Sample records for solid acid catalyst

  1. Industrial application of solid acid–base catalysts

    Microsoft Academic Search

    Kozo Tanabe; Wolfgang F. Hölderich

    1999-01-01

    A statistical survey of industrial processes using solid acid–base catalysts is presented. The number of processes such as alkylation, isomerization, amination, cracking, etherification, etc., and the catalysts such as zeolites, oxides, complex oxides, phosphates, ion-exchange resins, clays, etc., are 127 and 180, respectively. The classification of the types of catalysts into solid acid, solid base, and solid acid–base bifunctional catalysts

  2. Solid acid catalysts for hydrolyzing oligosaccharides derived from corn fiber

    Microsoft Academic Search

    Young Mi Kim

    2005-01-01

    Pretreatment of lignocellulosic biomass is a key step in the fuel ethanol production process. Liquid hot water pretreatment of plant biomass produces a liquid stream with dissolved oligosaccharides which are usually converted to fermentable sugars by enzymatic hydrolysis. The goals of this study are to use a solid acid catalyst, instead of liquid mineral acids or enzymes, to understand the

  3. Hydrolysis of oligosaccharides over solid acid catalysts: a review.

    PubMed

    Vilcocq, Léa; Castilho, Paula C; Carvalheiro, Florbela; Duarte, Luís C

    2014-04-01

    Mild fractionation/pretreatment processes are becoming the most preferred choices for biomass processing within the biorefinery framework. To further explore their advantages, new developments are needed, especially to increase the extent of the hydrolysis of poly- and oligosaccharides. A possible way forward is the use of solid acid catalysts that may overcome many current drawbacks of other common methods. In this Review, the advantages and limitations of the use of heterogeneous catalysis for the main groups of solid acid catalysts (zeolites, resins, carbon materials, clays, silicas, and other oxides) and their relation to the hydrolysis of model soluble disaccharides and soluble poly- and oligosaccharides are presented and discussed. Special attention is given to the hydrolysis of hemicelluloses and hemicellulose-derived saccharides into monosaccharides, the impact on process performance of potential catalyst poisons originating from biomass and biomass hydrolysates (e.g., proteins, mineral ions, etc.). The data clearly point out the need for studying hemicelluloses in natura rather than in model compound solutions that do not retain the relevant factors influencing process performance. Furthermore, the desirable traits that solid acid catalysts must possess for the efficient hemicellulose hydrolysis are also presented and discussed with regard to the design of new catalysts. PMID:24616436

  4. Modified zirconia solid acid catalysts for organic synthesis and transformations

    Microsoft Academic Search

    Benjaram M. Reddy; Pavani M. Sreekanth; Vangala R. Reddy

    2005-01-01

    A series of sulfate, molybdate and tungstate promoted ZrO2 catalysts were prepared by wet impregnation method. To incorporate these promoters to Zr(OH)4, sulfuric acid, ammonium heptamolybdate, and ammonium metatungstate were used as precursors, respectively. Further, a Pt promoted Mo-ZrO2 catalyst was also prepared separately by impregnating with hexachloroplatinic acid. The surface and bulk properties of various promoted ZrO2 catalysts were

  5. Solid acids and their use as environmentally friendly catalysts in organic synthesis

    Microsoft Academic Search

    Karen Wilson; James H. Clark

    2000-01-01

    Tightening environmental legislation is driving the fine and speciality chemicals industries to consider alternative processes that avoid the use of conventional mineral acids. The use of heterogeneous catalysts in these processes would vastly simplify catalyst removal, minimizing the amount of waste formed. However, diffusion limitation of liquids within porous solids dictates that effective solid acids for liquid-phase reactions require the

  6. Role of solid acid catalysts in bio diesel production.

    PubMed

    Shivayogimath, C B; Sunita, G; Manoj Kumar, B

    2009-07-01

    Biodiesel is gaining importance as an alternate source of attractive fuel because of depleting fossil fuel resources. It is produced by trans-esterification, in which oil or fat reacts with a monohydric alcohol in presence of a catalyst. In the present work, trans-esterification of sunflower oil with methanol is carried out by using zirconia supported isopoly and heteropoly tungstates (HPAs) as catalysts. Effects of reaction parameters, such as catalyst types and its concentration, molar ratio of sunflower oil to methanol, reaction temperature and time, have been optimized to get higher conversion of sunflower oil and the product distribution of fatty acid methyl esters (FAME) in the trans-esterfication reaction. PMID:21117436

  7. Conversion of biomass into 5-hydroxymethylfurfural using solid acid catalyst.

    PubMed

    Yang, Fengli; Liu, Qishun; Bai, Xuefang; Du, Yuguang

    2011-02-01

    5-Hydroxymethylfurfural (HMF) was produced from monosaccharide (fructose and glucose), polysaccharide (inulin) and the Jerusalem artichoke juice by a simple one-pot reaction including hydrolysis and dehydration using solid acid under mild condition. Hydrated niobium pentoxide (Nb(2)O(5)·nH(2)O(2)) after pretreatment showed high catalytic activities for dehydration of mono- and polysaccharide to HMF at 433 K in water-2-butanol (2:3 v/v) biphasic system, giving high HMF yield of 89% and 54% from fructose and inulin, respectively. The HMF yield was up to 74% and 65% when inulin and Jerusalem artichoke juice were hydrolyzed by exoinulinase. The solid acid made the process environment-friendly and energy-efficient to convert carbohydrates into bio-fuels and platform chemicals. PMID:21036606

  8. Mesoporous nickel-aluminosilicate nanocomposite: a solid acid catalyst for ether synthesis.

    PubMed

    Neelakandeswari, N; Karvembu, R; Dharmaraj, N

    2013-04-01

    Mesoporous nickel aluminosilicate, a solid acid catalyst prepared by sol-gel technique was utilized as a heterogeneous catalyst for the synthesis of symmetrical ethers by dehydro-condensation of alcohols. The prepared catalysts were characterized by Fourier-transform infra red spectroscopy (FT-IR), powder X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDAX), N2 adsorption-desorption analysis, temperature programmed desorption of ammonia (TPD) and X-ray photoelectron spectroscopic techniques. The presence of the catalyst assisted the etherification reaction in 30 minutes. Ethers formed in these reactions were quantified by gas chromatography (GC) and the identities of few of them were confirmed by nuclear magnetic resonance spectral data (NMR). PMID:23763171

  9. Comparison between liquid and solid acids catalysts on reducing sugars conversion from furfural residues via pretreatments.

    PubMed

    Lin, Keying; Ma, Baojun; Sun, Yuan; Liu, Wanyi

    2014-09-01

    Liquid sulphuric acid is adopted and compared with carbon-based sulfonated solid acids (coal tar-based and active carbon-based) for furfural residues conversion into reducing sugars. The optimum hydrolysis conditions of liquid acid are at 4% of sulphuric acid, 25:1 of liquid and solid ratio, 175°C of reaction temperature and 120 min of reaction time. The reducing sugar yields are reached over 60% on liquid acid via NaOH/H2O2, NaOH/microwave and NaOH/ultrasonic pretreatments, whereas only over 30% on solid acids. The TOFs (turnover number frequency) via NaOH/H2O2 pretreatments are 0.093, 0.020 and 0.023 h(-1) for liquid sulphuric acid, coal tar-based and active carbon-based solid acids catalysts, respectively. Considering the efficiency, cost and environment factors, the liquid and solid acids have their own advantages of potential commercial application values. PMID:24976491

  10. Preparation and application of zirconium sulfate supported on SAPO-34 molecular sieve as solid acid catalyst for esterification

    SciTech Connect

    Xu, Dongyan, E-mail: xdy0156@sina.com; Ma, Hong; Cheng, Fei

    2014-05-01

    Graphical abstract: - Highlights: • SAPO-34 supported zirconium sulfate solid acid catalyst was prepared. • Esterification of acetic acid with ethanol can be catalyzed by ZS/SAPO-34. • The hydration of ZS is vital to the acidic property and catalytic performance. • The ZS/SAPO-34 catalyst treated at 200 °C shows good reusability. - Abstract: Zirconium sulfate (ZS) was supported on SAPO-34 molecular sieve by using an incipient wetness impregnation method with zirconium sulfate as the precursor. The as-prepared catalysts were used as solid acid catalyst for esterification reaction of acetic acid with ethanol. The influence of calcination temperature on the acidic property, catalytic activity, and reusability of ZS/SAPO-34 catalysts were mainly investigated. FT-IR, SEM, EDS and TG analysis have been carried out to demonstrate the characteristics of ZS/SAPO-34 catalysts. It was found that the 30 wt%ZS/SAPO-34 catalysts display the property of superacid irrespective of calcination temperature. The ZS/SAPO-34 catalyst treated at 200 °C can enhance the interaction between the supported ZS and SAPO-34 and keep the catalyst remaining substantially active after several reaction cycles. However, further increasing calcination temperature will cause the transfer of ZS from hydrate to anhydrous phase, and thus the decrease of activity.

  11. Supported zirconium sulfate on carbon nanotubes as water-tolerant solid acid catalyst

    SciTech Connect

    Juan, Joon Ching [Institute of Modern Catalysis, Beijing University of Chemical Technology, State Key Laboratory of Chemical Resource Engineering, Ministry of Education, Beijing 100029 (China); Advanced Catalysis Technology Laboratory, School of Chemical Sciences and Food Technology, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, Bangi 43600 (Malaysia); Jiang Yajie [Institute of Modern Catalysis, Beijing University of Chemical Technology, State Key Laboratory of Chemical Resource Engineering, Ministry of Education, Beijing 100029 (China); Meng Xiujuan [Institute of Modern Catalysis, Beijing University of Chemical Technology, State Key Laboratory of Chemical Resource Engineering, Ministry of Education, Beijing 100029 (China); Cao Weiliang [Institute of Modern Catalysis, Beijing University of Chemical Technology, State Key Laboratory of Chemical Resource Engineering, Ministry of Education, Beijing 100029 (China); Yarmo, Mohd Ambar [Advanced Catalysis Technology Laboratory, School of Chemical Sciences and Food Technology, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, Bangi 43600 (Malaysia); Zhang Jingchang [Institute of Modern Catalysis, Beijing University of Chemical Technology, State Key Laboratory of Chemical Resource Engineering, Ministry of Education, Beijing 100029 (China)]. E-mail: zhangjc1@mail.buct.edu.cn

    2007-07-03

    A new solid acid of zirconium sulfate (CZ) was successfully supported on carbon nanotube (CNT) for esterification reaction. Preparation conditions of the supported CZ have been investigated, to obtain highest catalytic activity for esterification reaction. XRD, TEM, BET, X-ray photoelectron spectra (XPS) and in situ FTIR analysis has also been carried out to understand the characteristics of the catalyst. In the esterification of acrylic acid with n-octanol, the supported CZ exhibited high catalytic activity and stability. The catalytic activity was nearly unchanged during four times of reuse. XRD and TEM analysis indicated that CZ was finely dispersed on CNT. XPS analysis shows that the CZ species was preserved and the chemical environment of the CZ has changed after loaded on CNT. This finding show that CNT as CZ support is an efficient water-tolerant solid acid.

  12. Degradation of polyethylene and polypropylene into fuel oil by using solid acid and non-acid catalysts

    Microsoft Academic Search

    Yusaku Sakata; Akinori Muto

    1999-01-01

    The thermal and catalytic degradation of plastic polymers, polyethylene (PE) at 430°C and polypropylene (PP) at 380°C into fuel oil were carried out by batch operation. The catalysts employed were acid-catalysts silica–alumina (SA-1, SA-2), zeolite ZSM-5 and non acidic mesoporous silica catalysts (silicalite, mesoporous silica gel and mesoporous folded silica (FSM). The yields of product gas, liquid and residues; recovery

  13. Conversion of polar and non-polar algae oil lipids to fatty acid methyl esters with solid acid catalysts - A model compound study.

    PubMed

    Asikainen, Martta; Munter, Tony; Linnekoski, Juha

    2015-09-01

    Bio-based fuels are becoming more and more important due to the depleting fossil resources. The production of biodiesel from algae oil is challenging compared to terrestrial vegetable oils, as algae oil consists of polar fatty acids, such as phospholipids and glycolipids, as well as non-polar triglycerides and free fatty acids common in vegetable oils. It is shown that a single sulphonated solid acid catalyst can perform the esterification and transesterification reactions of both polar and non-polar lipids. In mild reaction conditions (60-70°C) Nafion NR50 catalyst produces methyl palmitate (FAME) from the palmitic acid derivatives of di-, and tri-glyceride, free fatty acid, and phospholipid with over 80% yields, with the glycolipid derivative giving nearly 40% yields of FAME. These results demonstrate how the polar and non-polar lipid derivatives of algal oil can be utilised as feedstocks for biodiesel production with a single catalyst in one reaction step. PMID:26004380

  14. Sulfuric acid functional zirconium (or aluminum) incorporated mesoporous MCM-48 solid acid catalysts for alkylation of phenol with tert-butyl alcohol

    NASA Astrophysics Data System (ADS)

    Jiang, Tingshun; Cheng, Jinlian; Liu, Wangping; Fu, Lie; Zhou, Xuping; Zhao, Qian; Yin, Hengbo

    2014-10-01

    Several zirconium (or aluminum) incorporated mesoporous MCM-48 solid acid catalysts (SO42-/Zr-MCM-48 and SO42-/Al-MCM-48) were prepared by the impregnation method and their physicochemical properties were characterized by means of XRD, FT-IR, TEM, NH3-TPD and N2 physical adsorption. Also, the catalytic activities of these solid acid catalysts were evaluated by the alkylation of phenol with tert-butyl alcohol. The effect of weight hour space velocity (WHSV), reaction time and reaction temperature on catalytic properties was also studied. The results show that the SO42-/Zr-MCM-48 and SO42-/Al-MCM-48 still have good mesoporous structure and long range ordering. Compared with the Zr (or Al)-MCM-48 samples, SO42-/Zr-MCM-48 and SO42-/Al-MCM-48 solid acid catalysts have strong acidity and exhibit high activities in alkylation reaction of phenol with tert-butyl alcohol. The SO42-/Zr-MCM-48-25 (molar ratio of Si/Zr=0.04) catalyst was found to be the most promising and gave the highest phenol conversion among all catalysts. A maximum phenol conversion of 91.6% with 4-tert-butyl phenol (4-TBP) selectivity of 81.8% was achieved when the molar ratio of tert-butyl alcohol:phenol is 2:1, reaction time is 2 h, the WHSV is 2 h-1 and the reaction temperature is 140 °C.

  15. Reactions of aqueous glucose solution over solid-acid Y-zeolite catalyst at 110-160 C

    SciTech Connect

    Lourvanij, K.; Rorrer, G.L. (Oregon State Univ., Corvallis (United States))

    1993-01-01

    Reactions of glucose with solid-acid Y-zeolite catalyst were studied to see if this heterogeneous system could produce oxygenated hydrocarbons by shape-selective, acid-catalyzed processes at fairly low temperatures. Experimentally, aqueous solutions of glucose (12 wt %) were reacted with HY-zeolite powder in a well-mixed batch reactor at temperatures ranging from 110 to 160 C and catalyst concentrations ranging from 2 to 20 g/150 ml. Unreacted glucose and oxygenated hydrocarbon products were measured by HPLC as a function of reaction time (0-24 h) and process conditions. Glucose conversions of 100% were obtained at 160 C after an 8-h reaction time. The apparent activation energy based on glucose conversion was 23.25 [plus minus] 0.40 kcal/mol. Several acid-catalyzed reactions were identified, including isomerization of glucose to fructose, partial dehydration of glucose to 5-(hydroxymethyl)furfural (HMF), rehydration and cleavage of HMF to formic acid and 4-oxo-pentanoic acid, and carbonization . Polymers of HMF and seven minor additional products in the lower molecular weight organic acids/aldehydes/ketones elution range were also isolated by HPLC. High yields of organic acids relative to HMF and lowered selectivity of HMF in the bulk phase relative to the homogeneous acid-catalyzed reaction suggests the possibility of molecular sieving reactions within the Y-zeolite in addition to reactions on the outer surface of the Y-zeolite particle.

  16. Low-quality vegetable oils as feedstock for biodiesel production using K-pumice as solid catalyst. Tolerance of water and free fatty acids contents.

    PubMed

    Díaz, L; Borges, M E

    2012-08-15

    Waste oils are a promising alternative feedstock for biodiesel production due to the decrease of the industrial production costs. However, feedstock with high free fatty acids (FFA) content presents several drawbacks when alkaline-catalyzed transesterification reaction is employed in biodiesel production process. Nowadays, to develop suitable processes capable of treating oils with high free fatty acids content, a two-step process for biodiesel production is being investigated. The major problem that it presents is that two catalysts are needed to carry out the whole process: an acidic catalyst for free fatty acids esterification (first step) and a basic catalyst for pretreated product transesterification (second step). The use of a bifunctional catalyst, which allows both reactions to take place simultaneously, could minimize the production costs and time. In the present study, the behavior of pumice, a natural volcanic material used as a heterogeneous catalyst, was tested using oils with several FFA and water contents as feedstock in the transesterification reaction to produce biodiesel. Pumice as a bifunctional solid catalyst, which can catalyze simultaneously the esterification of FFA and the transesterification of fatty acid glycerides into biodiesel, was shown to be an efficient catalyst for the conversion of low-grade, nonedible oil feedstock into biodiesel product. Using this solid catalyst for the transesterification reaction, high FAME yields were achieved when feedstock oils presented a FFA content until approximately 2% wt/wt and a water content until 2% wt/wt. PMID:22799882

  17. Recent advances in secondary ion mass spectrometry of solid acid catalysts: large zeolite crystals under bombardment.

    PubMed

    Hofmann, Jan P; Rohnke, Marcus; Weckhuysen, Bert M

    2014-03-28

    This Perspective aims to inform the heterogeneous catalysis and materials science community about the recent advances in Time-of-Flight-Secondary Ion Mass Spectrometry (ToF-SIMS) to characterize catalytic solids by taking large model H-ZSM-5 zeolite crystals as a showcase system. SIMS-based techniques have been explored in the 1980-1990's to study porous catalyst materials but, due to their limited spectral and spatiotemporal resolution, there was no real major breakthrough at that time. The technical advancements in SIMS instruments, namely improved ion gun design and new mass analyser concepts, nowadays allow for a much more detailed analysis of surface species relevant to catalytic action. Imaging with high mass and lateral resolution, determination of fragment ion patterns, novel sputter ion concepts as well as new mass analysers (e.g. ToF, FTICR) are just a few novelties, which will lead to new fundamental insight from SIMS analysis of heterogeneous catalysts. The Perspective article ends with an outlook on instrumental innovations and their potential use for catalytic systems other than zeolite crystals. PMID:24522877

  18. Transesterification of triacetin with methanol on solid acid and base catalysts

    Microsoft Academic Search

    Dora E. López; James G. Goodwin; David A. Bruce; Edgar Lotero

    2005-01-01

    Biodiesel is a particularly attractive renewable fuel as it can be used in existing engines, is environmentally friendly, and is readily synthesized from animal fats and vegetable oils. Heterogeneous catalysts offer exciting possibilities for improving the economics of biodiesel synthesis; however, few published investigations have addressed the use of such catalysts to date. The purpose of this research was to

  19. Surface characterization of sulfate, molybdate, and tungstate promoted TiO 2-ZrO 2 solid acid catalysts by XPS and other techniques

    Microsoft Academic Search

    Benjaram M Reddy; Pavani M Sreekanth; Yusuke Yamada; Qiang Xu; Tetsuhiko Kobayashi

    2002-01-01

    Titania–zirconia binary oxide supported sulfate, molybdate, and tungstate promoted solid acid catalysts were prepared by suspending the hydrous mixed oxide support in aqueous solutions of sulfuric acid, ammonium heptamolybdate, and ammonium metatungstate. The suspensions were refluxed at 383K followed by evaporation of the water, drying and calcination at 1073K. The resulting materials were characterized by means of X-ray powder diffraction,

  20. Surface characterization and catalytic activity of sulfate-, molybdate- and tungstate-promoted Al 2O 3–ZrO 2 solid acid catalysts

    Microsoft Academic Search

    Benjaram M. Reddy; Pavani M. Sreekanth; Yusuke Yamada; Tetsuhiko Kobayashi

    2005-01-01

    Alumina–zirconia mixed oxide-supported sulfate-, molybdate- and tungstate-promoted solid acid catalysts were synthesized and characterized by various techniques. The Al–Zr hydroxide gel was obtained by a co-precipitation method from their corresponding nitrate salts by hydrolysis with aqueous ammonia. To the Al–Zr-hydrous mixed oxide support, aqueous solutions of sulfuric acid, ammonium heptamolybdate and ammonium metatungstate were added and the mixtures were refluxed

  1. A one-pot method for the selective conversion of hemicellulose from crop waste into C5 sugars and furfural by using solid acid catalysts.

    PubMed

    Sahu, Ramakanta; Dhepe, Paresh Laxmikant

    2012-04-01

    We present a solid-acid catalyzed one-pot method for the selective conversion of solid hemicellulose without its separation from other lignocellulosic components, such as cellulose and lignin. The reactions were carried out in aqueous and biphasic media to yield xylose, arabinose, and furfural. To overcome the drawbacks posed by mineral acid methods in converting hemicelllulose, we used heterogeneous catalysts that work at neutral pH. In a batch reactor, these heterogeneous catalysts, such as solid acids (zeolites, clays, metal oxides etc.), resulted in >90 % conversion of hemicellulose. It has been shown that the selectivity for the products can be tuned by changing the reaction conditions, for example, a reaction carried out in water at 170 °C for 1 h with HBeta (Si/Al=19) and HUSY (Si/Al=15) catalysts gave yields of 62 and 56 % for xylose and arabinose, respectively. With increased reaction time (6 h) and in presence of only water, HUSY resulted in yields of 30 % xylose + arabinose and 18 % furfural. However, in a biphasic reaction system (water + p-xylene, 170 °C, 6 h) yields of 56 % furfural with 17 % xylose+arabinose could be achieved. It was shown that with the addition of organic solvent the furfural yield could be increased from 18 to 56 %. Under optimized reaction conditions, >90 % carbon balance was observed. The study revealed that catalysts were recyclable with a 20 % drop in activity for each subsequent run. It was observed that temperature, pressure, reaction time, substrate to catalyst ratio, solvent, and so forth had an effect on product formation. The catalysts were characterized by means of X-ray diffraction, temperature-programmed desorption of NH(3), inductively coupled plasma spectroscopy, elemental analysis, and solid-state NMR ((29)Si, (27)Al) spectroscopy techniques. PMID:22411884

  2. The performance of solid phosphoric acid catalysts and macroporous sulfonic resins on gasoline alkylation desulfurization

    Microsoft Academic Search

    Benshuai Guo; Rong Wang; Yonghong Li

    2010-01-01

    Sulfur removal has received increasing attention in recent years primarily for environmental protection purpose. As an attractive technology in the case of gasoline, OATS (olefinic alkylation of thiophenic sulfur) proposed to separate sulfur compounds by distillation after being weighed down by alkylation with olefins in the feed. In this paper, alkylation reactions of thiophenic compounds were studied over solid phosphoric

  3. Mechanism of Glucose Isomerization Using a Solid Lewis Acid Catalyst in Water

    SciTech Connect

    Roman-Leshkov, Yuriy; Moliner, Manuel; Labinger, J A; Davis, Mark E.

    2010-01-01

    {sup 1}H and {sup 13}C?NMR spectroscopy on isotopically labeled glucose reveals that in the presence of tin-containing zeolite Sn-Beta, the isomerization reaction of glucose in water proceeds by way of an intramolecular hydride shift rather than proton transfer. This is the first mechanistic demonstration of Sn-Beta acting as a Lewis acid in a purely aqueous environment.

  4. Synthesis of Waste Cooking Oil Based Biodiesel via Ferric-Manganese Promoted Molybdenum Oxide / Zirconia Nanoparticle Solid acid Catalyst: Influence of Ferric and Manganese Dopants.

    PubMed

    Alhassan, Fatah H; Rashid, Umer; Taufiq-Yap, Yun Hin

    2015-05-01

    The utilization of ferric-manganese promoted molybdenum oxide/zirconia (Fe-Mn- MoO3/ZrO2) (FMMZ) solid acid catalyst for production of biodiesel was demonstrated. FMMZ is produced through impregnation reaction followed by calcination at 600°C for 3 h. The characterization of FMMZ had been done using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), thermal gravimetric analysis (TGA), temperature programmed desorption of NH3 (TPD-NH3), transmission electron microscopy(TEM) and Brunner-Emmett-Teller (BET) surface area measurement. The effect of waste cooking oil methyl esters (WCOME's) yield on the reactions variables such as reaction temperature, catalyst loading, molar ratio of methanol/oil and reusability were also assessed. The catalyst was used to convert the waste cooking oil into corresponding methyl esters (95.6%±0.15) within 5 h at 200? reaction temperature, 600 rpm stirring speed, 1:25 molar ratio of oil to alcohol and 4% w/w catalyst loading. The reported catalyst was successfully recycled in six connective experiments without loss in activity. Moreover, the fuel properties of WCOME's were also reported using ASTM D 6751 methods. PMID:25843280

  5. Characterizing Surface Acidic Sites in Mesoporous-Silica-Supported Tungsten Oxide Catalysts Using Solid State NMR and Quantum Chemistry Calculations

    SciTech Connect

    Hu, Jian Z.; Kwak, Ja Hun; Wang, Yong; Hu, Mary Y.; Turcu, Romulus VF; Peden, Charles HF

    2011-10-18

    The acidic sites in dispersed tungsten oxide supported on SBA-15 mesoporous silica were investigated using a combination of pyridine titration, both fast-, and slow-MAS {sup 15}N NMR, static {sup 2}H NMR, and quantum chemistry calculations. It is found that the bridged acidic -OH groups in surface adsorbed tungsten dimers (i.e., W-OH-W) are the Broensted acid sites. The unusually strong acidity of these Broensted acid sites is confirmed by quantum chemistry calculations. In contrast, terminal W-OH sites are very stable and only weakly acidic as are terminal Si-OH sites. Furthermore, molecular interactions between pyridine molecules and the dimer Broensted and terminal W-OH sites for dispersed tungsten oxide species is strong. This results in restricted molecular motion for the interacting pyridine molecules even at room temperature, i.e., a reorientation mainly about the molecular 2-fold axis. This restricted reorientation makes it possible to estimate the relative ratio of the Broensted (tungsten dimer) to the weakly acidic terminal W-OH sites in the catalyst using the slow-MAS {sup 1}H-{sup 15}N CP PASS method.

  6. The n-butyl amine TPD measurement of Brönsted acidity for solid catalysts by simultaneous TG/DTG-DTA

    NASA Astrophysics Data System (ADS)

    Sasca, V.; Avram, Livia; Verdes, Orsina; Popa, A.

    2010-06-01

    The method for Brönsted acidity measurement based on TPD of alkyl amines desorption by gas-chromatography or thermogravimetry was adapted for simultaneous TG/DTG-DTA analysis. The acidity measurements were focused on the 12-tungstophosphoric acid (H 3PW 12O 40) and its salts, especially with Cesium since these posses the highest Brönsted acidity and they are among the most interesting catalysts. The n-butyl amine (NBA) desorption takes place in three steps for Cs xH 3- xPW 12O 40, x = 0-2, and four steps for the Cs 2.5H 0.5PW 12O 40. The steps of desorption correspond to the release of NBA molecules in stages, as NBA or butene molecules resulted from the Hofmann elimination reaction and NH 3 + H 2O formed by decomposition of ammonium salt. The quantities of desorption products, C 4H 8 and NH 3 + H 2O, corresponding to the stages with the maximum desorption rates at 400-420 °C, respectively 560-600 °C, are in the stoichiometric ratio with the Brönsted acidity.

  7. Etherification of 5-hydroxymethyl-2-furfural (HMF) with ethanol to biodiesel components using mesoporous solid acidic catalysts

    Microsoft Academic Search

    P. Lanzafame; D. M. Temi; S. Perathoner; G. Centi; A. Macario; A. Aloise; G. Giordano

    2011-01-01

    The etherification of 5-hydroxymethyl-2-furfural (HMF) with ethanol is studied over a series of mesoporous silica catalysts (Al-MCM-41 materials with different Si\\/Al ratio, and zirconia or sulfated zirconia supported over SBA-15) and compared with the behavior of H2SO4 and Amberlyst®15. The observed reaction products were 5-(ethoxymethyl)furan-2-carbaldehyde (EMF), 1,1-dietoxy ethane (DE) and ethyl 4-oxopentanoate (EOP). The selectivity to EMF and EOP is

  8. Characterizing Surface Acidic Sites in Mesoporous-Silica-Supported Tungsten Oxide Catalysts Using Solid State NMR and Quantum Chemistry Calculations

    Microsoft Academic Search

    Jian Z. Hu; Ja Hun Kwak; Yong Wang; Mary Y. Hu; Romulus VF Turcu; Charles HF Peden

    2011-01-01

    The acidic sites in dispersed tungsten oxide supported on SBA-15 mesoporous silica were investigated using a combination of pyridine titration, both fast-, and slow-MAS ¹N NMR, static ²H NMR, and quantum chemistry calculations. It is found that the bridged acidic -OH groups in surface adsorbed tungsten dimers (i.e., W-OH-W) are the Broensted acid sites. The unusually strong acidity of these

  9. Formic acid fuel cells and catalysts

    DOEpatents

    Masel, Richard I.; Larsen, Robert; Ha, Su Yun

    2010-06-22

    An exemplary fuel cell of the invention includes a formic acid fuel solution in communication with an anode (12, 134), an oxidizer in communication with a cathode (16, 135) electrically linked to the anode, and an anode catalyst that includes Pd. An exemplary formic acid fuel cell membrane electrode assembly (130) includes a proton-conducting membrane (131) having opposing first (132) and second surfaces (133), a cathode catalyst on the second membrane surface, and an anode catalyst including Pd on the first surface.

  10. Catalysts for direct formic acid fuel cells

    NASA Astrophysics Data System (ADS)

    Rice, C.; Ha, S.; Masel, R. I.; Wieckowski, A.

    Previous work has demonstrated that formic acid fuel cells show interesting properties for micro power generation. In this paper the effects of the anode catalyst composition on fuel cell performance is investigated. In particular, the performance of Pt, Pt/Pd and Pt/Ru catalysts for direct formic acid fuel cells is investigated and their effect on cell power density output at 30 °C are compared. It is found that the open cell potential varies significantly with the catalyst composition. The Pt/Pd catalyst shows an open cell potential of 0.91 V compared to 0.71 V with pure platinum and 0.59 V with Pt/Ru. The current at a cell potential of 0.5 V is 62 mA/cm 2 with Pt/Pd compared to 33 mA/cm 2 with pure platinum and 38 mA/cm 2 with Pt/Ru. Interestingly, the Pt/Ru catalyst gives the most power at low voltage 70 mW/cm 2 at 0.26 V, compared to 43 mW/cm 2 for pure platinum and 41 mW/cm 2 for Pt/Pd. All of the catalysts showed stable operation during several hour tests. Analysis of the data indicates that the addition of palladium enhances the rate of formic acid electrooxidation via a direct reaction mechanism, while ruthenium additions suppress the direct pathway and enhance electrooxidation via a reactive CO intermediate.

  11. Catalysts for portable, solid state hydrogen genration systems

    NASA Astrophysics Data System (ADS)

    Gabl, Jason Robert

    Hydrogen and air powered proton exchange membrane fuel cells are a potential alternative to batteries. In portable power systems, the design requirements often focus on cost efficiency, energy density, storability, as well as safety. Ammonia borane (AB), a chemical hydride containing 19.6 wt. % hydrogen, has a high hydrogen capacity and is a stable and non-toxic candidate for storing hydrogen in portable systems. Throughout this work, Department of Energy guidelines for low power portable hydrogen power systems were used as a baseline and comparison with commercially available systems. In order to make this comparison, the system parameters of a system using AB hydrolysis were estimated by developing capacity and cost correlations from the commercial systems and applying them to this work. Supporting experiments were designed to evaluate a system that would use a premixed solid storage bed of AB and a catalyst. This configuration would only require a user input of water in order to initiate the hydrogen production. Using ammonia borane hydrolysis, the hydrogen yield is ˜9 wt. %, when all reactants are considered. In addition to the simplicity of initiating the reaction, hydrolysis of AB has the advantage of suppressing the production of some toxic borazines that are present when AB is thermally decomposed. However, ammonia gas will be formed and this problem must be addressed, as ammonia is damaging to PEM fuel cells. The catalyst focused on throughout this work was Amberlyst - 15; an ion exchange resin with an acid capacity of 4.7 eq/kg and ammonia adsorbent. At less than 0.30/g, this is a cost effective alternative to precious metal catalysts. The testing with this catalyst was compared to a traditional catalyst in literature, 20% platinum in carbon, costing more than 40/g. The Amberlyst catalyst was found to reduce the formation of ammonia in the gas products from ˜3.71 wt. % with the Pt/C catalyst to <0.01 wt. %. Since Amberlyst adsorbs ammonia, it acts as a "consumable" catalyst, requiring a minimum loading for complete reaction. A mass ratio of a least ˜10:1 Amberlyst to AB is needed for a complete reaction. Conversely, the Pt/C is a reusable catalyst and only used at 5 wt. % loading throughout testing. The activation energy of the Amberlyst catalyzed reaction were measured to be 11.6 kJ/mol, which improves upon the activation energy measured with the Pt/C catalyst of 49.3 kJ/mol, making it a more effective catalyst. However, from the results of an aging study, the proposed system configuration of storing the AB and Amberlyst together will need further development, as the theoretical hydrogen yield dropped from > 90 % to < 30 % over a 70 day aging study. This results implies the need for a systems scale solution, such as mechanical separation, or a material scale solution, such as coating the Amberlyst or AB in a water soluble coating. It was found that ammonia borane catalyzed hydrolysis, using Amberlyst - 15 as a catalyst, has potential to be a cost effective, energy dense, and safe option for generating hydrogen for a portable fuel cell system.

  12. Solid superacid catalyzed fatty acid methyl esters production from acid oil

    Microsoft Academic Search

    Yan Li; Xiao-Dong Zhang; Li Sun; Min Xu; Wen-Guang Zhou; Xiao-Hui Liang

    2010-01-01

    A solid superacid catalyst was evaluated for the production of fatty acid methyl esters (FAMEs) from acid oil containing about 60wt.% free fatty acids. It was demonstrated that SO42-\\/ZrO2–TiO2\\/La3+ was an effective catalyst for simultaneous transesterification and esterification. The optimization of reaction parameters was performed, showing that maximum yield of above 90% could be obtained under the conditions that molar

  13. Novel Solid Base Catalysts for the Production of Biodiesel from Lipids

    E-print Network

    Zhao, Lina

    2010-12-17

    The primary commercial biodiesel production processes use homogeneous base catalysts which cause separation and wastewater discharge problems. Solid base catalysts can overcome these drawbacks. However, a solid base catalyst with high activity...

  14. Method of distributing liquefaction catalysts in solid carbonaceous material

    SciTech Connect

    Weller, S W

    1984-05-23

    A method of dispersing a liquefaction catalyst within coal or other carbonaceous solids involves providing a suspension in oil of microcapsules containing the catalyst. An aqueous solution of a catalytic metal salt is emulsified in the water-immiscible oil and the resulting minute droplets microencapsulated in polymeric shells by interfacial polycondensation. The catalyst is subsequently blended and dispersed throughout the powdered carbonaceous material to be liquefied. At liquefaction temperatures the polymeric microcapsules are destroyed and the catalyst converted to minute crystallites in intimate contact with the carbonaceous material. 2 tables.

  15. Method For Reactivating Solid Catalysts Used For Alklation Reactions

    DOEpatents

    Ginosar, Daniel M. (Idaho Falls, ID); Thompson, David N. (Idaho Falls, ID); Coates, Kyle (Shelley, ID); Zalewski, David J. (Proctorville, OH); Fox, Robert V. (Idaho Falls, ID)

    2005-05-03

    A method for reactivating a solid alkylation catalyst is provided which can be performed within a reactor that contains the alkylation catalyst or outside the reactor. Effective catalyst reactivation is achieved whether the catalyst is completely deactivated or partially deactivated. A fluid reactivating agent is employed to dissolve catalyst fouling agents and also to react with such agents and carry away the reaction products. The deactivated catalyst is contacted with the fluid reactivating agent under pressure and temperature conditions such that the fluid reactivating agent is dense enough to effectively dissolve the fouling agents and any reaction products of the fouling agents and the reactivating agent. Useful pressures and temperatures for reactivation include near-critical, critical, and supercritical pressures and temperatures for the reactivating agent. The fluid reactivating agent can include, for example, a branched paraffin containing at least one tertiary carbon atom, or a compound that can be isomerized to a molecule containing at least one tertiary carbon atom.

  16. Method for reactivating solid catalysts used in alkylation reactions

    DOEpatents

    Ginosar, Daniel M.; Thompson, David N.; Coates, Kyle; Zalewski, David J.; Fox, Robert V.

    2003-06-17

    A method for reactivating a solid alkylation catalyst is provided which can be performed within a reactor that contains the alkylation catalyst or outside the reactor. Effective catalyst reactivation is achieved whether the catalyst is completely deactivated or partially deactivated. A fluid reactivating agent is employed to dissolve catalyst fouling agents and also to react with such agents and carry away the reaction products. The deactivated catalyst is contacted with the fluid reactivating agent under pressure and temperature conditions such that the fluid reactivating agent is dense enough to effectively dissolve the fouling agents and any reaction products of the fouling agents and the reactivating agent. Useful pressures and temperatures for reactivation include near-critical, critical, and supercritical pressures and temperatures for the reactivating agent. The fluid reactivating agent can include, for example, a branched paraffin containing at least one tertiary carbon atom, or a compound that can be isomerized to a molecule containing at least one tertiary carbon atom.

  17. Tandem Catalytic Conversion of Glucose to 5Hydroxymethylfurfural with an Immobilized Enzyme and a Solid Acid

    E-print Network

    Zhao, Huimin

    and a Solid Acid Hua Huang, Carl A. Denard, Ricardo Alamillo, Anthony J. Crisci,,§ Yurun Miao, James. A to fructose and a solid acid catalyst for fructose dehydration to HMF. A base (-NH2) functionalized mesoporous with a Brønsted acid (-SO3H) functionalized mesoporous silica (propylsulfonic acid-FMS) allowed us to conduct

  18. Introduction of poly(4-vinylpyridinium) perchlorate as a new, efficient, and versatile solid acid catalyst for one-pot synthesis of substituted coumarins under ultrasonic irradiation.

    PubMed

    Khaligh, Nader Ghaffari; Shirini, Farhad

    2013-01-01

    Poly(4-vinylpyridinium) perchlorate, is a supported, recyclable, eco-benign catalyst for synthesis of substituted coumarins via Pechmann reaction using ultrasound irradiation at room temperature and neat condition in high yields with short reaction times. The catalyst was studied by FT-IR, X-ray diffraction, scanning electron microscope, thermo-gravimetric and energy dispersion X-ray analyses. All the products were extensively characterized by (1)H NMR, FT-IR, MS and melting point analyses. This methodology offers momentous improvements over various options for the synthesis of coumarins with regard to yield of products, simplicity in operation and green aspects by avoiding toxic catalysts and solvents. Further, the catalyst can be reused and recovered for several times without loss of activity. PMID:22922036

  19. Application of solid ash based catalysts in heterogeneous catalysis.

    PubMed

    Wang, Shaobin

    2008-10-01

    Solid wastes, fly ash, and bottom ash are generated from coal and biomass combustion. Fly ash is mainly composed of various metal oxides and possesses higher thermal stability. Utilization of fly ash for other industrial applications provides a cost-effective and environmentally friendly way of recycling this solid waste, significantly reducing its environmental effects. On the one hand, due to the higher stability of its major component, aluminosilicates, fly ash could be employed as catalyst support by impregnation of other active components for various reactions. On the other hand, other chemical compounds in fly ash such as Fe2O3 could also provide an active component making fly ash a catalyst for some reactions. In this paper, physicochemical properties of fly ash and its applications for heterogeneous catalysis as a catalyst support or catalyst in a variety of catalytic reactions were reviewed. Fly-ash-supported catalysts have shown good catalytic activities for H2 production, deSO(x), deNO(x), hydrocarbon oxidation,and hydrocracking, which are comparable to commercially used catalysts. As a catalyst itself, fly ash can also be effective for gas-phase oxidation of volatile organic compounds, aqueous-phase oxidation of organics, solid plastic pyrolysis, and solvent-free organic synthesis. PMID:18939526

  20. Chemical recycling of waste polystyrene into styrene over solid acids and bases

    Microsoft Academic Search

    Zhibo Zhang; Tamaki Hirose; Suehiro Nishio; Yoshio Morioka; Naoto Azuma; Akifumi Ueno; Hironobu Ohkita; Mitsunori Okada

    1995-01-01

    Catalytic degradation of waste polystyrene into styrene was studied using solid acids and bases as catalysts. Partially because of the high yield of distillates from polystyrene and partially because of the high selectivity into styrene in the distillates, solid bases were emphasized to be effective catalysts for the chemical recycling of waste polystyrene. Since there were significant differences in the

  1. Catalyst and electrode research for phosphoric acid fuel cells

    Microsoft Academic Search

    A. C. Antoine; R. B. King

    1987-01-01

    An account is given of the development status of phosphoric acid fuel cells' high performance catalyst and electrode materials. Binary alloys have been identified which outperform the baseline platinum catalyst; it has also become apparent that pressurized operation is required to reach the desired efficiencies, calling in turn for the use of graphitized carbon blacks in the role of catalyst

  2. Solid superacids as coal liquefaction catalysts

    Microsoft Academic Search

    J. W. Tierney; I. Wender

    1989-01-01

    This research is aimed at exploring the possibility of liquefying coal at mild conditions using titanium, zirconium, iron, and hafnium treated with sulfate ions. FeâOâ\\/SOâ²⁻ has been shown to be an impressively active catalyst in coal conversion at 400°C. A main objective is to find conditions under which FeâOâ\\/SOâ²⁻ and similar superacid systems catalyze the conversion of coal at mild

  3. Synthesis and acid catalysis of cellulose-derived carbon-based solid acid

    NASA Astrophysics Data System (ADS)

    Suganuma, Satoshi; Nakajima, Kiyotaka; Kitano, Masaaki; Yamaguchi, Daizo; Kato, Hideki; Hayashi, Shigenobu; Hara, Michikazu

    2010-06-01

    SO 3H-bearing amorphous carbon, prepared by partial carbonization of cellulose followed by sulfonation in fuming H 2SO 4, was applied as a solid catalyst for the acid-catalyzed hydrolysis of ?-1,4 glucan, including cellobiose and crystalline cellulose. Structural analyses revealed that the resulting carbon material consists of graphene sheets with 1.5 mmol g -1 of SO 3H groups, 0.4 mmol g -1 of COOH, and 5.6 mmol g -1 of phenolic OH groups. The carbon catalyst showed high catalytic activity for the hydrolysis of ?-1,4 glycosidic bonds in both cellobiose and crystalline cellulose. Pure crystalline cellulose was not hydrolyzed by conventional strong solid Brønsted acid catalysts such as niobic acid, Nafion ® NR-50, and Amberlyst-15, whereas the carbon catalyst efficiently hydrolyzes cellulose into water-soluble saccharides. The catalytic performance of the carbon catalyst is due to the large adsorption capacity for hydrophilic reactants and the adsorption ability of ?-1,4 glucan, which is not adsorbed to other solid acids.

  4. Synthesis, characterization and activity study of SO 4 2?\\/Ce x Zr 1? x O 2 solid superacid catalyst

    Microsoft Academic Search

    Benjaram M. Reddy; Pavani M. Sreekanth; Pandian Lakshmanan; Ataullah Khan

    2006-01-01

    Sulfated CexZr1?xO2 catalyst was found to exhibit solid super-acidity and good catalytic activity for synthesis of ?-amino ketones by a three-component Mannich type reaction in the liquid phase under solvent free conditions at ambient temperature. To make the sulfated CexZr1?xO2 catalyst, Ce-Zr hydroxide gel was prepared by a coprecipitation method and SO42? ions were deposited by treating the gel with

  5. Organometallic catalysts for primary phosphoric acid fuel cells

    Microsoft Academic Search

    Fraser Walsh

    1987-01-01

    A continuing effort by the U.S. Department of Energy to improve the competitiveness of the phosphoric acid fuel cell by improving cell performance and\\/or reducing cell cost is discussed. Cathode improvement, both in performance and cost, available through the use of a class of organometallic cathode catalysts, the tetraazaannulenes (TAAs), was investigated. A new mixed catalyst was identified which provides

  6. EPA'S CATALYST RESEARCH PROGRAM: ENVIRONMENTAL IMPACT OF SULFURIC ACID EMISSIONS

    EPA Science Inventory

    A sulfuric acid review conference sponsored by EPA's automotive Catalyst Research Program was held recently at Hendersonville, NC, for researchers whose work is funded by EPA. Emissions characterization research indicated that in-use catalyst-equipped vehicles emit low levels of ...

  7. Surface acidity and degree of carburization of modified silver catalysts

    SciTech Connect

    Pestryakov, A.N.; Belousova, V.N.; Roznina, M.I. [Tomsk Institute of Construction Engineering (Russian Federation)

    1993-11-10

    The effect has been studied of some compounds as modifying additives on the surface acidity, degree of carburization, aggregation and silver entrainement of silver-pumice catalysts for methanol oxidation. Catalyst samples have been tested in an industrial reactor. The probable mechanism of modifying action of the additives is discussed.

  8. Mechanistic investigations of the methanol-to-olefin (MTO) process on acidic zeolite catalysts by in situ solid-state NMR spectroscopy

    Microsoft Academic Search

    Wei Wang; Yijiao Jiang; Michael Hunger

    2006-01-01

    This paper reviews mechanistic investigations of the methanol-to-olefin (MTO) process by in situ solid-state NMR spectroscopy, mainly performed under continuous-flow and stopped-flow conditions. During methanol conversion on the silicoaluminophosphate H-SAPO-34 under continuous-flow conditions, a hydrocarbon-pool consisting of a mixture of C6–C12 olefins and aromatics was found. The hydrocarbon-pool mechanism was verified as the dominating route in the MTO process under

  9. Carbon-supported Pd–Ir catalyst as anodic catalyst in direct formic acid fuel cell

    Microsoft Academic Search

    Xin Wang; Yawen Tang; Ying Gao; Tianhong Lu

    2008-01-01

    It was reported for the first time that the electrocatalytic activity of the Carbon-supported Pd–Ir (Pd–Ir\\/C) catalyst with the suitable atomic ratio of Pd and Ir for the oxidation of formic acid in the direct formic acid fuel cell (DFAFC) is better than that of the Carbon-supported Pd (Pd\\/C) catalyst, although Ir has no electrocatalytic activity for the oxidation of

  10. Biodiesel production from non-edible Silybum marianum oil using heterogeneous solid base catalyst under ultrasonication.

    PubMed

    Takase, Mohammed; Chen, Yao; Liu, Hongyang; Zhao, Ting; Yang, Liuqing; Wu, Xiangyang

    2014-09-01

    The aim of this study is to investigate modified TiO2 doped with C4H4O6HK as heterogeneous solid base catalyst for transesterification of non-edible, Silybum marianum oil to biodiesel using methanol under ultrasonication. Upon screening the catalytic performance of modified TiO2 doped with different K-compounds, 0.7 C4H4O6HK doped on TiO2 was selected. The preparation of the catalyst was done using incipient wetness impregnation method. Having doped modified TiO2 with C4H4O6HK, followed by impregnation, drying and calcination at 600 °C for 6 h, the catalyst was characterized by XRD, FTIR, SEM, BET, TGA, UV and the Hammett indicators. The yield of the biodiesel was proportional to the catalyst basicity. The catalyst had granular and porous structures with high basicity and superior performance. Combined conditions of 16:1 molar ratio of methanol to oil, 5 wt.% catalyst amount, 60 °C reaction temperature and 30 min reaction time was enough for maximum yield of 90.1%. The catalyst maintained sustained activity after five cycles of use. The oxidative stability which was the main problem of the biodiesel was improved from 2.0 h to 3.2h after 30 days using ascorbic acid as antioxidant. The other properties including the flash point, cetane number and the cold flow ones were however, comparable to international standards. The study indicated that Ti-0.7-600-6 is an efficient, economical and environmentally, friendly catalyst under ultrasonication for producing biodiesel from S. marianum oil with a substantial yield. PMID:24768105

  11. Sulfonic acid functionalized poly(ethylene glycol dimethacrylate-1-vinyl-1,2,4-triazole) as a high-performance solid acid catalyst for the esterification of lactic acid with methanol

    Microsoft Academic Search

    Beyhan Erdem; Ali Kara

    Sulfonic acid functionalized poly(ethylene glycol dimethacrylate-1-vinyl-1,2,4-triazole), poly(EGDMA-VTAZ-SO3H), is evaluated in the esterification of lactic acid with methanol. From nitrogen physisorption data, high surface area (220m2\\/g) and type II isotherm are obtained. Conversion measurements indicate a stronger interaction of poly(EGDMA-VTAZ-20%SO3H) with water molecules than that occurring in poly(EGDMA-VTAZ-10%SO3H). Hence, the higher catalytic activity of poly(EGDMA-VTAZ-10%SO3H) is related to the more hydrophobic

  12. Esterification of higher fatty acids by a novel strong solid acid

    Microsoft Academic Search

    Atsushi Takagaki; Masakazu Toda; Mai Okamura; Junko N. Kondo; Shigenobu Hayashi; Kazunari Domen; Michikazu Hara

    2006-01-01

    Carbon material prepared from d-glucose has been examined as a solid acid catalyst. Sulfonation of incompletely carbonized d-glucose results in amorphous carbon consisting of small polycyclic aromatic carbon sheets with high density of SO3H groups. The carbon material exhibits remarkable catalytic performance for the esterification of higher fatty acids. This can be attributed to high density of SO3H groups with

  13. Low acid producing solid propellants

    NASA Technical Reports Server (NTRS)

    Bennett, Robert R.

    1995-01-01

    The potential environmental effects of the exhaust products of conventional rocket propellants have been assessed by various groups. Areas of concern have included stratospheric ozone, acid rain, toxicity, air quality and global warming. Some of the studies which have been performed on this subject have concluded that while the impacts of rocket use are extremely small, there are propellant development options which have the potential to reduce those impacts even further. This paper discusses the various solid propellant options which have been proposed as being more environmentally benign than current systems by reducing HCI emissions. These options include acid neutralized, acid scavenged, and nonchlorine propellants. An assessment of the acid reducing potential and the viability of each of these options is made, based on current information. Such an assessment is needed in order to judge whether the potential improvements justify the expenditures of developing the new propellant systems.

  14. Reactivity and Characterization of Solid State Hydrodesulfurization Catalysts.

    NASA Astrophysics Data System (ADS)

    Lindner, James Henry

    1990-01-01

    The identification of the phase responsible for hydrodesulfurization (HDS) activity has been the subject of extensive research. In this study, model solid state catalysts prepared from elemental starting materials were synthesized, characterized, and then used to desulfurize thiophene at temperatures ranging from 200-400 ^circC and a pressure of one atmosphere. The results of this work indicate that an increased HDS activity can be correlated with the presence of a poorly crystalline molybdenum sulfide-like phase detected by XRD, HREM, or AEM. The formation of this sulfur-deficient, non-stoichiometric phase could be accomplished by either removing sulfur directly from the catalyst synthesis mixture to yield a non-stoichiometric MoS_{ rm 2-x} moiety, or by introducing a transition metal promoter such as Fe, Co, Ni, or Cu into the system. The promoter atoms induced structural changes in the molybdenum sulfide edge planes by effectively scavenging sulfur during catalyst synthesis to form promoter sulfide species, which enhanced the formation of a non-stoichiometric, highly active molybdenum sulfide. This morphological effect was the primary function of the promoter in this system. All model catalysts displayed similar structure in the (0002) basal plane of MoS_2; however, only the catalytically active samples showed a high concentration of defects and disorder in the (1010), (1011), and (1012) edge planes. The HREM images obtained from these edge planes and their correlation with HDS activity dramatically illustrated the importance of the often-discussed edge plane structure of MoS_2 and its significance on HDS catalysis. Normalization of the HDS activities for the solid state models and a commercial catalyst with O_2 or CO chemisorption uptakes suggested that a similarity may exist between the catalytically active sites of these materials. In-situ XPS revealed that increasing promoter atom concentrations resulted in a more complete reduction of the promoter atom; but this shift to lower binding energies could not necessarily be correlated with activity. However, it was observed that the more active catalysts all exhibited the ability to dissociate H_2 and remove oxygen from their surface. This H_2 spillover or activation may also influence catalyst performance.

