significant research efforts over the last few decades, membrane fouling in anaerobic membrane bioreactors (AnMBRs) remains an unsolved problem that increases the overall operational costs and obstructs the industrial applications. Herein, we developed a method for effectively controlling the membrane fouling in a sponge-submerged AnMBRs using an anaerobic rotary disk MBR (ARMBR). The disk rotation led the effective collision between the sponge and membrane surface; thus successfully enhanced the membrane permeability in the ARMBR. The effect of the disk rotational speed and sponge volume fraction on the membrane permeability and the relationship between the water flow direction and membrane permeability were investigated. The long-term feasibility was tested over 100days of synthetic wastewater treatment. As a result, stable and economical performance was observed without membrane replacement and washing. The proposed integrated rotary disk-supporting media appears to be a feasible and even beneficial option in the AnMBR technology.

  16. Nanocrack-regulated self-humidifying membranes

    NASA Astrophysics Data System (ADS)

    Park, Chi Hoon; Lee, So Young; Hwang, Doo Sung; Shin, Dong Won; Cho, Doo Hee; Lee, Kang Hyuck; Kim, Tae-Woo; Kim, Tae-Wuk; Lee, Mokwon; Kim, Deok-Soo; Doherty, Cara M.; Thornton, Aaron W.; Hill, Anita J.; Guiver, Michael D.; Lee, Young Moo

    2016-04-01

    The regulation of water content in polymeric membranes is important in a number of applications, such as reverse electrodialysis and proton-exchange fuel-cell membranes. External thermal and water management systems add both mass and size to systems, and so intrinsic mechanisms of retaining water and maintaining ionic transport in such membranes are particularly important for applications where small system size is important. For example, in proton-exchange membrane fuel cells, where water retention in the membrane is crucial for efficient transport of hydrated ions, by operating the cells at higher temperatures without external humidification, the membrane is self-humidified with water generated by electrochemical reactions. Here we report an alternative solution that does not rely on external regulation of water supply or high temperatures. Water content in hydrocarbon polymer membranes is regulated through nanometre-scale cracks (‘nanocracks’) in a hydrophobic surface coating. These cracks work as nanoscale valves to retard water desorption and to maintain ion conductivity in the membrane on dehumidification. Hydrocarbon fuel-cell membranes with surface nanocrack coatings operated at intermediate temperatures show improved electrochemical performance, and coated reverse-electrodialysis membranes show enhanced ionic selectivity with low bulk resistance.

  17. Nanocrack-regulated self-humidifying membranes.

    PubMed

    Park, Chi Hoon; Lee, So Young; Hwang, Doo Sung; Shin, Dong Won; Cho, Doo Hee; Lee, Kang Hyuck; Kim, Tae-Woo; Kim, Tae-Wuk; Lee, Mokwon; Kim, Deok-Soo; Doherty, Cara M; Thornton, Aaron W; Hill, Anita J; Guiver, Michael D; Lee, Young Moo

    2016-04-28

    The regulation of water content in polymeric membranes is important in a number of applications, such as reverse electrodialysis and proton-exchange fuel-cell membranes. External thermal and water management systems add both mass and size to systems, and so intrinsic mechanisms of retaining water and maintaining ionic transport in such membranes are particularly important for applications where small system size is important. For example, in proton-exchange membrane fuel cells, where water retention in the membrane is crucial for efficient transport of hydrated ions, by operating the cells at higher temperatures without external humidification, the membrane is self-humidified with water generated by electrochemical reactions. Here we report an alternative solution that does not rely on external regulation of water supply or high temperatures. Water content in hydrocarbon polymer membranes is regulated through nanometre-scale cracks ('nanocracks') in a hydrophobic surface coating. These cracks work as nanoscale valves to retard water desorption and to maintain ion conductivity in the membrane on dehumidification. Hydrocarbon fuel-cell membranes with surface nanocrack coatings operated at intermediate temperatures show improved electrochemical performance, and coated reverse-electrodialysis membranes show enhanced ionic selectivity with low bulk resistance.

  18. Catalytic extraction processing of contaminated scrap metal

    SciTech Connect

    Griffin, T.P.; Johnston, J.E.; Payea, B.M.