  15. A carbon-supported PdP catalyst as the anodic catalyst in a direct formic acid fuel cell

    Microsoft Academic Search

    Lingling Zhang; Yawen Tang; Jianchun Bao; Tianhong Lu; Cun Li

    2006-01-01

    In this paper, it is reported for the first time that a carbon-supported Pd-P (Pd-P\\/C) catalyst for the anodic catalyst in the direct formic acid fuel cell (DFAFC) can be prepared. The Pd-P\\/C catalyst shows that its electrocatalytic activity and especially its stability for the oxidation of formic acid are much higher than that of a Pd\\/C catalyst. Therefore, the

  16. Staining of fluid-catalytic-cracking catalysts: localising Brønsted acidity within a single catalyst particle.

    PubMed

    Buurmans, Inge L C; Ruiz-Martínez, Javier; van Leeuwen, Sanne L; van der Beek, David; Bergwerff, Jaap A; Knowles, William V; Vogt, Eelco T C; Weckhuysen, Bert M

    2012-01-23

    A time-resolved in situ micro-spectroscopic approach has been used to investigate the Brønsted acidic properties of fluid-catalytic-cracking (FCC) catalysts at the single particle level by applying the acid-catalysed styrene oligomerisation probe reaction. The reactivity of individual FCC components (zeolite, clay, alumina and silica) was monitored by UV/Vis micro-spectroscopy and showed that only clay and zeolites (Y and ZSM-5) contain Brønsted acid sites that are strong enough to catalyse the conversion of 4-fluorostyrene into carbocationic species. By applying the same approach to complete FCC catalyst particles, it has been found that the fingerprint of the zeolitic UV/Vis spectra is clearly recognisable. This almost exclusive zeolitic activity is confirmed by the fact that hardly any reactivity is observed for FCC particles that contain no zeolite. Confocal fluorescence microscopy images of FCC catalyst particles reveal inhomogeneously distributed micron-sized zeolite domains with a highly fluorescent signal upon reaction. By examining laboratory deactivated FCC catalyst particles in a statistical approach, a clear trend of decreasing fluorescence intensity, and thus Brønsted acidity, of the zeolite domains is observed with increasing severity of the deactivation method. By comparing the average fluorescence intensities obtained with two styrenes that differ in reactivity, it has been found that the Brønsted acid site strength within FCC catalyst particles containing ZSM-5 is more uniform than within those containing zeolite Y, as confirmed with temperature-programmed desorption of ammonia. PMID:22161809

  17. Esterification of formic acid, acrylic acid and methacrylic acid with cyclohexene in batch and distillation column reactors: ion-exchange resins as catalysts

    Microsoft Academic Search

    Basudeb Saha; Man Mohan Sharma

    1996-01-01

    Esterification of formic acid, acrylic acid and methacrylic acid with cyclohexene was carried out in the presence of cation-exchange resins as catalysts. Effect of various parameters, e.g. speed of agitation, catalyst particle size, catalyst loading, types of catalyst, temperature, mole ratio of the reactants, was studied to optimise the reaction conditions. The reaction of formic acid, with different concentrations in

  18. Acid-base properties of titanium-antimony oxides catalysts

    SciTech Connect

    Zenkovets, G.A.; Paukshtis, E.A.; Tarasova, D.V.; Yurchenko, E.N.

    1982-06-01

    The acid-base properties of titanium-antimony oxide catalysts were studied by the methods of back titration and ir spectroscopy. The interrelationship between the acid-base and catalytic properties in the oxidative ammonolysis of propylene was discussed. 3 figures, 1 table.

  19. Ceria-based solid catalysts for organic chemistry.

    PubMed

    Vivier, Laurence; Duprez, Daniel

    2010-06-21

    Ceria has been the subject of thorough investigations, mainly because of its use as an active component of catalytic converters for the treatment of exhaust gases. However, ceria-based catalysts have also been developed for different applications in organic chemistry. The redox and acid-base properties of ceria, either alone or in the presence of transition metals, are important parameters that allow to activate complex organic molecules and to selectively orient their transformation. Pure ceria is used in several organic reactions, such as the dehydration of alcohols, the alkylation of aromatic compounds, ketone formation, and aldolization, and in redox reactions. Ceria-supported metal catalysts allow the hydrogenation of many unsaturated compounds. They can also be used for coupling or ring-opening reactions. Cerium atoms can be added as dopants to catalytic system or impregnated onto zeolites and mesoporous catalyst materials to improve their performances. This Review demonstrates that the exceptional surface (and sometimes bulk) properties of ceria make cerium-based catalysts very effective for a broad range of organic reactions. PMID:20486156

  20. Chemicals from biomass: Etherification of 5-hydroxymethyl-2-furfural (HMF) into 5,5?(oxy-bis(methylene))bis-2-furfural (OBMF) with solid catalysts

    Microsoft Academic Search

    O. Casanova; S. Iborra; A. Corma

    2010-01-01

    Starting from 5-hydroxymethyl-2-furaldehyde (HMF), it has been possible to produce 5,5?-oxy(bismethylene)-2-furaldehyde (OBMF), which is an interesting prepolymer and antiviral precursor, using Lewis and Brönsted solid acid catalysts. Structured micro- and mesoporous aluminosilicates are active and selective, but Al-MCM-41 displays the best performance owing to smaller diffusion constraints. The yield obtained is higher than with homogeneous acid catalysts. Metal-substituted zeolites and

  1. Green chemistry: Biodiesel made with sugar catalyst

    Microsoft Academic Search

    Masakazu Toda; Atsushi Takagaki; Mai Okamura; Junko N. Kondo; Shigenobu Hayashi; Kazunari Domen; Michikazu Hara

    2005-01-01

    The production of diesel from vegetable oil calls for an efficient solid catalyst to make the process fully ecologically friendly. Here we describe the preparation of such a catalyst from common, inexpensive sugars. This high-performance catalyst, which consists of stable sulphonated amorphous carbon, is recyclable and its activity markedly exceeds that of other solid acid catalysts tested for `biodiesel' production.

  2. Transesterification of crude palm kernel oil and crude coconut oil by different solid catalysts

    Microsoft Academic Search

    Jaturong Jitputti; Boonyarach Kitiyanan; Pramoch Rangsunvigit; Kunchana Bunyakiat; Lalita Attanatho; Peesamai Jenvanitpanjakul

    2006-01-01

    This work reports on the preliminary results of using several acidic and basic solids, such as ZrO2, ZnO, SO42?\\/SnO2, SO42?\\/ZrO2, KNO3\\/KL zeolite and KNO3\\/ZrO2 as heterogeneous catalysts for crude palm kernel oil (PKO) and crude coconut oil (CCO) transesterification with methanol. It was found that ZnO and SO42?\\/ZrO2 exhibited the highest activity for both PKO and CCO transesterification. In the

  3. Elucidating the nature of the cobalt centres in CoAPO-18 acid catalysts

    SciTech Connect

    Marchese, L.; Martra, G.; Damilano, N.; Coluccia, S. [Universita di Torino (Italy); Thomas, J.M. [Royal Institution of Great Britain, London (United Kingdom)

    1996-12-31

    A combined UV-Vis and FTIR spectroscopic approach, supplemented by the use of probe molecules (N{sub 2}, CO, C{sub 2}H{sub 4} and H{sub 2}O) as selective adsorbates, has clarified the atomic environment of cobalt centres in CoAPO-18 solid acid catalysts. These catalysts have both framework Co(II) ions in tetrahedral coordination and coordinatively-unsaturated Co(II) Lewis acid centres. But, only approximately half of the tetrahedral ions generate Bronsted OH groups (bridged between Co and P) and are oxidizable to framework Co(III). These bridged OHs, which are the active catalytic centres in acid-catalysis, are strongly influenced by the adsorbates in that the Co(H) ions of the [O{sub 3}CoO(H)] units undergo significant changes in the coordination sphere: the stronger is the ligand (adsorbate), the larger is the number of catalytic centres that are modified.

  4. Formic acid oxidation by carbon-supported palladium catalysts in direct formic acid fuel cell

    Microsoft Academic Search

    Jae Ho Choi; Soon Young Noh; Sam Duck Han; Soo Kyung Yoon; Chang-Soo Lee; Taek-Sung Hwang; Young Woo Rhee

    2008-01-01

    The oxidation of formic acid by the palladium catalysts supported on carbon with high surface area was investigated. Pd\\/C\\u000a catalysts were prepared by using the impregnation method. 30 wt% and 50 wt% Pd\\/C catalysts had a high BET surface area of\\u000a 123.7 m2\\/g and 89.9 m2\\/g, respectively. The fuel cell performance was investigated by changing various parameters such as anode

  5. Transition metal sulfide hydrogen evolution catalysts for hydrobromic acid electrolysis.

    PubMed

    Ivanovskaya, Anna; Singh, Nirala; Liu, Ru-Fen; Kreutzer, Haley; Baltrusaitis, Jonas; Nguyen, Trung Van; Metiu, Horia; McFarland, Eric

    2013-01-01

    Mixed metal sulfides containing combinations of W, Fe, Mo, Ni, and Ru were synthesized and screened for activity and stability for the hydrogen evolution reaction (HER) in aqueous hydrobromic acid (HBr). Co- and Ni-substituted RuS(2) were identified as potentially active HER electrocatalysts by high-throughput screening (HTS), and the specific compositions Co(0.4)Ru(0.6)S(2) and Ni(0.6)Ru(0.4)S(2) were identified by optimization. Hydrogen evolution activity of Co(0.4)Ru(0.6)S(2) in HBr is greater than RuS(2) or CoS(2) and comparable to Pt and commercial Rh(x)S(y). Structural and morphological characterizations of the Co-substituted RuS(2) suggest that the nanoparticulate solids are a homogeneous solid solution with a pyrite crystal structure. No phase separation is detected for Co substitutions below 30% by X-ray diffraction. In 0.5 M HBr electrolyte, the Co-Ru electrode material synthesized with 30% Co rapidly lost approximately 34% of the initial loading of Co; thereafter, it was observed to exhibit stable activity for HER with no further loss of Co. Density functional theory calculations indicate that the S(2)(2-) sites are the most important for HER and the presence of Co influences the S(2)(2-) sites such that the hydrogen binding energy at sufficiently high hydrogen coverage is decreased compared to ruthenium sulfide. Although showing high HER activity in a flow cell, the reverse reaction of hydrogen oxidation is slow on the RuS(2) catalysts tested when compared to platinum and rhodium sulfide, leaving rhodium sulfide as the only suitable tested material for a regenerative HBr cell due its stability compared to platinum. PMID:23205859

  6. On the nature of the deactivation of supported palladium nanoparticle catalysts in the decarboxylation of fatty acids.

    SciTech Connect

    Ping, E. W.; Pierson, J.; Wallace, R.; Miller, J. T.; Fuller, T. F.; Jones, C. W. (Chemical Sciences and Engineering Division); (Georgia Institute of Technology)

    2011-04-15

    Supported palladium catalysts are effective catalysts for the hydrogen-free decarboxylation of fatty acids. However, the catalysts deactivate severely after one use. Here, the recyclability of a well-defined, mesoporous silica-supported palladium nanoparticle catalyst is evaluated in the batch decarboxylation of stearic acid at 300 C under inert atmosphere, producing n-heptadecane. The nature of the catalyst deactivation is examined in detail via an array of characterization techniques. X-ray photoelectron spectroscopy (XPS) demonstrates that little palladium surface oxidation occurs over the course of the reaction, and a combination of X-ray absorption spectroscopy and transmission electron microscopy (TEM) suggests negligible particle sintering or agglomeration. Physisorption and chemisorption measurements demonstrate substantial loss in total surface area and porosity as well as accessible palladium surface area with these losses attributed to significant organic deposition on the catalyst, as verified via thermogravimetric analysis. High temperature calcination is applied to combust and remove these residues, but resultant nanoparticle agglomeration is significant. Solid state nuclear magnetic resonance spectroscopy (NMR), Fourier transform infrared spectroscopy (FT-IR) and solid dissolution followed by organic extraction methodologies demonstrate that the carbonaceous deposits are not coke but rather strongly adsorbed reactants and products. Detrimental coke formation, as suggested by prior literature, is verified to be absent, as extraction of the surface-deposited organic species yields nearly complete recovery of the total surface area, pore volume, and active palladium surface area. Furthermore, the regenerated catalyst exhibits a corresponding significant recovery of decarboxylation activity.

  7. Sulfated Carbon Quantum Dots as Efficient Visible-Light Switchable Acid Catalysts for Room-Temperature Ring-Opening Reactions.

    PubMed

    Li, Haitao; Sun, Chenghua; Ali, Muataz; Zhou, Fengling; Zhang, Xinyi; MacFarlane, Douglas R

    2015-07-13

    Acid catalytic processes play a classic and important role in modern organic synthesis. How well the acid can be controlled often plays the key role in the controllable synthesis of the products with high conversion yield and selectivity. The preparation of a novel, photo-switchable solid-acid catalyst based on carbon quantum dots is described. The carbon quantum dots are decorated with small amounts of hydrogensulfate groups and thus exhibit a photogenerated acidity that produces a highly efficient acid catalysis of the ring opening of epoxides with methanol and other primary alcohols. This reversible, light-switchable acidity is shown to be due to photoexcitation and charge separation in the carbon quantum dots, which create an electron withdrawing effect from the acidic groups. The catalyst is easily separated by filtration, and we demonstrate multiple cycles of its recovery and reuse. PMID:26032183

  8. Thermal decomposition of lignocellulosic biomass in the presence of acid catalysts.

    PubMed

    Larabi, Cherif; al Maksoud, Walid; Szeto, Kai C; Roubaud, Anne; Castelli, Pierre; Santini, Catherine C; Walter, Jean J

    2013-11-01

    Transformation of lignocellulosic biomass to biofuels involves multiple processes, in which thermal decomposition, hydrotreatment are the most central steps. Current work focuses on the impact of several solid acids and Keggin-type heteropolyacids on the decomposition temperature (Td) of pine wood and the characterization of the resulted products. It has been observed that a mechanical mixture of solid acids with pine wood has no influence on Td, while the use of heteropolyacids lower the Td by 100°C. Moreover, the treatment of biomass with a catalytic amount of H3PW12O40 leads to formation of three fractions: solid, liquid and gas, which have been investigated by elemental analysis, TGA, FTIR, GC-MS and NMR. The use of heteropolyacid leads, at 300°C, to a selective transformation of more than 50 wt.% of the holocellulose part of the lignocellulosic biomass. Moreover, 60 wt.% of the catalyst H3PW12O40 are recovered. PMID:24055967

  9. Corrosion-resistant catalyst supports for phosphoric acid fuel cells

    SciTech Connect

    Kosek, J.A.; Cropley, C.C.; LaConti, A.B.

    1990-01-01

    High-surface-area carbon blacks such as Vulcan XC-72 (Cabot Corp.) and graphitized carbon blacks such as 2700{degree}C heat-treated Black Pearls 2000 (HTBP) (Cabot Corp.) have found widespread applications as catalyst supports in phosphoric acid fuel cells (PAFCs). However, due to the operating temperatures and pressures being utilized in PAFCs currently under development, the carbon-based cathode catalyst supports suffer from corrosion, which decreases the performance and life span of a PAFC stack. The feasibility of using alternative, low-cost, corrosion-resistant catalyst support (CRCS) materials as replacements for the cathode carbon support materials was investigated. The objectives of the program were to prepare high-surface-area alternative supports and to evaluate the physical characteristics and the electrochemical stability of these materials. The O{sub 2} reduction activity of the platinized CRCS materials was also evaluated. 2 refs., 3 figs.

  10. The acidity and catalytic behavior of Mg-ZSM-5 prepared via a solid-state reaction

    Microsoft Academic Search

    Yu-Guang Li; Wei-Hong Xie; Shen Yong

    1997-01-01

    A series of Mg-ZSM-5 zeolite catalysts with different content of magnesium were prepared via a solid-state reaction of HZSM-5 with magnesium chloride at 327°C. X-ray determinations demonstrated that the structure and crystallinity of the catalysts were not changed as compared with HZSM-5 zeolite. The acidity of the catalysts was characterized by temperature programmed desorption of ammonia and infrared spectra of

  11. High activity of Pd–WO 3\\/C catalyst as anodic catalyst for direct formic acid fuel cell

    Microsoft Academic Search

    Ligang Feng; Liang Yan; Zhiming Cui; Changpeng Liu; Wei Xing

    2011-01-01

    Pd nanoparticles supported on the WO3\\/C hybrid are prepared by a two-step procedure and the catalysts are studied for the electrooxidation of formic acid. For the purpose of comparison, phosphotungstic acid (PWA) and sodium tungstate are used as the precursor of WO3. Both the Pd–WO3\\/C catalysts have much higher catalytic activity for the electrooxidation of formic acid than the Pd\\/C

  12. Polymerization of ?-pinene using Lewis acidic ionic liquid as catalyst

    Microsoft Academic Search

    Shiwei Liu; Congxia Xie; Shitao Yu; Fusheng Liu

    2009-01-01

    Polymerization of ?-pinene was investigated in the presence of various Lewis acidic ILs. The results showed that ILs 1-n-butyl-3-methylimidazolium chloroaluminate-[C4mim]Cl-AlCl3, especially molar fraction of AlCl3x=0.67, indicated excellent catalytic performance for the polymerization of ?-pinene. It is also found that the product was easily separated from reaction mixture and the IL catalyst was of good reusability. Hence, a clean and environmentally

  13. Proton conducting membrane using a solid acid

    NASA Technical Reports Server (NTRS)

    Chisholm, Calum (Inventor); Narayanan, Sekharipuram R. (Inventor); Boysen, Dane (Inventor); Haile, Sossina M. (Inventor)

    2002-01-01

    A solid acid material is used as a proton conducting membrane in an electrochemical device. The solid acid material can be one of a plurality of different kinds of materials. A binder can be added, and that binder can be either a nonconducting or a conducting binder. Nonconducting binders can be, for example, a polymer or a glass. A conducting binder enables the device to be both proton conducting and electron conducting. The solid acid material has the general form M.sub.a H.sub.b (XO.sub.t).sub.c.

  14. SBA-15-Oxynitrides as a Solid-Base Catalyst: Effect of Nitridation Temperature on Catalytic Activity.

    PubMed

    Singh, Baljeet; Mote, Kaustubh R; Gopinath, C S; Madhu, P K; Polshettiwar, Vivek

    2015-05-11

    Solid bases, such as SBA-15-oxynitrides, have attracted considerable interest for potential applications as catalysts in important industrial processes. Reported herein is that by simply tuning the temperature of nitridation (ammonolysis), the catalytic activity of these solid bases can be enhanced. Solid-state NMR spectroscopy and XPS studies provided the reasoning behind this change in activity. PMID:25801072

  15. Pb and Sb modified Pt\\/C catalysts for direct formic acid fuel cells

    Microsoft Academic Search

    Xingwen Yu; Peter G. Pickup

    2010-01-01

    PtPb\\/C and PtSb\\/C bi-metallic catalysts were synthesized by chemical deposition of Pb or Sb on a commercial 40% Pt\\/C catalyst. The performances of catalysts with a range of compositions were compared in a multi-anode direct formic acid fuel cell in order to optimize compositions and evaluate the statistical significance of differences between catalysts. The catalytic activity for formic acid oxidation

  16. Proton conducting membrane using a solid acid

    NASA Technical Reports Server (NTRS)

    Haile, Sossina M. (Inventor); Chisholm, Calum (Inventor); Boysen, Dane A. (Inventor); Narayanan, Sekharipuram R. (Inventor)

    2006-01-01

    A solid acid material is used as a proton conducting membrane in an electrochemical device. The solid acid material can be one of a plurality of different kinds of materials. A binder can be added, and that binder can be either a nonconducting or a conducting binder. Nonconducting binders can be, for example, a polymer or a glass. A conducting binder enables the device to be both proton conducting and electron conducting.

  17. Superprotonic solid acids: Structure, properties, and applications

    NASA Astrophysics Data System (ADS)

    Boysen, Dane Andrew

    In this work, the structure and properties of superprotonic MH nXO4-type solid acids (where M = monovalent cation, X = S, Se, P, As, and n = 1, 2) have been investigated and, for the first time, applied in fuel cell devices. Several MH nXO4-type solid acids are known to undergo a "superprotonic" solid-state phase transition upon heating, in which the proton conductivity increases by several orders of magnitude and takes on values of ˜10 -2O-1cm-1. The presence of superprotonic conductivity in fully hydrogen bonded solid acids, such as CsH2PO4, has long been disputed. In these investigations, through the use of pressure, the unequivocal identification of superprotonic behavior in both RbH2PO4 and CsH2PO 4 has been demonstrated, whereas for chemically analogous compounds with smaller cations, such as KH2PO4 and NaH2PO 4, superprotonic conductivity was notably absent. Such observations have led to the adoption of radius ratio rules, in an attempt to identify a critical ion size effect on the presence of superprotonic conductivity in solid acids. It has been found that, while ionic size does play a prominent role in the presence of superprotonic behavior in solid acids, equally important are the effects of ionic and hydrogen bonding. Next, the properties of superprotonic phase transition have been investigated from a thermodynamic standpoint. With contributions from this work, a formulation has been developed that accounts for the entropy resulting from both the disordering of both hydrogen bonds and oxy-anion librations in the superprotonic phase of solid acids. This formulation, fundamentally derived from Linus Pauling's entropy rules for ice, accurately accounts for the change in entropy through a superprotonic phase transition. Lastly, the first proof-of-priniciple fuel cells based upon solid acid electrolytes have been demonstrated. Initial results based upon a sulfate electrolyte, CsHSO4, demonstrated the viability of solid acids, but poor chemical stability under the highly reducing H2 gas environment of the fuel cell anode. Later experiments employing a CsH2PO4 electrolyte proved quite successful. The results of these solid acid-based fuel cell measurements suggest solid acids could serve as an alternative to current state-of-the-art fuel cell electrolytes.

  18. High activity of Pd-WO3/C catalyst as anodic catalyst for direct formic acid fuel cell

    NASA Astrophysics Data System (ADS)

    Feng, Ligang; Yan, Liang; Cui, Zhiming; Liu, Changpeng; Xing, Wei

    2011-03-01

    Pd nanoparticles supported on the WO3/C hybrid are prepared by a two-step procedure and the catalysts are studied for the electrooxidation of formic acid. For the purpose of comparison, phosphotungstic acid (PWA) and sodium tungstate are used as the precursor of WO3. Both the Pd-WO3/C catalysts have much higher catalytic activity for the electrooxidation of formic acid than the Pd/C catalyst. The Pd-WO3/C catalyst prepared from PWA shows the best catalytic activity and stability for formic acid oxidation; it also shows the maximum power density of approximately 7.6 mW cm-2 when tested with a small single passive fuel cell. The increase of electrocatalytic activity and stability is ascribed to the interaction between the Pd and WO3, which promotes the oxidation of formic acid in the direct pathway. The precursors used for the preparation of the WO3/C hybrid support have a great effect on the performance of the Pd-WO3/C catalyst. The WO3/C hybrid support prepared from PWA is beneficial to the dispersion of Pd nanoparticles, and the catalyst has potential application for direct formic acid fuel cell.

  19. An experimental comparison of transesterification process with different alcohols using acid catalysts

    Microsoft Academic Search

    N. Saravanan; Sukumar Puhan; G. Nagarajan; N. Vedaraman

    2010-01-01

    Vegetable oils and animal fats in their raw form have high viscosities that makes them unsuitable as fuels for diesel engines. Transesterification is one of the well-known processes by which fats and oils are converted into biodiesel. The reaction often makes use of acid\\/base catalyst. If the material possesses high free fatty acid then acid catalyst gives better results. In

  20. Kinetics of germanium nanowire growth by the vapor-solid-solid mechanism with a Ni-based catalyst

    NASA Astrophysics Data System (ADS)

    Thombare, Shruti V.; Marshall, Ann F.; McIntyre, Paul C.

    2013-12-01

    The kinetics of vapor-solid-solid (VSS) Ge nanowire growth using a Ni-based catalyst were investigated to probe the rate-limiting step for this complex nanoscale crystal growth process. The effects of key parameters such as temperature and precursor partial pressure on the nanowire growth rate were studied in order to gain detailed insights into the growth kinetics. Two different regimes were observed for VSS growth of Ge nanowires as function of temperature. At higher temperatures (345 °C-375 °C), kinetics data suggest that mass transport of germane precursor to the catalyst surface is rate limiting. At lower temperatures (<345 °C), either surface reaction of the GeH4 precursor on the catalyst or incorporation of Ge into the nanowire across the wire/catalyst interface is rate limiting.

  1. Solid-state NMR studies of Ziegler-Natta and metallocene catalysts.

    PubMed

    Tijssen, Koen C H; Blaakmeer, E S Merijn; Kentgens, Arno P M

    2015-01-01

    Ziegler-Natta catalysts are the workhorses of polyolefin production. However, although they have been used and intensively studied for half a century, there is still no comprehensive picture of their mechanistic operation. New techniques are needed to gain more insight in these catalysts. Solid-state NMR has reached a high level of sophistication over the last few decades and holds great promise for providing a deeper insight in Ziegler-Natta catalysis. This review outlines the possibilities for solid-state NMR to characterize the different components and interactions in Ziegler-Natta and metallocene catalysts. An overview is given of some of the expected mechanisms and the resulting polymer microstructure and other characteristics. In the second part of this review we present studies that have used solid-state NMR to investigate the composition of Ziegler-Natta and metallocene catalysts or the interactions between their components. PMID:25957882

  2. Cu Cr O nanocomposites: Synthesis and characterization as catalysts for solid state propellants

    NASA Astrophysics Data System (ADS)

    Li, Wei; Cheng, Hua

    2007-08-01

    In this article we present the synthesis of Cu-Cr-O nanocomposites via a citric acid (CA) complexing approach and the evaluation of the as-synthesized Cu-Cr-O nanocomposites as additives for the catalytic combustion of AP (ammonium perchlorate)-based solid state propellants. Techniques of thermo-gravimetric/differential thermal analyzer (TG-DTA), X-ray diffraction (XRD), transmission electron microscopy (TEM) as well as scanning electron microscopy (SEM) have been employed to characterize the thermal decomposition procedure, crystal phase, micro-structural morphologies and grain size of the as-synthesized materials, respectively. The results show that well-crystallized Cu-Cr-O nanocomposites can be produced by using a temperature as low as 600 °C. Phase structure of the as-obtained Cu-Cr-O nanocomposites depends on the Cu/Cr molar ratio in the starting reactants. Addition of the as-synthesized Cu-Cr-O nanocomposites as catalysts enhances the burning rate as well as lowers the pressure exponent of the AP-based solid state propellants considerably. Noticeably, solid state propellants containing Cu-Cr-O nanocomposites with a Cu/Cr molar ratio of 0.7 exhibits the most stable combustion at all pressures.

  3. Recent progress in the development of solid catalysts for biomass conversion into high value-added chemicals

    NASA Astrophysics Data System (ADS)

    Hara, Michikazu; Nakajima, Kiyotaka; Kamata, Keigo

    2015-06-01

    In recent decades, the substitution of non-renewable fossil resources by renewable biomass as a sustainable feedstock has been extensively investigated for the manufacture of high value-added products such as biofuels, commodity chemicals, and new bio-based materials such as bioplastics. Numerous solid catalyst systems for the effective conversion of biomass feedstocks into value-added chemicals and fuels have been developed. Solid catalysts are classified into four main groups with respect to their structures and substrate activation properties: (a) micro- and mesoporous materials, (b) metal oxides, (c) supported metal catalysts, and (d) sulfonated polymers. This review article focuses on the activation of substrates and/or reagents on the basis of groups (a)–(d), and the corresponding reaction mechanisms. In addition, recent progress in chemocatalytic processes for the production of five industrially important products (5-hydroxymethylfurfural, lactic acid, glyceraldehyde, 1,3-dihydroxyacetone, and furan-2,5-dicarboxylic acid) as bio-based plastic monomers and their intermediates is comprehensively summarized.

  4. Polyethylene as a nonvolatile solid cosolvent phase for catalyst separation and recovery.

    PubMed

    Yang, Yanfei; Priyadarshani, Nilusha; Khamatnurova, Tatyana; Suriboot, Jakkrit; Bergbreiter, David E

    2012-09-12

    The studies described here show that a relatively low molecular weight, narrow polydispersity polyethylene (PE) wax (Polywax) can serve as a nontoxic and nonvolatile alternative to alkane solvents in monophasic catalytic organic reactions where catalysts and products are separated under biphasic conditions. In this application, a polymer that is a solid at room temperature substitutes for a conventional alkane solvent at ca. 80 °C. In addition to the advantages of being a nonvolatile, nontoxic, reusable solvent, this hydrocarbon polymer solvent, like heptane, can sequester nonpolar soluble polymer-bound catalysts after a reaction and separate them from products. The extent of this separation and its generality were studied using polyisobutylene (PIB)- and poly(4-dodecylstyrene)-bound dyes and PE-bound Pd allylic substitution catalysts, PIB-bound Pd cross-coupling catalysts, and PE- and PIB-bound metathesis catalysts. Catalytic reactions were effected using single-phase reaction mixtures containing Polywax with toluene, THF, or THF/DMF at ca. 80 °C. These solutions either separate into two liquid phases on addition of a perturbing agent or separate as a solid/liquid mixture on cooling. The hydrocarbon polymer-bound dyes or catalysts either separate into the hot liquid Polywax phase or coprecipitate with Polywax and are subsequently isolated as a nonvolatile Polywax solid phase that contains the dye or the recyclable catalyst. PMID:22924456

  5. The acrylation of glycerol over solid base catalysts: A precursor to functionalized lipids

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Transesterification of lipids using lipases is a common strategy used to incorporate novel acids into triacylglycerides. This approach, however, is limited to acids with pKa’s similar to common fatty acids. To overcome this limitation, we have used heterogeneous basic catalysts for the synthesis o...

  6. Sulfonic acid-functionalized ?-zirconium phosphate single-layer nanosheets as a strong solid acid for heterogeneous catalysis applications.

    PubMed

    Zhou, Yingjie; Huang, Rongcai; Ding, Fuchuan; Brittain, Alex D; Liu, Jingjing; Zhang, Meng; Xiao, Min; Meng, Yuezhong; Sun, Luyi

    2014-05-28

    Solid acids have received considerable attention as alternatives to traditional corrosive and hazardous homogeneous acids because of their advantages in practical applications, including their low corrosion of equipment and high catalytic activity and recyclability. In this work, a strong solid acid was prepared by anchoring thiol group terminated chains on layered ?-zirconium phosphate (ZrP) single-layer nanosheets, followed by oxidation of thiol groups to form sulfonic acid groups. The obtained solid acids were thoroughly characterized and the results proved that sulfonic acid group terminated chains were successfully grafted onto the ZrP nanosheets with a high loading density. Such a strong solid acid based on inorganic nanosheets can be well-dispersed in polar solvents, leading to high accessibility to the acid functional groups. Meanwhile, it can be easily separated from the dispersion system by centrifugation or filtration. The strong solid acid can serve as an effective heterogeneous catalyst for various reactions, including the Bayer-Villiger oxidation of cyclohexanone to ?-caprolactone in the absence of organic solvents. PMID:24708469

  7. Radiation-induced reactions of CO?H 2 gas mixtures over various solid catalysts

    NASA Astrophysics Data System (ADS)

    Nagai, S.; Arai, H.; Hatada, M.

    Studies have been carried out of radiation-induced reactions of CO?H 2 gas mixtures in the presence of various solid catalysts in order to find possibilities of synthesizing organic raw materials from CO?H 2 by radiation for the future. The solid catalysts studied include Fischer-Tropsch catalyst (Fe?Cu supported by diatomaceous earth), titania(TiO 2), and silica gel. Analysis of the reaction products over Fischer-Tropsch catalyst or semiconductors such as TiO 2 and ZnO?Cr 2O 3 reveals that these solid catalysts do not sensitize the radiation chemical reaction of CO?H 2 but show the secondary effects on the reaction so as to induce the hydrogenation of olefins produced by the catalytic reaction and of aldehydes produced in gas phase by radiation. On the other hand, silica gel and other insulators such as alumina have been found to exhibit high catalytic activity in the formation of hydrocarbons from CO?H 2 under electron beam irradiation at 300°C. It has been shown experimentally that secondary reactions between H 2 and carbonaceous solid produced from CO make a substantial contribution to the formation of hydrocarbons from CO?H 2 over silica gel. In an attempt to find the role of silica gel in the reaction to produce hydrocarbons, radiation-induced reactions have been studied of H 2 with the carbonaceous solid that had been produced by irradiation of CO in the absence of solid catalyst, over TiO 2, or over silica gel. The results indicate that silica gel not only enhances the yields of CO 2 and carbonaceous solid from CO but also promotes hydrogenation reactions of the carbonaceous solid under electron beam irradiation.

  8. Improvement of electrocatalytic performance of carbon supported Pd anodic catalyst in direct formic acid fuel cell by ethylenediamine-tetramethylene phosphonic acid

    NASA Astrophysics Data System (ADS)

    Lu, Liang; Li, Huanzhi; Hong, Yujie; Luo, Yafen; Tang, Yawen; Lu, Tianhong

    2012-07-01

    The direct formic acid fuel cell (DFAFC) has two major shortcomings that limit its lifespan and performance: (i) the poor electrocatalytic stability of the carbon supported Pd (Pd/C) catalyst for the oxidation of formic acid and (ii) rapid decomposition of formic acid over the Pd/C catalyst. To solve the problems, the Pd/C catalyst is modified with ethylenediamine-tetramethylene phosphonic acid (EDTMP). The resulting catalyst is designated as Pd/C-E catalyst. It is found that the Pd/C-E catalyst can inhibit the decomposition of formic acid and promote the oxidation of formic acid through the direct pathway. Consistently, the Pd/C-E catalyst is significantly protected from CO poisoning. As compared to the Pd/C catalyst, the electrocatalytic performance of the Pd/C-E catalyst is significantly superior. These results provide the first proof of the concept that DFAFC can be significantly improved by Pd/C-E catalyst.

  9. Evaluation of direct formic acid fuel cells with catalyst layers coated by electrospray

    Microsoft Academic Search

    Yongchai Kwon; Seungmin Baek; Byungwan Kwon; Jinsoo Kim; Jonghee Han

    2010-01-01

    We investigated cell performance and performed phenomenological analyses of direct formic acid fuel cells (DFAFCs) incorporating\\u000a anode (palladium) and cathode (platinum) catalysts prepared using a new electrospray coating technique. To optimize the design\\u000a of the DFAFC, we examined the cell performance by the Pd catalyst loading and formic acid feed rate. Of Pd catalyst loaded\\u000a samples, 3 mg\\/cm2 sample showed

  10. Carbon supported PtBi catalysts for direct formic acid fuel cells

    Microsoft Academic Search

    Xingwen Yu; Peter G. Pickup

    2011-01-01

    Carbon supported PtBi bimetallic catalysts (PtBi\\/C) prepared by depositing Bi on a commercial Pt\\/C catalyst and by codeposition of Pt and Bi have been compared for formic acid oxidation in a multi-anode direct formic acid fuel cell. Both types of catalyst gave much higher cell performances than the Pt\\/C, with only low amounts of Bi (Pt to Bi mole ratios

  11. Deactivation resistant PdSb\\/C catalysts for direct formic acid fuel cells

    Microsoft Academic Search

    Xingwen Yu; Peter G. Pickup

    2010-01-01

    Formic acid oxidation at novel carbon supported PdSb alloy catalysts has been studied in a multi-anode direct formic acid fuel cell with supporting mechanistic studies in a conventional electrochemical cell. The optimized PdSb\\/C catalysts show better high voltage and long term performances than a comparable commercial Pd\\/C catalyst and much better resistance to poisoning (deactivation). Electrochemical stripping voltammograms show that

  12. Acidic and basic surface sites of zirconia-based biomass gasification gas clean-up catalysts

    Microsoft Academic Search

    Tiia Viinikainen; Hanne Rönkkönen; Heather Bradshaw; Hazel Stephenson; Sanna Airaksinen; Matti Reinikainen; Pekka Simell; Outi Krause

    2009-01-01

    The surface structures of ZrO2, Y2O3–ZrO2 and SiO2–ZrO2 catalysts were studied in relation to their basicity and acidity, and the relationship between surface structure and gasification gas clean-up activity was evaluated. The physical properties of the catalysts were characterized by BET, XRD and Raman spectroscopy. The basicity and acidity of the catalysts were measured by CO2-TPD and NH3-TPD, respectively. The

  13. Hydrogenation of lactic acid to propylene glycol over copper-containing catalysts

    Microsoft Academic Search

    Mikhail N. Simonov; Irina L. Simakova; Valentin N. Parmon

    2009-01-01

    Catalytic properties of different copper-containing catalysts synthesized from different precursors were studied in the hydrogenation\\u000a of lactic acid at mild conditions. The most active catalyst was found to be chrysocolla-like copper hydroxysilicate with the\\u000a copper loading of about 50 at%. At the optimal reaction conditions (T = 473 K, WHSV = 0.08 h?1), 95% conversion of lactic acid over this catalyst and 65% selectivity to 1,2-propylene glycol

  14. Comparison of catalysts for direct transesterification of fatty acids in freeze-dried forage samples

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Preparation of fatty acid methyl esters from forages comparing BF3 in CH3OH to HCl in CH3OH as a catalyst in single-step direct transesterification has not been reported. Our objective was to compare 1.09 M methanolic HCl to 7% BF3 in CH3OH as catalysts for direct transesterification of fatty acids ...

  15. Hydrogenation of succinic acid to ?-butyrolactone (GBL) over palladium catalyst supported on alumina xerogel: Effect of acid density of the catalyst

    Microsoft Academic Search

    Ung Gi Hong; Sunhwan Hwang; Jeong Gil Seo; Joongwon Lee; In Kyu Song

    2011-01-01

    Mesoporous alumina xerogel (AX) supports prepared by a sol–gel method were calcined at various temperatures to control their acid property. Palladium catalysts supported on mesoporous alumina xerogel (Pd\\/AX) were then prepared by an impregnation method. The Pd\\/AX catalysts were characterized by XRD, BET, NH3-TPD, N2 adsorption–desorption isotherm, and H2 chemisorption analyses. Liquid-phase hydrogenation of succinic acid to ?-butyrolactone (GBL) over

  16. Effectiveness of paper-structured catalyst for the operation of biodiesel-fueled solid oxide fuel cell

    NASA Astrophysics Data System (ADS)

    Quang-Tuyen, Tran; Kaida, Taku; Sakamoto, Mio; Sasaki, Kazunari; Shiratori, Yusuke

    2015-06-01

    Mg/Al-hydrotalcite (HDT)-dispersed paper-structured catalyst (PSC) was prepared by a simple paper-making process. The PSC exhibited excellent catalytic activity for the steam reforming of model biodiesel fuel (BDF), pure oleic acid methyl ester (oleic-FAME, C19H36O2) which is a mono-unsaturated component of practical BDFs. The PSC exhibited fuel conversion comparable to a pelletized catalyst material, here, conventional Ni-zirconia cermet anode for solid oxide fuel cell (SOFC) with less than one-hundredth Ni weight. Performance of electrolyte-supported cell connected with the PSC was evaluated in the feed of oleic-FAME, and stable operation was achieved. After 60 h test, coking was not observed in both SOFC anode and PSC.

  17. Bismuth-promoted palladium catalysts for the selective oxidation of glyoxal into glyoxalic acid

    Microsoft Academic Search

    F Alardin; P Ruiz; B Delmon; M Devillers

    2001-01-01

    The incorporation of bismuth in carbon-supported Pd-based catalysts is shown to increase significantly the catalytic activity in the selective oxidation of glyoxal into glyoxalic acid. Main side products are glycolic acid resulting from Cannizzaro dismutation and oxalic acid, generated by further oxidation of glyoxalic acid. Catalysts characterized by different Bi\\/Pd ratios (with Pd+Bi=10wt.%) were prepared according to various experimental procedures

  18. Acidity and catalytic activity of zeolite catalysts bound with silica and alumina

    E-print Network

    Wu, Xianchun

    2004-09-30

    -framework alumina in zeolites to form a new protonic acid. SiO2-bound catalysts have less strong acidity, Bronsted acidity and Lewis acidity than the zeolite powder. Also, the strength of strong acid sites of the zeolites is reduced when silica is embedded...

  19. An Eco-Friendly Improved Protocol for the Synthesis of Bis(3-indolyl)methanes Using Poly(4-vinylpyridinium)hydrogen Sulfate as Efficient, Heterogeneous, and Recyclable Solid Acid Catalyst

    PubMed Central

    Banothu, Janardhan; Gali, Rajitha; Velpula, Ravibabu; Bavantula, Rajitha; Crooks, Peter A.

    2013-01-01

    Highly efficient and eco-friendly protocol for the synthesis of bis(3-indolyl)methanes by the electrophilic substitution reaction of indole with aldehydes catalyzed by poly(4-vinylpyridinium)hydrogen sulfate was described. Excellent yields, shorter reaction times, simple work-up procedure, avoiding hazardous organic solvents, and reusability of the catalyst are the most obvious advantages of this method. PMID:24052864

  20. Manipulating catalytic pathways: deoxygenation of palmitic acid on multifunctional catalysts.

    PubMed

    Peng, Baoxiang; Zhao, Chen; Kasakov, Stanislav; Foraita, Sebastian; Lercher, Johannes A

    2013-04-01

    The mechanism of the catalytic reduction of palmitic acid to n-pentadecane at 260 °C in the presence of hydrogen over catalysts combining multiple functions has been explored. The reaction involves rate-determining reduction of the carboxylic group of palmitic acid to give hexadecanal, which is catalyzed either solely by Ni or synergistically by Ni and the ZrO2 support. The latter route involves adsorption of the carboxylic acid group at an oxygen vacancy of ZrO2 and abstraction of the ?-H with elimination of O to produce the ketene, which is in turn hydrogenated to the aldehyde over Ni sites. The aldehyde is subsequently decarbonylated to n-pentadecane on Ni. The rate of deoxygenation of palmitic acid is higher on Ni/ZrO2 than that on Ni/SiO2 or Ni/Al2O3, but is slower than that on H-zeolite-supported Ni. As the partial pressure of H2 is decreased, the overall deoxygenation rate decreases. In the absence of H2, ketonization catalyzed by ZrO2 is the dominant reaction. Pd/C favors direct decarboxylation (-CO2), while Pt/C and Raney Ni catalyze the direct decarbonylation pathway (-CO). The rate of deoxygenation of palmitic acid (in units of mmol moltotal metal(-1) h(-1)) decreases in the sequence r(Pt black) ?r(Pd black) >r(Raney Ni) in the absence of H2 . In situ IR spectroscopy unequivocally shows the presence of adsorbed ketene (C=C=O) on the surface of ZrO2 during the reaction with palmitic acid at 260 °C in the presence or absence of H2. PMID:23519964

  1. Solid-state NMR studies of the adsorption of acetylene on platinum/alumina catalysts 

    E-print Network

    Lambregts, Marsha Jo Lupher

    1991-01-01

    SOLID-STATE NMR STUDIES OF THE ADSORPTION OF ACETYLENE ON PLATINUM/ALUMINA CATALYSTS A Thesis by MARSHA JO LUPHER LAMBREGTS Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements... for the degree of MASTER OF SCIENCE December 1991 Major Subject: Chemistry SOLID-STATE NMR STUDIES OF THE ADSORPTION OF ACETYLENE ON PLATINUM/ALUMINA CATALYSTS A Thesis by MARSHA JO LUPHER LAMBREGTS Approved as to style and content by: ames F. Haw...

  2. Supported hydrotalcites as highly active solid base catalysts.

    PubMed

    Winter, Ferry; van Dillen, A Jos; de Jong, Krijn P

    2005-08-21

    Mg-Al hydrotalcite platelets with a lateral size of 20 nm were deposited on carbon nanofibers and the resulting supported catalyst exhibited a specific activity in the condensation of acetone four times that of unsupported hydrotalcites due to the higher number of active edge sites. PMID:16075091

  3. Heterogeneous interesterification of triacylglycerols catalyzed by using potassium-doped alumina as a solid catalyst.

    PubMed

    Xie, Wenlei; Chen, Jing

    2014-10-29

    Heterogeneous interesterification of vegetable oils offers an environmentally more attractive option for the modification of edible oils to meet the specifications for certain food applications. In this work, potassium-doped alumina (KNO3/Al2O3) was prepared using an impregnation method, followed by calcinations at a temperature of 700 °C, and was then employed as heterogeneous catalysts for the interesterification of triacylglycerols. The solid catalyst was characterized by means of Hammett titration method, power X-ray diffraction, scanning electron microscopy, and nitrogen adsorption-desorption techniques. It was determined that the catalyst with KNO3 loading of 35% on alumina support and calcined at 700 °C exhibited the best catalytic activities toward the interesterification between soybean oil and methyl stearate under solvent-free conditions. Also, the solid base catalyst was successfully applied to the interesterification of soybean oil and lard blends in a heterogeneous manner. The physicochemical properties of the interesterified products were investigated using gas chromatography, high-performance liquid chromatography, and confocal laser scanning microscopy. It was found that the slip melting point and crystal morphology had a significant variation after the interesterification reaction as a result of the modification in the TAG profile. With the solid base catalyst, an environmentally friendly approach for the interesterification of triacylglycerols in a heterogeneous manner was developed. PMID:25298314

  4. Detoxifying chlorine rich gas streams using solid supported nickel catalysts

    Microsoft Academic Search

    Eun-Jae Shin; Mark A. Keane

    1999-01-01

    Catalytic hydrogen treatment is presented as viable low energy means of treating\\/detoxifying concentrated chlorinated gas streams to generate recyclable raw materials. Nickel (1.5% ww and 15.2%) loaded silica and nickel (2.2% ww) exchanged Y zeolite catalysts have been used to hydrotreat a range of chlorophenols (CPs), dichlorophenols (DCPs), trichlorophenols (TCPs) and pentachlorophenol (PCP) over the temperature interval 473 K ?

  5. The behavior of palladium catalysts in direct formic acid fuel cells

    Microsoft Academic Search

    Yimin Zhu; Zakia Khan; R. I. Masel

    2005-01-01

    Previous work has considered the behavior of platinum based catalysts in direct methanol and Direct Formic Acid Fuel Cells (DFAFCs). In this paper, we explore the behavior of palladium-based anode catalyst for DFAFCs. The palladium catalysts produce significant performance enhancements. DFAFCs operated with dry air and zero back-pressure can generate power densities of 255?230mWcm?2 at relatively high voltages of 0.40?0.50V

  6. Novel Pd–Pb\\/C bimetallic catalysts for direct formic acid fuel cells

    Microsoft Academic Search

    Xingwen Yu; Peter G. Pickup

    2009-01-01

    Novel carbon supported bimetallic palladium–lead (Pd–Pb\\/C) anode catalysts have been prepared for use in direct formic acid fuel cells (DFAFC). Comparative studies, with a Pd\\/C catalyst, of performances, deactivation, and reactivation were performed in a multi-anode DFAFC. These Pd–Pb\\/C catalysts were found to be more resistant to deactivation in the DFAFC than Pd\\/C and to consistently show better long-term performances.

  7. The selective sorption of solvents on sulphonic acid polymer catalyst in binary mixtures

    Microsoft Academic Search

    Johanna Lilja; Elena Murzina; Henrik Grénman; Hanna Vainio; Tapio Salmi; Dmitry Yu. Murzin

    2005-01-01

    The sorption behaviour of a polymer-supported sulphonic acid catalyst, Smopex-101, was studied in different solvent mixtures at 60 and 70°C. The physical characteristics of the catalyst were investigated. Six catalysts with activities, ranging from 2.1 to 3.6mmol\\/g, various degrees of cross-linking, 0%, 0.5%, 2% and 4% divinylbenzene as well as dimensions (lengths and diameters) were studied. The analyses of the

  8. Chiral Brønsted Acid as a True Catalyst: Asymmetric Mukaiyama Aldol and Hosomi-Sakurai Allylation Reactions.

    PubMed

    Sai, Masahiro; Yamamoto, Hisashi

    2015-06-10

    Highly diastereo- and enantioselective Mukaiyama aldol reaction catalyzed by a new chiral Brønsted acid, N-(perfluorooctanesulfonyl)thiophosphoramide, is described. The perfluorooctyl substituent on the sulfonyl group of the catalyst plays an essential role in the stereoselection. The catalyst also allows the asymmetric Hosomi-Sakurai allylation, which has been considerably challenging due to the low reactivity of allylsilanes. (29)Si and (31)P NMR monitoring reveals the characteristic feature of the thiophosphoramide catalyst, acting as a strong Brønsted acid even in the presence of excess silyl nucleophiles, which cannot be found in other related phosphoric acid analogues. PMID:26017677

  9. Solid compositions for fuel cells, sensors and catalysts

    Microsoft Academic Search

    M. J. Madou; T. Otagawa; A. Sher

    1989-01-01

    This patent describes a use of a solid material as an electrolyte for a fuel cell. Each solid material having a polycrystal or single crystal structure, comprising: a structure of the formula: AFâ wherein A is independently selected from lanthanmun, cerium, neodymium, praseodymium, scandium, or mixtures thereof; wherein AFâ is a single crystal or portion thereof; or a structure of

  10. Effects of Nafion loading in anode catalyst inks on the miniature direct formic acid fuel cell

    Microsoft Academic Search

    Robert D. Morgan; John L. Haan; Richard I. Masel

    2010-01-01

    Nafion, within the anode and cathode catalyst layers, plays a large role in the performance of fuel cells, especially during the operation of the direct formic acid fuel cell (DFAFC). Nafion affects the proton transfer in the catalyst layers of the fuel cell, and studies presented here show the effects of three different Nafion loadings, 10wt.%, 30wt.% and 50wt.%. Short

  11. Performance of the direct formic acid fuel cell with electrochemically modified palladium–antimony anode catalyst

    Microsoft Academic Search

    John L. Haan; Kristin M. Stafford; Robert D. Morgan; Richard I. Masel

    2010-01-01

    Previous work has shown that palladium catalysts are quite active for formic acid electrooxidation, but the catalysts need to be periodically regenerated to remove a CO impurity from the surface. The objective of this paper is to determine whether antimony additions could suppress the CO formation under fuel cell conditions. We find that antimony doubles the rate of reaction in

  12. Nuclear magnetic resonance studies on the acidity of zeolites and related catalysts

    Microsoft Academic Search

    H. Pfeifer; D. Freude; M. Hunger

    1985-01-01

    A review is given on the possibilities of the various nuclear magnetic resonance techniques which have been applied up till now to study quantitatively the acidity of zeolites and related catalysts. From the intensity of the wide line proton magnetic resonance signal of unloaded catalysts, the total concentration of protons can be determined. A loading of the samples with (deuterated)

  13. Synthesis and characterization of triflic acid-functionalized mesoporous Zr-TMS catalysts: heterogenization of CF 3SO 3H over Zr-TMS and its catalytic activity

    Microsoft Academic Search

    M. Chidambaram; D. Curulla-Ferre; A. P. Singh; B. G. Anderson

    2003-01-01

    Triflic acid-functionalized Zr-TMS (zirconium oxide with a mesostructured framework; TMS, transition metal oxide mesoporous molecular sieves) catalysts have been synthesized by functionalizing triflic acid onto the walls of Zr-TMS via post synthesis method. The synthesized materials were characterized by powder XRD, N2-sorption, FT-IR spectroscopy, elemental analysis, solid-state 13C CP and DD\\/MAS NMR spectroscopy, FT-Raman analysis, NH3-TPD, SEM, TEM, TG-DTA, and

  14. A NiFeCu alloy anode catalyst for direct-methane solid oxide fuel cells

    NASA Astrophysics Data System (ADS)

    Wang, Wei; Zhu, Huaiyu; Yang, Guangming; Park, Hee Jung; Jung, Doh Won; Kwak, Chan; Shao, Zongping

    2014-07-01

    In this study, a new anode catalyst based on a NiFeCu alloy is investigated for use in direct-methane solid oxide fuel cells (SOFCs). The influence of the conductive copper introduced into the anode catalyst layer on the performance of the SOFCs is systematically studied. The catalytic activity for partial oxidation of methane and coking resistance tests are proposed with various anode catalyst layer materials prepared using different methods, including glycine nitrate process (GNP), physical mixing (PM) and impregnation (IMP). The surface conductivity tests indicate that the conductivities of the NiFe-ZrO2/Cu (PM) and NiFe-ZrO2/Cu (IMP) catalysts are considerably greater than that of NiFe-ZrO2/Cu (GNP), which is consistent with the SEM results. Among the three preparation methods, the cell containing the NiFe-ZrO2/Cu (IMP) catalyst layer performs best on CH4-O2 fuel, especially under reduced temperatures, because the coking resistance should be considered in real fuel cell conditions. The cell containing the NiFe-ZrO2/Cu (IMP) catalyst layer also delivers an excellent operational stability using CH4-O2 fuel for 100 h without any signs of decay. In summary, this work provides new alternative anode catalytic materials to accelerate the commercialization of SOFC technology.

  15. Sonophotochemical Degradation of Bisphenol A with Solid Catalysts

    NASA Astrophysics Data System (ADS)

    Myunghee Lim,; Younggyu Son,; Beomguk Park,; Jeehyeong Khim,

    2010-07-01

    In order to investigate the degradation of bisphenol A (BPA) solution under sono, photo, sonocatalytic, photocatalytic and sonophotocatalytic processes, the BPA concentration and the total organic carbon (TOC) concentration were analyzed. The degradation rate of BPA was higher at high frequency (1 MHz) than at low frequency (300 kHz). At high frequency the acoustic period is shorter, and a high H2O2 concentration is therefore produced in aqueous solutions, which can enhance the degradation rate. The degradation rates of BPA were 0.0060, 0.0258, and 0.0451 min-1 under the sonocatalytic (1 MHz), photocatalytic and sonophotocatalytic processes respectively. The combined system of the sonochemical and photocatalytic processes can enhance the degradation rate of BPA compared with individual processes (sono and photocatalytic processes). The order of degradation of BPA (CuO>ZnO?TiO2) and TOC (TiO2>ZnO>CuO) differed for each of the three types of catalysts. The separation characteristics of catalysts were dissimilar for each of the two frequencies.

  16. Performance characterization of direct formic acid fuel cell using porous carbon-supported palladium anode catalysts

    Microsoft Academic Search

    Sam Duck Han; Jae Ho Choi; Soon Young Noh; Soo Kyung Yoon; Young Woo Rhee

    2009-01-01

    Palladium particles supported on porous carbon of 20 and 50 nm pore diameters were prepared and applied to the direct formic\\u000a acid fuel cell (DFAFC). Four different anode catalysts with Pd loading of 30 and 50 wt% were synthesized by using impregnation\\u000a method and the cell performance was investigated with changing experimental variables such as anode catalyst loading, formic\\u000a acid

  17. Catalysts

    NSDL National Science Digital Library

    2012-07-19

    There are two types of catalysis reactions: homogeneous and heterogeneous. In a homogeneous reaction, the catalyst is in the same phase as the reactants. In a heterogeneous reaction, the catalyst is in a different phase from the reactants. This activity addresses homogeneous catalysis.

  18. Molybdenum phosphosulfide: an active, acid-stable, earth-abundant catalyst for the hydrogen evolution reaction.

    PubMed

    Kibsgaard, Jakob; Jaramillo, Thomas F

    2014-12-22

    Introducing sulfur into the surface of molybdenum phosphide (MoP) produces a molybdenum phosphosulfide (MoP|S) catalyst with superb activity and stability for the hydrogen evolution reaction (HER) in acidic environments. The MoP|S catalyst reported herein exhibits one of the highest HER activities of any non-noble-metal electrocatalyst investigated in strong acid, while remaining perfectly stable in accelerated durability testing. Whereas mixed-metal alloy catalysts are well-known, MoP|S represents a more uncommon mixed-anion catalyst where synergistic effects between sulfur and phosphorus produce a high-surface-area electrode that is more active than those based on either the pure sulfide or the pure phosphide. The extraordinarily high activity and stability of this catalyst open up avenues to replace platinum in technologies relevant to renewable energies, such as proton exchange membrane (PEM) electrolyzers and solar photoelectrochemical (PEC) water-splitting cells. PMID:25359678

  19. Size and ability do matter! Influence of acidity and pore size on the synthesis of hindered halogenated meso-phenyl porphyrins catalysed by porous solid oxides.

    PubMed

    Silva, Mónica; Fernandes, Auguste; Bebiano, Suse S; Calvete, Mário J F; Ribeiro, M Filipa; Burrows, Hugh D; Pereira, Mariette M

    2014-06-25

    The rationalisation of the influence of acidity and pore size of several solid oxides so that they selectively act as supports for preparation of encapsulated porphyrin hybrid materials or as catalysts for synthesis of porphyrins in solution is discussed. Encapsulated porphyrin yields are dependent on both the acidity and the material pore size, Al-MCM-41 being the best fitting solid, with Lewis acidity of 120 ?mol Py per g and a pore size 30 Å. On the other hand, when the goal is the synthesis of hindered mesoarylporphyrins in solution, the best solid porous catalyst is NaY, with Lewis acidity of 510 ?mol Py per g and a pore size 14 Å. This method provides an appealing efficient, reusable and scalable catalyst alternative for one-pot synthesis of meso-arylporphyrins in high yields. PMID:24643723

  20. Solid state 13C NMR characterisation study on fourth generation Ziegler-Natta catalysts.

    PubMed

    Heikkinen, Harri; Liitiä, Tiina; Virkkunen, Ville; Leinonen, Timo; Helaja, Tuulamari; Denifl, Peter

    2012-01-01

    In this study, solid state (13)C NMR spectroscopy was utilised to characterize and identify the metal-ester coordination in active fourth generation (phthalate) Ziegler-Natta catalysts. It is known that different donors affect the active species in ZN catalysts. However, there is still limited data available of detailed molecular information how the donors and the active species are interplaying. One of the main goals of this work was to get better insight into the interactions of donor and active species. Based on the anisotropy tensor values (?(11), ?(22), ?(33)) from low magic-angle spinning (MAS) (13)C NMR spectra in combination with chemical shift anisotropy (CSA) calculations (?(aniso) and ?), both the coordinative metal (Mg/Ti) and the symmetry of this interaction between metal and the internal donor in the active catalyst (MgCl(2)/TiCl(4)/electron donor) system could be identified. PMID:22425229

  1. Active phase of calcium oxide used as solid base catalyst for transesterification of soybean oil with refluxing methanol

    Microsoft Academic Search

    Masato Kouzu; Takekazu Kasuno; Masahiko Tajika; Shinya Yamanaka; Jusuke Hidaka

    2008-01-01

    For developing a process of biodiesel production with environmental benignity, much interest has been focused on solid base catalysts such as calcium oxide for transesterification of vegetable oils with methanol. In this paper, the active phase of calcium oxide was investigated by characterizing the catalyst collected after achieving the conversion of edible soybean oil into its methyl ester at reflux

  2. Metallo-solid lipid nanoparticles as colloidal tools for meso-macroporous supported catalysts.

    PubMed

    Kim, Sanghoon; Durand, Pierrick; Roques-Carmes, Thibault; Eastoe, Julian; Pasc, Andreea

    2015-02-10

    Meso-macroporous silica containing iron oxide nanoparticles (15-20 nm) was synthesized by formulating solid lipid nanoparticles and metallosurfactant as both template and metal source. Because of the high active surface area of the catalyst, the material exhibits an excellent performance in a Fenton-like reaction for methylene blue (MB) degradation, even at low amount of iron oxide (5% TOC after 14 h). PMID:25598433

  3. Chance and necessity in the selection of nucleic acid catalysts

    NASA Technical Reports Server (NTRS)

    Lorsch, J. R.; Szostak, J. W.

    1996-01-01

    In Tom Stoppard's famous play [Rosencrantz and Guildenstern are Dead], the ill-fated heroes toss a coin 101 times. The first 100 times they do so the coin lands heads up. The chance of this happening is approximately 1 in 10(30), a sequence of events so rare that one might argue that it could only happen in such a delightful fiction. Similarly rare events, however, may underlie the origins of biological catalysis. What is the probability that an RNA, DNA, or protein molecule of a given random sequence will display a particular catalytic activity? The answer to this question determines whether a collection of such sequences, such as might result from prebiotic chemistry on the early earth, is extremely likely or unlikely to contain catalytically active molecules, and hence whether the origin of life itself is a virtually inevitable consequence of chemical laws or merely a bizarre fluke. The fact that a priori estimates of this probability, given by otherwise informed chemists and biologists, ranged from 10(-5) to 10(-50), inspired us to begin to address the question experimentally. As it turns out, the chance that a given random sequence RNA molecule will be able to catalyze an RNA polymerase-like phosphoryl transfer reaction is close to 1 in 10(13), rare enough, to be sure, but nevertheless in a range that is comfortably accessible by experiment. It is the purpose of this Account to describe the recent advances in combinatorial biochemistry that have made it possible for us to explore the abundance and diversity of catalysts existing in nucleic acid sequence space.

  4. COMPARISON OF SODIUM HYPOPHOSPHITE WITH HYPOPHOSPHOROUS ACID AS CURING CATALYSTS FOR DP FINISHING WITH BTCA OR CITRIC ACID

    Technology Transfer Automated Retrieval System (TEKTRAN)

    It has been suggested that when sodium hypophosphite (SHP) is used to catalyze crosslinking of cotton by 1,2,3,4-butanetetracarboxylic acid (BTCA) at 160-190 degrees C, the active catalyst may be free hypophosphorous acid, which could form a mixed linear anhydride with, and subsequently a cyclic anh...

  5. Study of carbon-supported Au catalyst as the cathodic catalyst in a direct formic acid fuel cell prepared using a polyvinyl alcohol protection method

    Microsoft Academic Search

    Wei Chen; Yawen Tang; Jianchun Bao; Ying Gao; Changpeng Liu; Wei Xing; Tianhong Lu

    2007-01-01

    In this paper, it is reported for the first time that a carbon-supported Au (Au\\/C) catalyst for the cathodic catalyst in a direct formic acid fuel cell (DFAFC) was prepared using a polyvinyl alcohol (PVA) protection method. The results indicated that for oxygen reduction, the electrocatalytic activity of the Au\\/C catalyst prepared with the PVA protection method is much better

  6. Evaluating acid and base catalysts in the methylation of milk and rumen fatty acids with special emphasis on conjugated dienes and total trans fatty acids

    Microsoft Academic Search

    John K. G. Kramer; Vivek Fellner; Michael E. R. Dugan; Frank D. Sauer; Magdi M. Mossoba; Martin P. Yurawecz

    1997-01-01

    Milk analysis is receiving increased attention. Milk contains conjugated octadecadienoic acids (18?2) purported to be anticarcinogenic,\\u000a low levels of essential fatty acids, and trans fatty acids that increase when essential fatty acids are increased in dairy rations. Milk and rumen fatty acid methyl esters\\u000a (FAME) were prepared using several acid-(HCl, BF3, acetyl chloride, H2SO4) or base-catalysts (NaOCH3, tetramethylguanidine, diazomethane), or

  7. Benzene selectivity in competitive arene hydrogenation: effects of single-site catalyst···acidic oxide surface binding geometry.

    PubMed

    Gu, Weixing; Stalzer, Madelyn Marie; Nicholas, Christopher P; Bhattacharyya, Alak; Motta, Alessandro; Gallagher, James R; Zhang, Guanghui; Miller, Jeffrey T; Kobayashi, Takeshi; Pruski, Marek; Delferro, Massimiliano; Marks, Tobin J

    2015-06-01

    Organozirconium complexes are chemisorbed on Brønsted acidic sulfated ZrO2 (ZrS), sulfated Al2O3 (AlS), and ZrO2-WO3 (ZrW). Under mild conditions (25 °C, 1 atm H2), the supported Cp*ZrMe3, Cp*ZrBz3, and Cp*ZrPh3 catalysts are very active for benzene hydrogenation with activities declining with decreasing acidity, ZrS ? AlS ? ZrW, arguing that more Brønsted acidic oxides (those having weaker corresponding conjugate bases) yield stronger surface organometallic electrophiles and for this reason have higher benzene hydrogenation activity. Benzene selective hydrogenation, a potential approach for carcinogenic benzene removal from gasoline, is probed using benzene/toluene mixtures, and selectivities for benzene hydrogenation vary with catalyst as ZrBz3(+)/ZrS(-), 83% > Cp*ZrMe2(+)/ZrS(-), 80% > Cp*ZrBz2(+)/ZrS(-), 67% > Cp*ZrPh2(+)/ZrS(-), 57%. For Cp*ZrBz2(+)/ZrS(-), which displays the highest benzene hydrogenation activity with moderate selectivity in benzene/toluene mixtures. Other benzene/arene mixtures are examined, and benzene selectivities vary with arene as mesitylene, 99%, > ethylbenzene, 86% > toluene, 67%. Structural and computational studies by solid-state NMR spectroscopy, XAS, and periodic DFT methods applied to supported Cp*ZrMe3 and Cp*ZrBz3 indicate that larger Zr···surface distances are present in more sterically encumbered Cp*ZrBz2(+)/AlS(-) vs Cp*ZrMe2(+)/AlS(-). The combined XAS, solid state NMR, and DFT data argue that the bulky catalyst benzyl groups expand the "cationic" metal center-anionic sulfated oxide surface distances, and this separation/weakened ion-pairing enables the activation/insertion of more sterically encumbered arenes and influences hydrogenation rates and selectivity patterns. PMID:25884397

  8. Synthesis, solid-state NMR characterization, and application for hydrogenation reactions of a novel Wilkinson's-type immobilized catalyst.

    PubMed

    Abdulhussain, Safaa; Breitzke, Hergen; Ratajczyk, Tomasz; Grünberg, Anna; Srour, Mohamad; Arnaut, Danjela; Weidler, Heiko; Kunz, Ulrike; Kleebe, Hans Joachim; Bommerich, Ute; Bernarding, Johannes; Gutmann, Torsten; Buntkowsky, Gerd

    2014-01-20

    Silica nanoparticles (SiNPs) were chosen as a solid support material for the immobilization of a new Wilkinson's-type catalyst. In a first step, polymer molecules (poly(triphenylphosphine)ethylene (PTPPE); 4-diphenylphosphine styrene as monomer) were grafted onto the silica nanoparticles by surface-initiated photoinferter-mediated polymerization (SI-PIMP). The catalyst was then created by binding rhodium (Rh) to the polymer side chains, with RhCl3?x?H2O as a precursor. The triphenylphosphine units and rhodium as Rh(I) provide an environment to form Wilkinson's catalyst-like structures. Employing multinuclear ((31)P, (29)Si, and (13)C) solid-state NMR spectroscopy (SSNMR), the structure of the catalyst bound to the polymer and the intermediates of the grafting reaction have been characterized. Finally, first applications of this catalyst in hydrogenation reactions employing para-enriched hydrogen gas (PHIP experiments) and an assessment of its leaching properties are presented. PMID:24338904

  9. Phase Behavior of Complex Superprotonic Solid Acids

    NASA Astrophysics Data System (ADS)

    Panithipongwut, Chatr

    Superprotonic phase transitions and thermal behaviors of three complex solid acid systems are presented, namely Rb3H(SO4) 2-RbHSO4 system, Rb3H(SeO4)2-Cs 3H(SeO4)2 solid solution system, and Cs6 (H2SO4)3(H1.5PO4) 4. These material systems present a rich set of phase transition characteristics that set them apart from other, simpler solid acids. A.C. impedance spectroscopy, high-temperature X-ray powder diffraction, and thermal analysis, as well as other characterization techniques, were employed to investigate the phase behavior of these systems. Rb3H(SO4)2 is an atypical member of the M3H(XO4)2 class of compounds (M = alkali metal or NH4+ and X = S or Se) in that a transition to a high-conductivity state involves disproportionation into two phases rather than a simple polymorphic transition [1]. In the present work, investigations of the Rb3H(SO4)2-RbHSO4 system have revealed the disproportionation products to be Rb2SO 4 and the previously unknown compound Rb5H3(SO 4)4. The new compound becomes stable at a temperature between 25 and 140 °C and is isostructural to a recently reported trigonal phase with space group P3m of Cs5H 3(SO4)4 [2]. At 185 °C the compound undergoes an apparently polymorphic transformation with a heat of transition of 23.8 kJ/mol and a slight additional increase in conductivity. The compounds Rb3H(SeO4)2 and Cs 3H(SeO4)2, though not isomorphous at ambient temperatures, are quintessential examples of superprotonic materials. Both adopt monoclinic structures at ambient temperatures and ultimately transform to a trigonal (R3m) superprotonic structure at slightly elevated temperatures, 178 and 183 °C, respectively. The compounds are completely miscible above the superprotonic transition and show extensive solubility below it. Beyond a careful determination of the phase boundaries, we find a remarkable 40-fold increase in the superprotonic conductivity in intermediate compositions rich in Rb as compared to either end-member. The compound Cs6(H2SO4)3(H 1.5PO4)4 is unusual amongst solid acid compounds in that it has a complex cubic structure at ambient temperature and apparently transforms to a simpler cubic structure of the CsCl-type (isostructural with CsH2PO4) at its transition temperature of 100-120 °C [3]. Here it is found that, depending on the level of humidification, the superprotonic transition of this material is superimposed with a decomposition reaction, which involves both exsolution of (liquid) acid and loss of H2O. This reaction can be suppressed by application of sufficiently high humidity, in which case Cs6(H2SO4)3(H 1.5PO4)4 undergoes a true superprotonic transition. It is proposed that, under conditions of low humidity, the decomposition/dehydration reaction transforms the compound to Cs6(H2-0.5xSO 4)3(H1.5PO4)4-x, also of the CsCl structure type at the temperatures of interest, but with a smaller unit cell. With increasing temperature, the decomposition/dehydration proceeds to greater and greater extent and unit cell of the solid phase decreases. This is identified to be the source of the apparent negative thermal expansion behavior. References: [1] L.A. Cowan, R.M. Morcos, N. Hatada, A. Navrotsky, S.M. Haile, Solid State Ionics 179 (2008) (9-10) 305. [2] M. Sakashita, H. Fujihisa, K.I. Suzuki, S. Hayashi, K. Honda, Solid State Ionics 178 (2007) (21-22) 1262. [3] C.R.I. Chisholm, Superprotonic Phase Transitions in Solid Acids: Parameters affecting the presence and stability of superprotonic transitions in the MHnXO4 family of compounds (X=S, Se, P, As; M=Li, Na, K, NH4, Rb, Cs), Materials Science, California Institute of Technology, Pasadena, California (2003).

  10. Process for the generation of .alpha., .beta.-unsaturated carboxylic acids and esters using niobium catalyst

    DOEpatents

    Gogate, Makarand Ratnakav (Durham, NC); Spivey, James Jerome (Cary, NC); Zoeller, Joseph Robert (Kingsport, TN)

    1999-01-01

    A process using a niobium catalyst includes the step of reacting an ester or carboxylic acid with oxygen and an alcohol in the presence a niobium catalyst to respectively produce an .alpha.,.beta.-unsaturated ester or carboxylic acid. Methanol may be used as the alcohol, and the ester or carboxylic acid may be passed over the niobium catalyst in a vapor stream containing oxygen and methanol. Alternatively, the process using a niobium catalyst may involve the step of reacting an ester and oxygen in the presence the niobium catalyst to produce an .alpha.,.beta.-unsaturated carboxylic acid. In this case the ester may be a methyl ester. In either case, niobium oxide may be used as the niobium catalyst with the niobium oxide being present on a support. The support may be an oxide selected from the group consisting of silicon oxide, aluminum oxide, titanium oxide and mixtures thereof. The catalyst may be formed by reacting niobium fluoride with the oxide serving as the support. The niobium catalyst may contain elemental niobium within the range of 1 wt % to 70 wt %, and more preferably within the range of 10 wt % to 30 wt %. The process may be operated at a temperature from 150 to 450.degree. C. and preferably from 250 to 350.degree. C. The process may be operated at a pressure from 0.1 to 15 atm. absolute and preferably from 0.5-5 atm. absolute. The flow rate of reactants may be from 10 to 10,000 L/kg.sub.(cat) /h, and preferably from 100 to 1,000 L/kg.sub.(cat) /h.

  11. Deactivation of carbon supported palladium catalyst in direct formic acid fuel cell

    Microsoft Academic Search

    A. Mikolajczuk; A. Borodzinski; P. Kedzierzawski; L. Stobinski; B. Mierzwa; R. Dziura

    2011-01-01

    A new carbon black supported palladium catalyst for direct formic acid fuel cell applications has been prepared and characterized by X-ray diffraction. Bi-modal distribution of Pd crystallite sizes was observed. The average Pd size for crystallites in small size and large size ranges were about 2.7nm and 11.2nm, respectively. The initial activity of the catalyst in the oxidation of formic

  12. Carbon supported ruthenium chalcogenide as cathode catalyst in a microfluidic formic acid fuel cell

    Microsoft Academic Search

    A. S. Gago; D. Morales-Acosta; L. G. Arriaga; N. Alonso-Vante

    2011-01-01

    This work reports the electrochemical measurements of 20wt.% RuxSey\\/C for oxygen reduction reaction (ORR) in presence of different concentration of HCOOH and its use as cathode catalyst in a microfluidic formic acid fuel cell (?FAFC). The results were compared to those obtained with commercial Pt\\/C. Half-cell electrochemical measurements showed that the chalcogenide catalyst has a high tolerance and selectivity towards

  13. Preparation of Pt-Pd catalysts for direct formic acid fuel cell and their characteristics

    Microsoft Academic Search

    Ki Ho Kim; Jae-Keun Yu; Hyo Song Lee; Jae Ho Choi; Soon Young Noh; Soo Kyung Yoon; Chang-Soo Lee; Taek-Sung Hwang; Young Woo Rhee

    2007-01-01

    Pt-Pd catalysts were prepared by using the spontaneous deposition method and their characteristics were analyzed in a direct\\u000a formic acid fuel cell (DFAFC). Effects of calcination temperature and atmosphere on the cell performance were investigated.\\u000a The calcination temperatures were 300, 400 and 500 °C and the calcination atmospheres were air and nitrogen. The fuel cell\\u000a with the catalyst calcined at

  14. Carbon supported platinum–gold alloy catalyst for direct formic acid fuel cells

    Microsoft Academic Search

    J. B. Xu; T. S. Zhao; Z. X. Liang

    2008-01-01

    The Pt–Au nanoparticles with 1:1 atomic ratio supported on carbon powder were prepared by the co-reduction method using N,N-dimethylformamide coordinated Pt–Au complex as a precursor. Cyclic voltammetry results demonstrated that the PtAu\\/C catalyst exhibited a higher activity for the formic acid oxidation reaction than did the commercial Pt\\/C catalyst, reflected by its lower onset potential and higher peak current. The

  15. Catalytic ozonation of phenolic acids over a Mn–Ce–O catalyst

    Microsoft Academic Search

    Rui C. Martins; Rosa M. Quinta-Ferreira

    2009-01-01

    Catalytic ozonation of a simulated phenolic wastewater composed by six acids: syringic, vanillic, 3,4,5-trimethoxybenzoic, veratric, protocatechuic and 4-hydroxybenzoic normally present in olive mill wastewaters was studied over a Mn–Ce–O laboratorial catalyst under different operating conditions. A high improvement in total organic carbon (TOC) degradation was observed even when low catalyst concentrations were used when compared with single ozonation. The influence

  16. Structural analysis of nickel doped cerium oxide catalysts for fuel reforming in solid oxide fuel cells

    NASA Astrophysics Data System (ADS)

    Cavendish, Rio

    As world energy demands increase, research into more efficient energy production methods has become imperative. Heterogeneous catalysis and nanoscience are used to promote chemical transformations important for energy production. These concepts are important in solid oxide fuel cells (SOFCs) which have attracted attention because of their potential to provide an efficient and environmentally favorable power generation system. The SOFC is also fuel-flexible with the ability to run directly on many fuels other than hydrogen. Internal fuel reforming directly in the anode of the SOFC would greatly reduce the cost and complexity of the device. Methane is the simplest hydrocarbon and a main component in natural gas, making it useful when testing catalysts on the laboratory scale. Nickel (Ni) and gadolinium (Gd) doped ceria (CeO 2) catalysts for potential use in the SOFC anode were synthesized with a spray drying method and tested for catalytic performance using partial oxidation of methane and steam reforming. The relationships between catalytic performance and structure were then investigated using X-ray diffraction, transmission electron microscopy, and environmental transmission electron microscopy. The possibility of solid solutions, segregated phases, and surface layers of Ni were explored. Results for a 10 at.% Ni in CeO2 catalyst reveal a poor catalytic behavior while a 20 at.% Ni in CeO2 catalyst is shown to have superior activity. The inclusion of both 10 at.% Gd and 10 at.% Ni in CeO2 enhances the catalytic performance. Analysis of the presence of Ni in all 3 samples reveals Ni heterogeneity and little evidence for extensive solid solution doping. Ni is found in small domains throughout CeO2 particles. In the 20 at.% Ni sample a segregated, catalytically active NiO phase is observed. Overall, it is found that significant interaction between Ni and CeO2 occurs that could affect the synthesis and functionality of the SOFC anode.

  17. Magnetic solid base catalyst CaO/CoFe2O4 for biodiesel production: Influence of basicity and wettability of the catalyst in catalytic performance

    NASA Astrophysics Data System (ADS)

    Zhang, Pingbo; Han, Qiuju; Fan, Mingming; Jiang, Pingping

    2014-10-01

    A novel magnetic solid base catalyst CaO/CoFe2O4 was successfully prepared with CoFe2O4 synthesized by hydrothermal method as the magnetic core and applied to the transesterification of soybean oil for the production of biodiesel. The magnetic solid base catalysts were characterized by a series of techniques including CO2-TPD, powder XRD, TGA, TEM and the contact angle measurement of the water droplet. It was demonstrated that CaO/CoFe2O4 has stronger magnetic strength indicating perfect utility for repeated use and better basic strength. Compared with CaO/ZnFe2O4 and CaO/MnFe2O4, solid base catalyst CaO/CoFe2O4 has better catalytic performance, weaker hydroscopicity and stronger wettability, demonstrating that catalytic performance was relative to both basicity of catalyst and the full contact between the catalyst and the reactants, but the latter was a main factor in the catalytic system.

  18. Phosphotungstic acid supported on magnetic nanoparticles as an efficient reusable catalyst for epoxidation of alkenes

    SciTech Connect

    Kooti, M., E-mail: m_kooti@scu.ac.ir [Department of Chemistry, College of Science, Shahid Chamran University, Ahvaz 61357- 43169 (Iran, Islamic Republic of); Afshari, M. [Department of Chemistry, College of Science, Shahid Chamran University, Ahvaz 61357- 43169 (Iran, Islamic Republic of)] [Department of Chemistry, College of Science, Shahid Chamran University, Ahvaz 61357- 43169 (Iran, Islamic Republic of)

    2012-11-15

    Highlights: ? Phosphotungstic acid supported on functionalized cobalt ferrite was prepared. ? Silica coated cobalt ferrite nanoparticles were used as support. ? This composite was successfully used as catalyst for epoxidation of alkenes. ? Oxidation reactions were carried out in the presence of t-BuOOH as oxidant. ? The catalyst can be readily separated from solution by magnetic field. -- Abstract: A new magnetically separable catalyst consisting of phosphotungstic acid supported on imidazole functionalized silica coated cobalt ferrite nanoparticles was prepared. The synthesized catalyst was characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), vibrating sample magnetometry (VSM), thermogravimetric analysis (TGA), Fourier transform infrared (FT-IR), and inductively coupled plasma atomic emission spectroscopy (ICP-AES). This immobilized phosphotungstic acid was shown to be an efficient heterogeneous catalyst for the epoxidation of various alkenes using tert-butylhydroperoxide (t-BuOOH) as oxidant. The catalyst is readily recovered by simple magnetic decantation and can be recycled several times with no significant loss of catalytic activity.

  19. Stability of mechanical properties of vanadium catalysts for sulfuric acid manufacture in a humid atmosphere

    SciTech Connect

    Manaeva, L.N.; Malikman, V.I.; Dobkina, E.I.; Mukhlenov, I.P.

    1982-01-10

    Experience of the industrial use of catalysts in sulfuric acid manufacture shows that as the result of saturation with moisture the catalyst grains may lose strength and disintegrate during use. However, this question has not been examined experimentally and the mechanism of the effect has not been studied. Fresh catalyst may come into contact with atmospheric moisture during storage, and used catalyst as the result of uncontrolled leakages during stoppages and recharging of the catalytic converters. In the course of normal operation water vapor enters the catalytic converters together with sulfuric acid mist with the gas stream if the latter has not been adequately dried. The purpose of the present work was to study the mechanical stability, in a humid atmosphere, of industrial sulfuric acid catalysts: granulated SVD (5 mm in diameter) and SVS rings (8 x 8 x 2.5 mm). The catalysts were studied both in the fresh state and after use in a laboratory catalytic apparatus of the flow type.

  20. PdBi\\/C and PtPb\\/C Bimetallic Catalysts for Direct Formic Acid Fuel Cells

    Microsoft Academic Search

    Xingwen Yu; Peter G. Pickup

    2009-01-01

    An efficient methodology for comparing anode catalysts for direct formic acid fuel cells (DFAFCs) by employing a multi-anode, liquid-fed fuel cell is presented. PdBi\\/C bimetallic catalysts synthesized by co-depositing Pd and Bi on Vulcan XC-72 carbon black, as well as PtPb\\/C bimetallic catalysts synthesized by depositing Pb on a Pt\\/C catalyst, were systematically studied in a multi-anode DFAFC. The PdBi\\/C

  1. Sulfonic acid functionalized poly (ethylene glycol dimethacrylate-1-vinyl-1,2,4-triazole) as an efficient catalyst for the synthesis of methyl propionate

    Microsoft Academic Search

    Beyhan Erdem; Ali Kara

    2011-01-01

    Sulfonic acid functionalized poly (ethylene glycol dimethacrylate-1-vinyl-1,2,4-triazole), poly (EGDMA–VTAZ–SO3H) (average diameter 1.0–1.5mm), was found to be efficient solid acid catalyst for the esterification of methanol and propionic acid under heterogeneous reaction conditions. The pristine polymer, poly (EGDMA–VTAZ), was produced by suspension polymerization and then proton-conducting polymer was obtained by blending of poly (EGDMA–VTAZ) with different percentage of H2SO4 solutions. The

  2. Determination of relative acid strength and acid amount of solid acids by Ar adsorption

    Microsoft Academic Search

    Hiromi Matsuhashi; Ayumi Futamura

    2006-01-01

    Relative acid strength and acid amount of solid acids (alumina, silica-alumina, sulfated zirconia, mordenite, ZSM-5, beta, Y, and reduced MoO3) are determined by argon adsorption technique. To obtain the heat of Ar adsorption and saturated adsorption amount, the adsorption isotherm is analyzed using the theory reported by Cremer and Flügge. The obtained heats of Ar adsorption and saturated adsorption amounts

  3. CO oxidation on Ta-Modified SnO2 solid solution catalysts

    NASA Astrophysics Data System (ADS)

    Han, Xue; Xu, Xianglan; Liu, Wenming; Wang, Xiang; Zhang, Rongbin

    2013-06-01

    Co-precipitation method was adopted to prepare Sn-Ta mixed oxide catalysts with different Sn/Ta molar ratios and used for CO oxidation. The catalysts were investigated by N2-Brunauer-Emmett-Teller (N2-BET), X-ray diffraction patterns (XRD), H2-temperature programmed reduction (H2-TPR), Thermal Gravity Analysis - Differential Scanning Calorimetry (TGA-DSC) techniques. It is revealed that a small amount of Ta cations can be doped into SnO2 lattice to form solid solution by co-precipitation method, which resulted in samples having higher surface areas, improved thermal stability and more deficient oxygen species on the surface of SnO2. As a result, those Sn rich Sn-Ta solid solution catalysts with an Sn/Ta molar ratio higher than 4/2 showed significantly enhanced activity as well as good resistance to water deactivation. It is noted here that if tantala disperses onto SnO2 surface instead of doping into its lattice, it will then have negative effect on its activity.

  4. Organo-niobate Ionic Liquids: Synthesis, Characterization and Application as Acid Catalyst in Pechmann Reactions

    PubMed Central

    Soares, Valerio C. D.; Alves, Melquizedeque B.; Souza, Ernesto R.; Pinto, Ivana O.; Rubim, Joel C.; Andrade, Carlos Kleber Z.; Suarez, Paulo A. Z.

    2007-01-01

    The combinations of 1-butyl-3-methylimidazolium chloride with NbCl5 yielded ionic mixtures with different melting point temperatures and acidity depending on the niobium molar fraction. The mixtures were characterized by thermal (DSC) and spectroscopic (FT-IR and 1H NMR) analysis. The Pechmann reactions of different phenols with ethylacetoacetate, producing coumarins, was used as model to evaluate the catalytic behavior of these mixtures as acid Lewis catalyst. These reactions were carried out using acidic mixtures of 60 mol%.

  5. CO2-Free Power Generation on an Iron Group Nanoalloy Catalyst via Selective Oxidation of Ethylene Glycol to Oxalic Acid in Alkaline Media

    PubMed Central

    Matsumoto, Takeshi; Sadakiyo, Masaaki; Ooi, Mei Lee; Kitano, Sho; Yamamoto, Tomokazu; Matsumura, Syo; Kato, Kenichi; Takeguchi, Tatsuya; Yamauchi, Miho

    2014-01-01

    An Fe group ternary nanoalloy (NA) catalyst enabled selective electrocatalysis towards CO2-free power generation from highly deliverable ethylene glycol (EG). A solid-solution-type FeCoNi NA catalyst supported on carbon was prepared by a two-step reduction method. High-resolution electron microscopy techniques identified atomic-level mixing of constituent elements in the nanoalloy. We examined the distribution of oxidised species, including CO2, produced on the FeCoNi nanoalloy catalyst in the EG electrooxidation under alkaline conditions. The FeCoNi nanoalloy catalyst exhibited the highest selectivities toward the formation of C2 products and to oxalic acid, i.e., 99 and 60%, respectively, at 0.4?V vs. the reversible hydrogen electrode (RHE), without CO2 generation. We successfully generated power by a direct EG alkaline fuel cell employing the FeCoNi nanoalloy catalyst and a solid-oxide electrolyte with oxygen reduction ability, i.e., a completely precious-metal-free system. PMID:25004118

  6. Model heterogeneous acid catalysts and metal-support interactions: A combined surface science and catalysis study

    SciTech Connect

    Boszormenyi, I.

    1991-05-01

    This (<100 [Angstrom]) silica-alumina layers were tested as potential model heterogeneous acid catalysts for combined surface science and catalysis studies. Three preparation methods were used: oxidation of r3 [times] r3 R30 Al/Si(111) structure in UHV; deposition on Si(lll) from aqueous solution; and argon ion beam sputter deposition in UHV. The homogeneous thin layers are amorphous, and the chemical environment of surface atoms is similar to that of Si, Al and oxygen atoms on high surface area acid catalysts. Since the ion beam-deposited thin layer of silica-alumina has the same composition as the target zeolite this deposition method is a promising tool to prepare model catalysts using practical catalyst targets. The silica-alumina layers are active in cumene cracking, a typical acid catalyzed reaction. In order to clearly distinguish background reactions and the acid catalyzed reaction at least 20 cm[sup 2] catalyst surface area is needed. Two series of model platinum-alumina catalysts were prepared in a combined UHV -- high pressure reactor cell apparatus by depositing alumina on polycrystalline Pt foil and by vapor depositing Pt on a thin alumina layer on Au. Both model surfaces have been prepared with and without chlorine. AES, CO desorption as well as methyl cyclopentane (MCP) hydrogenolysis studies indicate that the Pt surface area is always higher if a chlorination step is involved. Selectivity patterns in MCP ring opening on Pt-on-alumina'' and on alumina-on-Pt'' are different; only the former is a linear combination of selective and statistical ring opening. Product distribution, however, changes with coverage and reaction time. The properties of the two model catalyst systems and role of chlorine in MCP hydrogenolysis are also discussed.

  7. Model heterogeneous acid catalysts and metal-support interactions: A combined surface science and catalysis study

    SciTech Connect

    Boszormenyi, I.

    1991-05-01

    This (<100 {Angstrom}) silica-alumina layers were tested as potential model heterogeneous acid catalysts for combined surface science and catalysis studies. Three preparation methods were used: oxidation of r3 {times} r3 R30 Al/Si(111) structure in UHV; deposition on Si(lll) from aqueous solution; and argon ion beam sputter deposition in UHV. The homogeneous thin layers are amorphous, and the chemical environment of surface atoms is similar to that of Si, Al and oxygen atoms on high surface area acid catalysts. Since the ion beam-deposited thin layer of silica-alumina has the same composition as the target zeolite this deposition method is a promising tool to prepare model catalysts using practical catalyst targets. The silica-alumina layers are active in cumene cracking, a typical acid catalyzed reaction. In order to clearly distinguish background reactions and the acid catalyzed reaction at least 20 cm{sup 2} catalyst surface area is needed. Two series of model platinum-alumina catalysts were prepared in a combined UHV -- high pressure reactor cell apparatus by depositing alumina on polycrystalline Pt foil and by vapor depositing Pt on a thin alumina layer on Au. Both model surfaces have been prepared with and without chlorine. AES, CO desorption as well as methyl cyclopentane (MCP) hydrogenolysis studies indicate that the Pt surface area is always higher if a chlorination step is involved. Selectivity patterns in MCP ring opening on ``Pt-on-alumina`` and on ``alumina-on-Pt`` are different; only the former is a linear combination of selective and statistical ring opening. Product distribution, however, changes with coverage and reaction time. The properties of the two model catalyst systems and role of chlorine in MCP hydrogenolysis are also discussed.

  8. Electrocatalytic properties of Pd/C catalyst for formic acid electrooxidation promoted by europium oxide

    NASA Astrophysics Data System (ADS)

    Feng, Ligang; Yao, Shikui; Zhao, Xiao; Yan, Liang; Liu, Changpeng; Xing, Wei

    2012-01-01

    It is found that the electrocatalytic activity and stability of Pd/C nanocatalyst for formic acid electrooxidation are enhanced by the introduction of EuOx. The morphology, composition and electrocatalytic properties of the PdEuOx/C catalyst are investigated by the transmission electronmicroscopy, energy dispersive X-ray analysis, X-ray diffraction, the linear sweep voltammetry and chronoamperometry, respectively. The EDX results confirm the existence of EuOx in the PdEuOx/C catalysts. The XRD results indicate that the Pd is in the state of face-centered cubic phase structure. The linear sweeping voltammetry and chronoamperometry measurements show that the current of formic acid electrooxidation on the PdEuOx/C catalyst is ca. 2.5 times and 9 times as high as that of the home-made Pd/C catalyst, respectively; moreover, the performances are also much higher than the commercial Pd/C catalyst. The high performances can be attributed to the larger electrochemical surface area and the electronic effect of the EuOx in the PdEuOx/C catalyst.

  9. Solid-state actinide acid phosphites from phosphorous acid melts

    SciTech Connect

    Oh, George N. [Department of Civil and Environmental Engineering and Earth Sciences, University of Notre Dame, 156 Fitzpatrick Hall, Notre Dame, IN 46556 (United States); Burns, Peter C., E-mail: pburns@nd.edu [Department of Civil and Environmental Engineering and Earth Sciences, University of Notre Dame, 156 Fitzpatrick Hall, Notre Dame, IN 46556 (United States); Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556 (United States)

    2014-07-01

    The reaction of UO{sub 3} and H{sub 3}PO{sub 3} at 100 °C and subsequent reaction with dimethylformamide (DMF) produces crystals of the compound (NH{sub 2}(CH{sub 3}){sub 2})[UO{sub 2}(HPO{sub 2}OH)(HPO{sub 3})]. This compound crystallizes in space group P2{sub 1}/n and consists of layers of uranyl pentagonal bipyramids that share equatorial vertices with phosphite units, separated by dimethylammonium. In contrast, the reaction of phosphorous acid and actinide oxides at 210 °C produces a viscous syrup. Subsequent dilution in solvents and use of standard solution-state methods results in the crystallization of two polymorphs of the actinide acid phosphites An(HPO{sub 2}OH){sub 4} (An=U, Th) and of the mixed acid phosphite–phosphite U(HPO{sub 3})(HPO{sub 2}OH){sub 2}(H{sub 2}O)·2(H{sub 2}O). ?- and ?-An(HPO{sub 2}OH){sub 4} crystallize in space groups C2/c and P2{sub 1}/n, respectively, and comprise a three-dimensional network of An{sup 4+} cations in square antiprismatic coordination corner-sharing with protonated phosphite units, whereas U(HPO{sub 3})(HPO{sub 2}OH){sub 2}(H{sub 2}O){sub 2}·(H{sub 2}O) crystallizes in a layered structure in space group Pbca that is composed of An{sup 4+} cations in square antiprismatic coordination corner-sharing with protonated phosphites and water ligands. We discuss our findings in using solid inorganic reagents to produce a solution-workable precursor from which solid-state compounds can be crystallized. - Graphical abstract: Reaction of UO{sub 3} and H{sub 3}PO{sub 3} at 100 °C and subsequent reaction with DMF produces crystals of (NH{sub 2}(CH{sub 3}){sub 2})[UO{sub 2}(HPO{sub 2}OH)(HPO{sub 3})] with a layered structure. Reaction of phosphorous acid and actinide oxides at 210 °C produces a viscous syrup and further solution-state reactions result in the crystallization of the actinide acid phosphites An(HPO{sub 2}OH){sub 4} (An=U, Th), with a three-dimensional network structure, and the mixed acid phosphite–phosphite U(HPO{sub 3})(HPO{sub 2}OH){sub 2}(H{sub 2}O){sub 2}·(H{sub 2}O) with a layered structure. - Highlights: • U(VI), U(IV) and Th(IV) phosphites were synthesized by solution-state methods. • A new uranyl phosphite structure is based upon uranyl phosphite anionic sheets. • New U and Th phosphites have framework structures.

  10. Performance improvement in direct formic acid fuel cells (DFAFCs) using metal catalyst prepared by dual mode spraying

    Microsoft Academic Search

    S. M. Baik; Jinsoo Kim; Jonghee Han; Yongchai Kwon

    2011-01-01

    In the present study, we investigate performance of direct formic acid fuel cells (DFAFCs) consisting of membrane electrode assembly (MEA) prepared by three different catalyst coating methods – direct painting, air spraying and dual mode spraying. For the DFAFC single cell tests, palladium (Pd) and platinum (Pt) are used as anode and cathode catalyst, respectively, and four different formic acid

  11. Catalysis Letters 51 (1998) 1522 15 The role of acid sites in cobalt zeolite catalysts for selective

    E-print Network

    Regalbuto, John R.

    1998-01-01

    Catalysis Letters 51 (1998) 15­22 15 The role of acid sites in cobalt zeolite catalysts Received 13 August 1997; accepted 9 January 1998 The role of the acidic support in ion-exchanged cobalt-zeolite, lean NOx catalysts has been determined by studying the individual steps in the selective reduction

  12. Codeposited PtSb/C catalysts for direct formic acid fuel cells

    NASA Astrophysics Data System (ADS)

    Yu, Xingwen; Pickup, Peter G.

    2011-10-01

    Carbon supported PtSb catalysts were synthesized by codeposition of platinum and antimony on Vulcan® carbon black. X-ray diffraction (XRD) analysis revealed that the Sb was alloyed with the Pt while XPS indicated that a large fraction of the Sb was in an oxidized state, with only partial alloying. The performances of catalysts with a range of compositions were compared in a multi-anode direct formic acid fuel cell (DFAFC). A 0.29 mol fraction of Sb was found to provide the best performance with a maximum specific power output of 280 W g-1 Pt. CO stripping results indicated that the addition of Sb at this optimum level greatly suppressed both CO adsorption and H adsorption/desorption, as well as promoting oxidative stripping of CO. The results are compared with those for previously studied catalysts prepared by the reductive deposition of Sb on a carbon supported Pt catalyst.

  13. Hydrothermal microwave valorization of eucalyptus using acidic ionic liquid as catalyst toward a green biorefinery scenario.

    PubMed

    Xu, Ji-Kun; Chen, Jing-Huan; Sun, Run-Cang

    2015-10-01

    The application of the acidic ionic liquid (IL), 1-butyl-3-methylimidazolium hydrogensulfate ([bmim]HSO4), as a catalyst in the hydrothermal microwave treatment (HMT) and green upgradation of eucalyptus biomass has been investigated. The process was carried out in a microwave reactor system at different temperatures (140-200°C) and evaluated for severities. The xylooligosaccharides (XOS, refers to a DP of 2-6) yield up to 5.04% (w/w) of the initial biomass and 26.72% (w/w) of xylan were achieved. Higher temperature resulted in lower molecular weight product, and enhanced the concentration of monosaccharides and byproducts. The morphology and structure of the solid residues were performed using an array of techniques, such as SEM, XRD, FTIR, BET surface area, and CP/MAS (13)C NMR, by which the increase of crystallinity, the destruction of surface structure, and the changes in functional groups and compositions were studied after the pretreatment, thus significantly enhancing the enzymatic hydrolysis. PMID:26119053

  14. Synthesis of sulfonated porous carbon nanospheres solid acid by a facile chemical activation route

    NASA Astrophysics Data System (ADS)

    Chang, Binbin; Guo, Yanzhen; Yin, Hang; Zhang, Shouren; Yang, Baocheng

    2015-01-01

    Generally, porous carbon nanospheres materials are usually prepared via a template method, which is a multi-steps and high-cost strategy. Here, we reported a porous carbon nanosphere solid acid with high surface area and superior porosity, as well as uniform nanospheical morphology, which prepared by a facile chemical activation with ZnCl2 using resorcinol-formaldehyde (RF) resins spheres as precursor. The activation of RF resins spheres by ZnCl2 at 400 °C brought high surface area and large volume, and simultaneously retained numerous oxygen-containing and hydrogen-containing groups due to the relatively low processing temperature. The presence of these functional groups is favorable for the modification of -SO3H groups by a followed sulfonation treating with sulphuric acid and organic sulfonic acid. The results of N2 adsorption-desorption and electron microscopy clearly showed the preservation of porous structure and nanospherical morphology. Infrared spectra certified the variation of surface functional groups after activation and the successful modification of -SO3H groups after sulfonation. The acidities of catalysts were estimated by an indirect titration method and the modified amount of -SO3H groups were examined by energy dispersive spectra. The results suggested sulfonated porous carbon nanospheres catalysts possessed high acidities and -SO3H densities, which endowed their significantly catalytic activities for biodiesel production. Furthermore, their excellent stability and recycling property were also demonstrated by five consecutive cycles.

  15. Catalyst-free direct decarboxylative coupling of ?-keto acids with thiols: a facile access to thioesters.

    PubMed

    Yan, Kelu; Yang, Daoshan; Wei, Wei; Zhao, Jing; Shuai, Yuanyuan; Tian, Laijin; Wang, Hua

    2015-07-14

    A novel, efficient, and catalyst-free strategy has been initially developed for the construction of thioesters via the direct radical oxidative decarboxylation of ?-keto acids with thiols, and the corresponding target products were obtained in moderate to good yields. It offers an alternative approach for the synthesis of useful diverse thioesters. PMID:26058949

  16. COMPARISON OF CATALYSTS FOR DIRECT TRANSESTERIFICATION OF FATTY ACIDS IN FREEZE-DRIED FORAGE SAMPLES

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Our objective was to compare 1.09 M methanolic HCl to 14% BF3 in methanol as catalysts for direct transesterification of fatty acids in freeze-dried forage samples. Samples included blue grama (Bouteloua gracilis), fringed sage (Artemisia frigida), western wheatgrass (Pascopyrum smithii), needle-an...

  17. Oxidizing of ferulic acid with the use of polyoxometalates as catalysts

    NASA Astrophysics Data System (ADS)

    Povarnitsyna, T. V.; Popova, N. R.; Bogolitsyn, K. G.; Beloglazova, A. L.; Pryakhin, A. N.; Lunin, V. V.

    2010-12-01

    The kinetics of catalytic oxidation for ferulic acid with polyoxometalates used as catalysts was studied. The effect of pH and concentrations of the principal reacting components on the process kinetics was studied. A kinetic scheme of oxidation is proposed, and the values of a number of kinetic parameters of the process are determined.

  18. An in situ Fourier transform infrared study of formic acid adsorption on a polycrystalline silver catalyst

    Microsoft Academic Search

    G. J. Millar; J. B. Metson; G. A. Bowmaker; R. P. Cooney

    1994-01-01

    Infrared spectra are reported for the adsorption of formic acid on a polycrystalline silver catalyst after various degrees of oxidation. Three distinct chemisorbed species were identified, two of which corresponded to adsorbed formate on Ag(110) and Ag(111) crystal planes and the other to adsorbed formate on a silver site modified by the presence of subsurface oxygen. Moreover, it was discovered

  19. Silica supported perchloric acid (HClO 4–SiO 2): A highly efficient and reusable catalyst for the protection of hydroxyl groups using HMDS under mild and ambient conditions

    Microsoft Academic Search

    Hamid Reza Shaterian; Fahimeh Shahrekipoor; Majid Ghashang

    2007-01-01

    Various alcohols, phenols, naphthols, and oximes were effectively converted into their corresponding trimethylsilyl ethers with hexamethyldisilazane in the presence of solid silica supported perchloric acid under very mild conditions at room temperature with short reaction time in good to excellent yields. The notable advantages of this protocol are: work up procedure is easy and the catalyst can be recovered by

  20. Screening of PdM and PtM catalysts in a multi-anode direct formic acid fuel cell

    Microsoft Academic Search

    Xingwen Yu; Peter G. Pickup

    2011-01-01

    Direct formic acid fuel cells (DFAFC) currently employ either Pt-based or Pd-based anode catalysts for oxidation of formic\\u000a acid. However, improvements are needed in either the activity of Pt-based catalysts or the stability of Pd-based catalysts.\\u000a In this study, a number of carbon-supported Pt-based and Pd-based catalysts, were prepared by co-depositing PdM (M = Bi, Mo,\\u000a or V) on Vulcan® XC-72 carbon

  1. Acylation of different amino derivatives with fatty acids on UL-MFI-type catalysts

    Microsoft Academic Search

    Mariana Musteata; Vasile Musteata; Alina Dinu; Mihaela Florea; Vinh-Thang Hoang; Do Trong-On; Serge Kaliaguine; Vasile I. Parvulescu

    2007-01-01

    Acylation of different amino derivatives (ethanol amine, diethanol amine, N-aminoethylpiperazine) was carried out under green conditions with oleic acid or tail oil fatty acids. The experiments were carried out using as heterogeneous catalysts mesoporous Al-Meso and UL-ZSM-5 with Si\\/Al ratios between 100 and 20, in the range of the tempera- tures 80-180 °C without any solvent or in octane or

  2. Synthesis of polylactic acid by direct polycondensation under vacuum without catalysts, solvents and initiators

    Microsoft Academic Search

    Feerzet Achmad; Kenji Yamane; Shi Quan; Takao Kokugan

    2009-01-01

    In order to reduce the production cost of polylactic acid (PLA), l-lactic acid was polymerized by direct polycondensation (DP) under vacuum without catalysts, solvents and initiators. Experiments were conducted at polymerization temperatures (Tp) of 150–250°C. The maximum PLA molecular weight obtained was 90kDa at 200°C after 89h under vacuum. Above 200°C, PLA is thermally degraded by specific scission. The DP

  3. Performance degradation of direct formic acid fuel cell incorporating a Pd anode catalyst

    NASA Astrophysics Data System (ADS)

    Jung, Won Suk; Han, Jonghee; Yoon, Sung Pil; Nam, Suk Woo; Lim, Tae-Hoon; Hong, Seong-Ahn

    2011-05-01

    Electrochemical and physical analysis is employed to verify the performance degradation mechanism in direct formic acid fuel cells (DFAFCs). The power density of a single cell measured at 200 mA cm-2 decreases by 40% after 11 h of operation. The performance of the single cell is partly recovered however, by a reactivation process. Various analytical methods such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), and electrochemical impedance spectroscopy (EIS) are used to investigate the mechanism of performance degradation. The analytical results show that the electrolyte membranes in the DFAFC are stable for 11 h of operation after the reactivation process. The major factors causing performance degradation in the DFAFC are an increment in the anode charge-transfer resistance and a growth in the particle size of the Pd anode catalyst. The anode charge-transfer resistance, confirmed by EIS, increases with operation time and is due to poisoning of the catalyst surface. Although it is not clear what chemical species poisons the catalyst surface, the catalyst surface is cleaned by the reactivation process. Performance losses caused by surface poisoning are completely recovered by the reactivation process. Increase in catalyst size induces a reduction in active surface area, and the performance loss caused by the growth in catalyst size cannot be recovered by the reactivation process.