    1995-10-01

    The U.S. Department of Energy issued a Planned Research and Development Announcement (PRDA) in 1993, with the objective of identifying unique technologies which could be applied to the most hazardous waste streams at DOE sites. The combination of radioactive contamination with additional contamination by hazardous constituents such as those identified by the Resource Conservation and Recovery Act (RCRA) pose an especially challenging problem. Traditional remediation technologies are increasingly becoming less acceptable to stakeholders and regulators because of the risks they pose to public health and safety. Desirable recycling technologies were described by the DOE as: (1) easily installed, operated, and maintained; (2) exhibiting superior environmental performance; (3) protective of worker and public health and safety; (4) readily acceptable to a wide spectrum of evaluators; and (5) economically feasible. Molten Metal Technology, Inc. (MMT) was awarded a contract as a result of the PRDA initiative to demonstrate the applicability of Catalytic Extraction Processing (CEP), MMT`s proprietary elemental recycling technology, to DOE`s inventory of low level mixed waste. This includes DOE`s inventory of radioactively- and RCRA-contaminated scrap metal and other waste forms expected to be generated by the decontamination and decommissioning (D&D) of DOE sites.

  19. Control of catalytic hydrotreating selectivity with ammonia

    SciTech Connect

    Satterfield, C.N.; Lee, Chung M.

    1990-01-01

    It was discovered that presence of low concentration of ammonia greatly reduces rate of hydrogenation of an aromatic compound (propylbenzene) on an industrial NiMo/Al[sub 2]O[sub 3] catalyst while it has only a mild inhibiting effect on hydrodenitrogenation (of quinoline). This suggests a way of industrial by reaction conditions of minimizing undesired aromatic hydrogenation during catalytic hydrodenitrogenation Coal liquids contain substantial amounts of a base fraction that consists of hydroxy pyridines, hydroxy indoles and/or hydroxy anilines. No information has been published on the HDN-HDO hydrotreating reactions of a compound in which a hydroxyl (phenolic) group is attached to a heterocyclic N compound. Thus the question has been raised of the extent to which quinoline HDN may or may not reflect the behaviour of such compounds. We have therefore performed a limited study with 8-hydroxy quinoline dissolved in tetralin utilizing a NiMo/Al[sub 2]O[sub 3] catalyst in a packed bed reactor operating at 360 and 385 and 6.9 MPa. We find that the N-heterocyclic ring is hydrogenated first to form an equilibrium mixture with a reaction intermediate identified as 8-OH-1,2,3,4 tetrahydroquinoline. Oxygen is then removed to form the same reaction intermediates we have observed from quinoline alone, but in somewhat different ratios. Therefore, with hydroxy-N-heterocyclic compounds, the OH group will likely be removed rapidly at the beginning.

  20. Final Report - Advanced MEA's for Enhanced Operating Conditions, Amenable to High Volume Manufacture

    SciTech Connect

    Debe, Mark K.

    2007-09-30

    This report summarizes the work completed under a 3M/DOE contract directed at advancing the key fuel cell (FC) components most critical for overcoming the polymer electrolyte membrane fuel cell (PEMFC) performance, durability & cost barriers. This contract focused on the development of advanced ion exchange membranes & electrocatalysts for PEMFCs that will enable operation under ever more demanding automotive operating conditions & the use high volume compatible processes for their manufacture. Higher performing & more durable electrocatalysts must be developed for PEMFCs to meet the power density & lifetime hours required for FC vehicles. At the same time the amount of expensive Pt catalyst must be reduced to lower the MEA costs. While these two properties are met, the catalyst must be made resistant to multiple degradation mechanisms to reach necessary operating lifetimes. In this report, we present the work focused on the development of a completely new approach to PEMFC electrocatalyts, called nanostructured thin film (NSTF) catalysts. The carbon black supports are eliminated with this new approach which eliminates the carbon corrosion issue. The thin film nature of the catalyst significantly improves its robustness against dissolution & grain growth, preserving the surface area. Also, the activity of the NSTF for oxygen reduction is improved by over 500% compared to dispersed Pt catalyts. Finally, the process for fabricating the NSTF catalysts is consistent with high volume roll-good manufacturing & extremely flexible towards the introduction of new catalyst compositions & structures. This report documents the work done to develop new multi-element NSTF catalysts with properties that exceed pure Pt, that are optimized for use with the membranes discussed below, & advance the state-of-the-art towards meeting the DOE 2010 targets for PEMFC electrocatalysts. The work completed advances the understanding of the NSTF catalyst technology, identifies new NSTF