  4. The behavior of palladium catalysts in direct formic acid fuel cells

    NASA Astrophysics Data System (ADS)

    Zhu, Yimin; Khan, Zakia; Masel, R. I.

    Previous work has considered the behavior of platinum based catalysts in direct methanol and Direct Formic Acid Fuel Cells (DFAFCs). In this paper, we explore the behavior of palladium-based anode catalyst for DFAFCs. The palladium catalysts produce significant performance enhancements. DFAFCs operated with dry air and zero back-pressure can generate power densities of 255˜230 mW cm -2 at relatively high voltages of 0.40˜0.50 V in a concentration range of formic acid from 3.0 to 15.0 M at a room temperature of 20 °C, which are not quite different from a hydrogen-air polymer exchange membrane (PEM) fuel cell with power density of 320 mW cm -2 obtained under the comparable conditions, and much higher than a direct methanol fuel cell (DMFC) with power density of 50 mW cm -2. The stability of the membrane electrode assembly (MEA) with palladium catalyst has also been evaluated. There is some decay in performance over several hours. However, the performance loss of DFAFCs can be fully recovered by applying a positive potential at the fuel cell anode after short-term life test. These results demonstrate that DFAFCs with palladium anode catalyst have exceptional properties for portable power applications.

  5. Superprotonic Solid Acids Thermochemistry, Structure, and Conductivity

    NASA Astrophysics Data System (ADS)

    Ikeda, Ayako

    In this work, in order to investigate the thermochemistry and property of the superprotonic solid acid compounds, the measurement methods were established for in situ observation, because superprotonic phases are neither stable at room temperature nor freezable to room temperature. A humidity-controlled TG, DSC and AC impedance measurement system, and high temperature stage for XRD were built for thermal analysis and characterization of the solid acid compounds. The thermodynamic and kinetics of the dehydration and hydration of CsH 2PO4 is investigated by TG, DSC, and XRD analysis. By making use of the enhanced kinetics afforded by SiO2, the phase boundary between CsH2PO4, CsPO3, and dehydrated liquid was precisely determined. The stability of CsH2PO4 and the liquid dehydrate, CsH2(1-x)PO4-x(l), were confirmed by the complete reversal of dehydration to recover these phases in the appropriate temperature and water partial pressure ranges. Rehydration and conversion of CsPO3(s) to CsH2PO4(s) occurs over a period of several hours, depending on temperature, water partial pressure, and morphology of the metaphosphate. High and small particles favor rapid dehydration, whereas the temperature dependence of the rehydration kinetics is nonmonotonic, reaching its fastest rate in the vicinity of the superprotonic transition. Doping Rb and K into CDP was examined and the stable region of Cs 1-xRbxH2PO4 and Cs1-xKxH2PO 4 are determined by in situ XRD and DSC measurement. Then the effects of doping to the structure and conductivity are discussed. It was found that Rb has whole-range solubility for both cubic and monoclinic CDP. Ts increases and Td decrease with Rb content. K has 27% solubility for cubic CDP, T s and Td decrease with K content. The eutectic temperature is 208 +/- 2°C. The lattice size of Rb- or K- doped CDP depends on the averaged cation size. Conductivity linearly decreases by dopant concentration. The impact of K doping is deeper than that of Rb for the equivalent averaged cation size. In situ XRD measurement was carried out using single-crystal CsH2PO4 in order to study the phase transformation mechanism of this compound. A plate-like single crystal with (100) orientation was prepared, and the phase transition was observed by heating and cooling with ramp rate 0.2 K/min. From the obtained XRD profile---the after-first-phase transition (monoclinic?cubic)---the distribution of the domain orientation was estimated. It was found that (100) is the preferential orientation after phase transition, however, the amount of the domains with other orientation is not ignorable. Therefore, it is considered that the phase transformation in CsH 2PO4 is not simple martensitic, but that some other event, such as recrystallization, happens during the transition process.

  6. Deactivation of carbon supported palladium catalyst in direct formic acid fuel cell

    NASA Astrophysics Data System (ADS)

    Miko?ajczuk, A.; Borodzinski, A.; Kedzierzawski, P.; Stobinski, L.; Mierzwa, B.; Dziura, R.

    2011-07-01

    A new carbon black supported palladium catalyst for direct formic acid fuel cell applications has been prepared and characterized by X-ray diffraction. Bi-modal distribution of Pd crystallite sizes was observed. The average Pd size for crystallites in small size and large size ranges were about 2.7 nm and 11.2 nm, respectively. The initial activity of the catalyst in the oxidation of formic acid tested in a fuel cell was similar to a commercial well dispersed 20 wt.% Pd/Vulcan. The rates of the fuel cell power decay were measured for formic acid of two purities for various current loadings. The results showed that various mechanisms contribute to the decrease of cell power with time. In direct formic acid fuel cell (DFAFC) fed with a very pure HCOOH accumulation of CO 2 gas bubbles in anode catalyst layer is responsible for observed power decay. In DFAFC fed with a pure for analysis (p.a.) grade formic acid the formation of CO ads poison from the formic acid impurities is the main deactivation reason.

  7. Vapor-solid-solid growth mechanism driven by epitaxial match between solid AuZn alloy catalyst particle and ZnO nanowire at low temperature

    NASA Astrophysics Data System (ADS)

    Lacerda, Rodrigo; Campos, Leonardo; Tonezzer, Matteo; Ferlauto, Andre; Paniago, Rogerio; Oliveira, Sergio; Orlando Ladeira, Luiz; Grillo, Vincenzo

    2008-03-01

    The present paper provides a comprehensive picture of the precise mechanism of ZnO vapor-solid-solid nanowire growth at low temperatures and gives the fundamental reasons responsible [1]. We demonstrate by using a combination of synchrotron XRD and high resolution TEM that the growth dynamics at low temperatures is not governed by the well-known VLS mechanisms. Based on the Au-Zn phase diagram, temperature measurement and temperature size effects, we show that growth occurs via VSS. The precise composition of the Au-Zn catalyst nanoparticle has been determined to be ?-AuZn. Furthermore, we experimentally observe that there is an indication of a epitaxial relationship between the ZnO nanowires and the ?-AuZn seed particle. A critical new insight on the driving factor of VSS growth is proposed in which the VSS process occurs by a solid diffusion mechanism that is driven by a preferential oxidation process of the Zn inside the alloy catalyst induced by an epitaxial match between the ZnO(10-10) plane and the ?-AuZn(222) plane. [1] L. C. Campos et al, Adv. Materials (accepted for publication).

  8. Automated solid-phase synthesis of oligosaccharides containing sialic acids

    PubMed Central

    Lai, Chian-Hui; Hahm, Heung Sik; Liang, Chien-Fu

    2015-01-01

    Summary A sialic acid glycosyl phosphate building block was designed and synthesized. This building block was used to prepare ?-sialylated oligosaccharides by automated solid-phase synthesis selectively. PMID:26124863

  9. Surface component distribution in a vanadium-molybdenum oxide catalyst for making acrylic acid from acrolein

    SciTech Connect

    Zazhigalov, V.A.; Kholyavenko, K.M.

    1986-11-01

    A scanning electron microscope and microprobe analyzer have been used to examine the surfaces of vanadium-molybdenum catalysts on aerosil. It is found that the phase VMo/sub 3/O/sub 11/ is formed, which is dispersed on the SiO/sub 2/. MoO/sub 3/ crystals of various shapes occur at the surface of the dispersed phase. It is suggested that this catalyst is highly active in oxidizing acrolein to acrylic acid because of the presence of VMo/sub 3/O/sub 11/.

  10. High-Performance Solid Acid Fuel Cells Through

    E-print Network

    . For direct meth- anol fuel cell (DMFC) applications, the solid, water-free nature of the electrolyte raisesHigh-Performance Solid Acid Fuel Cells Through Humidity Stabilization Dane A. Boysen, Tetsuya Uda-of-the-art fuel cells based on polymer electrolyte membrane fuel cells are inoperable above 100°C, require

  11. The effect of oleic acid stabilizer on the surface properties of bimetallic PtNi catalysts.

    PubMed

    Abu Bakar, N H H; Abu Bakar, M; Bettahar, M M; Ismail, J; Monteverdi, S

    2013-07-01

    A detailed study on the surface properties of oleic acid-stabilized PtNi nanoparticles supported on silica is reported. The oleic acid-stabilized PtNi nanoparticles were synthesized using NaBH4 as the reducing agent at various temperatures and oleic acid concentrations, prior to incorporation onto the silica support. X-ray diffraction studies of the unsupported oleic acid-stabilized PtNi particles revealed that the PtNi existed as alloys. Upon incorporation onto silica support, surface properties of the catalysts were investigated using H2-temperature reduction (H2-TPR), H2-temperature desorption (H2-TPD) and H2-chemisorption techniques. It was found that for the bimetallic catalysts, no oxides or very little oxidation occurred. Furthermore, these catalysts exhibited both Pt and Ni active sites on its surface though the availability of Ni active sites was dominant. A comparison of the surface properties of these materials with those prepared without oleic acid in our previous work [N. H. H. Abu Bakar et al., J. Catal. 265, 63 (2009)] and how they affect the hydrogenation of benzene is also discussed. PMID:23901527

  12. Characterization and application of electrodeposited Pt, Pt\\/Pd, and Pd catalyst structures for direct formic acid micro fuel cells

    Microsoft Academic Search

    R. S. Jayashree; J. S. Spendelow; J. Yeom; C. Rastogi; M. A. Shannon; P. J. A. Kenis

    2005-01-01

    In this work, we study the preparation, structural characterization, and electrocatalytic analysis of robust Pt and Pd-containing catalyst structures for silicon-based formic acid micro fuel cells. The catalyst structures studied were prepared and incorporated into the silicon fuel cells by a post CMOS-compatible process of electrodeposition, as opposed to the more common introduction of nanoparticle-based catalyst by ink painting. Robust,

  13. Fe x C–C hybrid material as a support for Pt anode catalyst in direct formic acid fuel cell

    Microsoft Academic Search

    Xiao-Ming Wang; Yong-Yao Xia

    2009-01-01

    FexC–C hybrid material as a support for Pt anode catalyst in direct formic acid fuel cell was investigated for the first time. The resultant Pt\\/FexC–C catalysts were prepared by using a simple reduction reaction to load Pt on FexC–C hybrid material, which was synthesized through the carbonization of sucrose and Fe(NO3)3. It was found that the Pt\\/FexC–C catalysts exhibited excellent

  14. Cyclobutane amino acids and peptidomimetics, parallel catalyst screening for aziridination

    E-print Network

    Li, Shih-ming

    1996-01-01

    of the hydantoin intermediate under basic conditions or of the o(- 2,28-30 cyano compounds with acidic conditions resulted in the formation of a mixture of amino acids. The pure cis- and trans- isomers obtained by these methods were isolated by recrystallization... was acidified with 50% sulfuric acid, extracted again with ether (8 x 25 mL). The ether extracts were washed with water, dried over MgSO4, and concentrated. Recrystallization from ether give the title compound as colorless crystal. Yield: mp: 11. 5 g (31...

  15. Synthesis of highly dispersed and active palladium/carbon nanofiber catalyst for formic acid electrooxidation

    NASA Astrophysics Data System (ADS)

    Qin, Yuan-Hang; Yue-Jiang; Yang, Hou-Hua; Zhang, Xin-Sheng; Zhou, Xing-Gui; Niu, Li; Yuan, Wei-Kang

    2011-05-01

    Highly dispersed and active palladium/carbon nanofiber (Pd/CNF) catalyst is synthesized by NaBH4 reduction with trisodium citrate as the stabilizing agent. The obtained Pd/CNF catalyst is characterized by high resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD). The results show that the Pd nanoparticles with an average particle size of ca. 3.8 nm are highly dispersed on the CNF support even with a small ratio of citrate to Pd precursor, which is believed to be due to the pH adjustment of citrate stabilized colloidal Pd nanoparticles. The cyclic voltammetry and chronoamperometry techniques show that the obtained Pd/CNF catalyst exhibits good catalytic activity and stability for the electrooxidation of formic acid.

  16. Catalytic pyrolysis of cellulose in sulfolane with some acidic catalysts

    Microsoft Academic Search

    Haruo Kawamoto; Shinya Saito; Wataru Hatanaka; Shiro Saka

    2007-01-01

    Catalytic pyrolysis of cellulose in sulfolane (tetramethylene sulfone) with sulfuric acid or polyphosphoric acid gave levoglucosenone,\\u000a furfural, and 5-hydroxymethyl furfural (5-HMF) up to 42.2%, 26.9%, and 8.8% (as mol% yield based on the glucose unit), respectively.\\u000a Pyrolysis behaviors of the intermediates indicated the conversion pathways, and the conversion: levoglucosenone ? furfural\\u000a was found to require water. The control of the

  17. Iron type catalysts for the ozonation of oxalic acid in water

    Microsoft Academic Search

    Fernando J. Beltrán; Francisco J. Rivas; R. Montero-de-Espinosa

    2005-01-01

    Two iron catalysts (Fe(III) and Fe2O3\\/Al2O3) have been used in the ozonation of oxalic acid in water at pH 2.5. Percentage removals of oxalic acid were 1.8%, 7% and 30% corresponding to the non-catalytic, homogeneous (Fe(III)) and heterogeneous (Fe2O3\\/Al2O3) catalytic ozonations, respectively. Catalytic oxalic acid ozonation leads in all cases to total mineralization. The mechanism of ozonation likely develops through

  18. Effect of deactivation and reactivation of palladium anode catalyst on performance of direct formic acid fuel cell (DFAFC)

    Microsoft Academic Search

    S. M. Baik; Jonghee Han; Jinsoo Kim; Yongchai Kwon

    2011-01-01

    In the present study, degradation and recovery in cell performance of direct formic acid fuel cells (DFAFCs) are investigated. For DFAFC tests, palladium (Pd) and platinum (Pt) are used as anode and cathode catalysts, respectively, and are applied to a Nafion membrane by catalyst-coated membrane (CCM) spraying. As multiple repeated DFAFC operations are performed, the cell performance of DFAFC is

  19. Tandem isomerization-decarboxylation of unsaturated fatty acids to olefins via ruthenium metal-as-ligand catalysts

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A new facile Ru-catalyzed route to bio-olefins3 from unsaturated fatty acids via readily accessible metal-as-ligand type catalyst precursors, [Ru(CO)2RCO2]n and Ru3(CO)12, will be described. The catalyst apparently functions in a tandem mode by dynamically isomerizing the positions of double bonds i...

  20. Enhancement of Biodiesel Production from Marine Alga, Scenedesmus sp. through In Situ Transesterification Process Associated with Acidic Catalyst

    PubMed Central

    Kim, Ga Vin; Choi, WoonYong; Kang, DoHyung; Lee, ShinYoung; Lee, HyeonYong

    2014-01-01

    The aim of this study was to increase the yield of biodiesel produced by Scenedesmus sp. through in situ transesterification by optimizing various process parameters. Based on the orthogonal matrix analysis for the acidic catalyst, the effects of the factors decreased in the order of reaction temperature (47.5%) > solvent quantity (26.7%) > reaction time (17.5%) > catalyst amount (8.3%). Based on a Taguchi analysis, the effects of the factors decreased in the order of solvent ratio (34.36%) > catalyst (28.62%) > time (19.72%) > temperature (17.32%). The overall biodiesel production appeared to be better using NaOH as an alkaline catalyst rather than using H2SO4 in an acidic process, at 55.07 ± 2.18% (based on lipid weight) versus 48.41 ± 0.21%. However, in considering the purified biodiesel, it was found that the acidic catalyst was approximately 2.5 times more efficient than the alkaline catalyst under the following optimal conditions: temperature of 70°C (level 2), reaction time of 10?hrs (level 2), catalyst amount of 5% (level 3), and biomass to solvent ratio of 1?:?15 (level 2), respectively. These results clearly demonstrated that the acidic solvent, which combined oil extraction with in situ transesterification, was an effective catalyst for the production of high-quantity, high-quality biodiesel from a Scenedesmus sp. PMID:24689039

  1. Physicochemical pretreatments and hydrolysis of furfural residues via carbon-based sulfonated solid acid.

    PubMed

    Ma, Bao Jun; Sun, Yuan; Lin, Ke Ying; Li, Bing; Liu, Wan Yi

    2014-03-01

    Potential commercial physicochemical pretreatment methods, NaOH/microwave and NaOH/ultrasound were developed, and the carbon-based sulfonated solid acid catalysts were prepared for furfural residues conversion into reducing sugars. After the two optimum pretreatments, both the content of cellulose increased (74.03%, 72.28%, respectively) and the content of hemicellulose (94.11%, 94.17% of removal rate, respectively) and lignin (91.75%, 92.09% of removal rate, respectively) decreased in furfural residues. The reducing sugar yields of furfural residues with the two physicochemical pretreatments on coal tar-based solid acid reached 33.94% and 33.13%, respectively, higher than that pretreated via NaOH alone (27%) and comparable to that pretreated via NaOH/H2O2 (35.67%). The XRD patterns, IR spectra and SEM images show microwave and ultrasound improve the pretreatment effect. The results demonstrate the carbon-based sulfonated solid acids and the physicochemical pretreatments are green, effective, low-cost for furfural residues conversion. PMID:24508657

  2. UreaFormaldehyde-Resin Gel Time As Affected by the pH Value, Solid Content, and Catalyst

    E-print Network

    Wang, Siqun

    . If this correction is not precise, the glue line will be uncured or overcured, and this will result in poor bond­1569, 2007 Key words: adhesives; catalysts; gelation; resins; thermo- sets INTRODUCTION The pH value, solid bond strength, the press time and temperature must be adjusted for the pH envi- ronment

  3. SOLID-STATE SYNTHESIS OF HETEROCYCLIC HYDRAZONES USING MICROWAVES UNDER CATALYST-FREE CONDITIONS: JOURNAL ARTICLE (1605)

    EPA Science Inventory

    NRMRL-CIN-1605 Jeselnik, M., Varma*, R.S., Polanc, S., and Kocevar, M. Solid-State Synthesis of Heterocyclic Hydrazones using Microwaves under Catalyst-free Conditions. Green Chemistry (White, J.D. (Ed.), Cambridge, United Kingdom: Royal Society of Chemistry) (4):35-38 (2002). ...

  4. Relationship between the structure of Ru\\/CeO 2 catalysts and their activity in the catalytic ozonation of succinic acid aqueous solutions

    Microsoft Academic Search

    F Delanoë; B Acedo; N Karpel Vel Leitner; B Legube

    2001-01-01

    Two Ru\\/CeO2 catalysts were used for the study of the catalytic ozonation of aqueous solutions of succinic acid (SA). These catalysts were prepared either by impregnation (I) or by acid exchange (AE). The objectives were (1) to determine the efficiency towards the oxidation of the organic molecule in relation to the catalysts characterization, and (2) to examine the modifications of

  5. Pd/C synthesized with citric acid: an efficient catalyst for hydrogen generation from formic acid/sodium formate.

    PubMed

    Wang, Zhi-Li; Yan, Jun-Min; Wang, Hong-Li; Ping, Yun; Jiang, Qing

    2012-01-01

    A highly efficient hydrogen generation from formic acid/sodium formate aqueous solution catalyzed by in situ synthesized Pd/C with citric acid has been successfully achieved at room temperature. Interestingly, the presence of citric acid during the formation and growth of the Pd nanoparticles on carbon can drastically enhance the catalytic property of the resulted Pd/C, on which the conversion and turnover frequency for decomposition of formic acid/sodium formate system can reach the highest values ever reported of 85% within 160 min and 64 mol H(2) mol(-1) catalyst h(-1), respectively, at room temperature. The present simple, low cost, but highly efficient CO-free hydrogen generation system at room temperature is believed to greatly promote the practical application of formic acid system on fuel cells. PMID:22953041

  6. Pd/C Synthesized with Citric Acid: An Efficient Catalyst for Hydrogen Generation from Formic Acid/Sodium Formate

    PubMed Central

    Wang, Zhi-Li; Yan, Jun-Min; Wang, Hong-Li; Ping, Yun; Jiang, Qing

    2012-01-01

    A highly efficient hydrogen generation from formic acid/sodium formate aqueous solution catalyzed by in situ synthesized Pd/C with citric acid has been successfully achieved at room temperature. Interestingly, the presence of citric acid during the formation and growth of the Pd nanoparticles on carbon can drastically enhance the catalytic property of the resulted Pd/C, on which the conversion and turnover frequency for decomposition of formic acid/sodium formate system can reach the highest values ever reported of 85% within 160?min and 64?mol H2 mol?1 catalyst h?1, respectively, at room temperature. The present simple, low cost, but highly efficient CO-free hydrogen generation system at room temperature is believed to greatly promote the practical application of formic acid system on fuel cells. PMID:22953041

  7. Pd/C Synthesized with Citric Acid: An Efficient Catalyst for Hydrogen Generation from Formic Acid/Sodium Formate

    NASA Astrophysics Data System (ADS)

    Wang, Zhi-Li; Yan, Jun-Min; Wang, Hong-Li; Ping, Yun; Jiang, Qing

    2012-08-01

    A highly efficient hydrogen generation from formic acid/sodium formate aqueous solution catalyzed by in situ synthesized Pd/C with citric acid has been successfully achieved at room temperature. Interestingly, the presence of citric acid during the formation and growth of the Pd nanoparticles on carbon can drastically enhance the catalytic property of the resulted Pd/C, on which the conversion and turnover frequency for decomposition of formic acid/sodium formate system can reach the highest values ever reported of 85% within 160 min and 64 mol H2 mol-1 catalyst h-1, respectively, at room temperature. The present simple, low cost, but highly efficient CO-free hydrogen generation system at room temperature is believed to greatly promote the practical application of formic acid system on fuel cells.

  8. Cyclobutane amino acids and peptidomimetics, parallel catalyst screening for aziridination 

    E-print Network

    Li, Shih-ming

    1996-01-01

    in dichloromethane (Scheme 2. 9). Purification by flash chromatography provided pure products. Crystals of the tripeptide mimics were grown via slow evaporation of a benzene-dichloromethane solution. 3-N-Acetylamino-N'-isopropylcyclobutane carboxylamide (40... while the flask was in ice-bath. The mixture was stirred at 25 'C for 4 h. Removal of the solvent and purification by flash chromatography (EtOAc/hexanes) gave the product 38 as white solid. Recrystallization from CHzClz-benzene yielded colorless...

  9. Composites of manganese oxide with carbon materials as catalysts for the ozonation of oxalic acid.

    PubMed

    Orge, C A; Órfão, J J M; Pereira, M F R

    2012-04-30

    Manganese oxide and manganese oxide-carbon composites were prepared and tested as catalysts for the removal of oxalic acid by ozonation. Their performances were compared with the parent carbon material (activated carbon or carbon xerogel) used to prepare the composites. Oxalic acid degradation by carbon materials is slower than that attained with manganese oxide or manganese oxide-carbon composites. A complete degradation after 90 and 45 min of reaction was obtained for carbon materials and for the catalysts containing manganese, respectively. The ozonation in the presence of the prepared composites are supposed to occur mainly by surface reactions, following a direct oxidation mechanism by molecular ozone and/or surface oxygenated radicals. PMID:22341747

  10. Oxidative conversion of methane to syngas over NiO\\/MgO solid solution supported on low surface area catalyst carrier

    Microsoft Academic Search

    V. R Choudhary; A. S Mamman

    1999-01-01

    Influence of time-on-stream (0.5–15 h), CH4\\/O2 ratio in feed (1.8–8.0), space velocity (6000–510,000 cm3 g?1 h?1), catalyst particle size (22–70 mesh), and catalyst dilution by inert solid particles (diluent\\/catalyst weight ratio=4) on the performance at different temperatures (600–900°C) of the NiO\\/MgO solid solution deposited on SA-5205 [which is a low surface area macroporous silica-alumina catalyst carrier] in the oxidative conversion

  11. COMPARISON OF CATALYSTS FOR DIRECT TRANSESTERIFICATION OF FATTY ACIDS IN FREEZE DRIED FORAGE SAMPLES

    Microsoft Academic Search

    T. R. Weston; J. D. Derner; C. M. Murrieta; B. W. Hess

    2006-01-01

    Our objective was to compare 1.09 M methanolic HCl to 14% BF3 in methanol as catalysts for direct transesterification of fatty acids in freeze-dried forage samples. Samples included blue grama (Bouteloua gracilis), fringed sage (Artemisia frigida), western wheatgrass (Pascopyrum smithii), needle-and-thread (Stipa comata), dalmation toadflax (Linaria dalmatica), needleleaf sedge (Carex eleocharis), and scarlet globemallow (Sphaelercea coccinea). Thin layer chromatographic evaluation

  12. Effect of temperature, oxidant and catalyst loading on the performance of direct formic acid fuel cell

    Microsoft Academic Search

    Jeong Soo Kim; Jae Keun Yu; Hyo Song Lee; Jin Yong Kim; Young Chun Kim; Jong Hee Han; In Hwan Oh; Young Woo Rhee

    2005-01-01

    We investigated the effect of temperature, oxidant and catalyst loading on the performance of direct formic acid fuel cell\\u000a (DFAFC). When oxidant was changed from air to oxygen, the power density was increased to 17.3 mW\\/ cm2 at 25 ‡C. The power density of DFAFC operated with oxygen showed a maximum value of 40.04 mW\\/cm2 with the temperature rise from

  13. Poisoning and regeneration of Pd catalyst in direct formic acid fuel cell

    Microsoft Academic Search

    Yi Zhou; Jianguo Liu; Jilei Ye; Zhigang Zou; Jinhua Ye; Jun Gu; Tao Yu; Aidong Yang

    2010-01-01

    Palladium catalyst poisoned in the anode of direct formic acid fuel cell (DFAFC) during constant current discharging can be fully regenerated by a non-electrochemical method, i.e. just switching pure water to DFAFC for 1h. Electrochemical impedance spectrum of DFAFC during the discharging and regeneration were recorded and analyzed. No much difference could be found for the high-frequency resistance of DFAFC

  14. Performance increase of microfluidic formic acid fuel cell using Pd\\/MWCNTs as catalyst

    Microsoft Academic Search

    D. Morales-Acosta; Luis A. Godinez; L. G. Arriaga

    2010-01-01

    This paper shows that the combination of an O2 saturated acidic fluid setup (O2-setup) and a composite of Pd nanoparticles supported on multiwalled-carbon nanotubes (Pd\\/MWCNTs) as anode catalyst material, results in the improvement of microfluidic fuel cell performance. Microfluidic fuel cells were constructed and evaluated at low HCOOH concentrations (0.1 and 0.5M) using Pd\\/V XC-72 and Pd\\/MWCNTs as anode and

  15. Activation of C 2–C 4 alkanes over acid and bifunctional zeolite catalysts

    Microsoft Academic Search

    G. Caeiro; R. H. Carvalho; X. Wang; M. A. N. D. A. Lemos; F. Lemos; M. Guisnet; F. Ramôa Ribeiro

    2006-01-01

    This review paper presents the significant advances which were made in the last decade in the understanding of the transformation over acid and bifunctional zeolite catalysts of the cheap and readily available C2–C4 alkanes into more valuable products: mechanism of activation, reaction scheme, nature of the active sites. Both the transformations of pure alkanes: n-butane isomerization, C2–C4 alkane aromatization and

  16. Low equivalent weight short-side-chain perfluorosulfonic acid ionomers in fuel cell cathode catalyst layers

    Microsoft Academic Search

    Chao Lei; Dmitri Bessarabov; Siyu Ye; Zhong Xie; Steven Holdcroft; Titichai Navessin

    2011-01-01

    The morphology and fuel cell performance of cathode catalyst layers (CCLs) using low equivalent weight (EW) short-side-chain (SSC) perfluorosulfonic acid ionomers have been investigated in this work. The results were compared with those for a baseline CCL containing 30wt% of the conventional ionomer 1100 EW Nafion®. The CCLs fabricated with 10–20wt% of the Aquivion™ ionomer displayed a similar morphology to

  17. Effects of catalyst pore structure and acid properties on the dehydration of glycerol.

    PubMed

    Choi, Youngbo; Park, Hongseok; Yun, Yang Sik; Yi, Jongheop

    2015-03-01

    Hierarchical porous catalysts have recently attracted increasing interest because of the enhanced accessibility to active sites on such materials. In this context, previously reported hierarchically mesoporous ASN and ASPN materials are evaluated by applying them to the dehydration of glycerol, and demonstrate excellent catalytic performance. In addition, a comprehensive understanding of the effects of pore structures and the acid properties on the reaction through comparative studies with microporous HZSM-5 and mesoporous AlMCM-41 is provided. PMID:25418679

  18. Memory effect-enhanced catalytic ozonation of aqueous phenol and oxalic acid over supported Cu catalysts derived from hydrotalcite

    Microsoft Academic Search

    Masato Shiraga; Tomonori Kawabata; Dalin Li; Tetsuya Shishido; Kenji Komaguchi; Tsuneji Sano; Katsuomi Takehira

    2006-01-01

    Mg\\/Al supported metal (Fe, Co, Ni and Cu) oxide catalysts were prepared by co-precipitation of hydrotalcite-like clay materials as precursors, calcined, and used for the ozonation reaction of phenol and oxalic acid. The reaction was carried out using the catalyst and aqueous solution of phenol or oxalic acid in an O3\\/O2 mixed gas-flow at 20 °C. In the ozonation of phenol,

  19. Development of molecular and solid catalysts for the direct low-temperature oxidation of methane to methanol.

    PubMed

    Palkovits, Regina; von Malotki, Christian; Baumgarten, Martin; Müllen, Klaus; Baltes, Christian; Antonietti, Markus; Kuhn, Pierre; Weber, Jens; Thomas, Arne; Schüth, Ferdi

    2010-02-22

    The direct low-temperature oxidation of methane to methanol is demonstrated on a highly active homogeneous molecular catalyst system and on heterogeneous molecular catalysts based on polymeric materials possessing ligand motifs within the material structure. The N-(2-methylpropyl)-4,5-diazacarbazolyl-dichloro-platinum(II) complex reaches significantly higher activity compared to the well-known Periana system and allows first conclusions on electronic and structural requirements for high catalytic activity in this reaction. Interestingly, comparable activities could be achieved utilizing a platinum modified poly(benzimidazole) material, which demonstrates for the first time a solid catalyst with superior activity compared to the Periana system. Although the material shows platinum leaching, improved activity and altered electronic properties, compared to the conventional Periana system, support the proposed conclusions on structure-activity relationships. In comparison, platinum modified triazine-based catalysts show lower catalytic activity, but rather stable platinum coordination even after several catalytic cycles. Based on these systems, further development of improved solid catalysts for the direct low-temperature oxidation of methane to methanol is feasible. PMID:19780100

  20. Liquefaction of municipal waste plastics in VGO over acidic and non-acidic catalysts

    Microsoft Academic Search

    Selhan Karagöz; Tamer Karayildirim; Suat Uçar; Mithat Yuksel; Jale Yanik

    2003-01-01

    Co-processing of municipal waste plastics (MWP) with vacuum gas oil (VGO) over HZSM-5, DHC-8 (commercial silica–alumina catalyst) and cobalt loaded active carbon catalyst has been comparatively studied. Co-processing experiments were carried out under hydrogen atmosphere at temperatures between 425 and 450°C. The composition, sulphur and chlorine amount of liquid products were determined. The product distribution and the composition of liquids

  1. Conversion of isoamyl alcohol over acid catalysts: Reaction dependence on nature of active centers

    SciTech Connect

    Babu, G.P.; Murthy, R.S.; Krishnan, V. [Hindustan Lever Research Centre, Bombay (India)] [Hindustan Lever Research Centre, Bombay (India)

    1997-02-01

    Acid catalysts are known to catalyze the dehydration of alcohols. In addition some oxide catalysts with basic properties have also been shown to play an important role in such dehydration reactions. The dehydration of aliphatic alcohols to olefins has been studied in detail using alumina silica-alumina and zeolite catalysts. The olefin products further undergo isomerization in presence of acidic sites. The reaction of isoamyl alcohol on catalytic surfaces has not been investigated in greater detail. The dehydration of isoamyl alcohol is of considerable interest in fine chemicals. Isoamyl alcohol may also undergo dehydrogenation as observed in the case of n-butanol. The scope of the present work is to identify the nature of the active sites selective for dehydration and dehydrogenation of isoamyl alcohol and to modify the active sites to promote isomerization of dehydrated products. Four catalytic surfaces on which the acidic strength can be varied, as well as selectively suppressed, are chosen for this study. 17 refs., 1 fig., 3 tabs.

  2. Nanorod vanadatesulfuric acid as a novel, recyclable and heterogeneous catalyst for the one-pot synthesis of tetrahydrobenzopyrans.

    PubMed

    Nasr-Esfahani, Masoud; Abdizadeh, Tooba

    2013-07-01

    Vanadatesulfuric acid (VSA), as a novel and heterogeneous nanorod catalyst, was used for an efficient synthesis of tetrahydrobenzo[b]pyrans using an aldehydes, 1,3-cyclohexanediones or beta-ketoester and malononitrile in C2H5OH/H2O mixture under reflux conditions. VSA is prepared via the reaction of sodium metavanadate and chlorosulfonic acid in high purity. The catalyst was characterized by FT-IR, XRD, TEM and EDAX analysis. Compared to the conventional method, this method consistently has the advantage of high yields, simple workup, short reaction times and reusability of the catalyst. PMID:23901523

  3. Isotope composition of carbon in amino acids of solid bitumens

    NASA Astrophysics Data System (ADS)

    Shanina, S. N.; Bushnev, D. A.

    2014-06-01

    Primary data are presented on the isotope composition of carbon in individual amino acids from solid bitumens and several biological objects. The amino acids of biological objects are characterized by wide variations of the isotope composition of carbon. This fact occurs owing to the difference in biochemical paths of metabolism resulting in the synthesis of individual amino acids. The ?13C values are somewhat decreased for individual amino acids in asphaltenes, varying from -7.7 to -31.7‰. The carbon of amino acids is weighted in kerits from Bad'el' compared to asphaltenes. All the natural bitumens retain the characteristic trend for natural substances: the isotopically heavy and light amino acids by carbon are glycine and leucine, respectively. The isotope composition of amino-acid carbon is lightened compared to natural bitumens in the samples formed under a pronounced thermal impact (asphalt-like crust and kirishite).

  4. Relative reactivities of solid benzoic acids 

    E-print Network

    Warwas, Edwin James

    1967-01-01

    -t-butylbenzoic acid and potassium p-t-butylbenzoate shows the growth of whisker-like protuberances of the reaction product on the surface of the salt crystal. After the whiskers virtually covered the salt surface, an X-ray powder diagram of the product was made.... This powder diagram matched identically the powder diagram of syntheti- cally prepared potassium hydrogen di-p-t-butylbenzoate. No evidence of reaction on the surface of the acid was ever observed. The time needed for complete reaction in the weighing...

  5. Acid-Base Mechanism for Ruthenium-Based Water Oxidation Catalysts

    SciTech Connect

    Wang, L.P.; Wu, Q.; Van Voorhis, T.

    2010-05-17

    We present a detailed theoretical study of the pathway for water oxidation in synthetic ruthenium-based catalysts. As a first step, we consider a recently discovered single center catalyst, where experimental observations suggest a purely single-center mechanism. We find low activation energies (<5 kcal/mol) for each rearrangement in the catalytic cycle. In the crucial step of O-O bond formation, a solvent water acts as a Lewis base and attacks a highly oxidized Ru{sup V} = O. Armed with the structures and energetics of the single-center catalyst, we proceed to consider a representative Ru-dimer which was designed to form O{sub 2} via coupling between the two centers. We discover a mechanism that proceeds in analogous fashion to the monomer case, with all the most significant steps occurring at a single catalytic center within the dimer. This acid-base mechanism suggests a new set of strategies for the rational design of multicenter catalysts: rather than coordinating the relative orientations of the subunits, one can focus on coordinating solvation-shell water molecules or tuning redox potentials.

  6. Hydroxyapatite supported caesium carbonate as a new recyclable solid base catalyst for the Knoevenagel condensation in water

    PubMed Central

    Gupta, Monika; Anand, Medha

    2009-01-01

    Summary The Knoevenagel condensation between aromatic aldehydes and malononitrile, ethyl cyanoacetate or malonic acid with hydroxyapatite supported caesium carbonate in water is described. HAP–Cs2CO3 was found to be a highly active, stable and recyclable catalyst under the reaction conditions. PMID:20300501

  7. Preparation and characterization of urea-oxalic acid solid form

    NASA Astrophysics Data System (ADS)

    Onija, Oana; Borodi, Gh.; Kacso, Irina; Pop, M. N.; Dadarlat, D.; Bratu, I.; Jumate, N.

    2012-02-01

    The selective production of crystalline polymorphs is an outstanding problem in solid-state chemistry. In this study, the preparation of a new urea solid form is based on pure urea and oxalic acid (1:1), by grinding the components at room temperature. The resulted compound was investigated by X-ray powder diffraction (PXRD), thermal analysis (DSC, PPE) and infrared (FTIR) spectroscopy. The difference between the PXRD patterns of urea-oxalic acid and of the starting components evidenced a new compound. Using X-ray powder diffraction method, the lattice parameters were determined. Some thermal properties of the obtained compound were also investigated by the previous mentioned calorimetric techniques.

  8. Influence of bi modification of pt anode catalyst in direct formic acid fuel cells.

    PubMed

    Kang, Sungjin; Lee, Jaeyoung; Lee, Jae Kwang; Chung, Seung-Young; Tak, Yongsug

    2006-04-13

    The influence of Bi modification of Pt anode catalyst on the performance of direct formic acid fuel cells was investigated. Compared with the unmodified Pt anode, the Bi modified Pt (PtBi(m)) electrode prepared by under-potential deposition (UPD) caused faster electrocatalytic oxidation of formic acid at the same value of the overpotential, and thus, PtBi(m) resulted in an increase in the power performance of direct formic acid fuel cells. Electrochemical impedance spectra helped to explain the difference of performance between the unmodified Pt and Bi modified Pt electrodes. Solution conductivity and dehydration phenomena occurring in highly concentrated formic acid solutions can also explain the higher power performance of PtBi(m). PMID:16599497

  9. Microbial production of gallic acid by modified solid state fermentation

    Microsoft Academic Search

    B Kar; R Banerjee; B C Bhattacharyya

    1999-01-01

      Bioconversion of tannin to gallic acid from powder of teri pod (Caesalpinia digyna) cover was achieved by the locally isolated fungus, Rhizopus oryzae, in a bioreactor with a perforated float for carrying solid substrate and induced inoculum. Modified Czapek-Dox medium, put\\u000a beneath the perforated float, with 2% tannic acid at pH 4.5, temperature 32°C, 93% relative humidity, incubated for 3

  10. Preparation method of an ultrafine carbon supported Pd catalyst as an anodic catalyst in a direct formic acid fuel cell

    Microsoft Academic Search

    Lingling Zhang; Tianhong Lu; Jianchun Bao; Yawen Tang; Cun Li

    2006-01-01

    It was reported for the first time that the carbon supported Pd (Pd\\/C) catalyst was prepared in the aqueous solution with NH4F and H3BO3. The average size and the relative crystallinity of the Pd particles in the Pd\\/C catalyst prepared with this method are much lower than that of the Pd\\/C catalyst prepared with general reduction method because PdCl2 can

  11. Solid-state acid-base reactions of indomethacin and flufenamic acid

    Microsoft Academic Search

    Xiaoming Chen

    2000-01-01

    The purpose of this study is to understand the mechanism of solid-state acid-base reactions and identify controlling factors for this type of reaction. The reactions between indomethacin and sodium bicarbonate, indomethacin and sodium carbonate, and flufenamic acid and magnesium oxide were investigated using X-ray powder diffraction, Fourier transform infrared spectroscopy, thermogravimetry, and solid-state nuclear magnetic resonance spectrometry. Quantitative methods based

  12. Gas diffusion electrode setup for catalyst testing in concentrated phosphoric acid at elevated temperatures.

    PubMed

    Wiberg, Gustav K H; Fleige, Michael; Arenz, Matthias

    2015-02-01

    We present a detailed description of the construction and testing of an electrochemical cell setup allowing the investigation of a gas diffusion electrode containing carbon supported high surface area catalysts. The setup is designed for measurements in concentrated phosphoric acid at elevated temperature, i.e., very close to the actual conditions in high temperature proton exchange membrane fuel cells (HT-PEMFCs). The cell consists of a stainless steel flow field and a PEEK plastic cell body comprising the electrochemical cell, which exhibits a three electrode configuration. The cell body and flow field are braced using a KF-25 vacuum flange clamp, which allows an easy assembly of the setup. As demonstrated, the setup can be used to investigate temperature dependent electrochemical processes on high surface area type electrocatalysts, but it also enables quick screening tests of HT-PEMFC catalysts under realistic conditions. PMID:25725862

  13. Catalyst for NO x removal in nitric-acid plant gaseous effluents

    NASA Astrophysics Data System (ADS)

    Avila, P.; Barthelemy, C.; Bahamonde, A.; Blanco, J.

    The behaviour of a V 2O 5?WO 3?TiO 2 phosphorated catalyst, in the Selective Catalytic Reduction (SCR) of equimolar NO + NO 2 mixtures, is studied in order to analyse the possibility of its industrial utilization for the treatment of nitric-acid plant stack gases. With this new catalyst, an NO x conversion higher than 90% molar can be achieved, the ammonia concentration at the exit gas being lower than that required to form ammonium salts, throughout the temperature range of commercial interest: 250-450°C, at a relatively high space velocity (GHSV ? 40000 h -1 NC). The effect of several operating variables such as oxygen concentration and NO 2/NO molar ratio in the feed is also discussed.

  14. Essential role of catalysts (Mn, Au, and Sn) in the vapor liquid solid growth kinematics of ZnS nanowires

    SciTech Connect

    Rehman, S.; Shehzad, M. A.; Hafeez, M.; Bhatti, A. S., E-mail: asbhatti@comsats.edu.pk [Center for Micro and Nano Devices (CMND), Department of Physics, COMSATS Institute of Information Technology, Islamabad 44000 (Pakistan)

    2014-01-14

    In this paper, we demonstrate that surface energy of the catalyst is a vital parameter for the growth rate, self doping of the self assembled nanowires synthesized by employing vapor liquid solid growth technique. The synthesis of ZnS nanowires was done by selectively using three different catalysts (Mn, Au, and Sn), where Au, is the most common catalyst, was used as a reference. The distinctive difference in the growth rate was due to the surface energy of the metal alloy droplet and the interface energies, as explained theoretically using thermodynamic approach. We have found that the activation energy of diffusion of (Zn, S) species in the catalyst droplet was low in Sn (0.41?eV for Zn and 0.13?eV for S) and high in Mn (1.79?eV for Zn and 0.61?eV for S) compared to Au (0.62?eV for Zn and 0.21?eV for S) catalyzed ZnS nanostructures. The thermodynamic calculations predicted the growth rates of Sn (7.5?nm/s) catalyzed nanowires was faster than Au (5.1?nm/s) and Mn (4.6?nm/s) catalyzed ZnS nanostructures, which were in agreement with the experimental results. Finally, the location of the catalyst as dopant in the grown nanostructure was predicted and compared with experimental observations.

  15. Effects of inherent/enhanced solid acidity and morphology of diatomite templates on the synthesis and porosity of hierarchically porous carbon.

    PubMed

    Liu, Dong; Yuan, Peng; Tan, Daoyong; Liu, Hongmei; Fan, Mingde; Yuan, Aihua; Zhu, Jianxi; He, Hongping

    2010-12-21

    The inherent or enhanced solid acidity of raw or activated diatomite is found to have significant effects on the synthesis of hierarchically porous diatomite-templated carbon with high surface area and special porous structure. The solid acidity makes raw/activated diatomite a catalyst for the generation of porous carbon, and the porous parameters of the carbon products are strongly dependent on the solid acidity of diatomite templates. The morphology of diatomite also dramatically affects the textural structure of porous carbon. Two types of macroporous structures in the carbon product, the partially solid pillars and the ordered hollow tubes, derive from the replication of the central and the edge pores of diatom shell, respectively. The hierarchically porous carbon shows good capability for the adsorption of solvent naphtha and H(2), enabling potential applications in adsorption and gas storage. PMID:21080632

  16. Propane conversion over a Ru\\/CGO catalyst and its application in intermediate temperature solid oxide fuel cells

    Microsoft Academic Search

    M. Lo Faro; D. La Rosa; G. Monforte; V. Antonucci; A. S. Arico; P. Antonucci

    2007-01-01

    A Ru\\/CGO catalyst was investigated in combination with a Cu current collector for the direct electro-oxidation and internal\\u000a reforming of propane in a solid oxide fuel cell. The electrochemical power densities for the direct oxidation were larger\\u000a than in the internal reforming process at 750 ?C. The electrochemical performance in the presence of propane was significantly\\u000a affected by the polarization resistance

  17. Calcium oxide as a solid base catalyst for transesterification of soybean oil and its application to biodiesel production

    Microsoft Academic Search

    Masato Kouzu; Takekazu Kasuno; Masahiko Tajika; Yoshikazu Sugimoto; Shinya Yamanaka; Jusuke Hidaka

    2008-01-01

    In order to study solid base catalyst for biodiesel production with environmental benignity, transesterification of edible soybean oil with refluxing methanol was carried out in the presence of calcium oxide (CaO), -hydroxide (Ca(OH)2), or -carbonate (CaCO3). At 1h of reaction time, yield of FAME was 93% for CaO, 12% for Ca(OH)2, and 0% for CaCO3. Under the same reacting condition,

  18. Promoting effect of vanadium ions on the anodic Pd\\/C catalyst for direct formic acid fuel cell application

    Microsoft Academic Search

    Junjie Ge; Xiumei Chen; Changpeng Liu; Tianhong Lu; Jianhui Liao; Liang Liang; Wei Xing

    2010-01-01

    In order to improve the catalytic activity and stability of the anodic Pd catalyst for a direct formic acid fuel cell, vanadium ions in very low concentration were introduced to the electrolyte. It was discovered that the electrooxidation of formic acid could be promoted greatly by addition of trace amount of vanadium ions. A much greater enhancement in catalytic stability

  19. Revealing the dynamic structure of complex solid catalysts using modulated excitation X-ray diffraction.

    PubMed

    Ferri, Davide; Newton, Mark A; Di Michiel, Marco; Chiarello, Gian Luca; Yoon, Songhak; Lu, Ye; Andrieux, Jérôme

    2014-08-18

    X-ray diffraction (XRD) is typically silent towards information on low loadings of precious metals on solid catalysts because of their finely dispersed nature. When combined with a concentration modulation approach, time-resolved high-energy XRD is able to provide the detailed redox dynamics of palladium nanoparticles with a diameter of 2?nm in 2?wt?% Pd/CZ (CZ = ceria-zirconia), which is a difficult sample for extended X-ray absorption fine structure (EXAFS) measurements because of the cerium component. The temporal evolution of the Pd(111) and Ce(111) reflections together with surface information from synchronous diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) measurements reveals that Ce maintains Pd oxidized in the CO pulse, whereas reduction is detected at the beginning of the O2 pulse. Oxygen is likely transferred from Pd to Ce(3+) before the onset of Pd re-oxidation. In this context, adsorbed carbonates appear to be the rate-limiting species for re-oxidation. PMID:24903631

  20. Acid catalysts based on Cu/Ru alumina: Conversion of butyraldehyde to dibutyl ether

    SciTech Connect

    Jansen, S.; Palmieri, M.; Gomez, M. [Temple Univ., Philadelphia, PA (United States)] [Temple Univ., Philadelphia, PA (United States); Lawrence, S. [Saginaw Valley State Univ., University Center, MI (United States)] [Saginaw Valley State Univ., University Center, MI (United States)

    1996-10-01

    A system made by combining two nonalloying metals, ruthenium and copper, using alumina as the oxide support was studied. This bimetallic supported catalyst has been used mainly in hydrogenoloysis, dehydrogenation, and oxidation reactions of hydrocarbons. The preparation of such materials has been proposed to effect the selectivity and activity of a highly active metal by inclusions of a second less active metal. The samples were characterized by electron paramagnetic resonance spectrometry (EPR), X-ray diffraction (XRD), surface area, and surface acidities. The techniques EPR and XRD are ideal for studying the electronic and structural changes of the samples at different temperatures and concentrations. The primary reaction involved in this study was the hydrogenation of an aldehyde to the corresponding alcohol. A secondary reaction occurred as well. The acid catalyzed, substitution or bimolecular dehydration of the alcohol to the dibutyl ether was observed under certain catalytic conditions. These catalysts appeared to act as acid/base. Therefore this reaction to produce the ether is of special importance. A correlation between the electronic, structural and catalytic properties has been made to understand molecular processes` role in catalytic phenomena. 44 refs., 6 figs., 5 tabs.

  1. The drastic effect of platinum on carbon-supported ruthenium-tin catalysts used for hydrogenation reactions of carboxylic acids

    Microsoft Academic Search

    Yoshinori Hara; Kouetsu Endou

    2003-01-01

    The incorporation of platinum on bimetallic ruthenium-tin catalysts supported on active carbon has profound effects on the catalytic behavior. The reaction rate was accelerated nearly three times compared with that of the bimetallic system for the hydrogenation of 1,4-cyclohexanedicarboxylic acid (CHDA). Moreover, it turned out that Pt can completely prevent Sn, one component of the catalyst, from dissolving into the

  2. PdCo supported on multiwalled carbon nanotubes as an anode catalyst in a microfluidic formic acid fuel cell

    Microsoft Academic Search

    D. Morales-Acosta; M. D. Morales-Acosta; L. A. Godinez; L. Álvarez-Contreras; S. M. Duron-Torres; J. Ledesma-García; L. G. Arriaga

    2011-01-01

    This work reports the synthesis of Pd-based alloys of Co and their evaluation as anode materials in a microfluidic formic acid fuel cell (?FAFC). The catalysts were prepared using the impregnation method followed by thermal treatment. The synthesized catalysts contain 22wt.% Pd on multiwalled carbon nanotubes (Pd\\/MWCNT) and its alloys with two Co atomic percent in the sample with 4

  3. Mercury oxidation by hydrochloric acid over TiO 2 supported metal oxide catalysts in coal combustion flue gas

    Microsoft Academic Search

    Hiroyuki Kamata; Shun-ichiro Ueno; Naoki Sato; Toshiyuki Naito

    2009-01-01

    Mercury oxidation by hydrochloric acid over the metal oxides supported by anatase type TiO2 catalysts, 1 wt.% MOx\\/TiO2 where M = V, Cr, Mn, Fe, Ni, Cu, and Mo, was investigated by the Hg0 oxidation and the NO reduction measurements both in the presence and absence of NH3. The catalysts were characterized by BET surface area measurement and Raman spectroscopy. The

  4. Electrooxidation of methanol on mixed catalysts based on platinum and organic metal complexes in acidic media

    Microsoft Academic Search

    Tatsuhiro Okada; Naoko Arimura; Chisato Ono; Makoto Yuasa

    2005-01-01

    New electro-catalysts were developed based on platinum and organic metal complexes for methanol oxidation reaction (MOR) in acidic media. As complexes nitrogen containing ligands such as N,N?-bis(salicylidene)ethylenediamine (salen), N,N?-bis(salicylidene)phenylenediamine (salophen), N,N?-mono-8-quinolyl-o-phenylenediamine (mqph) and N,N?-bis(anthranilidene)ethylenediamine (anthen), coordinated to V, Mn, Fe, Co, Ni, Cu, Mo, Pd and Sn were synthesized and tested. Mixture of platinum tetraammine complex with one of the

  5. Solid-state characterization of mefenamic acid.

    PubMed

    Panchagnula, Ramesh; Sundaramurthy, Prakash; Pillai, Omathanu; Agrawal, Shrutidevi; Raj, Yasvanth Ashok

    2004-04-01

    The purpose of this study was to characterize mefenamic acid (MA) from commercial samples and samples crystallized from different solvents. Various techniques used for characterization included microscopy (hot stage microscopy, scanning electron microscopy), intrinsic dissolution rate, differential scanning calorimetry (DSC), Fourier transform infrared (FTIR) spectroscopy and powder X-ray diffractometry (pXRD). The commercial samples varied in their crystal habit, thermal behavior, and intrinsic dissolution rate. It was found that the commercial samples were polymorphic Form I, which converted to Form II on heating in a DSC pan. Similarly, compression in an intrinsic dissolution rate (IDR) press resulted in the conversion of Form I to Form II. On the other hand, the samples recrystallized from different solvents under varying conditions yielded different crystal habits. Stirring and degree of supersaturation significantly influenced the crystal habit in all the solvents used in the study. Samples crystallized from ethanol and tetrahydrofuran yielded Form I, which behaved similarly to the commercial samples (M1 and M3). Recrystallization from ethyl acetate at a fast cooling rate yielded Form I, which on melting crystallized to Form II. The form I crystallized from ethyl acetate by fast cooling converted partially to form II on storing at ambient conditions. Forms I and II of MA were enantiotropically related. The results demonstrate the variable material characteristics of the commercial samples of MA and the influence of the crystallizing conditions on the formation of the polymorphs. PMID:14999737

  6. Insights into the interplay of Lewis and Brønsted acid catalysts in glucose and fructose conversion to 5-(hydroxymethyl)furfural and levulinic acid in aqueous media.

    PubMed

    Choudhary, Vinit; Mushrif, Samir H; Ho, Christopher; Anderko, Andrzej; Nikolakis, Vladimiros; Marinkovic, Nebojsa S; Frenkel, Anatoly I; Sandler, Stanley I; Vlachos, Dionisios G

    2013-03-13

    5-(Hydroxymethyl)furfural (HMF) and levulinic acid production from glucose in a cascade of reactions using a Lewis acid (CrCl3) catalyst together with a Brønsted acid (HCl) catalyst in aqueous media is investigated. It is shown that CrCl3 is an active Lewis acid catalyst in glucose isomerization to fructose, and the combined Lewis and Brønsted acid catalysts perform the isomerization and dehydration/rehydration reactions. A CrCl3 speciation model in conjunction with kinetics results indicates that the hydrolyzed Cr(III) complex [Cr(H2O)5OH](2+) is the most active Cr species in glucose isomerization and probably acts as a Lewis acid-Brønsted base bifunctional site. Extended X-ray absorption fine structure spectroscopy and Car-Parrinello molecular dynamics simulations indicate a strong interaction between the Cr cation and the glucose molecule whereby some water molecules are displaced from the first coordination sphere of Cr by the glucose to enable ring-opening and isomerization of glucose. Additionally, complex interactions between the two catalysts are revealed: Brønsted acidity retards aldose-to-ketose isomerization by decreasing the equilibrium concentration of [Cr(H2O)5OH](2+). In contrast, Lewis acidity increases the overall rate of consumption of fructose and HMF compared to Brønsted acid catalysis by promoting side reactions. Even in the absence of HCl, hydrolysis of Cr(III) decreases the solution pH, and this intrinsic Brønsted acidity drives the dehydration and rehydration reactions. Yields of 46% levulinic acid in a single phase and 59% HMF in a biphasic system have been achieved at moderate temperatures by combining CrCl3 and HCl. PMID:23432136

  7. Modification of phosphomolybdic acid and its compounds. Catalysts for the selective oxidation of methylacrolein to methacrylic acid. II. Systems modified by ammonium, vanadium, and zinc ions

    Microsoft Academic Search

    I. N. Staroverova; M. Yu. Kutyrev; B. V. Rozentuller

    1986-01-01

    X-ray diffraction and IR and ESR spectroscopy were used to study the structure of modified oxide catalysts for the selective oxidation of methylacrolein containing molybdenum, phosphorus, ammonium, vanadium, and zinc ions. (NHâ)PMoââOâânHâO is formed after roasting at 320degreeC upon using phosphomolybdic acid and ammonium carbonate or ammonium paramolybdate and ammonium phosphate. The introduction of vanadium and zinc during catalyst preparation

  8. Continuous esterification of free fatty acids in crude biodiesel by an integrated process of supercritical methanol and sodium methoxide catalyst.

    PubMed

    Zeng, Dan; Li, Ruosong; Feng, Mingjun; Fang, Tao

    2014-10-01

    An integrated process of supercritical methanol (SCM) and sodium methoxide catalyst was developed to produce fatty acid methyl esters (FAMEs) via continuous esterification from crude biodiesel. The crude biodiesel with high free fatty acid (FFA) content must be refined to reduce the acid value (AV) for meeting the quality standards. The process parameters were studied by Box-Behnken design (BBD) of response surface methodology (RSM). The experimental results revealed that the AV of crude biodiesel decreased from 18.66 to 0.55 mg KOH g(-1) at the reaction conditions of 350 °C, 0.5 % amount of sodium methoxide catalyst, and 10 MPa. Temperature shows the most significant effect on the esterification, followed by pressure and amount of sodium methoxide catalyst. This integrated process proved to be a potential route to refine the crude biodiesel because of its continuity, high efficiency, and less energy consumption with relatively moderate reaction conditions compared with conventional methods. PMID:25119550

  9. An effective Pd-Ni(2)P/C anode catalyst for direct formic acid fuel cells.

    PubMed

    Chang, Jinfa; Feng, Ligang; Liu, Changpeng; Xing, Wei; Hu, Xile

    2014-01-01

    The direct formic acid fuel cell is an emerging energy conversion device for which palladium is considered as the state-of-the-art anode catalyst. In this communication, we show that the activity and stability of palladium for formic acid oxidation can be significantly enhanced using nickel phosphide (Ni(2)P) nanoparticles as a cocatalyst. X-ray photoelectron spectroscopy (XPS) reveals a strong electronic interaction between Ni(2)P and Pd. A direct formic acid fuel cell incorporating the best Pd–Ni(2)P anode catalyst exhibits a power density of 550 mWcm(-2), which is 3.5 times of that of an analogous device using a commercial Pd anode catalyst. PMID:24511636

  10. Biomass into chemicals: aerobic oxidation of 5-hydroxymethyl-2-furfural into 2,5-furandicarboxylic acid with gold nanoparticle catalysts.

    PubMed

    Casanova, Onofre; Iborra, Sara; Corma, Avelino

    2009-01-01

    5-hydroxymethyl-2-furfural is selectively converted into 2,5-furandicarboxylic acid (99 mol % yield) in water, under mild conditions (65-130 degrees C, 10 bar air) with gold nanoparticles supported on nanoparticulate ceria (Au-CeO(2)) and on titania (Au-TiO(2)); the former being more active and selective. A reaction mechanism is established and the rate-limiting step of the reaction is the alcohol oxidation of 5-hydroxymethyl-2-furancarboxylic acid into 2,5-furandicarboxylic acid. The effects of pressure, temperature, substrate-to-catalyst ratio, and amount of base are studied to find the most suitable reaction conditions. The absence of metal leaching is verified by chemical analysis of the reaction solution and by confirming that the reaction does not occur after catalyst removal by filtration in hot water. Substrate degradation is strongly diminished and the catalyst life increased by performing the reaction in two temperature steps. PMID:19760702

  11. Kinetics of liquid-solid reactions in naphthenic acid conversion and Kraft pulping

    Microsoft Academic Search

    Ling Yang

    2009-01-01

    Two liquid-solid reactions, in which the morphology of the solid changes as the reactions proceeds, were examined. One is the NA conversion in oil by decarboxylation on metal oxides and carbonates, and the other is the Kraft pulping in which lignin removal by delignification reaction. In the study of the NA conversion, CaO was chosen as the catalyst for the

  12. The active component of vanadium-molybdenum catalysts for the oxidation of acrolein to acrylic acid

    SciTech Connect

    Andrushkevich, T.V.; Kuznetsova, T.G.

    1986-12-01

    The catalytic properties of the vanadium-molybdenum oxide system were investigated in the oxidation of acrolein to acrylic acid. The active component of the catalyst is the compound VMo/sub 3/O/sub 11/, the maximum amount of which is observed at a content of 7-15 mole% V/sub 2/O/sub 4/. The compound VMo/sub 3/O/sub 11/ is formed in the thermodecomposition of silicomolybdovanadium heteropoly acids or isopoly compounds, reduced with respect to vanadium, and contains V/sup 4 +/ and Mo/sup 6 +/. The optimum treatment for the formation of this compound is treatment in the reaction mixture at 400 degrees C.

  13. Evaluating chemical degradation of proton conducting perfluorosulfonic acid ionomers in a Fenton test by solid-state 19F NMR spectroscopy

    Microsoft Academic Search

    L. Ghassemzadeh; K. D. Kreuer; J. Maier; K. Müller

    2011-01-01

    Chemical degradation and stability of perfluorosulfonic acid (PFSA) ionomers against radical attack were investigated by an (ex situ) Fenton test. Solid-state and solution NMR as well as ATR-FTIR studies were performed on the samples before and after the Fenton reaction. By changing the concentration of the Fenton's solution it is found that the metallic catalyst (Fe2+) is a critical factor

  14. Liquid Hydrofluoric Acid Sorption Using Solid Media - Part 1

    Microsoft Academic Search

    Osborne

    2000-01-01

    The conversion of the uranium hexafluoride (UFâ) which is removed from the Molten Salt Reactor Experiment (MSRE), into a stable oxide for long-term storage will produce a significant amount of slightly contaminated, concentrated aqueous hydrofluoric acid (HF). Sin&the handling of this HF is complicated and dangerous, it was decided to transform it into a stable solid fluoride (e.g., CaFâ, AlFâ,

  15. Iron type catalysts for the ozonation of oxalic acid in water.

    PubMed

    Beltrán, Fernando J; Rivas, Francisco J; Montero-de-Espinosa, R

    2005-09-01

    Two iron catalysts (Fe(III) and Fe2O3/Al2O3) have been used in the ozonation of oxalic acid in water at pH 2.5. Percentage removals of oxalic acid were 1.8%, 7% and 30% corresponding to the non-catalytic, homogeneous (Fe(III)) and heterogeneous (Fe2O3/Al2O3) catalytic ozonations, respectively. Catalytic oxalic acid ozonation leads in all cases to total mineralization. The mechanism of ozonation likely develops through formation of iron-oxalate complexes that further react with ozone without the participation of hydroxyl radicals. Because of the stringent acidic conditions, some metal leaching has been observed and quantified in the heterogeneous process. In the homogeneous catalysis, the kinetics was found to be first order with respect to ozone and oxalic acid while for the heterogeneous catalysis, the kinetic order depends on the concentration of ozone in the gas fed. Thus, at ozone concentrations lower than 30 mg L(-1), the heterogeneous ozonation is between first and zero order with respect to both ozone and oxalic acid while at higher ozone gas concentrations, the kinetics was found to be first and zero order with respect to oxalic acid and ozone, respectively. This kinetics is supported through an Eley-Rideal mechanism that involves a surface reaction between non-adsorbed ozone and adsorbed oxalic acid. Apparent activation energies of the homogeneous and heterogeneous catalytic ozonations were found to be 18.2 and 13.6 kcal mol(-1), respectively. PMID:16095660

  16. Effect of acid speciation on solid waste liquefaction in an anaerobic acid digester

    Microsoft Academic Search

    Sandhya Babel; Kensuke Fukushi; Bunpot Sitanrassamee

    2004-01-01

    Laboratory scale experiments were carried out to evaluate and determine the suitable working conditions for the enhancement of volatile fatty acids (VFAs) production with the stabilization of solid pineapple waste (peel) simultaneously when operating two-phase anaerobic digestion. It was found that acid production, enhanced when the digester was operated at neutral pH. VFAs, could be obtained at about 50g\\/kg-waste within

  17. Catalyst Activity and Post-operation Analyses of Pt/TiO2 (Rutile) Catalysts Used in the Sulfuric Acid Decomposition Reaction

    SciTech Connect

    Lucia M. Petkovic; Daniel M. Ginosar; Harry W. Rollins; Kyle C. Burch; Patrick J. Pinhero; Helen H. Farrell

    2007-06-01

    Production of hydrogen by splitting of water at lower temperatures than by direct thermal decomposition can be achieved by a series of particular chemical reactions that establish a thermochemical cycle [1]. Among the high number of thermochemical water-splitting cycles proposed in the literature [2], the sulfur-based group is of considerable interest. All the sulfur-based cycles employ the catalytic decomposition of sulfuric acid into SO2 and O2. The produced O2 corresponds to the O2 generated from water in the overall cycle. Research performed at the Idaho National Laboratory [3] has found that even one of the most stables catalysts, Pt supported on low surface area titania, deactivates with time on stream (TOS). To develop an understanding of the factors that cause catalyst deactivation, samples of 1% Pt supported on titania (rutile) catalyst were submitted to flowing concentrated sulfuric acid at 1123 K and atmospheric pressure for different TOSs between 0 and 548 h and a number of chemical and spectroscopic analyses applied to the spent samples.

  18. Surface solid-state interactions in copper-nickel-cement catalysts for hydrogenation of oxygen

    Microsoft Academic Search

    A. A. Dulov; L. A. Abramova; E. M. Stasenko; V. N. Efremov; G. M. Tesakova; E. Z. Golosman; V. I. Yakerson

    1994-01-01

    The surface phase composition of alumocalcium cement-supported CuO and CuO-NiO catalysts prepared by chemical mixing has been studied using the method of thermo-vacuum curves of electric conductivity. The deactivation of these catalysts due to overheating to 800 °C under conditions of hydrogenation of oxygen is rationalized by the partial extraction of CuO (and NiO) from the stabilizing structure of the

  19. Structural diversity of solid dispersions of acetylsalicylic acid as seen by solid-state NMR.

    PubMed

    Policianova, Olivia; Brus, Jiri; Hruby, Martin; Urbanova, Martina; Zhigunov, Alexander; Kredatusova, Jana; Kobera, Libor

    2014-02-01

    Solid dispersions of active pharmaceutical ingredients are of increasing interest due to their versatile use. In the present study polyvinylpyrrolidone (PVP), poly[N-(2-hydroxypropyl)-metacrylamide] (pHPMA), poly(2-ethyl-2-oxazoline) (PEOx), and polyethylene glycol (PEG), each in three Mw, were used to demonstrate structural diversity of solid dispersions. Acetylsalicylic acid (ASA) was used as a model drug. Four distinct types of the solid dispersions of ASA were created using a freeze-drying method: (i) crystalline solid dispersions containing nanocrystalline ASA in a crystalline PEG matrix; (ii) amorphous glass suspensions with large ASA crystallites embedded in amorphous pHPMA; (iii) solid solutions with molecularly dispersed ASA in rigid amorphous PVP; and (iv) nanoheterogeneous solid solutions/suspensions containing nanosized ASA clusters dispersed in a semiflexible matrix of PEOx. The obtained structural data confirmed that the type of solid dispersion can be primarily controlled by the chemical constitutions of the applied polymers, while the molecular weight of the polymers had no detectable impact. The molecular structure of the prepared dispersions was characterized using solid-state NMR, wide-angle X-ray scattering (WAXS), and differential scanning calorimetry (DSC). By applying various (1)H-(13)C and (1)H-(1)H correlation experiments combined with T1((1)H) and T1?((1)H) relaxation data, the extent of the molecular mixing was determined over a wide range of distances, from intimate intermolecular contacts (0.1-0.5 nm) up to the phase-separated nanodomains reaching ca. 500 nm. Hydrogen-bond interactions between ASA and polymers were probed by the analysis of (13)C and (15)N CP/MAS NMR spectra combined with the measurements of (1)H-(15)N dipolar profiles. Overall potentialities and limitations of individual experimental techniques were thoroughly evaluated. PMID:24417442

  20. Preparation and characterization of a composite hydrogel with graphene oxide as an acid catalyst.

    PubMed

    Jiang, Ting; Sui, Zhu-Yin; Yang, Quan-Sheng; Zhang, Xuetong; Han, Bao-Hang

    2015-04-28

    In this study, a facile method for synthesizing a novel graphene oxide/pyrrole-formaldehyde (GOP-1) composite hydrogel was developed via in situ polymerization of pyrrole and formaldehyde in the presence of graphene oxide sheets without any additional catalyst. During the polymerization, graphene oxide can act as a two-dimensional template to regulate the aggregation state of polymer and as an acid catalyst to accelerate the reaction rate of pyrrole and formaldehyde. The morphology and microstructure were investigated by scanning electron microscopy, transmission electron microscopy, and X-ray diffraction, respectively. The chemical properties were analyzed via X-ray photoelectron spectroscopy, infrared spectroscopy, and Raman spectroscopy. The freeze-dried GOP-1 composite hydrogel exhibited a large specific surface area, high nitrogen content, and three-dimensional network structure. Based on the above features, the freeze-dried GOP-1 composite hydrogel used as a gas adsorbent showed a high carbon dioxide uptake capacity at 1.0 bar and 273 K (11.1 wt%), in sharp contrast to that of graphene oxide (7.4 wt%). Furthermore, the as-prepared composite hydrogel may possess attractive potential in the fields of electrode material, tissue engineering, and water treatment. PMID:25760407

  1. Gas chromatographic analysis of free fatty acids and glycerides of milk fat using tetramethylammonium hydroxide as catalyste

    Microsoft Academic Search

    I. Martínez-Castro; L. Alonso; M. Juárez

    1986-01-01

    Summary  Tetramethylammonium hydroxide in methanol has been proposed as a catalyst for preparing methyl esters of both free fatty acids and glycerides of fats. Nevertheless, procedures normally recognized as suitable can be inadequate when the fat under study contains noticeable amounts of low relative molecular mass esters. The method using tetramethylammonium hydroxide has been examined and modified in order to analyze

  2. Passive micro tubular direct formic acid fuel cells (DFAFCs) with chemically assembled Pd anode nano-catalysts on polymer electrolytes

    Microsoft Academic Search

    H. Qiao; H. Shiroishi; T. Okada

    2007-01-01

    Wet-chemical assembling process has been developed for the formation of the anode electrocatalyst layers of a micro tubular direct formic acid fuel cell. By using this method, a porous layer of Pd nano-catalyst was bonded onto the inner surface of a tubular polymer electrolyte membrane by chemical reduction of Pd complex impregnated in the membrane. The performance characteristics as a

  3. Addition reactions of thiophenol to ?,?-unsaturated carbonyl compounds using organic acid radical basic anion-exchange resins as catalysts

    Microsoft Academic Search

    Mingxia Li; Jinxia Huang; Wanxuan Zhang

    2001-01-01

    A series of organic acid radical basic anion-exchange resins were prepared from strongly basic quarternary ammonium I type anion-exchange resins, using as the catalysts in addition reactions of thiophenol to ?,?-unsaturated carbonyl compounds. The catalytic activity are influenced by exchange capacity, reaction temperature, solvent and molecular structure.

  4. One-pot synthesis of 3,4-dihydropyrimidin-2(1 H)-ones using boric acid as catalyst

    Microsoft Academic Search

    Shujang Tu; Fang Fang; Chunbao Miao; Hong Jiang; Youjian Feng; Daqing Shi; Xiangshan Wang

    2003-01-01

    A simple effective synthesis of 3,4-dihydropyrimidin-2(1H)-one derivatives, using boric acid as catalyst, from aromatic aldehydes, 1,3-dicarbonyl compounds and urea in glacial acetic acid is described. Compared with the classical Biginelli reaction conditions, this new method has the advantage of excellent yields (86–97%) and short reaction time (0.5–2 h).

  5. Enhanced electrochemical oxidation of Acid Red 3R wastewater with iron phosphomolybdate supported catalyst.

    PubMed

    Wang, Li; Yue, Lin; Shi, Feng; Guo, Jianbo; Yang, Jingliang; Lian, Jing; Luo, Xiao; Guo, Yankai

    2015-01-01

    Electrochemical oxidation of Acid Red 3R (AR3R) was investigated with the new catalyst of iron phosphomolybdate (FePMo12) supported on modified molecular sieves type 4 Å (4A) as packing materials in the reactor. The results of the Fourier transform infrared spectroscopy and X-ray diffraction indicated that the heteropolyanion had a Keggin structure. The optimal conditions for decolorization of simulated AR3R wastewater were as follows: current density 35 mA/cm(2), initial pH 4.0, airflow 0.08 m(3)/hour and inter-electrode distance 3.0 cm. With the addition of NaCl to the system, the decolorization efficiency increased. But Na2SO4 had a negative effect on the decolorization efficiency, which was attributed to the negative salt effect. The degradation mechanisms of AR3R were also discussed in detail. PMID:25812093

  6. An in situ Fourier transform infrared study of formic acid adsorption on a polycrystalline silver catalyst

    SciTech Connect

    Millar, G.J.; Metson, J.B.; Bowmaker, G.A.; Cooney, R.P. (Univ. of Auckland (New Zealand))

    1994-06-01

    Infrared spectra are reported for the adsorption of formic acid on a polycrystalline silver catalyst after various degrees of oxidation. Three distinct chemisorbed species were identified, two of which corresponded to adsorbed formate on Ag(110) and Ag(111) crystal planes and the other to adsorbed formate on a silver site modified by the presence of subsurface oxygen. Moreover, it was discovered that subsurface oxygen species were primarily located in the vicinity of grain boundary defects. Desorption profiles suggested that coadsorbed oxygen moieties could destabilize chemisorbed formate. Because of the invariance in infrared band positions associated with formate species, regardless of whether or not neighbouring atomic oxygen species were present, a kinetic stabilization mechanism is proposed. The pivotal role of subsurface oxygen species (found in the region of grain boundaries) in the mechanism for the selective oxidation of methanol to formaldehyde is discussed. 59 refs., 13 figs.

  7. Approaches to mitigate metal catalyst deactivation in solid oxide fuel cell (SOFC) fuel electrodes

    NASA Astrophysics Data System (ADS)

    Adijanto, Lawrence

    While Ni/YSZ cermets have been used successfully in SOFCs, they also have several limitations, thus motivating the use of highly conductive ceramics to replace the Ni components in SOFC anodes. Ceramic electrodes are promising for use in SOFC anodes because they are expected to be less susceptible to sintering and coking, be redox stable, and be more tolerant of impurities like sulfur. In this thesis, for catalytic studies, the infiltration procedure has been used to form composites which have greatly simplified the search for the best ceramics for anode applications. In the development of ceramic fuel electrodes for SOFC, high performance can only be achieved when a transition metal catalyst is added. Because of the high operating temperatures, deactivation of the metal catalyst by sintering and/or coking is a severe problem. In this thesis, two approaches aimed at mitigating metal catalyst deactivation which was achieved by: 1) designing a catalyst that is resistant to coking and sintering and 2) developing a new method for catalyst deposition, will be presented. The first approach involved synthesizing a self-regenerating, "smart" catalyst, in which Co, Cu, or Ni were inserted into the B-site of a perovskite oxide under oxidizing conditions and then brought back to the surface under reducing conditions. This restores lost surface area of sintered metal particles through an oxidation/reduction cycle. Results will be shown for each of the metals, as well as for Cu-Co mixed metal systems, which are found to exhibit good tolerance to carbon deposition and interesting catalytic properties. The second strategy involves depositing novel Pd CeO2 core-shell nanostructure catalysts onto a substrate surface which had been chemically modified to anchor the nanoparticles. The catalyst deposited onto the chemically modified, hydrophobic surface is shown to be uniform and well dispersed, and exhibit excellent thermal stability to temperatures as high as 1373 K. Similar metal catalyst deposition method was also employed to access their suitability for use in SOFC anodes.

  8. In Situ High Temperature Surface Enhanced Raman Spectroscopy for the Study of Interface Phenomena: Probing a Solid Acid on Alumina

    SciTech Connect

    Dai, Sheng [ORNL; Formo, Eric V [ORNL; Mahurin, Shannon Mark [ORNL; Wu, Zili [ORNL

    2011-01-01

    Herein, we utilize surface enhanced Raman spectroscopy (SERS) for the in situ analyses of catalyst structure while operating at elevated temperatures in various atmospheres. In order to accomplish this, robust SERS substrates were generated by depositing an ultrathin protective coating of alumina on top of silver nanowires (NWs) via atomic layer deposition (ALD). In situ studies were then conducted by analyzing the effects of heating a solid acid, phosphotungstic acid (PTA), on the alumina surface in either an oxygen or hydrogen environment at temperatures up to 400 C. Interestingly, the distance-dependent decay of the enhancement factor of the SERS signal from the underlying NWs allowed us to probe with great detail the interfacial region between the PTA and the alumina surface. The ability to analyze the area closest to the alumina surface was further confirmed by assembling vanadia onto the substrate and monitoring the intensity differences between the V-O-Al and outer V = O bonds.

  9. Organometallic catalysts for primary phosphoric acid fuel cells: Final report, 1981-1985

    Microsoft Academic Search

    Walsh

    1987-01-01

    Cathode improvement, both in performance and cost, available through the use of a class of organometallic cathode catalysts, the tetraazaannulenes (TAAs), was investigated. A new mixed catalyst was identified which provides improved cathode performance without the need for the use of a noble metal. This mixed catalyst was tested under load for 1000 h in full cell at 160 to

  10. A General, Simple Catalyst for Enantiospecific Cross Couplings of Benzylic Ammonium Triflates and Boronic Acids: No Phosphine Ligand Required

    PubMed Central

    Basch, Corey H.; Song, Ye-Geun; Watson, Mary P.

    2014-01-01

    Highly improved conditions for the enantiospecific cross coupling of benzylic ammonium triflates with boronic acids are reported. This method relies on the use of Ni(cod)2 without ancillary phosphine or N-heterocyclic carbene ligands as catalyst. These conditions enable the coupling of new classes of boronic acids and benzylic ammonium triflates. In particular, both heteroaromatic and vinyl boronic acids are well tolerated as coupling partners. In addition, these conditions enable the use of ammonium triflates with a variety of substituents at the benzylic stereocenter. Further, naphthyl-substitution is not required on the benzylic ammonium triflate; ammonium triflates with simple aromatic substituents also undergo this coupling. Good to high yields and levels of stereochemical fidelity are observed. This new catalyst system greatly expands the utility of enantiospecific cross couplings of these amine-derived substrates for the preparation of highly enantioenriched products. PMID:25364060

  11. Effect of Nafion ionomer and catalyst in cathode layers for the direct formic acid fuel cell with complex capacitance analysis on the ionic resistance

    Microsoft Academic Search

    Sunhyung Kim; Jonghee Han; Yongchai Kwon; Kug-Seung Lee; Tae-Hoon Lim; Suk Woo Nam; Jong Hyun Jang

    2011-01-01

    Using platinum (Pt) black and carbon-supported Pt (Pt\\/C) as cathode catalysts, membrane-electrode assemblies (MEAs) were fabricated with various Nafion ionomer content, and their direct formic acid fuel cell (DFAFC) performances were investigated. In MEAs incorporating Pt black catalysts, the current density at 0.6V was highest at ionomer\\/catalyst volume ratio of 1.0, which was consistent with the electrochemical active area (EAS)

  12. Solid-state phase transitions of DL-aminobutyric acid.

    PubMed

    Görbitz, Carl Henrik; Alebachew, Fassil; Pet?í?ek, Václav

    2012-09-01

    Four polymorphs are known for the amino acid racemate DL-aminobutyric acid: one tetragonal form B and three monoclinic forms A, C, and D for which two solid-solid phase transitions take place between 209 and 337 K. The intermediate form A, in space group P2(1)/c, is known to display disorder in the crystalline state with the ethyl side chain occupying three different conformations. The high temperature form D and the low temperature form C have been assumed to display a similar type of disorder in the space group C2/c. The present investigation, on the basis of high quality crystal structures at 100 K (C form), 220 K (A form), 295 K (A form), and 295 K (D form), provides updated results for all three forms and in particular demonstrates that the A ? C and A ? D transitions in fact involve only a partial space group conversion, so that two monoclinic phases are simultaneously present at high and low temperatures. To the best of our knowledge, such a phenomenon has not been observed previously for an organic molecule. The nonroutine refinement of the crystallographic data was performed with a specially adapted version of the program JANA2006. The observed polymorphs are compared with those found for DL-norvaline, DL-norleucine, and DL-methionine. PMID:22867532

  13. Heterogenization of Homogeneous Catalysts: the Effect of the Support

    SciTech Connect

    Earl, W.L.; Ott, K.C.; Hall, K.A.; de Rege, F.M.; Morita, D.K.; Tumas, W.; Brown, G.H.; Broene, R.D.

    1999-06-29

    We have studied the influence of placing a soluble, homogeneous catalyst onto a solid support. We determined that such a 'heterogenized' homogeneous catalyst can have improved activity and selectivity for the asymmetric hydrogenation of enamides to amino acid derivatives. The route of heterogenization of RhDuPhos(COD){sup +} cations occurs via electrostatic interactions with anions that are capable of strong hydrogen bonding to silica surfaces. This is a novel approach to supported catalysis. Supported RhDuPhos(COD){sup +} is a recyclable, non-leaching catalyst in non-polar media. This is one of the few heterogenized catalysts that exhibits improved catalytic performance as compared to its homogeneous analog.

  14. Stepwise engineering of a Pichia pastoris D-amino acid oxidase whole cell catalyst

    PubMed Central

    2010-01-01

    Background Trigonopsis variabilis D-amino acid oxidase (TvDAO) is a well characterized enzyme used for cephalosporin C conversion on industrial scale. However, the demands on the enzyme with respect to activity, operational stability and costs also vary with the field of application. Processes that use the soluble enzyme suffer from fast inactivation of TvDAO while immobilized oxidase preparations raise issues related to expensive carriers and catalyst efficiency. Therefore, oxidase preparations that are more robust and active than those currently available would enable a much broader range of economically viable applications of this enzyme in fine chemical syntheses. A multi-step engineering approach was chosen here to develop a robust and highly active Pichia pastoris TvDAO whole-cell biocatalyst. Results As compared to the native T. variabilis host, a more than seven-fold enhancement of the intracellular level of oxidase activity was achieved in P. pastoris through expression optimization by codon redesign as well as efficient subcellular targeting of the enzyme to peroxisomes. Multi copy integration further doubled expression and the specific activity of the whole cell catalyst. From a multicopy production strain, about 1.3 × 103 U/g wet cell weight (wcw) were derived by standard induction conditions feeding pure methanol. A fed-batch cultivation protocol using a mixture of methanol and glycerol in the induction phase attenuated the apparent toxicity of the recombinant oxidase to yield final biomass concentrations in the bioreactor of ? 200 g/L compared to only 117 g/L using the standard methanol feed. Permeabilization of P. pastoris using 10% isopropanol yielded a whole-cell enzyme preparation that showed 49% of the total available intracellular oxidase activity and was notably stabilized (by three times compared to a widely used TvDAO expressing Escherichia coli strain) under conditions of D-methionine conversion using vigorous aeration. Conclusions Stepwise optimization using a multi-level engineering approach has delivered a new P. pastoris whole cell TvDAO biocatalyst showing substantially enhanced specific activity and stability under operational conditions as compared to previously reported preparations of the enzyme. The production of the oxidase through fed-batch bioreactor culture and subsequent cell permeabilization is high-yielding and efficient. Therefore this P. pastoris catalyst has been evaluated for industrial purposes. PMID:20420682

  15. Bimetallic Bi–Pt, Ru–Pt and Ru–Pd and trimetallic catalysts for the selective oxidation of glyoxal into glyoxalic acid in aqueous phase

    Microsoft Academic Search

    Aurore Deffernez; Sophie Hermans; Michel Devillers

    2005-01-01

    Various bi- and trimetallic associations have been tested as catalysts for the selective oxidation of glyoxal into glyoxalic acid in aqueous phase. All catalysts were supported on carbon and consisted of a noble metal (Pd or Pt) in association with a second (or third) metal acting as promoter (Ru or Bi). Out of all the possible combinations, some families of

  16. PEG-SO3H as Soluble Acidic Polymeric Catalyst for Regioselective Ring Opening of Epoxides: A High-Efficient Synthetic Approach to ?-Hydroxy Thiocyanates

    Microsoft Academic Search

    Ali Reza Kiasat; Mehdi Fallah Mehrjardi

    2008-01-01

    Poly(ethylene glycol)–bound sulfonic acid, PEG-SO3H, was developed as an environmentally friendly and efficient homogeneous polymeric catalyst in organic synthesis. This polymeric phase-transfer catalyst catalyzed the regioselective ring opening of epoxides by thiocyanate ion to give thiocyanohydrins as key intermediates in agricultural and pharmaceutical chemistry in high yields.

  17. Version du 9/04/04 Optical basicity: a scale of acidity/basicity of solids

    E-print Network

    Paris-Sud XI, Université de

    of transition metal cations and of oxides, oxysalts, mixed oxides is built by using ICP, the Ionic Covalent of metals or of other oxides. Redox catalysts are mainly found among the transition metal oxides for the solid state properties of transition metal oxides. Indeed there are little answers when one tries

  18. Modification of phosphomolybdic acid and its compounds. Catalysts for the selective oxidation of methylacrolein to methacrylic acid. II. Systems modified by ammonium, vanadium, and zinc ions

    SciTech Connect

    Staroverova, I.N.; Kutyrev, M.Yu.; Rozentuller, B.V.

    1986-12-01

    X-ray diffraction and IR and ESR spectroscopy were used to study the structure of modified oxide catalysts for the selective oxidation of methylacrolein containing molybdenum, phosphorus, ammonium, vanadium, and zinc ions. (NH/sub 4/)PMo/sub 12/O/sub 40/nH/sub 2/O is formed after roasting at 320degreeC upon using phosphomolybdic acid and ammonium carbonate or ammonium paramolybdate and ammonium phosphate. The introduction of vanadium and zinc during catalyst preparation in the former case does not lead to the formation of new compounds and the activity of the starting system increases slightly. In the latter method, it becomes possible to activate the catalyst due to the formation, on one hand, of a two-phase system and, on the other, by insertion of vanadium ions into the heteropoly anion structure.

  19. In situ infrared monitoring of the solid/liquid catalyst interface during the three-phase hydrogenation of nitrobenzene over nanosized Au on TiO2.

    PubMed

    Richner, Gilles; van Bokhoven, Jeroen A; Neuhold, Yorck-Michael; Makosch, Martin; Hungerbühler, Konrad

    2011-07-21

    The three-phase hydrogenation of nitrobenzene catalysed by nanosized gold over titania was investigated in a slurry. Simultaneous in situ ATR-FTIR monitoring of the liquid phase and at the solid/liquid catalyst interface identified the species adsorbed on the catalyst and those in the liquid phase during the reaction. Nitrosobenzene was not detected analytically while the spectroscopic measurements strongly indicated phenylhydroxylamine as an intermediate reacting before desorbing from the catalyst surface. Under the same reaction conditions, azobenzene and hydrazobenzene were identified as intermediates during the hydrogenation of azoxybenzene to aniline. When nitrosobenzene or phenylhydroxylamine was alternately fed as reactant, azoxybenzene was produced via a disproportionation route. With the former, azoxybenzene was not further reduced by hydrogen because nitrosobenzene deactivated the catalyst. Combined with H(2) uptake, the spectroscopic measurements provided new insights into the reaction mechanism of the gold catalysed hydrogenation of nitrobenzene and an update of the corresponding kinetics. PMID:21660327

  20. Mesoporous Ti(0.5)Cr(0.5)N supported PdAg nanoalloy as highly active and stable catalysts for the electro-oxidation of formic acid and methanol.

    PubMed

    Cui, Zhiming; Yang, Minghui; DiSalvo, Francis J

    2014-06-24

    We report a robust noncarbon Ti0.5Cr0.5N support synthesized by an efficient solid-solid phase separation method. This ternary nitride exhibits highly porous, sintered, and random network structure with a crystallite size of 20-40 nm, resulting in a high specific surface area. It is not only kinetically stable in both acid and alkaline media, but also electrochemically stable in the potential range of fuel cell operation. Two typical anode reactions, formic acid oxidation in acid media and methanol oxidation in alkaline media, are employed to investigate the possibility of Ti0.5Cr0.5N as an alternative to carbon. Bimetallic PdAg nanoparticles (?4 nm) act as anode catalysts for the two anode reactions. PdAg/Ti0.5Cr0.5N exhibits much higher mass activity and durability for the two reactions than PdAg/C and Pd/C catalyst, suggesting that mesoporous Ti0.5Cr0.5N is a very promising support in both acid and alkaline media. PMID:24836603

  1. Adsorption and desorption of small molecules for the characterization of solid acids

    Microsoft Academic Search

    Hiromi Matsuhashi; Kazushi Arata

    2006-01-01

    The relative acid strength and acid amount of solid acids has been determined from the adsorption and desorption of small molecules, such as argon. The order of activation energy for desorption of Ar from a solid acid, determined using temperature-programmed desorption (TPD), is sulfated zirconia > Cs2.5H0.5PW12O40 > proton-type zeolites > silica–alumina. The adsorption isotherms were analyzed using Langmuir and Henry equations. The Henry-type adsorption isotherms

  2. Selective catalytic reduction of NOx with NH3 over a Cu-SSZ-13 catalyst prepared by a solid state ion exchange method

    SciTech Connect

    Wang, Di; Gao, Feng; Peden, Charles HF; Li, Junhui; Kamasamudram, Krishna; Epling, William S.

    2014-10-28

    A novel solid state method was developed to synthesize Cu-SSZ-13 catalysts with excellent NH3-SCR performance and durable hydrothermal stability. After the solid state ion exchange (SSIE) process, the SSZ framework structure and surface area was maintained. In-situ DRIFTS and NH3-TPD experiments provide evidence that isolated Cu ions were successfully exchanged into the pores, which are the active centers for the NH3-SCR reaction.

  3. New entries in Lewis acid-Lewis base bifunctional asymmetric catalyst: catalytic enantioselective Reissert reaction of pyridine derivatives.

    PubMed

    Ichikawa, Eiko; Suzuki, Masato; Yabu, Kazuo; Albert, Matthias; Kanai, Motomu; Shibasaki, Masakatsu

    2004-09-29

    The first catalytic enantioselective Reissert reaction of pyridine derivatives that affords products with excellent regio- and enantioselectivity is described. The key for success is the development of new Lewis acid-Lewis base bifunctional asymmetric catalysts containing an aluminum as a Lewis acid and sulfoxides or phosphine sulfides as a Lewis base. These reactions are useful for the synthesis of a variety of chiral piperidine subunits, and catalytic enantioselective formal synthesis of CP-293,019, a selective D4 receptor antagonist, was achieved. Preliminary mechanistic studies indicated that both sulfoxides and phosphine sulfides can activate TMSCN as a Lewis base. In addition, the sulfoxides with appropriate stereochemistry might stabilize a highly enantioselective bimetallic complex (a presumed active catalyst) through internal coordination to aluminum. PMID:15382912

  4. Attrition resistance and catalytic performance of spray-dried SAPO-34 catalyst for MTO process: Effect of catalyst phase and acidic solution

    Microsoft Academic Search

    Min Kim; Ho-Jeong Chae; Tae-Wan Kim; Kwang-Eun Jeong; Chul-Ung Kim; Soon-Yong Jeong

    2011-01-01

    SAPO-34 is the most well-known catalyst for MTO (methanol to olefins) reaction because of its good selectivity to light olefins. However, SAPO-34 catalyst is rapidly deactivated by coke, and thus it should be used in circulating fluidized bed (CFB) reactors so that the deactivated catalyst can be continuously regenerated. To apply a catalyst into a CFB reactor, strong mechanical strength

  5. Model Reaction for the in-Situ Characterization of the Hydrogenating and Acid Properties of Industrial Hydrocracking Catalysts

    Microsoft Academic Search

    M. Guisnet; C. Thomazeau; J. L. Lemberton; S. Mignard

    1995-01-01

    A kinetic study of o-xylene transformation was carried out on a sulfided NiMo on Y zeolite catalyst during the hydrocracking of a model compound (n-heptane) under the following conditions of the process: high hydrogen pressure (5.7 MPa), presence of nitrogen and sulfur-containing compounds. o-Xylene inhibits n-heptane transformation, which can be explained by a competition for the adsorption on the acid

  6. Novel catalyst-support interaction for direct formic acid fuel cell anodes: Pd electrodeposition on surface-modified graphite felt

    Microsoft Academic Search

    Tommy T. Cheng; El?d L. Gyenge

    2009-01-01

    The electrodeposition of Pd on graphite felt (GF, thickness ~3 mm in uncompressed state) was studied and the resulting catalyst\\u000a was compared with Pt-Ru\\/GF for the electro-oxidation of formic acid. A micellar solution composed of the non-ionic surfactant\\u000a Triton X-102 and an aqueous phase containing PdCl2 were utilized for the galvanostatic electrodeposition of Pd nanoparticles. The presence of the surfactant during

  7. Hollow core\\/mesoporous shell carbon as a highly efficient catalyst support in direct formic acid fuel cell

    Microsoft Academic Search

    Baizeng Fang; Minsik Kim; Jong-Sung Yu

    2008-01-01

    Spherical carbon capsules with a hollow macroporous core of ca. 260nm and a ca. 40nm thick mesoporous shell were explored for the first time as an anode catalyst support in direct formic acid fuel cell (DFAFC). Hollow core\\/mesoporous shell carbon (HCMSC) possesses fantastic structural characteristics such as uniform particle size, well-developed three-dimensionally interconnected bimodal porosity, and large specific surface area

  8. CuO\\/NiO monolithic catalysts for NO x removal from nitric acid plant flue gas

    Microsoft Academic Search

    Jesús Blanco; Pedro Avila; Silvia Suárez; Malcolm Yates; Juan Antonio Martin; Luis Marzo; Carlos Knapp

    2004-01-01

    The performance of copper\\/nickel oxide catalysts supported on ceramic monoliths of ?-alumina\\/silicate, for the selective catalytic reduction (SCR) of nitrogen oxides in flue gas from nitric acid plants ([NO]\\/[NOx]=0.7) has been studied. The monoliths prepared were characterised by thermogravimetry, nitrogen adsorption–desorption, mercury intrusion porosimetry (MIP), X-ray diffraction (XRD), electron probe microanalysis wavelength dispersion spectroscopy (EPMA-WDS) and their mechanical strengths were

  9. Acid zeolites as catalysts in organic reactions. Friedel-Crafts reaction of 2-alkylfurans with 3-substituted allylic alcohols

    Microsoft Academic Search

    Felipe Algarra; Avelino Corma; Hermenegildo García; Jaime Primo

    1995-01-01

    Methyl 3-(2-furyl) propanoate (1) and 3-(2-furyl) propyl acetate (3) can be conveniently alkylated with high conversion and selectivity by cinnamyl and crotyl alcohols in the liquid phase at moderate temperatures using acid zeolites of medium and large pore size as heterogeneous catalysts. ZSM-5 zeolite exhibited the highest turnover number for the heteroaromatic alkylation. This reaction was found to be totally

  10. Effects of Pt\\/C, Pd\\/C and PdPt\\/C anode catalysts on the performance and stability of air breathing direct formic acid fuel cells

    Microsoft Academic Search

    Ping Hong; Fan Luo; Shijun Liao; Jianhuang Zeng

    2011-01-01

    Pt\\/C, Pd\\/C and PdPt\\/C catalysts are potential anodic candidates for electro-oxidation of formic acid. In this work we designed a miniature air breathing direct formic acid fuel cell, in which gold plated printed circuit boards are used as end plates and current collectors, and evaluated the effects of anode catalysts on open circuit voltage, power density and long-term discharging stability

  11. Deactivation\\/reactivation of a Pd\\/C catalyst in a direct formic acid fuel cell (DFAFC): Use of array membrane electrode assemblies

    Microsoft Academic Search

    Xingwen Yu; Peter G. Pickup

    2009-01-01

    Palladium-based catalysts exhibit high activity for formic acid oxidation, but their catalytic activity decreases quite rapidly under direct formic acid fuel cell (DFAFC) operating conditions. This paper presents a systematic study of the deactivation and electrochemical reactivation of a carbon supported palladium catalyst (Pd\\/C) employing anode arrays in a DFAFC. Deactivation of Pd\\/C is caused by the electro-oxidation of the

  12. Stability and spinodal decomposition of the solid-solution phase in the ruthenium-cerium-oxide electro-catalyst.

    PubMed

    Li, Yanmei; Wang, Xin; Shao, Yanqun; Tang, Dian; Wu, Bo; Tang, Zhongzhi; Lin, Wei

    2015-01-14

    The phase diagram of Ru-Ce-O was calculated by a combination of ab initio density functional theory and thermodynamic calculations. The phase diagram indicates that the solubility between ruthenium oxide and cerium oxide is very low at temperatures below 1100 K. Solid solution phases, if existing under normal experimental conditions, are metastable and subject to a quasi-spinodal decomposition to form a mixture of a Ru-rich rutile oxide phase and a Ce-rich fluorite oxide phase. To study the spinodal decomposition of Ru-Ce-O, Ru0.6Ce0.4O2 samples were prepared at 280 °C and 450 °C. XRD and in situ TEM characterization provide proof of the quasi-spinodal decomposition of Ru0.6Ce0.4O2. The present study provides a fundamental reference for the phase design of the Ru-Ce-O electro-catalyst. PMID:25418197

  13. FEASIBILITY STUDY TO PRODUCE BIODIESEL FROM LOW COST OILS AND NEW CATALYSTS DERIVED FROM AGRICULTURAL & FORESTRY RESIDUES - PHASE I

    EPA Science Inventory

    This research will develop and demonstrate the feasibility of preparing reusable and recoverable solid, porous acid and base catalysts for biodiesel production using activated carbon generated from agricultural and forestry residues (i.e., a sustainable biomass).  These ne...

  14. Photocatalytic detoxification of Acid Red 18 by modified ZnO catalyst under sunlight irradiation

    NASA Astrophysics Data System (ADS)

    Senthilraja, A.; Subash, B.; Dhatshanamurthi, P.; Swaminathan, M.; Shanthi, M.

    2015-03-01

    In this work, hybrid structured Bi-Au-ZnO composite was prepared by precipitation-decomposition method. This method is mild, economical and efficient. Bi-Au-ZnO was characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM), energy dispersive spectrum (EDS), diffuse reflectance spectra (DRS), photoluminescence spectra (PL) and BET surface area measurements. Photocatalytic activity of Bi-Au-ZnO was evaluated by irradiating the Acid Red 18 (AR 18) dye solution under sun light. Heterostructured Bi-Au-ZnO photocatalyst showed higher photocatalytic activity than those of individual Bi-ZnO, Au-ZnO, bare ZnO, and TiO2-P25 at pH 11. The effects of operational parameters such as the amount of catalyst dosage, dye concentration, initial pH on photo mineralization of AR 18 dye have been analyzed. The mineralization of AR 18 has been confirmed by chemical oxygen demand (COD) measurements. A possible mechanism is proposed for the degradation of AR 18 under sun light. Finally, Bi-Au-ZnO heterojunction photocatalyst was more stable and could be easily recycled several times opening a new avenue for potential industrial applications.

  15. Catalytic Upgrading of bio-oil using 1-octene and 1-butanol over sulfonic acid resin catalysts

    SciTech Connect

    Zhang, Zhijun; Wang, Qingwen; Tripathi, Prabhat; Pittman, Charles U.

    2011-02-04

    Raw bio-oil from fast pyrolysis of biomass must be refined before it can be used as a transporation fuel, a petroleum refinery feed or for many other fuel uses. Raw bio-oil was upgraded with the neat model olefin, 1-octene, and with 1-octene/1-butanol mixtures over sulfonic acid resin catalysts frin 80 to 150 degrees celisus in order to simultaneously lower water content and acidity and to increase hydrophobicity and heating value. Phase separation and coke formation were key factors limiting the reaction rate during upgrading with neat 1-octene although octanols were formed by 1-octene hydration along with small amounts of octyl acetates and ethers. GC-MS analysis confirmed that olefin hydration, carboxylic acid esterification, acetal formation from aldehydes and ketones and O- and C-alkylations of phenolic compounds occurred simultaneously during upgrading with 1-octene/1-butanol mixtures. Addition of 1-butanol increased olefin conversion dramatically be reducing mass transfer restraints and serving as a cosolvent or emulsifying agent. It also reacted with carboxylic acids and aldehydes/ketones to form esters, and acetals, respectively, while also serving to stabilize bio-oil during heating. 1-Butanol addition also protected the catalysts, increasing catalyst lifetime and reducing or eliminationg coking. Upgrading sharply increased ester content and decreased the amounts of levoglucosan, polyhydric alcohols and organic acids. Upgrading lowered acidity (pH value rise from 2.5 to >3.0), removed the uppleasant ordor and increased hydrocarbon solubility. Water content decreased from 37.2% to < 7.5% dramatically and calorific value increased from 12.6 MJ kg to about 30.0 MJ kg.

  16. Hydrogenation of Succinic Acid to ?-Butyrolactone (GBL) Over Palladium-Alumina Composite Catalyst Prepared by a Single-Step Sol–Gel Method

    Microsoft Academic Search

    Ung Gi Hong; Joongwon Lee; Sunhwan Hwang; In Kyu Song

    2011-01-01

    \\u000a Abstract  Mesoporous palladium-alumina (Pd-A) composite catalysts prepared by a single-step sol–gel method were calcined at various\\u000a temperatures to control palladium surface area and acidity. The Pd-A catalysts were characterized by XRD, BET, N2 adsorption–desorption isotherm, H2 chemisorption, 27Al MAS NMR, NH3-TPD, and HR-TEM analyses. Liquid-phase hydrogenation of succinic acid to ?-butyrolactone (GBL) was carried out over Pd-A\\u000a catalyst in a batch

  17. The effect of the distance between acidic site and basic site immobilized on mesoporous solid on the activity in catalyzing aldol condensation

    SciTech Connect

    Yu Xiaofang [College of Chemistry, Jilin University, Jiefang Road 2519, Changchun 130023 (China); Yu Xiaobo [China Pharmaceutical University, Nanjing 210009 (China); Wu Shujie; Liu Bo; Liu Heng [College of Chemistry, Jilin University, Jiefang Road 2519, Changchun 130023 (China); Guan Jingqi, E-mail: guanjq@jlu.edu.c [College of Chemistry, Jilin University, Jiefang Road 2519, Changchun 130023 (China); Kan Qiubin, E-mail: catalysischina@yahoo.com.c [College of Chemistry, Jilin University, Jiefang Road 2519, Changchun 130023 (China)

    2011-02-15

    Acid-base bifunctional heterogeneous catalysts containing carboxylic and amine groups, which were immobilized at defined distance from one another on the mesoporous solid were synthesized by immobilizing lysine onto carboxyl-SBA-15. The obtained materials were characterized by X-ray diffraction (XRD), N{sub 2} adsorption, Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), scanning electron micrographs (SEM), transmission electron micrographs (TEM), elemental analysis, and back titration. Proximal-C-A-SBA-15 with a proximal acid-base distance was more active than maximum-C-A-SBA-15 with a maximum acid-base distance in aldol condensation reaction between acetone and various aldehydes. It appears that the distance between acidic site and basic site immobilized on mesoporous solid should be an essential factor for catalysis optimization. -- Graphical abstract: Proximal-C-A-SBA-15 with a proximal acid-base distance and maximum-C-A-SBA-15 with a maximum acid-base distance were synthesized by immobilizing lysine onto carboxyl-SBA-15. Display Omitted Research highlights: {yields} Proximal-C-A-SBA-15 with a proximal acid-base distance. {yields} Maximum-C-A-SBA-15 with a maximum acid-base distance. {yields} Compared to maximum-C-A-SBA-15, proximal-C-A-SBA-15 was more active toward aldol condensation reaction between acetone and various aldehydes.

  18. Solid-state NMR studies of the adsorption of acetylene on platinum/alumina catalysts

    E-print Network

    Lambregts, Marsha Jo Lupher

    1991-01-01

    is invisible in "C MAS spectra, presumably due to susceptibility broadening. This observation reconciles the conflicting conclusions of two previous NMR investigations of the system. This thesis underscores the need to apply complementary NMR techniques... REFERENCES 15 19 34 VITA 37 LIST OF FIGURES FIGURE PAGE A Langmuir isotherm obtained for a representative 10%Pt/rt-alumina catalyst sample. 16 uC CP/MAS NMR spectra obtained at a resonance frequency of 50 MHz. 20 uC Interrupted Decoupling MAS...

  19. Codeposited PtSb\\/C catalysts for direct formic acid fuel cells

    Microsoft Academic Search

    Xingwen Yu; Peter G. Pickup

    2011-01-01

    Carbon supported PtSb catalysts were synthesized by codeposition of platinum and antimony on Vulcan® carbon black. X-ray diffraction (XRD) analysis revealed that the Sb was alloyed with the Pt while XPS indicated that a large fraction of the Sb was in an oxidized state, with only partial alloying. The performances of catalysts with a range of compositions were compared in

  20. Preparation of Hydrotreating catalyst from spent catalyst

    SciTech Connect

    Gardner, L.E.; Kidd, D.R.

    1990-01-01

    This patent describes a process for preparing an active hydrotreating catalyst composition from a spent hydrotreating catalyst composition. The process comprising the steps of: grinding a substantially dry spent hydrotreating composition; mixing the ground spent hydrotreating catalyst composition with alumina; shaping the mixture into compacted particles comprising the ground spent hydrotreating catalyst composition and the alumina; and heating the compacted particles in a free oxygen containing gas to a temperature in the range of from about 700{degrees} to about 1000{degrees}F, under such conditions as to substantially convert the solid carbonaceous deposits to carbon oxides, and to obtain an active hydrotreating catalyst composition.

  1. The study of Au\\/MoS 2 anode catalyst for solid oxide fuel cell (SOFC) using H 2S-containing syngas fuel

    Microsoft Academic Search

    Zheng-Rong Xu; Jing-Li Luo; Karl T. Chuang

    2009-01-01

    Au\\/MoS2 is a promising anode catalyst for conversion of all components of H2S-containing syngas in solid oxide fuel cell (SOFC). MoS2-supported nano-Au particles have catalytic activity for conversion of CO when syngas is used as fuel in SOFC systems, thus preventing poisoning of MoS2 active sites by CO. In contrast to use of MoS2 as anode catalyst, performance of Au\\/MoS2

  2. New chitosan microspheres supported [bis(2-methylallyl)(1,5-cyclooctadienne)ruthenium(II)] as efficient catalysts for colour degradation in the presence of hydrogen peroxide

    Microsoft Academic Search

    Mahjoub Jabli; Ridha Touati; Yakdhane Kacem; Bechir Ben Hassine

    2012-01-01

    This paper concerns the immobilisation of either [bis(2-methylallyl)(1,5-cyclooctadienne)ruthenium(II)] (I) or ruthenium chloride (RuCl3) (II) on chitosan microspheres (catalyst I and catalyst II, respectively). These heterogenised catalysts were used for the oxidative degradation of two acid dyes, i.e. [Calmagite (Calma) and Acid Blue 25 (AB25)] in aqueous solution at pH 7.0 in the presence of hydrogen peroxide (H2O2). Prepared solid supports

  3. New chitosan microspheres supported [bis(2-methylallyl)(1,5-cyclooctadienne)ruthenium(II)] as efficient catalysts for colour degradation in the presence of hydrogen peroxide

    Microsoft Academic Search

    Mahjoub Jabli; Ridha Touati; Yakdhane Kacem; Bechir Ben Hassine

    2011-01-01

    This paper concerns the immobilisation of either [bis(2-methylallyl)(1,5-cyclooctadienne)ruthenium(II)] (I) or ruthenium chloride (RuCl3) (II) on chitosan microspheres (catalyst I and catalyst II, respectively). These heterogenised catalysts were used for the oxidative degradation of two acid dyes, i.e. [Calmagite (Calma) and Acid Blue 25 (AB25)] in aqueous solution at pH 7.0 in the presence of hydrogen peroxide (H2O2). Prepared solid supports

  4. Interaction of Peroxynitric Acid with Solid H2O Ice

    NASA Technical Reports Server (NTRS)

    Li, Zhuangjie; Friedl, Randall R.; Moore, Steven B.; Sander, Stanley P.

    1996-01-01

    The uptake of peroxynitric acid (PNA), HO2NO2 or HNO4, on solid H2O ice at 193 K (-80 C) was studied using a fast flow-mass spectrometric technique. An uptake coefficient of 0.15 +/- 0.10 was measured, where the quoted uncertainty denotes 2 standard deviations. The uptake process did not result in the production of gas phase products. The composition of the condensed phase was investigated using programmed heating (3 K/min) of the substrate coupled with mass spectrometric detection of desorbed species. Significant quantities of HNO, and HNO3 desorbed from the substrates at temperatures above 225 K and 246 K, respectively. The desorbed HNO3, which was less than 9% of the desorbed HNO, and remained unchanged upon incubation of the substrate, was likely due to impurities in the HNO4 samples rather than reaction of HNO, on the substrate. The onset temperatures for HNO4 desorption increased with increasing H2O to HNO4 ratios, indicating that HNO4, like HNO3, tends to be hydrated in the presence of water. These observations suggest possible mechanisms for removal of HNO4 or repartitioning of total odd nitrogen species in the Earth's upper troposphere and stratosphere.

  5. Solid state radiolysis of non-proteinaceous amino acids in vacuum: astrochemical implications

    E-print Network

    Solid state radiolysis of non-proteinaceous amino acids in vacuum: astrochemical implications´miai Kiado´, Budapest, Hungary 2012 Abstract The analysis of the amino acids present in Murchison meteorite and in other carbonaceous chondrites has revealed the presence of 66 different amino acids. Only eight

  6. Metal hydride synthesis through reactive milling of metals with solid acids in a planetary ball mill

    Microsoft Academic Search

    Christoph Ney; Holger Kohlmann; Guido Kickelbick

    2011-01-01

    In this paper we report on a new type of synthesis of calcium hydride through reactive milling under an argon atmosphere. Therefore we have used two different protic acids (phosphoric acid and phenylphosphonic acid) which are solid at room temperature and have milled them together with calcium. For the synthesis calcium had two functions: It shall work as reduction agent

  7. Comparative study of CoFeNx/C catalyst obtained by pyrolysis of hemin and cobalt porphyrin for catalytic oxygen reduction in alkaline and acidic electrolytes

    NASA Astrophysics Data System (ADS)

    Jiang, Rongzhong; Chu, Deryn

    2014-01-01

    Comparative studies of the oxygen reduction kinetics and mechanisms of CoFeNx/C catalysts have been conducted with rotating disk electrode (RDE) and rotating ring-disk electrode (RRDE) in aqueous acid and alkaline solutions, as well as acidic and alkaline polymer electrolytes. The CoFeNx/C catalysts in this study were obtained by the pyrolysis of hemin and a cobalt porphyrin. In an alkaline electrolyte, a larger electron transfer coefficient (0.63) was obtained in comparison to that in an acidic electrolyte (0.44), signifying a lower free energy barrier for oxygen reduction. The kinetic rate constant (2.69 × 10-2 cm s-1) for catalytic oxygen reduction in alkaline solution at 0.6 V (versus RHE) is almost 4 times larger than that in acidic solution (7.3 × 10-3 cm s-1). A synergetic catalytic mechanism is proposed. The overall reduction is a 4-electron reduction of oxygen. The obtained CoFeNx/C catalyst was further evaluated as a cathode catalyst in single fuel cells with acidic, neutral and alkaline electrolyte membranes. The order of the single cell performances either for power density or for stability is acidic > neutral > alkaline. The different behaviors of the CoFeNx/C catalyst in half cell and single cell are discussed.

  8. Application of rare earth modified Zr-based ceria-zirconia solid solution in three-way catalyst for automotive emission control.

    PubMed

    Wang, Qiuyan; Zhao, Bo; Li, Guangfeng; Zhou, Renxian

    2010-05-15

    Automotive exhaust emission is a major cause of air pollution. Three-way catalyst (TWC) which can eliminate CO, HC (hydrocarbons), and NO(x) simultaneously has been used to control exhaust emissions. Ceria-zirconia is a key component in TWC and most researchers pay attention to Ceria-Zirconia (Ce-rich) solid solution. The research presented in this paper is focused on the intrinsic structure of Ceria-Zirconia (Zr-based) solid solution and its application in TWC. A series of Ce(0.2)Zr(0.8)O(2) modified with rare earths (La, Nd, Pr, Sm, and Y) have been prepared by coprecipitation method combined with supercritical drying technique. All samples showed single tetragonal solid solution, indicating that the rare earth ion inserted into the lattice structure completely, and an approximately linearly relationship between lattice parameter a and the ionic radius of doped rare earth was observed. The catalytic performances of corresponding Pd-only catalysts were investigated in simulated exhaust gas. The presence of La, Nd, and Pr was favorable to the catalytic activity and wide air/fuel operation window. The relationship between the intrinsic structure of the Zr-based ceria-zirconia solid solution and catalytic activity was discussed in detail, which has some reference value for catalyst design and application. PMID:20408547

  9. Nanostructured Pt\\/C and Pd\\/C catalysts for direct formic acid fuel cells

    Microsoft Academic Search

    Zhaolin Liu; Liang Hong; Mun Pun Tham; Tze Han Lim; Huixin Jiang

    2006-01-01

    Platinum (Pt) and palladium (Pd) nanoparticles supported on Vulcan XC-72 carbon are prepared by a microwave-assisted polyol process. The catalysts are characterized by transmission electron microscopy and X-ray diffraction analysis. The average particle size of Pt and Pd nanoparticles, which are uniformly dispersed on carbon, is 4 and 5nm, respectively. The Pt\\/C and Pd\\/C catalysts exhibit four diffraction peaks that

  10. Effects of acid catalyst type on structural, morphological, and optoelectrical properties of spin-coated TiO2 thin film

    NASA Astrophysics Data System (ADS)

    Golobostanfard, Mohammad Reza; Abdizadeh, Hossein

    2013-03-01

    The effects of different acid catalysts of nitric acid, hydrochloric acid, sulfuric acid, phosphoric acid, boric acid, acetic acid, and citric acid on structural, morphological, and optoelectrical properties of nanocrystalline spin-coated TiO2 thin films synthesized via alkoxide sol-gel route were investigated. It was found that only the sols with HNO3 and HCl are suitable for film preparation. The X-ray diffractometry and Raman analysis showed that crystalline phases could be controlled by the type of acid catalyst. Although the H2SO4 sol shows good stability, it causes extremely different morphology to form due to its different sol nature and high contact angle. Fourier transformed infrared spectra confirmed the presence of acid anion species in all samples even after calcination. Furthermore, it was inferred from UV-visable absorption spectra that although the band gap and thickness of the films are independent of acid catalyst type, the refractive index and porosity of the films are strongly affected by the type of acids.

  11. Direct production of crystalline boric acid through heterogeneous reaction of solid borax with propionic acid: Operation and simulation

    Microsoft Academic Search

    Bahman ZareNezhad

    2004-01-01

    The production of boric acid through reaction of borax crystals with propionic acid was investigated in batch mode. It was\\u000a found that the product boric acid precipitates on the solid borax reactant. An increase in the coefficient of variation of\\u000a feed crystals resulted in an increase in the time of completion of the reaction. A sharp interface model with variable

  12. SO{sub 4}{sup 2{minus}}/TiO{sub 2}-SiO{sub 2} mixed oxide catalyst. 1: Synthesis, characterization, and acidic properties

    SciTech Connect

    Parida, K.M.; Samantaray, S.K.; Mishra, H.K. [CSIR, Orissa (India). Regional Research Lab.] [CSIR, Orissa (India). Regional Research Lab.

    1999-08-01

    A series of sulfate-doped titania-silica mixed oxides have been prepared by immersing titania-silica gel in the required volume of sulfuric acid, followed by drying. The mixed oxide gel is obtained by hydrolyzing an equimolar mixture of tetraethylorthosilicate (TEOS) and tetrabutylorthotitanate (TBOT) at pH 3. The materials, after calcining at 723 K for 4 h, are characterized by XRD, FT-IR, the BET method, and surface acid strength by the Hammett indicator method. The catalytic activity tests are carried in a fixed bed catalytic reactor (i.e. = 10 mm) for alcohol conversion, whereas cumene cracking/dehydrogenation reactions are carried out in a micropulse reactor. XRD results shows that the titania-silica mixture is amorphous and the crystallization starts with sulfation. The surface of the mixed oxide contains both bridged and normal hydroxyl groups, as observed from FT-IR data. The surface area of the material is not much altered by sulfation and lies within 50 m{sup 2}/g. The acid strength of 4 wt% SO{sub 4}{sup 2{minus}}/TiO{sub 2}-SiO{sub 2} is found to be stronger than that of 100% concentrated H{sub 2}SO{sub 4}. In the case of 2-propanol conversion, low acetone selectivity indicates the presence of weak basic sites, whereas methanol conversion over all solids shows that dehydration follows a parallel and consecutive pathway. A good correlation is found between the cumene cracking and the acidity of the catalysts.

  13. Nanoporous PdNi Alloy Nanowires As Highly Active Catalysts for the Electro-Oxidation of Formic Acid.

    PubMed

    Du, Chunyu; Chen, Meng; Wang, Wengang; Yin, Geping

    2011-02-01

    Highly active and durable catalysts for formic acid oxidation are crucial to the development of direct formic acid fuel cell. In this letter, we report the synthesis, characterization, and electrochemical testing of nanoporous Pd(57)Ni(43) alloy nanowires for use as the electrocatalyst towards formic acid oxidation (FAO). These nanowires are prepared by chemically dealloying of Ni from Ni-rich PdNi alloy nanowires, and have high surface area. X-ray diffraction data show that the Pd(57)Ni(43) nanowires have the face-centered cubic crystalline structure of pure Pd, whereas X-ray photoelectron spectroscopy confirm the modification of electronic structure of Pd by electron transfer from Ni to Pd. Electrocatalytic activity of the nanowires towards FAO exceeds that of the state-of-the-art Pd/C. More importantly, the nanowires are highly resistant to deactivation. It is proposed that the high active surface area and modulated surface properties by Ni are responsible for the improvement of activity and durability. Dealloyed nanoporous Pd(57)Ni(43) alloy nanowires are thus proposed as a promising catalyst towards FAO. PMID:21192691

  14. Selective aerobic oxidation of 1,3-propanediol to 3-hydroxypropanoic acid using hydrotalcite supported bimetallic gold nanoparticle catalyst in water

    NASA Astrophysics Data System (ADS)

    Mohammad, Mujahid; Nishimura, Shun; Ebitani, Kohki

    2015-02-01

    Selective oxidation of 1,3-propanediol (1,3-PD) to 3-hydroxypropanoic acid (3-HPA), an important industrial building block, was successfully achieved using hydrotalcite-supported bimetallic Au nanoparticle catalysts in water at 343 K under aerobic and base-free conditions. The highest yield of 42% with 73% selectivity towards 3-HPA was afforded by 1wt% Au0.8Pd0.2-PVP/HT catalyst.

  15. Development of biomimetic catalytic oxidation methods and non-salt methods using transition metal-based acid and base ambiphilic catalysts.

    PubMed

    Murahashi, Shun-Ichi

    2011-01-01

    This review focuses on the development of ruthenium and flavin catalysts for environmentally benign oxidation reactions based on mimicking the functions of cytochrome P-450 and flavoenzymes, and low valent transition-metal catalysts that replace conventional acids and bases. Several new concepts and new types of catalytic reactions based on these concepts are described. (Communicated by Ryoji Noyori, M.J.A.). PMID:21558760

  16. Supported Molecular Catalysts: Synthesis, In-Situ Characterization and Performance

    SciTech Connect

    Davis, Mark E.

    2009-03-13

    The objectives of our work are: (i) to create solid catalysts with active sites that can function in a cooperative manner to enhance reactivity and selectivity, and (ii) to prepare solid catalysts that can perform multiple reactions in a network that in some cases would not be possible in solution due to the incompatibilities of the various catalytic entities (for example an acid and a base). We carried out extensive reactions to test the nature of the cooperative effect caused by thiol/sulfonic acid interactions. The acid/thiol combination provided an example where the two organic groups should be positioned as close to one another as possible. We also studied a system where this is not possible (acid-base). We investigated simultaneously incorporating acid and base groups into the same material. For the case of acid and bases, there is an optimal separation distance (too close allows for neutralization while too far eliminates any cooperative behavior).

  17. Transesterification of soybean oil catalyzed by potassium loaded on alumina as a solid-base catalyst

    Microsoft Academic Search

    Wenlei Xie; Hong Peng; Ligong Chen

    2006-01-01

    Biodiesel fuel, consisting of methyl esters of long chain fatty acids produced by transesterification of vegetable oils or animal fats with methanol, is a promising alternative diesel fuel regarding the limited resources of fossil fuels and the environmental concerns. In this work, an environmentally benign process for the transesterification of soybean oil to methyl esters using alumina loaded with potassium

  18. A mixed NCP pincer palladacycle as catalyst precursor for the coupling of aryl halides with aryl boronic acids

    Microsoft Academic Search

    Gilber R. Rosa; Clarissa H. Rosa; Frank Rominger; Jairton Dupont; Adriano L. Monteiro

    2006-01-01

    The reaction of phosphinite Me2NCH2CC(CH2)2OP(i-Pr)2 (2) with Li2PdCl4 in methanol at room temperature affords the air and water stable mixed pincer palladacycle (Me2NCH2(Cl)CC(CH2)2OP(i-Pr)2-?N?C?P)PdCl (3) whose structure has been ascertained by means of an X-ray diffraction study. This pincer palladacycle is a highly efficient catalyst precursor for the coupling of aryl boronic acids and aryl chlorides. Both electron-rich and -poor aryl

  19. Synthesis of carbon supported palladium nanoparticles catalyst using a facile homogeneous precipitation-reduction reaction method for formic acid electrooxidation

    NASA Astrophysics Data System (ADS)

    Ma, Juan; Ji, Yigang; Sun, Hanjun; Chen, Yu; Tang, Yawen; Lu, Tianhong; Zheng, Junwei

    2011-10-01

    A highly dispersed and ultrafine carbon supported Pd nanoparticles (Pd/C) catalyst is synthesized by a facile homogeneous precipitation-reduction reaction method. Under the appropriate pH conditions, [PdCl 4] 2- species in PdCl 2 solution are slowly transformed into the insoluble palladium oxide hydrate (PdO·H 2O) precipitation by heat treatment due to a slow hydrolysis reaction, which results in the generation of carbon supported PdO·H 2O nanoparticles (PdO·H 2O/C) sample with the high dispersion and small particle size. Consequently, a highly dispersed and ultrafine Pd/C catalyst can be synthesized by PdO·H 2O ? Pd 0 in situ reduction reaction path in the presence of NaBH 4. As a result, the resulting Pd/C catalyst possesses a significantly electrocatalytic performance for formic acid electrooxidation, which is attributed to the uniformly sized and highly dispersed nanostructure.

  20. Photocatalytic oxidation technology for humic acid removal using a nano-structured TiO2/Fe2O3 catalyst.

    PubMed

    Qiao, S; Sun, D D; Tay, J H; Easton, C

    2003-01-01

    A novel TiO2 coated haematite photocatalyst was prepared and used for removal of colored humic acids from wastewater in an UV bubble photocatalytic reactor. XRD analysis confirmed that nano-size anatase crystals of TiO2 were formed after calcination at 480 degrees C. SEM results revealed that nano-size particles of TiO2 were uniformly coated on the surface of Fe2O3 to form a bulk of nano-structured photocatalyst Fe2O3/TiO2. The porous catalyst had a BET surface area of 168 m2/g. Both the color and total organic carbon (TOC) conversion versus the residence time were measured at various conditions. The effects of pH value, catalyst loaded, initial humic acid concentration and reaction temperature on conversion were monitored. The experimental results proved that the photocatalytic oxidation process was not temperature sensitive and the optimum catalyst loading was found to be 0.4 g/l. Degradation and decolorization of humic acids have higher efficiency in acidic medium and at low initial humic acid concentration. The new catalyst was effective in removing TOC at 61.58% and color400 at 93.25% at 180 minutes illumination time and for 20 mg/l neutral humic acid aqueous solution. The kinetic analysis showed thatthe rate of photocatalytic degradation of humic acids obeyed the first order reaction kinetics. PMID:12578197

  1. Physical stability of spray dried solid dispersions of amorphous tolfenamic acid and polyvinylpyrolidone K30

    E-print Network

    Thybo, Pia

    2006-10-25

    PHYSICAL STABILITY OF SPRAY DRIED SOLID DISPERSIONS OF AMORPHOUS TOLFENAMIC ACID AND POLYVINYLPYRROLIDONE K-30 Pia Thybo The Danish University of Pharmaceutical Sciences Copenhagen, Denmark GPEN October 2006 Side 2 Pia Thybo The Danish University...

  2. Heterogeneous base catalysts for edible palm and non-edible Jatropha-based biodiesel production

    PubMed Central

    2014-01-01

    Background Transesterification catalyzed by solid base catalyst is a brilliant technology for the noble process featuring the fast reaction under mild reacting condition in biodiesel production. Heterogeneous base catalysts are generally more reactive than solid acid catalysts which require extreme operating condition for high conversion and biodiesel yield. In the present study, synthesis of biodiesel was studied by using edible (palm) or non-edible (Jatropha) feedstock catalyzed by heterogeneous base catalysts such as supported alkali metal (NaOH/Al2O3), alkaline-earth metal oxide (MgO, CaO and SrO) and mixed metal oxides catalysts (CaMgO and CaZnO). Results The chemical characteristic, textural properties, basicity profile and leaching test of synthesized catalysts were studied by using X-ray diffraction, BET measurement, TPD-CO2 and ICP-AES analysis, respectively. Transesterification activity of solid base catalysts showed that?>?90% of palm biodiesel and?>?80% of Jatropha biodiesel yield under 3 wt.% of catalyst, 3 h reaction time, methanol to oil ratio of 15:1 under 65°C. This indicated that other than physicochemical characteristic of catalysts; different types of natural oil greatly influence the catalytic reaction due to the presence of free fatty acids (FFAs). Conclusions Among the solid base catalysts, calcium based mixed metal oxides catalysts with binary metal system (CaMgO and CaZnO) showed capability to maintain the transesterification activity for 3 continuous runs at?~?80% yield. These catalysts render high durability characteristic in transesterification with low active metal leaching for several cycles. PMID:24812574

  3. Mechanisms of catalyst deactivation

    Microsoft Academic Search

    Calvin H Bartholomew

    2001-01-01

    The literature treating mechanisms of catalyst deactivation is reviewed. Intrinsic mechanisms of catalyst deactivation are many; nevertheless, they can be classified into six distinct types: (i) poisoning, (ii) fouling, (iii) thermal degradation, (iv) vapor compound formation accompanied by transport, (v) vapor-solid and\\/or solid-solid reactions, and (vi) attrition\\/crushing. As (i), (iv), and (v) are chemical in nature and (ii) and (v)

  4. Production of biodiesel from soapstock using an ion-exchange resin catalyst

    Microsoft Academic Search

    Ji-Yeon Park; Deog-Keun Kim; Zhong-Ming Wang; Joon-Pyo Lee; Soon-Chul Park; Jin-Suk Lee

    2008-01-01

    The feasibility of biodiesel production from soapstock containing high water content and fatty matters by a solid acid catalyst\\u000a was investigated. Soapstock was converted to high-acid acid oil (HAAO) by the hydrolysis by KOH and the acidulation by sulfuric\\u000a acid. The acid value of soapstock-HAAO increased to 199.1 mg KOH\\/g but a large amount of potassium sulfate was produced. To

  5. Encapsulation of ployunsaturated fatty acid esters with solid lipid particles

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Polyunsaturated fatty acids (PUFA) such as a-linolenic acid (ALA) and docosahexaenoic acid (DHA) are known to improve cardiovascular and nervous system health. These compounds are increasingly used in food and animal feed formulations. However, the high degree of unsaturation in these structures can...

  6. One-Pot Synthesis of Graphene-Supported Monodisperse Pd Nanoparticles as Catalyst for Formic Acid Electro-oxidation

    NASA Astrophysics Data System (ADS)

    Yang, Sudong; Dong, Jing; Yao, Zhaohui; Shen, Chengmin; Shi, Xuezhao; Tian, Yuan; Lin, Shaoxiong; Zhang, Xiaogang

    2014-03-01

    To synthesize monodisperse palladium nanoparticles dispersed on reduced graphene oxide (RGO) sheets, we have developed an easy and scalable solvothermal reduction method from an organic solution system. The RGO-supported palladium nanoparticles with a diameter of 3.8 nm are synthesized in N-methyl-2-pyrrolidone (NMP) and in the presence of oleylamine and trioctylphosphine, which facilitates simultaneous reduction of graphene oxide and formation of Pd nanocrystals. So-produced Pd/RGO was tested for potential use as electrocatalyst for the electro-oxidation of formic acid. Pd/RGO catalyzes formic acid oxidation very well compared to Pd/Vulcan XC-72 catalyst. This synthesis method is a new way to prepare excellent electrocatalysts, which is of great significance in energy-related catalysis.

  7. Development of acidity on sol-gel prepared TiO{sub 2}-SiO{sub 2} catalysts

    SciTech Connect

    Calvino, J.J.; Cauqui, M.A.; Gatica, J.M.; Perez, J.A.; Rodriguez-Izquierdo, J.M. [Univ. de Cadiz, Puerto Real (Spain)

    1994-12-31

    Three different TiO{sub 2}-SiO{sub 2} gels (Xerogel, Carbogel and Aerogel) are more active acid catalysts than other reference samples used here. As deduced from FTIR, XRD and XANES studies, the structural properties of these gels are quite different to each other, thus revealing the strong influence of the drying treatment. It is found that the degree of Si-O-Ti linking and the surface acidity follows the same trend (X > C > A). The authors conclude that supercritical drying at 600 K and 190 bars can induce Ti leaching followed by redeposition in the narrower pores of the gel. These effects modify both the textural and surface chemical properties of the resulting material.

  8. One-Pot Synthesis of Graphene-Supported Monodisperse Pd Nanoparticles as Catalyst for Formic Acid Electro-oxidation

    PubMed Central

    Yang, Sudong; Dong, Jing; Yao, Zhaohui; Shen, Chengmin; Shi, Xuezhao; Tian, Yuan; Lin, Shaoxiong; Zhang, Xiaogang

    2014-01-01

    To synthesize monodisperse palladium nanoparticles dispersed on reduced graphene oxide (RGO) sheets, we have developed an easy and scalable solvothermal reduction method from an organic solution system. The RGO-supported palladium nanoparticles with a diameter of 3.8?nm are synthesized in N-methyl-2-pyrrolidone (NMP) and in the presence of oleylamine and trioctylphosphine, which facilitates simultaneous reduction of graphene oxide and formation of Pd nanocrystals. So-produced Pd/RGO was tested for potential use as electrocatalyst for the electro-oxidation of formic acid. Pd/RGO catalyzes formic acid oxidation very well compared to Pd/Vulcan XC-72 catalyst. This synthesis method is a new way to prepare excellent electrocatalysts, which is of great significance in energy-related catalysis. PMID:24675779

  9. The Aerobic Oxidation of Bromide to Dibromine Catalyzed by Homogeneous Oxidation Catalysts and Initiated by Nitrate in Acetic Acid

    SciTech Connect

    Partenheimer, Walt; Fulton, John L.; Sorensen, Christina M.; Pham, Van Thai; Chen, Yongsheng

    2014-06-01

    A small amount of nitrate, ~0.002 molal, initiates the Co/Mn catalyzed aerobic oxidation of bromide compounds (HBr,NaBr,LiBr) to dibromine in acetic acid at room temperature. At temperatures 40oC or less , the reaction is autocatalytic. Co(II) and Mn(II) themselves and mixed with ionic bromide are known homogeneous oxidation catalysts. The reaction was discovered serendipitously when a Co/Br and Co/Mn/Br catalyst solution was prepared for the aerobic oxidation of methyaromatic compounds and the Co acetate contained a small amount of impurity i.e. nitrate. The reaction was characterized by IR, UV-VIS, MALDI and EXAFS spectroscopies and the coordination chemistry is described. The reaction is inhibited by water and its rate changed by pH. The change in these variables, as well as others, are identical to those observed during homogeneous, aerobic oxidation of akylaromatics. A mechanism is proposed. Accidental addition of a small amount of nitrate compound into a Co/Mn/Br/acetic acid mixture in a large, commercial feedtank is potentially dangerous.

  10. Biodiesel production by free fatty acid esterification using Lanthanum (La3+) and HZSM-5 based catalysts.

    PubMed

    Vieira, Sara S; Magriotis, Zuy M; Santos, Nadiene A V; Saczk, Adelir A; Hori, Carla E; Arroyo, Pedro A

    2013-04-01

    In this work the use of the heterogeneous catalysts pure (LO) and sulfated (SLO) lanthanum oxide, pure HZSM-5 and SLO/HZSM-5 (HZSM-5 impregnated with sulfated lanthanum oxide (SO4(2-)/La2O3)) was evaluated. The structural characterization of the materials (BET) showed that the sulfation process led to a reduction of the SLO and SLO/HZSM-5 surface area values. FTIR showed bands characteristic of the materials and, FTIR-pyridine indicated the presence of strong Brønsted sites on the sulfated material. In the catalytic tests the temperature was the parameter that most influenced the reactions. The best reaction conditions were: 10% catalyst, 100°C temperature and 1:5 m(OA)/m(meOH) for LO, SLO, SLO/HZSM-5 and 10% catalyst, 100°C temperature and 1:20 m(OA)/m(meOH) for HZSM-5. Under these conditions the conversions were: 67% and 96%, for LO and SLO, respectively and 80% and 100%, for HZSM-5 and SLO/HZSM-5, respectively. All catalysts deactivated after the first use, but the deactivation of SLO/HZSM-5 was smaller. PMID:23428822

  11. Electro-oxidation of methanol on platinum-organic metal complex mixed catalysts in acidic media.

    PubMed

    Okada, T; Suzuki, Y; Hirose, T; Toda, T; Ozawa, T

    2001-12-01

    Novel mixed catalysts systems have been developed using a platinum tetraammine complex with a cobalt or nickel quinolyldiamine complex supported on graphite powder and heart treated at 600 degrees C in argon atmosphere, for the methanol oxidation reaction in direct methanol fuel cells. PMID:12240030

  12. Acidity and catalytic activity of zeolite catalysts bound with silica and alumina 

    E-print Network

    Wu, Xianchun

    2004-09-30

    . Micropore surface area and micropore volume are reduced by about 19% and 18%, respectively, indicating some micropores of ZSM-5 are blocked on binding with silica. SiO2-bound ZSM-5 catalysts have less catalytic activity for butane transformation (cracking...

  13. Heteropoly Acids as Heterogeneous and Reusable Catalyst for ?-Thiocyanation of Ketones

    Microsoft Academic Search

    Atul C. Chaskar; Arun A. Yadav; Bhushan P. Langi; Anita Murugappan; Chetan Shah

    2010-01-01

    Simple, efficient, and mild method for ?-thiocyanation of ketones in presence of heteropolyacid has been developed. This methodology offered ?-oxothiocyanates in good to excellent yields at room temperature in a highly selective manner. The catalyst could be efficiently recovered from the reaction and reused.

  14. Synthetic Method for 2,2'-Disubstituted Fluorinated Binaphthyl Derivatives and Application as Chiral Source in Design of Chiral Mono-Phosphoric Acid Catalyst.

    PubMed

    Momiyama, Norie; Okamoto, Hiroshi; Shimizu, Masahiro; Terada, Masahiro

    2015-08-01

    A practical synthetic method for 2,2'-disubstituted fluorinated binaphthyl derivatives was achieved using magnesium bis(2,2,6,6-tetramethylpiperamide) [Mg(TMP)2 ], prepared from LiTMP (2 equiv) and MgBr2 (1 equiv), which allows for access to a variety of fluorinated binaphthyl compounds. The utility of the fluorinated binaphthyl backbone was evaluated in F10 BINOL derived chiral mono-phosphoric acid (R)- as the chiral Brønsted acid catalyst. The catalyst (R)- performs exceptionally well in the catalytic enantioselective imino-ene reaction, demonstrating the potential of a fluorinated binaphthyl framework. Chirality 27:464-475, 2015. © 2015 Wiley Periodicals, Inc. PMID:25665035

  15. Biodiesel fuel production with solid superacid catalysis in fixed bed reactor under atmospheric pressure

    Microsoft Academic Search

    Satoshi Furuta; Hiromi Matsuhashi; Kazushi Arata

    2004-01-01

    Solid superacid catalysts of sulfated tin and zirconium oxides and tungstated zirconia are prepared and evaluated in the trans-esterification of soybean oil with methanol at 200–300 °C and the esterification of n-octanoic acid with methanol at 175–200 °C. Tungstated zirconia–alumina is a promising solid acid catalyst for the production of biodiesel fuels from soybean oil because of its high performance

  16. Solid Phase Synthesis of Polyamides Containing Imidazole and Pyrrole Amino Acids

    E-print Network

    Dervan, Peter B.

    -methylpyrrole (Py) amino acids is described. Two monomer building blocks, Boc-Py-OBt ester and Boc-Im acid, are prepared on a 50 g scale without column chromatography. Using commercially available Boc- - alanine and machine-assisted Boc-chemistry solid phase synthesis of the pyrrole-imidazole polyamides which reduce

  17. Utilisation of fruits waste for citric acid production by solid state fermentation

    Microsoft Academic Search

    D. Kumar; V. K. Jain; G. Shanker; A. Srivastava

    2003-01-01

    A solid state fermentation method was used to utilise pineapple, mixed fruit and maosmi waste as substrates for citric acid production using Aspergillus niger DS 1. Experiments were carried out in the presence and absence of methanol at different moisture levels. In the absence of methanol the maximum citric acid was obtained at 60% moisture level whereas in the presence

  18. Analysis of solids resulted from dilute-acid pretreatment of lignocellulosic biomass

    Microsoft Academic Search

    T. Hsu; Q. Nguyen

    1995-01-01

    Lignocellulosic biomass materials were pretreated with dilute sulfuric acid, followed by analysis of partially and extensively washed pretreated solids. It is demonstrated that it is of crucial importance to perform extensive washing for accurate carbohydrate analyses to be obtained. Klason lignin, acid-soluble lignin, and ash analyses were not significantly affected by the extent of washing.

  19. Two-Stage Conversion of High Free Fatty Acid Jatropha curcas Oil to Biodiesel Using Brønsted Acidic Ionic Liquid and KOH as Catalysts

    PubMed Central

    Das, Subrata; Thakur, Ashim Jyoti; Deka, Dhanapati

    2014-01-01

    Biodiesel was produced from high free fatty acid (FFA) Jatropha curcas oil (JCO) by two-stage process in which esterification was performed by Brønsted acidic ionic liquid 1-(1-butylsulfonic)-3-methylimidazolium chloride ([BSMIM]Cl) followed by KOH catalyzed transesterification. Maximum FFA conversion of 93.9% was achieved and it reduced from 8.15?wt% to 0.49?wt% under the optimum reaction conditions of methanol oil molar ratio 12?:?1 and 10?wt% of ionic liquid catalyst at 70°C in 6?h. The ionic liquid catalyst was reusable up to four times of consecutive runs under the optimum reaction conditions. At the second stage, the esterified JCO was transesterified by using 1.3?wt% KOH and methanol oil molar ratio of 6?:?1 in 20?min at 64°C. The yield of the final biodiesel was found to be 98.6% as analyzed by NMR spectroscopy. Chemical composition of the final biodiesel was also determined by GC-MS analysis. PMID:24987726

  20. Synthesis, characterization and application of a nano-manganese-catalyst as an efficient solid catalyst for solvent free selective oxidation of ethylbenzene, cyclohexene, and benzylalcohol

    NASA Astrophysics Data System (ADS)

    Habibi, Davood; Faraji, Ali Reza

    2013-07-01

    The object of this study is to synthesize the heterogeneous Mn-nano-catalyst (MNC) which has been covalently anchored on a modified nanoscaleSiO2/Al2O3, and characterized by FT-IR, UV-Vis, CHN elemental analysis, EDS, TEM, and EDX. The method is efficient for the highly selective oxidation of ethylbenzene, cyclohexene, and benzylalcohol without the need to any solvents, using tert-butyl hydroperoxide (TBHP) as an oxidant. Oxidation of ethylbenzene, cyclohexene, and benzylalcohol gave acetophenone, 2-cyclohexene-1-one and benzaldehyde, respectively, as major products. Reaction conditions have been optimized by considering the effect of various factors such as reaction time, amounts of substrates and oxidant, Mn-nano-catalyst and application of various solvents.

  1. Simultaneous determination of gibberellic acid, indole-3-acetic acid and abscisic acid in wheat extracts by solid-phase extraction and liquid chromatography–electrospray tandem mass spectrometry

    Microsoft Academic Search

    Shengjie Hou; Jiang Zhu; Mingyu Ding; Guohua Lv

    2008-01-01

    A liquid chromatography–tandem mass spectrometry (LC–MS\\/MS) method was developed for simultaneous determination of three representative phytohormones in plant samples: gibberellic acid (GA3), indole-3-acetic acid (IAA) and abscisic acid (ABA). A solid-phase extraction (SPE) pretreatment method was used to concentrate and purify the three phytohormones of different groups from plant samples. The separation was carried out on a C18 reversed-phase column,

  2. Clay Minerals as Solid Acids and Their Catalytic Properties.

    ERIC Educational Resources Information Center

    Helsen, J.

    1982-01-01

    Discusses catalytic properties of clays, attributed to acidity of the clay surface. The formation of carbonium ions on montmorillonite is used as a demonstration of the presence of surface acidity, the enhanced dissociation of water molecules when polarized by cations, and the way the surface can interact with organic substances. (Author/JN)

  3. Tandem decarboxylative hydroformylation-hydrogenation reaction of ?,?-unsaturated carboxylic acids toward aliphatic alcohols under mild conditions employing a supramolecular catalyst system.

    PubMed

    Diab, Lisa; Gellrich, Urs; Breit, Bernhard

    2013-10-28

    A new atom economic catalytic method for a highly chemoselective reduction of ?,?-unsaturated carboxylic acids to the corresponding saturated alcohols under mild reaction conditions, compatible with a wide range reactive functional groups, is reported. The new methodology consists of a novel tandem decarboxylative hydroformylation/aldehyde reduction sequence employing a unique supramolecular catalyst system. PMID:24022335

  4. Stable and catalytically active iron porphyrin-based porous organic polymer: Activity as both a redox and Lewis acid catalyst

    PubMed Central

    Oveisi, Ali R.; Zhang, Kainan; Khorramabadi-zad, Ahmad; Farha, Omar K.; Hupp, Joseph T.

    2015-01-01

    A new porphyrin-based porous organic polymer (POP) with BET surface area ranging from 780 to 880?m2/g was synthesized in free-base form via the reaction of meso-tetrakis(pentafluorophenyl) porphyrin and a rigid trigonal building block, hexahydroxytriphenylene. The material was then metallated with Fe(III) imparting activity for Lewis acid catalysis (regioselective methanolysis ring-opening of styrene oxide), oxidative cyclization catalysis (conversion of bis(2-hydroxy-1-naphthyl)methanes to the corresponding spirodienone), and a tandem catalytic processes: an in situ oxidation-cyclic aminal formation-oxidation sequence, which selectively converts benzyl alcohol to 2-phenyl-quinazolin-4(3H)-one. Notably, the catalyst is readily recoverable and reusable, with little loss in catalytic activity. PMID:26177563

  5. Stable and catalytically active iron porphyrin-based porous organic polymer: Activity as both a redox and Lewis acid catalyst.

    PubMed

    Oveisi, Ali R; Zhang, Kainan; Khorramabadi-Zad, Ahmad; Farha, Omar K; Hupp, Joseph T

    2015-01-01

    A new porphyrin-based porous organic polymer (POP) with BET surface area ranging from 780 to 880?m(2)/g was synthesized in free-base form via the reaction of meso-tetrakis(pentafluorophenyl) porphyrin and a rigid trigonal building block, hexahydroxytriphenylene. The material was then metallated with Fe(III) imparting activity for Lewis acid catalysis (regioselective methanolysis ring-opening of styrene oxide), oxidative cyclization catalysis (conversion of bis(2-hydroxy-1-naphthyl)methanes to the corresponding spirodienone), and a tandem catalytic processes: an in situ oxidation-cyclic aminal formation-oxidation sequence, which selectively converts benzyl alcohol to 2-phenyl-quinazolin-4(3H)-one. Notably, the catalyst is readily recoverable and reusable, with little loss in catalytic activity. PMID:26177563

  6. Reforming of raw fuel gas from biomass gasification to syngas over highly stable nickel–magnesium solid solution catalysts

    Microsoft Academic Search

    Tiejun Wang; Jie Chang; Xiaoqin Cui; Qi Zhang; Yan Fu

    2006-01-01

    The gasification of biomass to obtain a syngas provides a competitive means for clean energy from renewable resources. The feasibility of the process depends on the performance of catalyst for upgrading of the raw fuel gas from gasifier. The highly stable NiO–MgO catalyst (Ni\\/(Ni+Mg)=15, atomic ratio) was prepared by co-precipitation method for the reforming of raw fuel gas. Its performance

  7. Evaluating chemical degradation of proton conducting perfluorosulfonic acid ionomers in a Fenton test by solid-state 19F NMR spectroscopy

    NASA Astrophysics Data System (ADS)

    Ghassemzadeh, L.; Kreuer, K. D.; Maier, J.; Müller, K.

    2011-03-01

    Chemical degradation and stability of perfluorosulfonic acid (PFSA) ionomers against radical attack were investigated by an (ex situ) Fenton test. Solid-state and solution NMR as well as ATR-FTIR studies were performed on the samples before and after the Fenton reaction. By changing the concentration of the Fenton's solution it is found that the metallic catalyst (Fe2+) is a critical factor which may affect the solid-state NMR results. After adjusting the experimental conditions, i.e., by reducing the Fe2+ concentration, it was possible to detect by solid-state 19F NMR spectroscopy the structural changes of the perfluorosulfonic acid ionomers during the ex situ Fenton test. A comparative study was made on the degradation of Nafion and Hyflon Ion membranes which differ in the length of the side chains. It is shown that the Hyflon Ion membrane with shorter side chains is more stable against side chain attack, most probably because of the absence of an additional tertiary carbon in the side chain. At the same time, there is evidence for enhanced main chain degradation in membranes with unprotected backbone chain ends.

  8. Direct synthesis of H 2O 2 from H 2 and O 2 over Pd\\/H-beta catalyst in an aqueous acidic medium: Influence of halide ions present in the catalyst or reaction medium on H 2O 2 formation

    Microsoft Academic Search

    Chanchal Samanta; Vasant R. Choudhary

    2007-01-01

    The influence of different halide ions present in the catalyst or reaction medium on the performance of Pd\\/H-beta catalyst in the direct H2O2 synthesis in an aqueous acidic (0.03M H3PO4) reaction medium at 27°C and atmospheric pressure has been thoroughly investigated. The results showed a strong influence of both the bulk Pd oxidation state in the catalyst and the halide

  9. A simple, efficient and environmentally benign synthetic protocol for the synthesis of spirooxindoles using choline chloride-oxalic acid eutectic mixture as catalyst/solvent system.

    PubMed

    Khandelwal, Sarita; Rajawat, Anshu; Tailor, Yogesh Kumar; Kumar, Mahendra

    2014-01-01

    An efficient and environmentally benign domino protocol has been presented for the synthesis of structurally diverse spirooxindoles spiroannulated with pyranopyridopyrimidines, indenopyridopyrimidines, and chromenopyridopyrimidines involving three-component reaction of aminouracils, isatins and cyclic carbonyl compounds in deep eutectic solvent (choline chloride-oxalic acid: 1:1) which acts as efficient catalyst and environmentally benign reaction medium. The present protocol offers several advantages such as operational simplicity with easy workup, shorter reaction times excellent yields with superior atom economy and environmentally benign reaction conditions with the use of cost-effective, recyclable, non-toxic and bio-degradable DES as catalyst/solvent. PMID:25329839

  10. Selective Oxidation of 1,6-Hexanediol to 6-Hydroxycaproic Acid over Reusable Hydrotalcite-Supported Au-Pd Bimetallic Catalysts.

    PubMed

    Tuteja, Jaya; Nishimura, Shun; Choudhary, Hemant; Ebitani, Kohki

    2015-06-01

    Selective oxidation of 1,6-hexanediol into 6-hydroxycaproic acid was achieved over hydrotalcite-supported Au-Pd bimetallic nanoparticles as heterogeneous catalyst using aqueous H2 O2 . N,N-dimethyldodecylamine N-oxide (DDAO) was used as an efficient capping agent. Spectroscopic analyses by UV/Vis, TEM, XPS, and X-ray absorption spectroscopy suggested that interactions between gold and palladium atoms are responsible for the high activity of the reusable Au40 Pd60 -DDAO/HT catalyst. PMID:25990616

  11. Liquefaction with microencapsulated catalysts

    DOEpatents

    Weller, Sol W. (Williamsville, NY)

    1985-01-01

    A method of dispersing a liquefaction catalyst within coal or other carbonaceous solids involves providing a suspension in oil of microcapsules containing the catalyst. An aqueous solution of a catalytic metal salt is emulsified in the water-immiscible oil and the resulting minute droplets microencapsulated in polymeric shells by interfacial polycondensation. The catalyst is subsequently blended and dispersed throughout the powdered carbonaceous material to be liquefied. At liquefaction temperatures the polymeric microcapsules are destroyed and the catalyst converted to minute crystallites in intimate contact with the carbonaceous material.

  12. Design of an effective bifunctional catalyst organotriphosphonic acid-functionalized ferric alginate (ATMP-FA) and optimization by Box-Behnken model for biodiesel esterification synthesis of oleic acid over ATMP-FA.

    PubMed

    Liu, Wei; Yin, Ping; Liu, Xiguang; Qu, Rongjun

    2014-12-01

    Biodiesel production has become an intense research area because of rapidly depleting energy reserves and increasing petroleum prices together with environmental concerns. This paper focused on the optimization of the catalytic performance in the esterification reaction of oleic acid for biodiesel production over the bifunctional catalyst organotriphosphonic acid-functionalized ferric alginate ATMP-FA. The reaction parameters including catalyst amount, ethanol to oleic acid molar ratio and reaction temperature have been optimized by response surface methodology (RSM) using the Box-Behnken model. It was found that the reaction temperature was the most significant factor, and the best conversion ratio of oleic acid could reach 93.17% under the reaction conditions with 9.53% of catalyst amount and 8.62:1 of ethanol to oleic acid molar ratio at 91.0 °C. The research results show that two catalytic species could work cooperatively to promote the esterification reaction, and the bifunctional ATMP-FA is a potential catalyst for biodiesel production. PMID:25310862

  13. The performance of perovskites and spinels as catalysts for oxygen reduction in solid oxide fuel cell cathodes

    NASA Astrophysics Data System (ADS)

    Martin, Boris E.

    The lack of understanding of the catalytic process at the state-of-the-art cathode material surface in solid oxide fuel cells, (La0.8Sr 0.2)0.98MnO3+delta (LSM), has hindered the design of better catalysts. The objectives of this study were to design a system enabling the comparison of catalytic activities of different cathode materials independently of morphological factors, as well as to resolve catalytic processes at the LSM surface. The selection and optimization of potential cathode materials were performed on the basis of thermal expansion, four-probe dc-conductivity and thermoelectric power measurements in air. The materials studied as potential cathodes were tungsten, niobium and molybdenum doped barium cobaltite perovskites, copper manganese, cobalt manganese and cobalt ferrite spinels as well as strontium doped lanthanum cobalt ferrites and lanthanum manganite perovskites. The doped barium cobaltites were found lo offer superior electrical conductivity when octahedral site transition metal average valence was mixed 3+ /4+ compared to mixed 2+/3+. On the other hand, the loss of conductivity associated with octahedral site doping rendered these materials inadequate for solid oxide fuel cells (SOFC) cathode applications. Copper manganese spMd was found to exhibit electrical conductivity as high as ˜200 S.cm-1 at 1073 K and thermal expansion ˜ 11 ppm/K between 298 K and 1200 K. Thermal and chrono-potentiometric studies were used to determine the oxygen diffusivity, in cobalt and strontium doped lanthanum iron perovskites (LSCF), and revealed that the activation of strontium doped lanthanum manganese perovskites (LSM) under cathodic bias is kinetically limited by its rate of oxygen surface exchange, suggesting that the cathodic activation of LSM is due to its change in oxygen content under bias. The electronic defect structure of the cubic spinels was resolved in a defect reaction model involving the thermally activated redox of Cu + and Mn4+ to Cu2+ and Mn3+, as well as the disproportionation of Jahn-Teller ion Mn3+ into Mn2+ and Mn4+ and demonstrated that copper doping enhanced the amount of Mn4+ on octahedral sites. Cyclic voltammetry and potential-dependent electrochemical impedance spectroscopy studies of dense (La0.8Sr0.2)0.98MnO3+delta polycrystalline films revealed that the rate determining step in the oxygen reduction reaction, in the conditions of our study was the first charge transfer between oxygen ad-atoms and octahedral manganese III, as described by (S)Oad + MnxMn?O -adS +Mn•Mn. The catalytic activity of CuzMn3-- zO4 cubic spinets was found superior to that of LSM and of stoichiometrie CoFe2O4 and Co2MnO 4 spinal at intermediate temperature, suggesting that the Mn 3+/Mn4+ redox couple on octahedral sites plays a major role in the catalysis of the oxygen reduction reaction on those transition metal oxide surfaces.

  14. CONDENSED MATTER: STRUCTURE, MECHANICAL AND THERMAL PROPERTIES: Electro-oxidation of Formic Acid on Carbon Supported Edge-Truncated Cubic Platinum Nanoparticles Catalysts

    NASA Astrophysics Data System (ADS)

    Li, She-Qiang; Fu, Xing-Qiu; Hu, Bing; Deng, Jia-Jun; Chen, Lei

    2009-11-01

    The oxidation of formic acid on edge-truncated cubic platinum nanoparticles/C catalysts is investigated. X-ray photoelectron spectroscopy analysis indicates that the surface of edge-truncated cubic platinum nanoparticles is composed of two types of coordination sites. The oxidation behavior of formic acid on edge-truncated cubic platinum nanoparticles/C is investigated using cyclic voltammetry. The apparent activation energies are found to be 54.2, 55.0, 61.8, 69.5, 71.9, 69.26, 65.28kJ/mol at 0.15, 0.3, 0.4, 0.5, 0.6, 0.65, 0.7V, respectively. A specific surface area activity of 1.76 mA·cm-2 at 0.4 V indicates that the edge-truncated cubic Platinum nanoparticles are a promising anode catalyst for direct formic acid fuel cells.

  15. Direct synthesis of H 2O 2 from H 2 and O 2 and decomposition\\/hydrogenation of H 2O 2 in an aqueous acidic medium over halide-modified Pd\\/Al 2O 3 catalysts

    Microsoft Academic Search

    Chanchal Samanta; Vasant R. Choudhary

    2007-01-01

    Direct synthesis of H2O2 from its elements was carried out in an acidic aqueous reaction medium over halide-modified oxidized and reduced Pd\\/Al2O3 catalysts under very mild conditions (at 27°C and atmospheric pressure). The halide ions were introduced into the catalyst by incorporating halide ions into supported Pd\\/?-Al2O3 catalyst or via depositing halide ions on the support (?-Al2O3) prior to Pd

  16. Hydrogen production from steam reforming of ethanol with nano-Ni\\/SiO 2 catalysts prepared at different Ni to citric acid ratios using a sol–gel method

    Microsoft Academic Search

    Chunfei Wu; Paul T. Williams

    2011-01-01

    Steam reforming of ethanol to produce hydrogen was carried out using a two-stage reaction system with several nano-Ni\\/SiO2 catalysts prepared at different citric acid (CA) contents using the sol–gel process. The fresh (non-calcined and calcined) catalysts and the reacted catalysts were analysed using surface area and pore size analysis, Fourier-transform infrared (FTIR) spectroscopy, thermo-gravimetry analysis (TGA), scanning electron microscopy (SEM)

  17. Anaerobic degradation of phthalic acid esters during digestion of municipal solid waste under landfilling conditions

    Microsoft Academic Search

    J. Ejlertsson; U. Meyerson; B. H. Svensson

    1996-01-01

    Anaerobic microorganisms in municipal solid waste samples from laboratory-scale landfill reactors and a pilot-plant biogas digestor were investigated with the aim of assessing their ability to transform four commercially used phthalic acid esters (PAEs) and phthalic acid (PA). The PAEs studied were diethyl phthalate (DEP), butylbenzyl phthalate (BBP), dibutyl phthalate (DBP) and bis(2-ethylhexyl) phthalate (DEHP). No biological transformation of DEHP

  18. Nano-Tribological and Wear Behavior of Boric Acid Solid Lubricant©

    Microsoft Academic Search

    S. Mirmiran; Vladimir V. Tsukruk; Ali Erdemir

    1999-01-01

    One uses atomic force microscopy to explore the surface morphology, frictional characteristics (i.e., friction mapping) and surface adhesive forces of boric acid-treated aluminum surfaces. In earlier studies, boric acid was shown to be an effective solid lubricant providing 0.02 to 0.1 friction coefficients to the sliding surfaces of metallic and ceramic materials. In this study, the authors mainly focused on

  19. Pineapple waste - a novel substrate for citric acid production by solid-state fermentation

    Microsoft Academic Search

    Chau T. Tran; David A. Mitchell

    1995-01-01

    Citric acid production in solid-state fermentation by Aspergillus foetidus ACM3996 was better on pineapple waste than on apple pomace, wheat bran or rice bran. The highest citric acid content achieved on pineapple waste was 16.1 g per 100 g dried pineapple waste, with a moisture content of 70% and in the presence of 3% methanol. This represents a yield of

  20. Optimization of mycophenolic acid production in solid state fermentation using response surface methodology

    Microsoft Academic Search

    A K Sadhukhan; MV Ramana Murthy; R Ajaya Kumar; E V S Mohan; G Vandana; C Bhar; K Venkateswara Rao

    1999-01-01

      Mycophenolic acid (MPA) can be produced in solid state fermentation. An isolate of Penicillium brevi-compactum ATCC 16024 grown on moist wheat bran produced a titre of 425?mg per kg of wheat bran. Central composite rotatable design\\u000a and response surface methodology were employed to derive a statistical model for media optimization towards production of\\u000a mycophenolic acid. Five levels with a five

  1. Unique properties of silver cations in solid-acid catalysis by zeolites and heteropolyacids.

    PubMed

    Ono, Yoshio; Baba, Toshihide

    2015-06-28

    Ag(+)-exchanged zeolites exhibit unique catalytic properties caused by the combination of their redox and acidic properties. Partial reduction of Ag(+) ions in zeolites with hydrogen leads to the formation of acidic protons and silver metal particles, which can be observed using X-ray powder diffraction patterns (XRD). By simply evacuating hydrogen from the system, the silver metal particles are returned back to Ag(+) ions and at the same time, acidic protons are eliminated. This interconversion of Ag(+) ions and silver metal or gaseous hydrogen and surface protons is reflexed in the catalytic activities of Ag(+)-exchanged zeolites for acid-catalyzed reactions: the activity of Ag(+)-exchanged Y zeolite (Ag-Y) reversibly changes with the partial pressure of hydrogen. Furthermore, the activity of Ag-Y in the presence of hydrogen is higher than that of H(+)-exchanged Y zeolite (H-Y). Similar phenomena are also observed for the silver salt of dodecatungstophosphoric acid (Ag3PW12O40). Ag(+)-exchanged ZSM-5 zeolite (Ag-ZSM-5) is a very selective catalyst for aromatization of alkanes, alkenes and methanol. Examination of the activation step of lower alkanes revealed that Ag(+) ions dramatically enhance the dehydrogenation of the alkanes via heterolytic dissociation of the alkanes into carbenium ions and hydride species. Ag(+)-exchanged zeolites can also activate methane. The reaction of methane with ethene and benzene gives propene and toluene, respectively. Ag-ZSM-5 is a very stable catalyst under hydrothermal conditions because of the interconversion properties of Ag(+) ions and silver metal in the zeolite. PMID:26018842

  2. Structural and electrochemical characterization of carbon supported Pt-Pr catalysts for direct ethanol fuel cells prepared using a modified formic acid method in a CO atmosphere.

    PubMed

    Corradini, Patricia Gon; Antolini, Ermete; Perez, Joelma

    2013-07-28

    Pt-Pr/C electrocatalysts were prepared using a modified formic acid method, and their activity for carbon monoxide and ethanol oxidation was compared to Pt/C. No appreciable alloy formation was detected by XRD analysis. By TEM measurements it was found that Pt particle size increases with an increasing Pr content in the catalysts and with decreasing metal precursor addition time. XPS measurements indicated Pt segregation on the catalyst surface and the presence of Pr2O3 and PrO2 oxides. The addition of Pr increased the electro-catalytic activity of Pt for both CO and CH3CH2OH oxidation. The enhanced activity of Pt-Pr/C catalysts was ascribed to both an electronic effect, caused by the presence of Pr2O3, and the bi-functional mechanism, caused by the presence of PrO2. PMID:23752757

  3. Solid-State 17O NMR Study of Benzoic Acid Adsorption On Metal Oxide Surfaces

    SciTech Connect

    Hagaman, Edward {Ed} W [ORNL; Chen, Banghao [ORNL; Jiao, Jian [ORNL; Parsons, Williams [Oak Ridge National Laboratory (ORNL)

    2012-01-01

    Solid-state 17O NMR spectra of 17O-labeled benzoic and anisic acids are reported and benzoic acid is used to probe the surface of metal oxides. Complexes formed when benzoic acid is dry-mixed with mesoporous silica, and nonporous titania and alumina are characterized. Chemical reactions with silica are not observed. The nature of benzoic acid on silica is a function of the water content of the oxide. The acid disperses in the pores of the silica if the silica is in equilibrium with ambient laboratory humidity. The acid displays high mobility as evidenced by a liquid-like, Lorentzian resonance. Excess benzoic acid remains as the crystalline hydrogen-bonded dimer. Benzoic acid reacts with titania and alumina surfaces in equilibrium with laboratory air to form the corresponding titanium and aluminum benzoates. In both materials the oxygen of the 17O-labeled acid is bound to the metal, showing the reaction proceeds by bond formation between oxygen deficient metal sites and the oxygen of the carboxylic acid. 27Al MAS NMR confirms this mechanism for the reaction on alumina. Dry mixing of benzoic acid with alumina rapidly quenches pentacoordinate aluminum sites, excellent evidence that these sites are confined to the surface of the alumina particles.

  4. Enhanced production of ganoderic acids and cytotoxicity of Ganoderma lucidum using solid-medium culture.

    PubMed

    You, Bang-Jau; Lee, Hong-Zin; Chung, Kuang-Ren; Lee, Miin-Huey; Huang, Mei-Jung; Tien, Ni; Chan, Chiao-Wei; Kuo, Yueh-Hsiung

    2012-01-01

    Submerged cultures of Ganoderma lucidum are used to produce fungal mycelium, which is used as a functional food and in the production of various triterpenoids, including ganoderic acids (GAs). Specific culture approaches that produce fungal mycelium with high levels of GAs and good biological activity are critical in the functional food industry. In this study, a solid-medium culture approach to producing mycelium was compared to the submerged culture system. Production of GAs, biomass, intracellular polysaccharides, and cytotoxicity of the cultured mycelium were compared as between solid and submerged culture. Growing G. lucidum strains on solid potato dextrose agar medium increased biomass, the production of ganoderic acid 24 (lanosta-7,9(11), 24-trien-3?-o1-26-oic acid), GAs, and total intracellular polysaccharides as compared to fungi grown in submerged culture. Triterpenoid-enriched methanol extracts of mycelium from solid-medium culture showed higher cytotoxicity than those from submerged culture. The IC(50) values of methanol extracts from solid-medium culture were 11.5, 8.6, and 9.9 times less than submerged culture on human lung cancer cells CH27, melanoma cells M21, and oral cancer cells HSC-3 respectively. The squalene synthase and lanosterol synthase coding genes had higher expression on the culture of solid potato dextrose medium. This is the first report that solid-medium culture is able to increase GA production significantly as compared to submerged culture and, in the process, produces much higher biological activity. This indicates that it may be possible to enhance the production of GAs by implementing mycelium culture on solid medium. PMID:22878212

  5. Carbon fiber cloth supported Au nano-textile fabrics as an efficient catalyst for hydrogen peroxide electroreduction in acid medium

    NASA Astrophysics Data System (ADS)

    Yang, Fan; Cheng, Kui; Wang, Guiling; Cao, Dianxue

    2015-09-01

    The size-controlled hierarchical textile-like Au nanostructures supported carbon fiber cloth (Au NTs/CFC) is successfully fabricated through a simple low-cost electrochemical route. The electrodes are characterised by scanning electron microscopy equipped with an energy dispersive X-ray spectrometer, transmission electron microscopy and X-ray diffractometer. Without any conducting carbons and polymer binders, the 3D electrode with unique structure is directly used as the electrocatalyst for H2O2 reduction in acid solution and the catalytic performance is evaluated by voltammetry and chronoamperometry. The Au NTs/CFC electrode exhibits much higher catalytic activity and remarkably improved utilization of Au than Au nanoparticles (Au NPs/CFC) prepared by the same method owing to its unique structure. In the solution of 3.0 mol L-1 H2SO4 + 0.1 mol L-1 H2O2, with the reduction potential of 0 V, the current of -0.72 A cm-2 mg-1 can be obtained on Au NTs/CFC electrode and only a current of -0.09 A cm-2 mg-1 can be achieved on Au NPs/CFC electrode. All these results reveal that the novel Au NTs/CFC electrode exhibits excellent catalytic performance and superior stability for H2O2 electroreduction in acid medium, benefitting from the unique 3D structure which can ensure high utilization of catalyst.

  6. 3D-nanoarchitectured Pd/Ni catalysts prepared by atomic layer deposition for the electrooxidation of formic acid.

    PubMed

    Assaud, Loïc; Monyoncho, Evans; Pitzschel, Kristina; Allagui, Anis; Petit, Matthieu; Hanbücken, Margrit; Baranova, Elena A; Santinacci, Lionel

    2014-01-01

    Three-dimensionally (3D) nanoarchitectured palladium/nickel (Pd/Ni) catalysts, which were prepared by atomic layer deposition (ALD) on high-aspect-ratio nanoporous alumina templates are investigated with regard to the electrooxidation of formic acid in an acidic medium (0.5 M H2SO4). Both deposition processes, Ni and Pd, with various mass content ratios have been continuously monitored by using a quartz crystal microbalance. The morphology of the Pd/Ni systems has been studied by electron microscopy and shows a homogeneous deposition of granularly structured Pd onto the Ni substrate. X-ray diffraction analysis performed on Ni and NiO substrates revealed an amorphous structure, while the Pd coating crystallized into a fcc lattice with a preferential orientation along the [220]-direction. Surface chemistry analysis by X-ray photoelectron spectroscopy showed both metallic and oxide contributions for the Ni and Pd deposits. Cyclic voltammetry of the Pd/Ni nanocatalysts revealed that the electrooxidation of HCOOH proceeds through the direct dehydrogenation mechanism with the formation of active intermediates. High catalytic activities are measured for low masses of Pd coatings that were generated by a low number of ALD cycles, probably because of the cluster size effect, electronic interactions between Pd and Ni, or diffusion effects. PMID:24605281

  7. Production of acrolein from glycerol over silica-supported heteropoly acids

    Microsoft Academic Search

    Eriko Tsukuda; Satoshi Sato; Ryoji Takahashi; Toshiaki Sodesawa

    2007-01-01

    Dehydration of glycerol to produce acrolein was performed over several solid acids. Supported heteropoly acids were effective as a catalyst for the dehydration of glycerol. The catalytic activity depended on the types of heteropoly acid and on the size of the mesopores in the silica support. Silicotungstic acid supported on silica with mesopores of 10nm showed the highest catalytic activity

  8. Perrhenic acid as catalyst for hydrosilylation of aldehydes and ketones and dehydrogenative silylation of alcohols

    Microsoft Academic Search

    Patr?´cia M. Reis; Beatriz Royo

    2007-01-01

    Hydrosilylation of aldehydes and ketones with dimethylphenylsilane was catalyzed by perrhenic acid, HReO4, to give silylated ethers in good yields. These hydrosilylation reactions appear to be radical processes, since they were inhibited in the presence of 5,5-dimethyl-4,5-dihydro-3H-pyrrole-N-oxide (DMPO) and Ph2NH, two well-known radical scavengers. Perrhenic acid also catalyzes the dehydrogenative silylation of alcohols in neat conditions at 25°C. It is

  9. Topologically unique heterometallic Cu(II)/Li coordination polymers self-assembled from N,N-bis(2-hydroxyethyl)-2-aminoethanesulfonic acid biobuffer: versatile catalyst precursors for mild hydrocarboxylation of alkanes to carboxylic acids.

    PubMed

    Kirillova, Marina V; Kirillov, Alexander M; Martins, André N C; Graiff, Claudia; Tiripicchio, Antonio; Pombeiro, Armando J L

    2012-05-01

    The facile aqueous medium reactions of copper(II) nitrate with BES biobuffer [(HOCH(2)CH(2))(2)N(CH(2)CH(2)SO(3)H), hereinafter referred as H(3)bes] in the presence of various benzenecarboxylic acids [benzoic (Hba), 3-hydroxybenzoic (Hhba), and 3,5-dihydroxybenzoic (Hdhba) acid] and lithium hydroxide gave rise to the self-assembly generation of three new heterometallic Cu(II)/Li materials, [Li(H(2)O)(4)][Cu(4)(?(2)-Hbes)(4)(?(2)-ba)]·H(2)O (1) and [Cu(4)(?(3)-Hbes)(4)(L){Li(H(2)O)(2)}](n)·3nH(2)O {L = ?(2)-hba (2) and ?(2)-dhba (3)}. They were isolated as air-stable crystalline solids and fully characterized by infrared (IR) and UV-vis spectroscopy and electrospray ionization (ESI)-MS(±), elemental, thermal, and single-crystal X-ray diffraction analyses. The latter revealed that 1-3 have comparable packing patterns and unit cell parameters, being composed of similar [Cu(4)(?-Hbes)(4)(?-carboxylate)](-) cores and [Li(H(2)O)(4)](+) cations (in 1) or [?-Li(H(2)O)(2)](+) groups (in 2 and 3), which are arranged into discrete 0D aggregates in 1 or infinite 3D noninterpenetrating metal-organic networks in 2 and 3. The topological analysis of the coordination polymers 2 and 3 disclosed the trinodal 3,3,4-connected underlying nets with an unprecedented topology defined by the point symbol of (4.6.8)(4)(4(2).6)(2)(6(2).16(2).18(2)), further simplification of which resulted in the binodal 4,4-connected nets with the pts (PtS) topology. Apart from representing very rare examples of coordination compounds derived from H(3)bes, 1-3 feature solubility in water and were applied as efficient and versatile catalyst precursors for the mild (60 °C) single-pot hydrocarboxylation, by CO and H(2)O, of various gaseous, linear, and cyclic C(n) (n = 2-9) alkanes into the corresponding C(n+1) carboxylic acids, in H(2)O/MeCN medium under homogeneous conditions and in the presence of potassium peroxodisulfate. Total yields (based on alkane) of carboxylic acids up to 78% were achieved, which are remarkable in the field of alkane functionalization under mild conditions, especially for a C-C bond formation reaction in aqueous acid-solvent-free medium. PMID:22482365

  10. Reaction Kinetics and Intermediate Determination of Solid Acid Catalysed Liquid-phase Hydrolysis Reactions: A Real-time in situ ATR FT-IR Study

    Microsoft Academic Search

    Gerben M. Hamminga; Guido Mul; Jacob A. Moulijn

    2006-01-01

    The appearance of catalyst–reactant interactions observed in on-line ATR FT-IR spectra of Nafion\\/silica catalysed esterification\\u000a and etherification reactions of 1-octanol was investigated. It was assessed by variation of catalyst and solvent that the\\u000a catalyst–reactant band is a result of the reaction of silica with 1-octanol, yields Si–O–R functionalities. Based on off-line\\u000a TPD-MS and TGA characterisation of the used solid catalyst

  11. Vibrational spectroscopic study on polymorphism of erucic acid and palmitoleic acid: ?1??1 and ??? reversible solid state phase transitions

    NASA Astrophysics Data System (ADS)

    Kaneko, Fumitoshi; Yamazaki, Kazuhiro; Kobayashi, Masamichi; Sato, Kiyotaka; Suzuki, Masao

    1994-08-01

    The infrared and Raman spectra of four polymorphic phases (?, ?1, ? and ?1) of erucic acid ( cis-13-docosenoic acid) and those of two polymorphic phases (? and ?) of palmitoleic acid ( cis-9-hexadecenoic acid) were investigated. The ? and ?1 phases of erucic acid were analyzed on the basis of crystal structures determined by us. There were large spectral differences between ? and ?1 phases, which could be ascribed to the differences in the conformation of cis-olefin groups and the subcell structure. Two types of reversible solid state phase transitions (??? and ?1??1 transitions) were followed by the infrared and Raman spectra. It was concluded that the mechanism of the ??? phase transition of erucic and palmitoleic acids is essentially the same as that of oleic acid previously reported by us [ J. Phys. Chem.90, 6371 (1986)], i.e. this phase transition is of order-disorder type accompanied by a conformational disordering at the methyl-terminal chain. Spectral changes on the ?1??1 transition suggested that a similar structural change took place during this transition but there were large structural differences between ? and ?1.

  12. Solid acid proton conductors: from laboratory curiosities to fuel cell electrolytes

    E-print Network

    Solid acid proton conductors: from laboratory curiosities to fuel cell electrolytes Sossina M cells, in which a composite mixture of the electrolyte, Pt supported on carbon, Pt black and carbon of 100 mV at 100 mA cmÀ2 . Thus, for fuel cells in which the supported electrolyte membrane was only 25

  13. New materials for solar thermal storage—solid\\/liquid transitions in fatty acid esters

    Microsoft Academic Search

    R Nikoli?; M Marinovi?-Cincovi?; S Gadžuri?; I. J Zsigrai

    2003-01-01

    Solid\\/liquid transitions were studied by DSC measurements in the following fatty acid esters: methyl stearate, methyl palmitate, cetyl stearate, cetyl palmitate and their binary mixtures. Four systems, with phase transition temperature close to room temperature and with high enthalpy of transition and low hysteresis, were selected for further studies relevant to passive solar thermal storage. The selected systems were: methyl

  14. Relationship of soluble solids, acidity and aroma volatiles to flavor in late-season navel oranges

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Navel orange flavor development during early fruit maturation is strongly dependent on changes in soluble solids concentration (SSC) and titratable acidity (TA), while later in the season other factors, such as aroma volatiles, also become important. The flavor of individual oranges can differ gre...

  15. Solid state and sub-cooled liquid vapour pressures of cyclic aliphatic dicarboxylic acids

    NASA Astrophysics Data System (ADS)

    Booth, A. M.; Montague, W. J.; Barley, M. H.; Topping, D. O.; McFiggans, G.; Garforth, A.; Percival, C. J.

    2010-10-01

    Knudsen Effusion Mass Spectrometry (KEMS) has been used to measure for the first time the solid state vapour pressures of a series of aliphatic cyclic dicarboxylic acids with increasing ring size. Additionally the atmospherically important compounds; cis-pinonic acid and levoglucosan were also measured. Differential Scanning Calorimetry (DSC) was used to measure melting points, enthalpies and entropies of fusion, which were used to determine sub-cooled liquid vapour pressures for the compounds. The sub-cooled liquid vapour pressure of straight chain, branched and cyclic dicarboxylic acids was compared to a selection of estimation methods.

  16. Solid state and sub-cooled liquid vapour pressures of cyclic aliphatic dicarboxylic acids

    NASA Astrophysics Data System (ADS)

    Booth, A. M.; Montague, W. J.; Barley, M. H.; Topping, D. O.; McFiggans, G.; Garforth, A.; Percival, C. J.

    2011-01-01

    Knudsen Effusion Mass Spectrometry (KEMS) has been used to measure for the first time the solid state vapour pressures of a series of aliphatic cyclic dicarboxylic acids with increasing ring size. Additionally the atmospherically important compounds; cis-pinonic acid and levoglucosan were also measured. Differential Scanning Calorimetry (DSC) was used to measure melting points, enthalpies and entropies of fusion, which were used to determine sub-cooled liquid vapour pressures for the compounds. The sub-cooled liquid vapour pressure of straight chain, branched and cyclic dicarboxylic acids was compared to a selection of estimation methods.

  17. Further work on sodium montmorillonite as catalyst for the polymerization of activated amino acids

    NASA Technical Reports Server (NTRS)

    Eirich, F. R.; Paecht-Horowitz, M.

    1986-01-01

    When the polycondensation of amino acid acylates was catalyzed with Na-montmorillonite, the polypeptides were consistently found to exhibit a distribution of discrete molecular weights, for as yet undiscovered reasons. One possible explanation was connected to the stepwise mode of monomer addition. New experiments have eliminated this possibility, so that there is the general assumption that this discreteness is the result of a preference of shorter oligomers to add to others of the same length, a feature that could be attributed to some structure of the platelet aggregates of the montmorillonite. The production of optical stereoisomers is anticipated when D,L-amino acids are polymerized on montmorillonite. Having used an optically active surface, the essence of the results lies not only in the occurrence of optically active oligomers and polymers, but also in the fact that the latter exhibit the same molecular weight characteristics as the D,L-polymers. Preparatory to work contemplated on a parallel synthesis of amino acid and nucleotide oligomers, studies were continued on the co-adsorption of amino acids, nucleotides, and amino acid-nucleotides on montmorillonite.

  18. Effects of natural water ions and humic acid on catalytic nitrate reduction kinetics using an alumina supported Pd-Cu catalyst.

    PubMed

    Chaplin, Brian P; Roundy, Eric; Guy, Kathryn A; Shapley, John R; Werth, Charles J

    2006-05-01

    Catalytic nitrate reduction was evaluated for the purpose of drinking water treatment. Common anions present in natural waters and humic acid were evaluated for their effects on NO3(-) hydrogenation over a bimetallic supported catalyst (Pd-Cu/gamma-Al2O3). Groundwater samples, with and without powder activated carbon (PAC) pretreatment, were also evaluated. In the absence of inhibitors the NO3- reduction rate was 2.4 x 10(-01) L/min g cat. However, the addition of constituents (SO4(2-), SO3(2-), HS-, CI-, HCO3-, OH-, and humic acid) on the order of representative concentrations for drinking water decreased the NO3- reduction rate. Sulfite, sulfide, and elevated chloride decreased the NO3- reduction rate by over 2 orders of magnitude. Preferential adsorption of Cl- inhibited NO3- reduction to a greater extent than NO2- reduction. Partial regeneration of catalysts exposed to SO3(2-) was achieved by using a dilute hypochlorite solution, however Cu dissolution occurred. Dissolved constituents in the groundwater sample decreased the NO3- reduction rate to 3.7 x 10(-03) L/min g cat and increased ammonia production. Removal of dissolved organic matter from the groundwater using PAC increased the NO3- reduction rate to 5.06 x 10(-02) L/min g cat and decreased ammonia production. Elemental analyses of catalysts exposed to the natural groundwater suggest that mineral precipitation may also contribute to catalyst fouling. PMID:16719114

  19. Tetraphosphine Linker Scaffolds with a Tetraphenyltin Core for Superior Immobilized Catalysts: A Solid-State NMR Study 

    E-print Network

    Perera, Melanie Ingrid

    2012-10-19

    -resolution magic angle spinning) NMR spectra of several phosphonium salts, adsorbed on SiO2, have been studied. This technique allows one to probe the leaching and mobility of the linkers on the surface. The mobilities of the linkers and the catalysts are crucial...

  20. Conversion of municipal solid waste to carboxylic acids using a mixed culture of mesophilic microorganisms.

    PubMed

    Aiello-Mazzarri, Cateryna; Agbogbo, Frank K; Holtzapple, Mark T

    2006-01-01

    Waste biomass was anaerobically converted to carboxylate salts by using a mixed culture of acid-forming microorganisms. Municipal solid waste (MSW) was the energy source (carbohydrates) and sewage sludge (SS) was the nutrient source (minerals, metals, and vitamins). Four fermentors were arranged in series and solids and liquids were transferred countercurrently in opposite directions, which allows both high conversions and high product concentrations. Fresh biomass was added to Fermentor 1 (highest carboxylic acid concentration) and fresh media was added to Fermentor 4 (most digested biomass). All fermentations were performed at 40 degrees C. Calcium carbonate was added to the fermentors to neutralize the acids to their corresponding carboxylate salts. Iodoform was used to inhibit methane production and urea was added as a nitrogen source. Product concentrations were up to 25 g/L, with productivities up to 1.4 g total acid/(L liquid d). Mass balances with closure between 93% and 105% were obtained for all systems. Continuum particle distribution modeling (CPDM) was applied to correlate batch fermentation data to countercurrent fermentation data and predict product concentration over a wide range of solids loading rates and residence times. CPDM for lime-treated MSW/SS fermentation system predicted the experimental total acid concentration and conversion within 4% and 16% respectively. PMID:16154502

  1. Regeneration of a deactivated USY alkylation catalyst using supercritical isobutane

    SciTech Connect

    Daniel M. Ginosar; David N. Ghompson; Kyle C. Burch

    2005-01-01

    Off-line, in-situ alkylation activity recovery from a completely deactivated solid acid catalyst was examined in a continuous-flow reaction system employing supercritical isobutane. A USY zeolite catalyst was initially deactivated during the liquid phase alkylation of butene with isobutane in a single-pass reactor and then varying amounts of alkylation activity were recovered by passing supercritical isobutane over the catalyst bed at different reactivation conditions. Temperature, pressure and regeneration time were found to play important roles in the supercritical isobutane regeneration process when applied to a completely deactivated USY zeolite alkylation catalyst. Manipulation of the variables that influence solvent strength, diffusivity, surface desorption, hydride transfer rates, and coke aging, strongly influence regeneration effectiveness.

  2. The oxidation of tetrabromobisphenol A by potassium monopersulfate with an iron(III)-phthalocyanine-tetrasulfonic acid catalyst in the presence of humic acid.

    PubMed

    Maeno, Shohei; Mizutani, Yusuke; Zhu, Qianqian; Miyamoto, Takafumi; Fukushima, Masami; Kuramitz, Hideki

    2014-01-01

    Tetrabromobisphenol A (TBBPA), a type of brominated flame retardant that shows endocrine disruption effects, has been identified in leachates from landfills. Iron(III)-porphyrins that mimic the active site of peroxidases have been shown to be effective in oxidizing halogenated phenols, such as TBBPA. In the present study, TBBPA was subjected to oxidation with potassium monopersulfate (KHSO5) using an iron(III)-phthalocyanine-tetrasulfonic acid (FePcTS), structural analogue of iron(III)-porphyrin, in the presence of humic acid (HA), a major component in landfill leachates. When TBBPA was oxidized using the above system, the levels of degradation and debromination increased with increasing pH in the presence of HA. Because of landfill leachates are weakly alkaline (around pH 8), oxidation products derived from TBBPA were investigated at pH 8. Approximately 48% of the bromine in the degraded TBBPA was incorporated into HA, and hydroxy-tribromobisphenol A was determined to be the major brominated intermediate in the HA fraction. In the iron(III)-porphyrin catalytic systems, the brominated intermediate incorporated into HA is mainly TBBPA, and no hydroxy-substituted bromophenols are found. Thus, the catalytic power of FePcTS is higher than that of iron(III)-porphyrin catalysts. PMID:24798896

  3. Solid supported in situ derivatization extraction of acidic degradation products of nerve agents from aqueous samples.

    PubMed

    Chinthakindi, Sridhar; Purohit, Ajay; Singh, Varoon; Tak, Vijay; Dubey, D K; Pardasani, Deepak

    2014-09-12

    This study deals with the solid supported in situ derivatization extraction of acidic degradation products of nerve agents present in aqueous samples. Target analytes were alkyl alkylphosphonic acids and alkylphosphonic acids, which are important environmental signatures of nerve agents. The method involved tert-butyldimethylchlorosilane mediated in situ silylation of analytes on commercially available diatomaceous solid phase extraction cartridges. Various parameters such as derivatizing reagent, its concentration, reaction time, temperature and eluting solvent were optimized. Recoveries of the analytes were determined by GC-MS which ranged from 60% to 86%. The limits of detection (LOD) and limit of quantification (LOQ) with selected analytes were achieved down to 78 and 213ngmL(-1) respectively, in selected ion monitoring mode. The successful applicability of method was also demonstrated on samples of biological origin such as plasma and to the samples received in 34th official proficiency test conducted by the Organization for Prohibition the of Chemical Weapons. PMID:25103280

  4. Polyfunctional lewis acids: intriguing solid-state structure and selective detection and discrimination of nitroaromatic explosives.

    PubMed

    Swamy P, Chinna Ayya; Thilagar, Pakkirisamy

    2015-06-01

    Synthesis and crystal structures of three porphyrin-based polyfunctional Lewis acids 1-3 are reported. Intermolecular HgCl???HgCl (linear and ?-type) interactions in the solid state of the peripherally ArHgCl-decorated compound 3 lead to a fascinating 3D supramolecular architecture. Compound?3 shows a selective fluorescence quenching response to picric acid and discriminates other nitroaromatic-based explosives. For the first time, an electron-deficient polyfunctional Lewis acid is shown to be useful for the selective detection and discrimination of nitroaromatic explosives. The Stern-Volmer quenching constant and detection limits of compound?3 for picric acid are the best among the reported small-molecular receptors for nitroaromatic explosives. The electronic structure, Lewis acidity, and selective sensing characteristics of 3 are well corroborated by DFT calculations. PMID:25950287

  5. Structure-Property Relationships in Solid AlF3 Lewis Acids

    NASA Astrophysics Data System (ADS)

    Weiher, Norbert; Makarowicz, Anna; Beesley, Angela M.; Kemnitz, Erhard; Schroeder, Sven L. M.

    2007-02-01

    Understanding the structural cause of the high Lewis acidity in the novel solid Lewis acid AlF3 is of crucial importance to tailor this important material property to the specific needs of potential applications. Based on Al and F K-edge XAS studies, we are able to correlate high Lewis acidity with geometric distortions of the [AlF6] building blocks of AlF3. These distortions are induced by the presence of i-OPr ligands in the AlF3-x(i-OPr)x precursor material and can only be preserved by the application of a mild fluorinating agent like CCl2F2. High Lewis acidity is not caused by electronic modification of the aluminium atom, but by the better exposure of reactants to the acid site in the high surface area materials.

  6. Mesoporous Silica-Supported Diarylammonium Catalysts for Esterification of Free Fatty Acids in Greases

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Biodiesel, typically fatty acid methyl esters (FAME), has received much attention because it is a renewable biofuel that contributes little to global warming compared to petroleum-based diesel fuel. The most common method used for biodiesel production is based on the alkali-catalyzed transesterific...

  7. Catalyst Alloys Processing

    NASA Astrophysics Data System (ADS)

    Tan, Xincai

    2014-10-01

    Catalysts are one of the key materials used for diamond formation at high pressures. Several such catalyst products have been developed and applied in China and around the world. The catalyst alloy most widely used in China is Ni70Mn25Co5 developed at Changsha Research Institute of Mining and Metallurgy. In this article, detailed techniques for manufacturing such a typical catalyst alloy will be reviewed. The characteristics of the alloy will be described. Detailed processing of the alloy will be presented, including remelting and casting, hot rolling, annealing, surface treatment, cold rolling, blanking, finishing, packaging, and waste treatment. An example use of the catalyst alloy will also be given. Industrial experience shows that for the catalyst alloy products, a vacuum induction remelt furnace can be used for remelting, a metal mold can be used for casting, hot and cold rolling can be used for forming, and acid pickling can be used for metal surface cleaning.

  8. Process of making supported catalyst

    DOEpatents

    Schwarz, James A. (Fayetteville, NY); Subramanian, Somasundaram (Melvindale, MI)

    1992-01-01

    Oxide supported metal catalysts have an additional metal present in intimate association with the metal catalyst to enhance catalytic activity. In a preferred mode, iridium or another Group VIII metal catalyst is supported on a titania, alumina, tungsten oxide, silica, or composite oxide support. Aluminum ions are readsorbed onto the support and catalyst, and reduced during calcination. The aluminum can be added as aluminum nitrate to the iridium impregnate solution, e.g. chloroiridic acid.

  9. Combustion Catalysts in Industry- An Update 

    E-print Network

    Merrell, G. A.; Knight, R. S.

    1985-01-01

    Combustion catalysts improve boiler efficiency by extracting more heat energy from the fuel and by reducing heat losses when operating at minimum excess air. In addition, an effective combustion catalyst may reduce the level of smoke and solid...

  10. Graphite-supported perchloric acid (HClO4-C): an efficient and recyclable heterogeneous catalyst for the one-pot synthesis of amidoalkyl naphthols.

    PubMed

    Lei, Zhen-Kai; Xiao, Li; Lu, Xiao-Quan; Huang, He; Liu, Chen-Jiang

    2013-01-01

    An efficient and direct protocol for the preparation of amidoalkylnaphthols employing a multi-component, one-pot condensation reaction of 2-naphthol, aromatic aldehydes and acetamide or benzamide in the presence of graphite supported perchloric acid under solvent-free conditions is described. The thermal solvent-free procedure offers advantages such as simple work-up, shorter reaction times and higher product yields, and the catalyst exhibited remarkable reactivity and can be recycled. PMID:23358323

  11. Effect of the structural characteristics of binary Pt-Ru and ternary Pt-Ru-M fuel cell catalysts on the activity of ethanol electrooxidation in acid medium.

    PubMed

    Antolini, Ermete

    2013-06-01

    In view of their possible use as anode materials in acid direct ethanol fuel cells, the electrocatalytic activity of Pt-Ru and Pt-Ru-M catalysts for ethanol oxidation has been investigated. This minireview examines the effects of the structural characteristics of Pt-Ru, such as the degree of alloying and Ru oxidation state, on the electrocatalytic activity for ethanol oxidation. PMID:23650220

  12. Preparation and evaluation of advanced catalysts for phosphoric acid fuel cells

    NASA Technical Reports Server (NTRS)

    Stonehart, P.; Baris, J.; Hockmuth, J.; Pagliaro, P.

    1984-01-01

    The platinum electrocatalysts were characterized for their crystallite sizes and the degree of dispersion on the carbon supports. One application of these electrocatalysts was for anodic oxidation of hydrogen in hot phosphoric acid fuel cells, coupled with the influence of low concentrations of carbon monoxide in the fuel gas stream. In a similar way, these platinum on carbon electrocatalysts were evaluated for oxygen reduction in hot phosphoric acid. Binary noble metal alloys were prepared for anodic oxidation of hydrogen and noble metal-refractory metal mixtures were prepared for oxygen reduction. An exemplar alloy of platinum and palladium (50/50 atom %) was discovered for anodic oxidation of hydrogen in the presence of carbon monoxide, and patent disclosures were submitted. For the cathode, platinum-vanadium alloys were prepared showing improved performance over pure platinum. Preliminary experiments on electrocatalyst utilization in electrode structures showed low utilization of the noble metal when the electrocatalyst loading exceeded one weight percent on the carbon.

  13. ZnO/carbon nano composite: Effective catalyst for the photo degradation of Acid Blue 113

    NASA Astrophysics Data System (ADS)

    Sunitha, S.; Rao, A. Nageswara; Karthikeyan, J.; Krithiga, T.

    2013-06-01

    Zinc oxide carbon composite (ZnO/C) was synthesized by self - propagating solution combustion method. This method enabled the addition of carbon insitu to the metal oxide. The composite synthesized were characterised by XRD, SEM and BET analysis. This composite was used for the removal of organic pollutants such as the dye Acid blue 113 by UV irradiation performed in a batch reactor. The influence of various experimental parameters such as the initial concentration of the dye, Concentration of the photocatalyst and the pH on the photo catalytic degradation under UV irradiation was studied. It has been observed that the degradation of the dye to be more pronounced in neutral medium. The degradation of acid blue 113 was found to increase with ZnO/C composites loading and decreases with decrease in concentration of the composite.

  14. Preparation and evaluation of advanced catalysts for phosphoric acid fuel cells

    NASA Astrophysics Data System (ADS)

    Stonehart, P.; Baris, J.; Hockmuth, J.; Pagliaro, P.

    1984-06-01

    The platinum electrocatalysts were characterized for their crystallite sizes and the degree of dispersion on the carbon supports. One application of these electrocatalysts was for anodic oxidation of hydrogen in hot phosphoric acid fuel cells, coupled with the influence of low concentrations of carbon monoxide in the fuel gas stream. In a similar way, these platinum on carbon electrocatalysts were evaluated for oxygen reduction in hot phosphoric acid. Binary noble metal alloys were prepared for anodic oxidation of hydrogen and noble metal-refractory metal mixtures were prepared for oxygen reduction. An exemplar alloy of platinum and palladium (50/50 atom %) was discovered for anodic oxidation of hydrogen in the presence of carbon monoxide, and patent disclosures were submitted. For the cathode, platinum-vanadium alloys were prepared showing improved performance over pure platinum. Preliminary experiments on electrocatalyst utilization in electrode structures showed low utilization of the noble metal when the electrocatalyst loading exceeded one weight percent on the carbon.

  15. Radionuclide Leaching from Residual Solids Remaining after Acid Dissolution of Composite K East Canister Sludge

    SciTech Connect

    Delegard, C.H.; Rinehart, D.E.; Soderquist, C.Z.; Fadeff, S.K.

    1999-04-02

    Laboratory tests were performed to examine mixed nitric/hydrofluoric acid leach treatments for decontaminating dissolver residual solids (KECDVSR24H-2) produced during a 20- to 24-hr dissolution of a composite K East (KE) Basin canister sludge in 95 C 6 M nitric acid (HNO{sub 3}). The scope of this testing has been described in Section 4.5 of ''Testing Strategy to Support the Development of K Basin Sludge Treatment Process'' (Flament 1998). Radionuclides sorbed or associated with the residual solids generated in the K Basin sludge treatment process can restrict disposal of this solid to the Environmental Restoration Disposal Facility (ERDF). The starting dissolver residual solid for this testing, KECDVSR24H-2, contains radionuclides at concentrations which exceed the ERDF Waste Acceptance Criteria for TRU by about a factor of 70, for {sup 239}Pu by a factor of 200, and for {sup 241}Am by a factor of 50. The solids also exceed the ERDF criterion for {sup 137}Cs by a factor of 2 and uranium by a factor of 5. Therefore, the radionuclides of greatest interest in this leaching study are first {sup 239}Pu and {sup 241}Am (both components of TRU) and then uranium and {sup 137}Cs.

  16. Oxidation catalyst

    DOEpatents

    Ceyer, Sylvia T. (Cambridge, MA); Lahr, David L. (Cambridge, MA)

    2010-11-09

    The present invention generally relates to catalyst systems and methods for oxidation of carbon monoxide. The invention involves catalyst compositions which may be advantageously altered by, for example, modification of the catalyst surface to enhance catalyst performance. Catalyst systems of the present invention may be capable of performing the oxidation of carbon monoxide at relatively lower temperatures (e.g., 200 K and below) and at relatively higher reaction rates than known catalysts. Additionally, catalyst systems disclosed herein may be substantially lower in cost than current commercial catalysts. Such catalyst systems may be useful in, for example, catalytic converters, fuel cells, sensors, and the like.

  17. Study on Preparation Process of Lubrication from 1-Decene with Acidic Ionic Liquid Catalyst

    Microsoft Academic Search

    H. Ding; B. Y. Zhang; J. Liu

    2009-01-01

    Poly-alpha-olefin (PAO) was researched over acidic ionic liquid catalyzed the oligomerization of 1-decene. Ionic liquid used was 1-butyl-3-methyl imidazolium as a cation and aluminum chloride as an anion, which could effectively catalyze oligomerization and had a higher selectivity. The optimum process conditions for the synthesis of PAO were that the reaction temperature was 160°C, the reaction time was 3 h,

  18. A Gold-Nickel Alloy as Anodic Catalyst in a Direct Formic Acid Fuel Cell

    Microsoft Academic Search

    Zhang Lijuan; Tian Ruili; Hu Pu; Ma Yuru; Xia Dingguo

    2010-01-01

    Gold-nickel alloy was synthesized by arc-melted process. The electro-oxidation of formic acid of Au-Ni alloy was investigated at room temperature by cyclic voltammetry and chronoamperometry. The results were compared with those at a polycrystalline gold electrode surface. It is found that Au-Ni alloy is catalytically more active than pure gold according to the comparison of the main peak potential and

  19. Mo oxide modified catalysts for direct methanol, formaldehydeand formic acid fuel cells

    Microsoft Academic Search

    Chaojie Song; Mohammad Khanfar; Peter G. Pickup

    2006-01-01

    Pt black and PtRu black fuel cell anodes have been modified with Mo oxide and evaluated in direct methanol, formaldehyde and\\u000a formic acid fuel cells. Mo oxide deposition by reductive electrodeposition from sodium molybdate or by spraying of the fuel\\u000a cell anode with aqueous sodium molybdate resulted in similar performance gains in formaldehyde cells. At current densities\\u000a below ca. 20 mA cm?2,

  20. Performance degradation of direct formic acid fuel cell incorporating a Pd anode catalyst

    Microsoft Academic Search

    Won Suk Jung; Jonghee Han; Sung Pil Yoon; Suk Woo Nam; Tae-Hoon Lim; Seong-Ahn Hong

    2011-01-01

    Electrochemical and physical analysis is employed to verify the performance degradation mechanism in direct formic acid fuel cells (DFAFCs). The power density of a single cell measured at 200mAcm?2 decreases by 40% after 11h of operation. The performance of the single cell is partly recovered however, by a reactivation process. Various analytical methods such as scanning electron microscopy (SEM), transmission

  1. Stepwise engineering of a Pichia pastoris D-amino acid oxidase whole cell catalyst

    Microsoft Academic Search

    Sandra Abad; Jozef Nahalka; Gabriele Bergler; S Alison Arnold; Robert Speight; Ian Fotheringham; Bernd Nidetzky; Anton Glieder

    2010-01-01

    BACKGROUND: Trigonopsis variabilis D-amino acid oxidase (TvDAO) is a well characterized enzyme used for cephalosporin C conversion on industrial scale. However, the demands on the enzyme with respect to activity, operational stability and costs also vary with the field of application. Processes that use the soluble enzyme suffer from fast inactivation of TvDAO while immobilized oxidase preparations raise issues related

  2. Surface acidity and solid-state compatibility of excipients with an acid-sensitive API: case study of atorvastatin calcium.

    PubMed

    Govindarajan, Ramprakash; Landis, Margaret; Hancock, Bruno; Gatlin, Larry A; Suryanarayanan, Raj; Shalaev, Evgenyi Y

    2015-04-01

    The objectives of this study were to measure the apparent surface acidity of common excipients and to correlate the acidity with the chemical stability of an acid-sensitive active pharmaceutical ingredient (API) in binary API-excipient powder mixtures. The acidity of 26 solid excipients was determined by two methods, (i) by measuring the pH of their suspensions or solutions and (ii) the pH equivalent (pHeq) measured via ionization of probe molecules deposited on the surface of the excipients. The chemical stability of an API, atorvastatin calcium (AC), in mixtures with the excipients was evaluated by monitoring the appearance of an acid-induced degradant, atorvastatin lactone, under accelerated storage conditions. The extent of lactone formation in AC-excipient mixtures was presented as a function of either solution/suspension pH or pHeq. No lactone formation was observed in mixtures with excipients having pHeq > 6, while the lactone levels were pronounced (> 0.6% after 6 weeks at 50°C/20% RH) with excipients exhibiting pHeq < 3. The three pHeq regions (> 6, 3-6, and < 3) were consistent with the reported solution pH-stability profile of AC. In contrast to the pHeq scale, lactone formation did not show any clear trend when plotted as a function of the suspension/solution pH. Two mechanisms to explain the discrepancy between the suspension/solution pH and the chemical stability data were discussed. Acidic excipients, which are expected to be incompatible with an acid-sensitive API, were identified based on pHeq measurements. The incompatibility prediction was confirmed in the chemical stability tests using AC as an example of an acid-sensitive API. PMID:25319055

  3. Perfluorosulfonic acid membrane catalysts for optical sensing of anhydrides in the gas phase.

    PubMed

    Ayyadurai, Subasri M; Worrall, Adam D; Bernstein, Jonathan A; Angelopoulos, Anastasios P

    2010-07-15

    Continuous, on-site monitoring of personal exposure levels to occupational chemical hazards in ambient air is a long-standing analytical challenge. Such monitoring is required to institute appropriate health measures but is often limited by the time delays associated with batch air sampling and the need for off-site instrumental analyses. In this work, we report on the first attempt to use the catalytic properties of perfluorosulfonic acid (PSA) membranes to obtain a rapid, selective, and highly sensitive optical response to trimellitic anhydride (TMA) in the gas phase for portable sensor device application. TMA is used as starting material for various organic products and is recognized to be an extremely toxic agent by the National Institute for Occupational Safety and Health (NIOSH). Resorcinol dye is shown to become immobilized in PSA membranes and diffusionally constrain an orange brown product that results from acid-catalyzed reaction with more rapidly diffusing TMA molecules. FTIR, UV/vis, reaction selectivity to TMA versus trimellitic acid (TMLA), and homogeneous synthesis are used to infer 5,7- dihydroxyanthraquinone-2-carboxylic acid as the acylation product of the reaction. The color response has a sensitivity to at least 3 parts per billion (ppb) TMA exposure and, in addition to TMLA, excludes maleic anhydride (MA) and phthalic anhydride (PA). Solvent extraction at long times is used to determine that the resorcinol extinction coefficient in 1100 EW PSA membrane has a value of 1210 m(2)/g at 271.01 nm versus a value of 2010 m(2)/g at 275.22 nm in 50 vol% ethanol/water solution. The hypsochromic wavelength shift and reduced extinction coefficient suggest that the polar perfluorosulfonic acid groups in the membrane provide the thermodynamic driving force for diffusion and immobilization. At a resorcinol concentration of 0.376 g/L in the membrane, a partition coefficient of nearly unity is obtained between the membrane and solution concentrations and a maximum conversion rate of one ambient TMA molecule for every two membrane-immobilized resorcinol molecules is observed in 15 min. PMID:20560534

  4. Solid/Liquid phase diagram of the ammonium sulfate/succinic acid/water system.

    PubMed

    Pearson, Christian S; Beyer, Keith D

    2015-05-14

    We have studied the low-temperature phase diagram and water activities of the ammonium sulfate/succinic acid/water system using differential scanning calorimetry and infrared spectroscopy of thin films. Using the results from our experiments, we have mapped the solid/liquid ternary phase diagram, determined the water activities based on the freezing point depression, and determined the ice/succinic acid phase boundary as well as the ternary eutectic composition and temperature. We also compared our results to the predictions of the extended AIM aerosol thermodynamics model (E-AIM) and found good agreement for the ice melting points in the ice primary phase field of this system; however, differences were found with respect to succinic acid solubility temperatures. We also compared the results of this study with those of previous studies that we have published on ammonium sulfate/dicarboxylic acid/water systems. PMID:25431860

  5. Synthesis and electrochemical performances of LiNiCuZn oxides as anode and cathode catalyst for low temperature solid oxide fuel cell.

    PubMed

    Jing, Y; Qin, H; Liu, Q; Singh, M; Zhu, B

    2012-06-01

    Low temperature solid oxide fuel cell (LTSOFC, 300-600 degrees C) is developed with advantages compared to conventional SOFC (800-1000 degrees C). The electrodes with good catalytic activity, high electronic and ionic conductivity are required to achieve high power output. In this work, a LiNiCuZn oxides as anode and cathode catalyst is prepared by slurry method. The structure and morphology of the prepared LiNiCuZn oxides are characterized by X-ray diffraction and field emission scanning electron microscopy. The LiNiCuZn oxides prepared by slurry method are nano Li0.28Ni0.72O, ZnO and CuO compound. The nano-crystallites are congregated to form ball-shape particles with diameter of 800-1000 nm. The LiNiCuZn oxides electrodes exhibits high ion conductivity and low polarization resistance to hydrogen oxidation reaction and oxygen reduction reaction at low temperature. The LTSOFC using the LiNiCuZn oxides electrodes demonstrates good cell performance of 1000 mW cm(-2) when it operates at 470 degrees C. It is considered that nano-composite would be an effective way to develop catalyst for LTSOFC. PMID:22905585

  6. Hydrogenation of succinic acid to ?-butyrolactone (GBL) over ruthenium catalyst supported on surfactant-templated mesoporous carbon

    Microsoft Academic Search

    Ung Gi Hong; Hai Woong Park; Joongwon Lee; Sunhwan Hwang; In Kyu Song

    Mesoporous carbon support (denoted as STC) was prepared by a surfactant-templating method for use as a support for ruthenium catalyst. For comparison, porous carbon (denoted as TC), spherical carbon (denoted as SC), and microporous carbon (denoted as DC) supports were also prepared by a templating method, hydrothermal method, and direct carbonization method, respectively. Ruthenium catalysts supported on carbon supports (Ru\\/C)

  7. Arginine as a General Acid Catalyst in Serine Recombinase-mediated DNA Cleavage*

    PubMed Central

    Keenholtz, Ross A.; Mouw, Kent W.; Boocock, Martin R.; Li, Nan-Sheng; Piccirilli, Joseph A.; Rice, Phoebe A.

    2013-01-01

    Members of the serine family of site-specific DNA recombinases use an unusual constellation of amino acids to catalyze the formation and resolution of a covalent protein-DNA intermediate. A recent high resolution structure of the catalytic domain of Sin, a particularly well characterized family member, provided a detailed view of the catalytic site. To determine how the enzyme might protonate and stabilize the 3?O leaving group in the strand cleavage reaction, we examined how replacing this oxygen with a sulfur affected the cleavage rate by WT and mutant enzymes. To facilitate direct comparison of the cleavage rates, key experiments used suicide substrates that prevented religation after cleavage. The catalytic defect associated with mutation of one of six highly conserved arginine residues, Arg-69 in Sin, was partially rescued by a 3? phosphorothiolate substrate. We conclude that Arg-69 has an important role in stabilizing the 3?O leaving group and is the prime candidate for the general acid that protonates the 3?O, in good agreement with the position it occupies in the high resolution structure of the active site of Sin. PMID:23970547

  8. Convenient synthesis of N-methylamino acids compatible with Fmoc solid-phase peptide synthesis.

    PubMed

    Biron, Eric; Kessler, Horst

    2005-06-24

    N(alpha)-Methylamino acid containing peptides exhibit interesting therapeutic profiles and are increasingly recognized as potentially useful therapeutics. Unfortunately, their synthesis is hampered by the high price and unavaibility of many N(alpha)-methylamino acids. An efficient and practical preparation of N(alpha)-methyl-N(alpha)-(o-nitrobenzenesulfonyl)-alpha-amino acids without extensive purification is described. The procedure is based on the well-known N-alkylation of N(alpha)-arylsulfonylamino esters which was improved by using dimethyl sulfate and DBU as base. Ester cleavage is efficiently achieved by using an S(N)2-type saponification with lithium iodide, avoiding racemization observed with lithium hydroxide hydrolysis. Compatibility of the synthesized N(alpha)-methylamino acids with Fmoc solid-phase peptide synthesis is demonstrated by using normal coupling conditions to efficiently prepare N-methyl dipeptides. The described procedure allows the preparation of N(alpha)-methylamino acids in a very short period of time and a rapid synthesis of N-methyl peptides using Fmoc solid-phase peptide synthesis. PMID:15960522

  9. Highly active carbon supported palladium catalysts decorated by a trace amount of platinum by an in-situ galvanic displacement reaction for formic acid oxidation

    NASA Astrophysics Data System (ADS)

    Li, Zuopeng; Li, Muwu; Han, Mingjia; Wu, Xin; Guo, Yong; Zeng, Jianhuang; Li, Yuexia; Liao, Shijun

    2015-03-01

    Aimed at reducing platinum usage and improved catalytic activity for formic acid oxidation, a series of Pt decorated Pd/C catalysts are prepared by an in-situ galvanic displacement reaction between freshly prepared Pd/C ink and H2PtCl6 in an aqueous solution. The catalysts with 4 nm particle sizes and 20 wt.% loadings have been characterized by transmission electron microscopy, thermogravimetric analysis and X-ray photoelectron spectroscopy (XPS). The electrochemical evaluations by cyclic voltammetry are conducted to test out the CO tolerance and catalytic activities. In addition to XPS analysis, a theoretical calculation has been attempted the first time to find out the surface Pd/Pt molar ratios. The decay rate of the catalysts has been evaluated by the percentage of the forward/backward peak current retained using the value at the 20th cycle divided by that in the first cycle. Compared with a Pd/C benchmark, all Pt decorated Pd/C register enhanced activity while the cost remains virtually unchanged. The optimized catalyst is found to have a Pd/Pt molar ratio of 75:1 but with 2.5 times activity relative to that of Pd/C.

  10. Prototype demonstration of dual sorbent injection for acid gas control on municipal solid waste combustion units

    SciTech Connect

    None

    1994-05-01

    This report gathered and evaluated emissions and operations data associated with furnace injection of dry hydrated lime and duct injection of dry sodium bicarbonate at a commercial, 1500 ton per day, waste-to-energy facility. The information compiled during the project sheds light on these sorbents to affect acid gas emissions from municipal solid waste combustors. The information assesses the capability of these systems to meet the 1990 Clean Air Act and 1991 EPA Emission Guidelines.

  11. Infrared spectrum of solid isocyanic acid (HNCO): vibrational assignments and integrated band intensities

    NASA Astrophysics Data System (ADS)

    Lowenthal, M. S.; Khanna, R. K.; Moore, Marla H.

    2002-01-01

    Infrared spectra of thin films of solid HNCO condensed from the gas phase are characterized in terms of their vibrational frequencies, mode assignments, and integrated band intensities at low temperatures (˜20-145 K). Isocyanic acid is shown to react with water (H 2O) and ammonia (NH 3) even at low temperatures; consequently, it may be an important species in the chemistry of interstellar ices and comets.

  12. The Effect of Crystallization on the Solid State Polycondensation of Poly(L?lactic Acid)

    Microsoft Academic Search

    Hong Xu; Minghua Luo; Muhuo Yu; Cuiqing Teng; Si Xie

    2006-01-01

    Melt solid polycondensation is an approach to increase the molecular weight of poly (L?lactic acid) (PLLA). For this report, the effect of crystallization time of PLLA prepolymer on the molecular weight of the biomaterial was studied. In this process, PLLA prepolymer with a molecular weight of 18,000 was first prepared by the ordinary melt?polycondensation process. The prepolymer was crystallized at

  13. Evaluation of biofilm reactor solid support for mixed-culture lactic acid production

    Microsoft Academic Search

    Ali Demirci; Anthony L. Pometto; Kenneth E. Johnson

    1993-01-01

    A combination of lactobacilli and biofilm-forming bacteria were evaluated in continuous fermentations for lactic acid production using various supports. Twelve different bacteria, including species of Bacillus, Pseudomonas, Streptomyces, Thermoactinomyces, and Thermomonospora were tested for biofilm-forming capabilities. Solid supports that were evaluated in either batch or continuous fermentations were pea gravels, 3M-macrolite ceramic spheres, and polypropylene mixed with 25% of various

  14. Development of ternary alloy cathode catalysts for phosphoric acid fuel cells: Final report

    SciTech Connect

    Jalan, V.; Kosek, J.; Giner, J.; Taylor, E. J.; Anderson, E.; Bianchi, V.; Brooks, C.; Cahill, K.; Cropley, C.; Desai, M.; Frost, D.; Morriseau, B.; Paul, B.; Poirier, J.; Rousseau, M.; Swette, L.; Waterhouse, R.

    1988-11-01

    The overall objective of the program was the identification development and incorporation of high activity platinum ternary alloys on corrosion resistant supports, for use in advanced phosphoric acid fuel cells. Two high activity ternary alloys, Pr-Cr-Ce and Pt-Ni-Co, both supported on Vulcan XC-72, were identified during the course of the program. The Pr-Ni-Co system was selected for optimization, including preparation and evaluation on corrosion resistant supports such as 2700/degree/C heat-treated Vulcan XC-72 and 2700/degree/ heat-treated Black Pearls 2000. A series of tests identified optimum metal ratios, heat-treatment temperatures and heat-treatment atmospheres for the Pr-Ni-Co system. During characterization testing, it was discovered that approximately 50% of the nickel and cobalt present in the starting material could be removed, subsequent to alloy formation, without degrading performance. Extremely stable full cell performance was observed for the Pt-Ni-Co system during a 10,000 hour atmosphere pressure life test. Several theories are proposed to explain the enhancement in activity due to alloy formation. Recommendations are made for future research in this area. 62 refs., 23 figs., 27 tabs.

  15. Metal-loaded CeO 2-ZrO 2 solid solutions as innovative catalysts for automotive catalytic converters

    Microsoft Academic Search

    Paolo Fornasiero; Gabriele Balducci; Sergio Meriani; Roberta di Monte; Mauro Graziani

    1996-01-01

    The redox behaviour of a Ce0.5Zr0.5O2 solid solution is investigated by means of temperature programmed reduction (TPR) and oxygen uptake measurements. It is shown that the introduction of ZrO2 into the CeO2 framework, strongly modifies the reduction behaviour in comparison to pure CeO2. Remarkably, in contrast to the CeO2, upon repetitive reduction-oxidation processes, the temperature of reduction of the solid

  16. Electrochemical performance and durability of carbon supported Pt catalyst in contact with aqueous and polymeric proton conductors.

    PubMed

    Andersen, Shuang Ma; Skou, Eivind

    2014-10-01

    Significant differences in catalyst performance and durability are often observed between the use of a liquid electrolyte (e.g., sulfuric acid), and a solid polymer electrolyte (e.g., Nafion). To understand this phenomenon, we studied the electrochemical behavior of a commercially available carbon supported platinum catalyst in four different electrode structures: catalyst powder (CP), catalyst ionomer electrode (CIE), half membrane electrode assembly (HMEA), and full membrane electrode assembly (FMEA) in both ex situ and in situ experiments under a simulated start/stop cycle. We found that the catalyst performance and stability are very much influenced by the presence of the Nafion ionomers. The proton conducting phase provided by the ionomer and the self-assembled electrode structure render the catalysts a higher utilization and better stability. This is probably due to an enhanced dispersion, an improved proton-catalyst interface, the restriction of catalyst particle aggregation, and the improved stability of the ionomer phase especially after the lamination. Therefore, an innovative electrode HMEA design for ex-situ catalyst characterization is proposed. The electrode structure is identical to the one used in a real fuel cell, where the protons transport takes place solely through solid state proton conducting phase. PMID:25216270

  17. Kinetics of Mo, Ni, V and Al leaching from a spent hydrodesulphurization catalyst in a solution containing oxalic acid and hydrogen peroxide.

    PubMed

    Szymczycha-Madeja, Anna

    2011-02-28

    The kinetics of molybdenum, nickel, vanadium and aluminium leaching from a spent hydrodesulphurization catalyst in a solution containing oxalic acid and hydrogen peroxide was investigated. The effects of temperature and particle size were examined. In addition, the reaction mechanism for the dissolution of the spent catalyst was discussed. The results of the kinetic analysis for various experimental conditions indicated that the reaction rate of leaching process is controlled by chemical reaction at the particle surface. The values of the activation energies of 31±2, 36±4, 30±4 and 57±3 kJ mol(-1) for Mo, Ni, V and Al, respectively, are characteristic for mechanism controlled by chemical reaction. PMID:21167639

  18. Improved catalysts and method

    SciTech Connect

    Taylor, C.E.; Noceti, R.P.

    1990-12-31

    An improved catalyst and method for the oxyhydrochlorination of methane is disclosed. The catalyst includes a pyrogenic porous support on which is layered as active material, cobalt chloride in major proportion, and minor proportions of an alkali metal chloride and of a rare earth chloride. On contact of the catalyst with a gas flow of methane, HCl and oxygen, more than 60% of the methane is converted and of that converted more than 40% occurs as monochloromethane. Advantageously, the monochloromethane can be used to produce gasoline boiling range hydrocarbons with the recycle of HCl for further reaction. This catalyst is also of value for the production of formic acid as are analogous catalysts with lead, silver or nickel chlorides substituted for the cobalt chloride. 8 figs., 3 tabs.

  19. Nano-tribological and wear behavior of boric acid solid lubricant.

    SciTech Connect

    Mirmiran, S.; Tsukruk, V. V.; Erdemir, A.; Energy Technology; Western Michigan Univ.

    1999-01-01

    One uses atomic force microscopy to explore the surface morphology, frictional characteristics (i.e., friction mapping) and surface adhesive forces of boric acid-treated aluminum surfaces. In earlier studies, boric acid was shown to be an effective solid lubricant providing 0.02 to 0.1 friction coefficients to the sliding surfaces of metallic and ceramic materials. In this study, the authors mainly focused on the friction and wear behavior of cleaved single crystals of boric acid. Tests were performed on uncoated and boric acid-coated surfaces of aluminum substrates, as well as the bulk boric acid material. The nano-scale wear of the boric acid crystals manifested itself in the displacement of atomic planes which, in turn, resulted in the formation of the worn area grown by a spiral-growth mechanism. In addition, new crystals in the vicinity of the sliding contact areas were formed. These crystals formed by a spiral dislocation mechanism. The nanoscale friction measurements showed that the friction coefficient of a Si{sub 3}N{sub 4} tip against the boric acid single crystal, was in the range of 0.07 to 0.13, depending on the sliding direction with respect to the crystallographic orientation. The friction coefficients of the boric acid-coated aluminum substrates varied between 0.11 and 0.19. While these values were consistent with earlier findings and further demonstrated the lubricity of boric acid, they were higher than the previous measurements (i.e., 0.011-0.1) obtained on a pin-on-disk machine using steel or ceramic pins. An explanation is provided for this phenomenon.

  20. Improved molecular weight control in ring-opening metathesis polymerization (ROMP) reactions with ru-based olefin metathesis catalysts using N donors and acid: a kinetic and mechanistic investigation.

    PubMed

    Dunbar, Miles A; Balof, Shawna L; LaBeaud, Lawrence J; Yu, Bing; Lowe, Andrew B; Valente, Edward J; Schanz, Hans-Jörg

    2009-11-16

    The effect of the addition of H(3)PO(4) on the ROMP activity of cyclooctene (COE) with first- [Cl(2)(PCy(3))(2)Ru=CHPh] and second-generation [(H(2)IMes)Cl(2)(PCy(3))Ru=CHPh] Grubbs' catalysts 1 and 4 (Cy=cyclohexyl, Ph=phenyl, Mes=2,4,6-trimethylphenyl (mesityl)), their inhibited mixtures with 1-methylimidazole (MIM), as well as their isolated bis-N,N'-dimethylaminopyridine (DMAP) derivatives [Cl(2)(PCy(3))(DMAP)(2)Ru=CHPh)] (5 b) and [Cl(2)(H(2)IMes)(DMAP)(2)Ru=CHPh] (7 b) (DMAP=dimethylaminopyridine), a novel catalyst, has been investigated. The studies include the determination of their initiation rates, as well as a determination of the molecular weights and molecular weight distributions of the polymers obtained with these catalysts and catalyst mixtures from the exo-7-oxanorbornene derivative 11. The structure of catalyst 7 b was confirmed by means of X-ray diffraction. All N-donor-bearing catalysts or N-donor-containing catalyst mixtures not only exhibited elevated activity in the presence of acid, but also increased initiation rates. Using the reversible inhibition/activation protocol with MIM and H(3)PO(4) enabled us to conduct controlled ROMP with catalyst 4 producing the isolated exo-7-oxanorbornene-based polymer 12 with predetermined molecular weights and narrow molecular weight distributions. This effect was based on fast and efficient catalyst initiation in contrast to the parent catalyst 4. Hexacoordinate complex 5 b also experienced a dramatic increase in initiation rates upon acid-addition and the ROMP reactions became well-controlled in contrast to the acid-free reaction. In contrast, complex 7 b performs well-controlled ROMP in the absence of acid, whereas the polymerization of the same monomer becomes less controlled in the presence of H(3)PO(4). The closer evaluation of catalysts 5 b and 7 b demonstrated that their initiation rates exhibit a linear dependency on the substrate concentration in contrast to catalysts 1 and 4. As a consequence, their initiation rates are determined by an associative step, not a dissociative step as seen for catalysts 1 and 4. A feasible associative metathesis initiation mechanism is proposed. PMID:19821457

  1. Significant Enhancement of PEDOT Thin Film Adhesion to Inorganic Solid Substrates with EDOT-Acid.

    PubMed

    Wei, Bin; Liu, Jinglin; Ouyang, Liangqi; Kuo, Chin-Chen; Martin, David C

    2015-07-22

    With its high conductivity, tunable surface morphology, relatively soft mechanical response, high chemical stability, and excellent biocompatibility, poly(3,4-ethylenedioxythiophene) (PEDOT) has become a promising coating material for a variety of electronic biomedical devices. However, the relatively poor adhesion of PEDOT to inorganic metallic and semiconducting substrates still poses challenges for long-term applications. Here, we report that 2,3-dihydrothieno(3,4-b)(1,4)dioxine-2-carboxylic acid (EDOT-acid) significantly improves the adhesion between PEDOT thin films and inorganic solid electrodes. EDOT-acid molecules were chemically bonded onto activated oxide substrates via the chemisorption of the carboxylic groups. PEDOT was then polymerized onto the EDOT-acid modified substrates, forming covalently bonded coatings. The adsorption of EDOT-acid onto the electrode surfaces was characterized by cyclic voltammetry (CV), contact angle measurements, atomic force microscopy, and X-ray photoelectron spectroscopy. The electrical properties of the subsequently coated PEDOT films were studied by electrochemical impedance spectroscopy and CV. An aggressive ultrasonication test confirmed the significantly improved adhesion and mechanical stability of the PEDOT films on electrodes with EDOT-acid treatment over those without treatment. PMID:26052833

  2. Reactivation of hydroformylation catalysts

    SciTech Connect

    Babin, J.E.; Bryant, D.R.; Harrison, A.M.; Miller, D.J.

    1993-08-17

    A process is described for improving the catalytic activity of a partially deactivated solubilized rhodium-tertiary organophosphine complex hydroformylation catalyst, which comprises (1) mixing under non-hydroformylating conditions, a organic liquid medium containing said solubilized partially deactivated complex catalyst, with propargyl alcohol and a carboxylic acid of the formula RCOOH wherein R represents hydrogen or an alkyl or aryl radical to obtain a treated solubilized rhodium-tertiary organophosphine complex product solution; and (2) removing from said product solution, the carboxylic acid employed in Step (1) to obtain a rhodium-tertiary organophosphine complex hydroformylation catalyst that is more catalytically active than said partially deactivated rhodium-tertiary organophosphine complex hydroformylation catalyst starting material of Step (1).

  3. Immobilized bisdiazaphospholane catalysts for asymmetric hydroformylation.

    PubMed

    Adint, Tyler T; Landis, Clark R

    2014-06-01

    Condensation reactions of enantiopure bis-3,4-diazaphospholanes (BDPs) that are functionalized with carboxylic acids enable covalent attachment to bead and silica supports. Exposure of tethered BDPs to the hydroformylation catalyst precursor, Rh(acac)(CO)2, yields catalysts for immobilized asymmetric hydroformylation (iAHF) of prochiral alkenes. Compared with homogeneous catalysts, catalysts immobilized on Tentagel resins exhibit similarly high regioselectivity and enantioselectivity. When corrected for apparent catalyst loading, the activity of the immobilized catalysts approaches that of the homogeneous analogues. Excellent recyclability with trace levels of rhodium leaching are observed in batch and flow reactor conditions. Silica-bound catalysts exhibit poorer enantioselectivities. PMID:24742285

  4. Amino acid/KI as multi-functional synergistic catalysts for cyclic carbonate synthesis from CO2 under mild reaction conditions: a DFT corroborated study.

    PubMed

    Roshan, Kuruppathparambil Roshith; Kathalikkattil, Amal Cherian; Tharun, Jose; Kim, Dong Woo; Won, Yong Sun; Park, Dae Won

    2014-02-01

    Naturally occurring amino acids were identified as efficient co-catalysts for the alkali metal halide-mediated synthesis of cyclic carbonates from carbon dioxide and epoxides under mild, solvent free reaction conditions. The binary system of histidine/potassium iodide gave an appreciable turnover number of 535 for propylene oxide in 3 h. Detailed studies evaluating a variety of amino acids revealed that the basic amino acids afforded better conversion rates. The formation of a seven membered ring involving the zwitterionic ends of the amino acid, the metal halide, and the epoxide was considered to accelerate the catalysis rate. Density functional theory calculations were performed for the first time on amino acid co-catalyzed cycloaddition to provide further evidence for this hypothesis. The iodide ions of the alkali metal halide displayed excellent synergism with the hydrogen bonding groups of the amino acids in the production of cyclic carbonates, whereas bromide and chloride anions functioned less efficiently. The utilization of amino acids to enhance the catalytic activity of the cheap and eco-friendly alkali metal halides for cyclic carbonate synthesis represents a cost-effective, greener route towards the chemical fixation of carbon dioxide. PMID:24270098

  5. Method of studying primary acts of adsorption and the active centers of solid catalysts by infrared spectroscopy

    Microsoft Academic Search

    G. D. Chukin; L. A. Ignat'eva

    1970-01-01

    Sample Preparation and Heat Treatment. The spectroscopic investigation of inorganic substances is fairly complicated. Powders of solid adsorbents cause severe light scattering. In order to reduce the scattering of the infrared radiation, samples have recently been prepared in the form of pressed tablets or plates of various sizes without any binding constituents, it being essential to use pure samples free

  6. Multinuclear Solid-State NMR Studies of Polymers and Immobilized Sonogashira Catalysts for Cross-Coupling Reactions

    E-print Network

    Pope, Jacqueline Christine

    2014-08-28

    °C (ca. 600 °F). Interactions and reactions of H2O with the functional groups of the polymers are studied using D2O in combination with IR, 2H MAS, and 1H wideline solid-state NMR. Three different processes taking place during high-temperature steam...

  7. The effect of metal ions as co-catalysts on acidic ionic liquid catalyzed single-step saccharification of corn stover in water.

    PubMed

    Wiredu, Bernard; Amarasekara, Ananda S

    2015-08-01

    The effects of adding Cr(3+), Mn(2+), Fe(3+), Co(2+) Ni(2+), Cu(2+), Zn(2+) and La(3+) chlorides as co-catalysts to 1-(1-propylsulfonic)-3-methylimidazolium chloride acidic ionic liquid catalyzed saccharification of corn stover in aqueous medium was studied at 140-170°C, by measuring the total reducing sugar (TRS) and glucose yields. The samples with Mn(2+), Fe(3+), Co(2+) as co-catalysts produced higher TRS yields compared to the sample without the metal ions. The Mn(2+) produced the highest catalytic effect enhancements and produced TRS yields of 68.0%, 72.9%, 90.2% and 87.9% at 140, 150, 160 and 170°C respectively; whereas the corn stover samples without the Mn(2+) produced TRS yields of 42.9%, 52.3%, 54.4% and 53.5% at the same four temperatures. At higher temperatures of 160 and 170°C, all metal ions studied produced significant enhancements in glucose yields, except Cr(3+). The addition of La(3+) as a co-catalyst produced the highest glucose yield improvement. PMID:25911191

  8. Selective aerobic oxidation of 5-HMF into 2,5-furandicarboxylic acid with Pt catalysts supported on TiO2 - and ZrO2 -based supports.

    PubMed

    Ait Rass, Hicham; Essayem, Nadine; Besson, Michèle

    2015-04-13

    Pt catalysts prepared over different metallic oxide supports were investigated in the oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA) in alkaline aqueous solutions with air, to examine the combined effect of the support and base addition. The base (nature and amount) played a significant role in the degradation or oxidation of HMF. Increasing amounts of the weak NaHCO3 base improved significantly the overall catalytic activity of Pt/TiO2 and Pt/ZrO2 by accelerating the oxidation steps, especially for the aldehyde group. This was highlighted by a proposed kinetic model that gave very good concentration-time fittings. Moreover, the promotion of the catalyst with bismuth yielded a Pt?Bi/TiO2 catalytic system with improved activity and stability. Y2 O3 ? and La2 O3 ?ZrO2 -supported catalysts exhibited lower activity than Pt/ZrO2 , which suggests no cooperative effect of the weakly basic properties introduced and the homogeneous base. Quantitative oxidation of HMF (0.1?M) and high yields of FDCA (>99?%) were obtained in less than 5?h by using an HMF/Pt molar ratio of 100 and Na2 CO3 as a weak base over Pt?Bi/TiO2 (Bi/Pt=0.22). PMID:25736596

  9. Regeneration of three-way automobile catalysts using biodegradable metal chelating agent--S, S-ethylenediamine disuccinic acid (S, S-EDDS).

    PubMed

    Subramanian, B; Christou, S Y; Efstathiou, A M; Namboodiri, V; Dionysiou, D D

    2011-02-28

    Regeneration of the activity of three-way catalytic converters (TWCs) was tested for the first time using a biodegradable metal chelating agent (S, S-ethylenediamine disuccinic acid (S, S-EDDS). The efficiency of this novel environmentally friendly solvent in removing various contaminants such as P, Zn, Pb, Cu and S from commercial aged three-way catalysts, and improving their catalytic performance towards CO and NO pollutants removal has been investigated. Four samples of catalysts from the front and rear inlets of two different TWCs with different mileages and aged under completely different driving conditions were investigated. The catalysts were characterized using various techniques, such as X-ray diffraction (XRD), Scanning electron microscopy (SEM), and Brunauer-Emmett-Teller (BET) surface area measurements (N(2) adsorption at 77 K). Quantitative ICP-MS analyses and SEM-EDS studies show the removal of Zn, P and Pb. SEM-EDS images obtained at low magnification (50 ?m) showed considerable differences in the surface morphology and composition after washing with S, S-EDDS. However, XRD studies indicated neither little to no removal of major contaminant compound phases nor major structural changes due to washing. Correspondingly, little or no enhancement in BET surface area was observed between the used and washed samples. Light-off curves show that the regeneration procedure employed can effectively improve the catalytic performance towards NO pollutant. PMID:21177030

  10. Selection of a strain of Aspergillus for the production of citric acid from pineapple waste in solid-state fermentation

    Microsoft Academic Search

    C. T. Tran; L. I. Sly; D. A. Mitchell

    1998-01-01

    Aspergillus foetidus ACM 3996 (=FRR 3558) and three strains of Aspergillus niger ACM 4992 (=ATCC 9142), ACM 4993 (=ATCC 10577), ACM 4994 (=ATCC 12846) were compared for the production of citric acid from pineapple peel in solid-state fermentation. A. niger ACM 4992 produced the highest amount of citric acid, with a yield of 19.4g of citric acid per 100g of

  11. Recovery of Alkylation Activity in Deactivated USY Catalyst Using Supercritical Fluids: A Comparison of Light Hydrocarbons

    SciTech Connect

    Daniel M. Ginosar; David N. Thompson; Kyle C. Burch

    2004-05-01

    Off-line, in-situ alkylation activity recovery from a completely deactivated solid acid catalyst was examined in a continuous-flow reaction system employing supercritical fluids (SCF). A USY zeolite catalyst was initially deactivated during the liquid phase alkylation of butene with isobutane in a single-pass reactor and then varying amounts of alkylation activity were recovered by passing supercritical fluids over the catalyst bed. A comparison of reactivation fluids on catalyst activity recovery is reported. Fluids examined included helium, propane, n-butane, isobutane, n-pentane, and isopentane. Phases studied included gas, liquid, and supercritical. As much as 82% of the fresh catalyst activity was recovered when employing supercritical isobutane. The ability of the fluid to facilitate a hydride reaction with the adsorbed deactivating high-molecular weight carbocations was indicated as an important property necessary to attain high levels of catalyst activity recovery. Activity recovery utilizing supercritical fluids that enhance reactivation by both reacting with and desorbing fouling compounds appears to be a promising technique to advance solid catalyst alkylation.

  12. Catalytic activity of zeolitic and mesostructured catalysts in the cracking of pure and waste polyolefins

    Microsoft Academic Search

    J. Aguado; D. P. Serrano; G. San Miguel; J. M. Escola; J. M. Rodríguez

    2007-01-01

    Six acid solids of varying acid and textural characteristics has been investigated for their catalytic activity in the degradation of plastic polymers using thermogravimetric and differential thermal analysis. The polymers included pure low-density polyethylene, pure high-density polyethylene and two samples of recycled polyethylene of urban and agricultural origins. The catalysts were three zeolitic materials (standard ZSM-5, nanocrystalline n-ZSM-5 and Beta)

  13. pKa Modulation of the Acid/Base Catalyst within GH32 and GH68: A Role in Substrate/Inhibitor Specificity?

    PubMed Central

    Yuan, Shuguang; Le Roy, Katrien; Venken, Tom; Lammens, Willem; Van den Ende, Wim; De Maeyer, Marc

    2012-01-01

    Glycoside hydrolases of families 32 (GH32) and 68 (GH68) belong to clan GH-J, containing hydrolytic enzymes (sucrose/fructans as donor substrates) and fructosyltransferases (sucrose/fructans as donor and acceptor substrates). In GH32 members, some of the sugar substrates can also function as inhibitors, this regulatory aspect further adding to the complexity in enzyme functionalities within this family. Although 3D structural information becomes increasingly available within this clan and huge progress has been made on structure-function relationships, it is not clear why some sugars bind as inhibitors without being catalyzed. Conserved aspartate and glutamate residues are well known to act as nucleophile and acid/bases within this clan. Based on the available 3D structures of enzymes and enzyme-ligand complexes as well as docking simulations, we calculated the pKa of the acid-base before and after substrate binding. The obtained results strongly suggest that most GH-J members show an acid-base catalyst that is not sufficiently protonated before ligand entrance, while the acid-base can be fully protonated when a substrate, but not an inhibitor, enters the catalytic pocket. This provides a new mechanistic insight aiming at understanding the complex substrate and inhibitor specificities observed within the GH-J clan. Moreover, besides the effect of substrate entrance on its own, we strongly suggest that a highly conserved arginine residue (in the RDP motif) rather than the previously proposed Tyr motif (not conserved) provides the proton to increase the pKa of the acid-base catalyst. PMID:22662155

  14. Sorption of radioactive cesium and barium ions onto solid humic acid.

    PubMed

    Celebi, O; Kilikli, A; Erten, H N

    2009-09-15

    In this study, the sorption behavior of two important fission product radionuclides ((137)Cs and (140)Ba) onto sodium form of insolubilized humic acid (INaA) were investigated as a function of time, cation concentration and temperature, utilizing the radiotracer method. The sorption processes are well described by both Freundlich and Dubinin-Radushkevich type isotherms. Thermodynamic constants such as; free energy (DeltaG(ads)), enthalpy (DeltaH(ads)), entropy (DeltaS(ads)) of adsorption were determined. It was found that Ba(2+) was adsorbed five times more than Cs(+) onto structurally modified humic acid and kinetic studies indicated that adsorption behavior of both ions obey the pseudo second order rate law. The effect of pH change on sorption was also examined. FTIR and solid-state carbon NMR ((13)CNMR) spectroscopic techniques were used to understand the structural changes during insolubilization process. Quantitative determination of adsorption sites was carried out using potantiometric titration. PMID:19321261

  15. Characterization of vanadium oxide catalysts supported on TiO{sub 2}-ZrO{sub 2} by solid-state {sup 51}V and {sup 1}H NMR spectroscopy

    SciTech Connect

    Reddy, B.M.; Reddy, E.P.; Srinivas, S.T. [Indian Inst. of Chemical Technology, Hyderabad (India)] [and others

    1992-08-20

    A series of TiO{sub 2}-ZrO{sub 2} mixed oxide supported vanadia catalysts with various V{sub 2}O{sub 5} loadings ranging from 1 to 16 wt % were prepared by a wet impregnation method and were characterized by means of solid-state {sup 51}V and {sup 1}H NMR spectroscopic techniques. The solid-state {sup 51}V NMR spectra of V{sub 2}O{sub 5}/TiO{sub 2}-ZrO{sub 2} catalysts reveal the existence of two types of dispersed surface vanadium oxide complexes in a tetrahedral oxygen environment at lower vanadium loadings adn a third three-dimensional crystalline V{sub 2}O{sub 5} in distorted octahedral environment at higher vanadium contents. The proton NMR results provide evidence for the existence of metal oxide support interaction through the support hydroxyl groups. 33 regs., 4 figs.

  16. Cryomilling-induced solid dispersion of poor glass forming/poorly water-soluble mefenamic acid with polyvinylpyrrolidone K12.

    PubMed

    Kang, Naewon; Lee, Jangmi; Choi, Ji Na; Mao, Chen; Lee, Eun Hee

    2015-06-01

    The effect of mechanical impact on the polymorphic transformation of mefenamic acid (MFA) and the formation of a solid dispersion of mefenamic acid, a poor glass forming/poorly-water soluble compound, with polyvinylpyrrolidone (PVP) K12 was investigated. The implication of solid dispersion formation on solubility enhancement of MFA, prepared by cryomilling, was investigated. Solid state characterization was conducted using powder X-ray diffraction (PXRD) and Fourier-transform infrared (FTIR) spectroscopy combined with crystal structure analysis. Apparent solubility of the mixtures in pH 7.4 buffer was measured. A calculation to compare the powder patterns and FTIR spectra of solid dispersions with the corresponding physical mixtures was conducted. Solid state characterization showed that (1) MFA I transformed to MFA II when pure MFA I was cryogenically milled (CM); and (2) MFA forms a solid dispersion when MFA was cryogenically milled with PVP K12. FTIR spectral analysis showed that hydrogen bonding facilitated by mechanical impact played a major role in forming solid dispersions. The apparent solubility of MFA was significantly improved by making a solid dispersion with PVP K12 via cryomilling. This study highlights the importance of cryomilling with a good hydrogen bond forming excipient as a technique to prepare solid dispersion, especially when a compound shows a poor glass forming ability and therefore, is not easy to form amorphous forms by conventional method. PMID:24849785

  17. Nuclear resonance investigtion of hydrogen mobility in chromous acid (. cap alpha. -HCrOâ). [For possible use as hydrogen ion conducting solid electrolyte for fuel cell

    Microsoft Academic Search

    D. M. Follstaedt; R. M. Biefeld; D. S. Ginley

    1977-01-01

    There is considerable interest in developing a hydrogen ion conducting solid electrolyte because solids with fast proton conduction could be of considerable utility as separators in fuel cells. Chromous acid (HCrOâ) was chosen as a possible hydrogen ion solid electrolyte because of the similarity of its structure to that of the well known solid electrolyte, Na ..beta..-alumina. The structure of

  18. Far infrared spectra of solid state aliphatic amino acids in different protonation states

    NASA Astrophysics Data System (ADS)

    Trivella, Aurélien; Gaillard, Thomas; Stote, Roland H.; Hellwig, Petra

    2010-03-01

    Far infrared spectra of zwitterionic, cationic, and anionic forms of aliphatic amino acids in solid state have been studied experimentally. Measurements were done on glycine, L-alanine, L-valine, L-leucine, and L-isoleucine powder samples and film samples obtained from dried solutions prepared at pH ranging from 1 to 13. Solid state density functional theory calculations were also performed, and detailed potential energy distributions were obtained from normal mode results. A good correspondence between experimental and simulated spectra was achieved and this allowed us to propose an almost complete band assignment for the far infrared spectra of zwitterionic forms. In the 700-50 cm-1 range, three regions were identified, each corresponding to a characteristic set of normal modes. A first region between 700 and 450 cm-1 mainly contained the carboxylate bending, rocking, and wagging modes as well as the ammonium torsional mode. The 450-250 cm-1 region was representative of backbone and sidechain skeletal bending modes. At last, the low wavenumber zone, below 250 cm-1, was characteristic of carboxylate and skeletal torsional modes and of lattice modes. Assignments are also proposed for glycine cationic and anionic forms, but could not be obtained for all aliphatic amino acids due to the lack of structural data. This work is intended to provide fundamental information for the understanding of peptides vibrational properties.

  19. An Investigation of Solid-State Amidization and Imidization Reactions in Vapor Deposited Poly (amic acid)

    SciTech Connect

    Anthamatten, M; Letts, S A; Day, K; Cook, R C; Gies, A P; Hamilton, T P; Nonidez, W K

    2004-06-28

    The condensation polymerization reaction of 4,4'-oxydianiline (ODA) with pyromellitic dianhydride (PMDA) to form poly(amic acid) and the subsequent imidization reaction to form polyimide were investigated for films prepared using vapor deposition polymerization techniques. Fourier-transform infrared spectroscopy (FT-IR), thermal analysis, and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) of films at different temperatures indicate that additional solid-state polymerization occurs prior to imidization reactions. Experiments reveal that, upon vapor deposition, poly(amic acid) oligomers form that have a number-average molecular weight of about 1500 Daltons. Between 100 - 130 C these chains undergo additional condensation reaction to form slightly higher molecular weight oligomers. Calorimetry measurements show that this reaction is exothermic ({Delta}H {approx} -30 J/g) with an activation energy of about 120 kJ/mol. Experimental reaction enthalpies are compared to results from ab initio molecular modeling calculations to estimate the number of amide groups formed. At higher temperatures (150 - 300 C) imidization of amide linkages occurs as an endothermic reaction ({Delta}H {approx} +120 J/g) with an activation energy of about 130 kJ/mol. Solid-state kinetics were found to depend on reaction conversion as well as the processing conditions used to deposit films.

  20. Electron-Withdrawing Trifluoromethyl Groups in Combination with Hydrogen Bonds in Polyols: Brønsted Acids, Hydrogen-Bond Catalysts, and Anion Receptors

    SciTech Connect

    Shokri, Alireza; Wang, Xue B.; Kass, Steven R.

    2013-06-26

    Electron withdrawing trifluoromethyl groups were characterized in combination with hydrogen bond interactions in three polyols (i.e., CF3CH(OH)CH2CH(OH)CF3, 1; (CF3)2C(OH)C(OH)(CF3)2, 2; ((CF3)2C(OH)CH2)2CHOH, 3) by pKa measurements in DMSO and H2O, negative ion photoelectron spectroscopy and binding constant determinations with Cl–. Their catalytic behavior in several reactions were also examined and compared to a BrØnsted acid (HOAc) and a commonly employed thiourea ((3,5-(CF3)3C6H3NH)2CS). The combination of inductive stabilization and hydrogen bonds was found to afford potent acids which are effective catalysts. It also appears that hydrogen bonds can transmit the inductive effect over distance even in an aqueous environment, and this has far reaching implications.

  1. Reuse of sewage sludge as a catalyst in ozonation--efficiency for the removal of oxalic acid and the control of bromate formation.

    PubMed

    Wen, Gang; Pan, Zhi-Hui; Ma, Jun; Liu, Zheng-Qian; Zhao, Lei; Li, Jun-Jing

    2012-11-15

    Sewage derived sludge is produced with an annual amount increase of 2% all over the world and it is an urgent issue to be addressed by human being. In the present study, sludge was converted into sludge-based catalyst (SBC) with ZnCl2 as activation agent and characterized by several methods (e.g., scanning electron microscope, X-ray photoelectron spectroscope and Fourier transform infrared spectroscope). Then it was used as a catalyst to enhance the removal of refractory organic matter, oxalic acid, and to control the formation of bromate (BrO3-) in bench semi-continuous ozonation experiments. The effects of various operating parameters on the control of BrO3- formation were investigated. Furthermore, the mechanism for the enhancement of organic matter removal and the control of BrO3- formation was discussed as well. Results indicate that the combination of SBC with ozone shows a strong synergistic effect, resulting in a notable improvement on oxalic acid removal. A crucial surface reaction mechanism for the enhancement of organic matter removal is proposed on the basis of negative effect of higher pH and no inhibition effect of tert-butanol. The control for BrO3- formation was demonstrated and the reason for its control in the process of O3/SBC is the combined effect of SBC reductive properties, ozone exposure decrease and hydrogen peroxide concentration increase. PMID:23021317

  2. Acid zirconium phosphates and phosphonates as proton conductors and their use for solid state gas sensors

    SciTech Connect

    Alberti, G.; Casciola, M.; Palombari, R. [Elce di Sotto, Perugia (Italy)

    1993-12-01

    Solid state proton conductors can be employed in several electrochemical devices, among which fuel cells and gas sensors are of particular interest. Microcrystalline {alpha}-layered zirconium phosphate [{alpha}-Zr(HPO){sub 4}){sub 2}{center_dot}H{sub 2}O] is a proton conductor, but its conductivity {sigma} {approx} 10{sup -5} - 10{sup -6}{omega}{sup -1} cm{sup -1} at 20{degrees}C and 90% relative humidity) is too low for practical applications in some electrochemical devices. Conductivity enhancements have been obtained by (1) preparation of membranes made up of highly oriented particles (pellicular zirconium phosphate), (2) intercalation of suitable organic molecules (especially hydrazine and pyrazole), and (3) synthesis of organic derivatives containing acid ionogenic groups in the interlayer region. The best results have been obtained for Zr alkylsulfophenyl phosphonates possessing -SO{sub 3}H in the interlayer region. The highest conductivity is on the order of 10{sup -2}{omega}{sup -1} cm{sup -1} at 100{degrees}C and 60% relative humidity. Pellicular zirconium phosphate has already been used in the development of amperometric and potentiometric solid state sensors for hydrogen, oxygen and carbon monoxide. Noncatalytic metal hybrides such as ZrH{sub x} and TiH{sub x} are very suitable solid reference electrodes for these sensors, since they are non-blocking electrodes for protons, but, at the same time, they are not sensitive to molecular hydrogen.

  3. Direct formic acid fuel cells

    NASA Astrophysics Data System (ADS)

    Rice, C.; Ha, S.; Masel, R. I.; Waszczuk, P.; Wieckowski, A.; Barnard, Tom

    The performance of formic acid fuel oxidation on a solid PEM fuel cell at 60 °C is reported. We find that formic acid is an excellent fuel for a fuel cell. A model cell, using a proprietary anode catalyst produced currents up to 134 mA/cm 2 and power outputs up to 48.8 mW/cm 2. Open circuit potentials (OCPs) are about 0.72 V. The fuel cell runs successfully over formic acid concentrations between 5 and 20 M with little crossover or degradation in performance. The anodic polarization potential of formic acid is approximately 0.1 V lower than that for methanol on a standard Pt/Ru catalyst. These results show that formic acid fuel cells are attractive alternatives for small portable fuel cell applications.

  4. Hydrogen generation from magnesium hydride by using organic acid

    NASA Astrophysics Data System (ADS)

    Ho, Yen-Hsi

    In this paper, the hydrolysis of solid magnesium hydride has been studied with the high concentration of catalyst at the varying temperature. An organic acid (acetic acid, CH3COOH) has been chosen as the catalyst. The study has three objectives: first, using three different weights of MgH 2 react with aqueous solution of acid for the hydrogen generation experiments. Secondly, utilizing acetic acid as the catalyst accelerates hydrogen generation. Third, emphasizing the combination of the three operating conditions (the weight of MgH2, the concentration of acetic acid, and the varying temperature) influence the amount of hydrogen generation. The experiments results show acetic acid truly can increase the rate of hydrogen generation and the weight of MgH2 can affect the amount of hydrogen generation more than the varying temperature.

  5. Catalyst Of A Metal Heteropoly Acid Salt That Is Insoluble In A Polar Solvent On A Non-Metallic Porous Support And Method Of Making

    DOEpatents

    Wang. Yong (Richland, WA); Peden. Charles H. F. (West Richland, WA); Choi. Saemin (Richland, WA)

    2004-11-09

    The present invention includes a catalyst having (a) a non-metallic support having a plurality of pores; (b) a metal heteropoly acid salt that is insoluble in a polar solvent on the non-metallic support; wherein at least a portion of the metal heteropoly acid salt is dispersed within said plurality of pores. The present invention also includes a method of depositing a metal heteropoly acid salt that is insoluble in a polar solvent onto a non-metallic support having a plurality of pores. The method has the steps of: (a) obtaining a first solution containing a first precursor of a metal salt cation; (b) obtaining a second solution containing a second precursor of a heteropoly acid anion in a solvent having a limited dissolution potential for said first precursor; (c) impregnating the non-metallic support with the first precursor forming a first precursor deposit within the plurality of pores, forming a first precursor impregnated support; (d) heating said first precursor impregnated support forming a bonded first precursor impregnated support; (e) impregnating the second precursor that reacts with the precursor deposit and forms the metal heteropoly acid salt.

  6. An Efficient Protocol for the Green and Solvent-Free Synthesis of Azine Derivatives at Room Temperature Using BiCl3-Loaded Montmorillonite K10 as a New Recyclable Heterogeneous Catalyst

    PubMed Central

    Ravi, K.; Krishnakumar, B.; Swaminathan, M.

    2012-01-01

    A new BiCl3-loaded montmorillonite K10 catalyst has been prepared by solid dispersion method and was characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and cyclic voltammetry (CV) measurements. BiCl3 loaded K10 (BiCl3-K10) has been used as solid acid catalyst for the synthesis of azine derivatives from benzophenone hydrazone and ketones/aldehydes by simple physical grinding. This BiCl3-K10 gives an excellent yield with short reaction time and is an inexpensive, easily recyclable catalyst for this reaction. PMID:24052847

  7. Effects of iron-tetrasulfophthalocyanine on the catalytic activities of Pt\\/C, PtRu\\/C, and Pd\\/C catalysts in a multi-anode direct formic acid fuel cell

    Microsoft Academic Search

    Xingwen Yu; Peter G. Pickup

    2010-01-01

    This paper reports a systematic study of the effects of a promoter, iron-tetrasulfophthalocyanine (FeTSPc), on the catalytic\\u000a activities of carbon supported Pt, PtRu, and Pd catalysts (Pt\\/C, PtRu\\/C, and Pd\\/C) for formic acid oxidation. A multi-anode\\u000a direct formic acid fuel cell (DFAFC) was used to compare the effects on each catalyst of adding FeTSPc to the fuel stream.\\u000a The FeTSPc

  8. Tunneling isomerization of small carboxylic acids and their complexes in solid matrixes: a computational insight.

    PubMed

    Tsuge, Masashi; Khriachtchev, Leonid

    2015-03-19

    We have studied hydrogen-atom tunneling in the cis-to-trans conformational change of some carboxylic acid monomers and formic acid (FA) complexes and dimers at the MP2(full) and CCSD(T) levels of theory within the Wentzel-Kramers-Brillouin approximation. The barrier for the minimum energy path, where the OH bond length and the COH bending angle are optimized, is found to be a good approximation for providing the highest barrier transparency. The matrix effect on the transmission coefficients of cis-FA monomer, trans-cis FA dimer (tc1), and cis-acetic acid monomer are modeled by the polarizable continuum model (PCM) at the MP2(full) level of theory in different environments. For the cis-FA monomer and trans-cis FA dimer (tc1), the calculated transmission coefficients agree with the experimental lifetimes observed in noble-gas solids. However, this method cannot reproduce the experimental results obtained for cis-acetic acid. Moreover, the long lifetime of cis-FA and cis-acetic acid in the N2 environment cannot be reproduced either, which is most probably due to specific interactions that are not included in the PCM. The calculation for cis-HCOOD shows a strong decrease of the barrier transparency compared to that for cis-HCOOH, which is consistent with the experiments. In general, good agreement is observed between the calculated barrier transparency (including PCM) and experimental tunneling rate. However, some exceptions are found, which shows that additional factors influence the tunneling rate. PMID:25393052

  9. Potential effects of clean coal technologies on acid precipitation, greenhouse gases, and solid waste disposal

    SciTech Connect

    Blasing, T.J.; Miller, R.L.; McCold, L.N.

    1993-11-01

    The US Department of Energy`s (DOE`s) Clean Coal Technology Demonstration Program (CCTDP) was initially funded by Congress to demonstrate more efficient, economically feasible, and environmentally acceptable coal technologies. Although the environmental focus at first was on sulfur dioxide (SO{sub 2}) and nitrogen oxides (NO{sub x}) because their relationship to acid precipitation, the CCTDP may also lead to reductions in carbon dioxide (CO{sub 2}) emissions and in the volume of solid waste produced, compared with conventional technologies. The environmental effects of clean coal technologies (CCTs) depend upon which (if any) specific technologies eventually achieve high acceptance in the marketplace. In general, the repowering technologies and a small group of retrofit technologies show the most promise for reducing C0{sub 2} emissions and solid waste. These technologies also compare favorably with other CCTs in terms of SO{sub 2} and NO{sub x} reductions. The upper bound for CO{sup 2} reductions in the year 2010 is only enough to reduce global ``greenhouse`` warming potential by about 1%. However, CO{sub 2} emissions come from such variety of sources around the globe that no single technological innovation or national policy change could realistically be expected to reduce these emissions by more than a few percent. Particular CCTs can lead to either increases or decreases in the amount of solid waste produced. However, even if decreases are not achieved, much of the solid waste from clean coal technologies would be dry and therefore easier to dispose of than scrubber sludge.

  10. Quantitative study of solid-state acid–base reactions between polymorphs of flufenamic acid and magnesium oxide using X-ray powder diffraction

    Microsoft Academic Search

    Xiaoming Chen; Joseph G. Stowell; Kenneth R. Morris; Stephen R. Byrn

    2010-01-01

    The purpose of this study is to investigate solid-state acid–base reactions between polymorphs of flufenamic acid (FFA) and magnesium oxide (MgO) using X-ray powder diffraction (XRPD). Polymorphs of FFA were blended with MgO and stored under conditions of 96.5% RH and 89% RH at 40°C. The disappearance of FFA and production of magnesium flufenamate were monitored by XRPD. It was

  11. Synthesis and Evaluation of Cu/SAPO-34 Catalysts for NH3-SCR 2: Solid-state Ion Exchange and One-pot Synthesis

    SciTech Connect

    Gao, Feng; Walter, Eric D.; Washton, Nancy M.; Szanyi, Janos; Peden, Charles HF

    2015-01-01

    Cu-SAPO-34 catalysts are synthesized using two methods: solid-state ion exchange (SSIE) and one-pot synthesis. SSIE is conducted by calcining SAPO-34/CuO mixtures at elevated temperatures. For the one-pot synthesis method, Cu-containing chemicals (CuO and CuSO4) are added during gel preparation. A high-temperature calcination step is also needed for this method. Catalysts are characterized with surface area/pore volume measurements, temperature programmed reduction (TPR), electron paramagnetic resonance (EPR) and nuclear magnetic resonance (NMR) spectroscopies, and scanning electron microscopy (SEM). Catalytic properties are examined using standard ammonia selective catalytic reduction (NH3-SCR) and ammonia oxidation reactions. In Cu-SAPO-34 samples formed using SSIE, Cu presents both as isolated Cu2+ ions and unreacted CuO. The former is highly active and selective in NH3-SCR, while the latter catalyzes a side reaction; notably, the non-selective oxidation of NH3 above 350 ºC. Using the one-pot method followed by a high-temperature aging treatment, it is possible to form Cu SAPO-34 samples with predominately isolated Cu2+ ions at low Cu loadings. However at much higher Cu loadings, isolated Cu2+ ions that bind weakly with the CHA framework and CuO clusters also form. These Cu moieties are very active in catalyzing non-selective NH3 oxidation above 350 ºC. Low-temperature reaction kinetics indicate that Cu-SAPO-34 samples formed using SSIE have core-shell structures where Cu is enriched in the shell layers; while Cu is more evenly distributed within the one-pot samples. Reaction kinetics also suggest that at low temperatures, the local environment next to Cu2+ ion centers plays little role on the overall catalytic properties. The authors gratefully acknowledge the US Department of Energy (DOE), Energy Efficiency and Renewable Energy, Vehicle Technologies Office for the support of this work. The research described in this paper was performed at the Environmental Molecular Sciences Laboratory (EMSL), a national scientific user facility sponsored by the DOE’s Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory (PNNL). PNNL is operated for the US DOE by Battelle under contract number DE-AC05-76RL01830. The authors also thank Shari Li (PNNL) for surface area/pore volume measurements, and Bruce W. Arey (PNNL) for SEM measurements. Discussions with Drs. A. Yezerets, K. Kamasamudram, J.H. Li, N. Currier and J.Y. Luo from Cummins, Inc. and H.Y. Chen and H. Hess from Johnson-Matthey are greatly appreciated.

  12. Pore structure modification of diatomite as sulfuric acid catalyst support by high energy electron beam irradiation and hydrothermal treatment

    NASA Astrophysics Data System (ADS)

    Li, Chong; Zhang, Guilong; Wang, Min; Chen, Jianfeng; Cai, Dongqing; Wu, Zhengyan

    2014-08-01

    High energy electron beam (HEEB) irradiation and hydrothermal treatment (HT), were applied in order to remove the impurities and enlarge the pore size of diatomite, making diatomite more suitable to be a catalyst support. The results demonstrated that, through thermal, charge, impact and etching effects, HEEB irradiation could make the impurities in the pores of diatomite loose and remove some of them. Then HT could remove rest of them from the pores and contribute significantly to the modification of the pore size distribution of diatomite due to thermal expansion, water swelling and thermolysis effects. Moreover, the pore structure modification improved the properties (BET (Brunauer-Emmett-Teller) specific surface area, bulk density and pore volume) of diatomite and the catalytic efficiency of the catalyst prepared from the treated diatomite.

  13. Natural DNA-modified graphene/Pd nanoparticles as highly active catalyst for formic acid electro-oxidation and for the Suzuki reaction.

    PubMed

    Qu, Konggang; Wu, Li; Ren, Jinsong; Qu, Xiaogang

    2012-09-26

    Natural DNA has been considered as a building block for developing novel functional materials. It is abundant, renewable, and biodegradable and has a well-defined structure and conformation with many unique features, which are difficult to find in other polymers. Herein, calf thymus DNA modified graphene/Pd nanoparticle (DNA-G-Pd) hybrid materials are constructed for the first time using DNA as a mediator, and the prepared DNA-G-Pd hybrid shows high catalytic activity for fuel cell formic acid electro-oxidation and for organic Suzuki reaction. The main advantages of using DNA are not only because the aromatic nucleobases in DNA can interact through ?-? stacking with graphene basal surface but also because they can chelate Pd via dative bonding in such defined sites along the DNA lattice. Our results indicate that isolated, homogeneous, and ultrafine spherical Pd nanoparticles are densely in situ decorated on DNA-modified graphene surfaces with high stability and dispersibility. The prepared DNA-G-Pd hybrid has much greater activity and durability for formic acid electro-oxidation than the commercial Pd/C catalyst and polyvinylpyrrolidone-mediated graphene/Pd nanoparticle (PVP-G-Pd) hybrid used for direct formic acid fuel cells (DFAFCs). Besides, the DNA-G-Pd hybrid can also be an efficient and recyclable catalyst for the organic Suzuki reaction in aqueous solution under aerobic conditions without any preactivation. Since DNA can chelate various transition metal cations, this proof-of-concept protocol provides the possibility for the tailored design of other novel catalytic materials based on graphene with full exploitation of their properties. PMID:22973944

  14. Metal oxide nanostructures synthesized on flexible and solid substrates and used for catalysts, UV detectors, and chemical sensors

    NASA Astrophysics Data System (ADS)

    Willander, Magnus; Sadollahkhani, Azar; Echresh, Ahmad; Nur, Omer

    2014-03-01

    In this paper we demonstrate the visibility of the low temperature chemical synthesis for developing device quality material grown on flexible and solid substrates. Both colorimetric sensors and UV photodetectors will be presented. The colorimetric sensors developed on paper were demonstrated for heavy metal detection, in particular for detecting copper ions in aqueous solutions. The demonstrated colorimetric copper ion sensors developed here are based on ZnO@ZnS core-shell nanoparticles (CSNPs). These sensors demonstrated an excellent low detection limit of less than 1 ppm of copper ions. Further the colorimetric sensors operate efficiently in a wide pH range between 4 and 11, and even in turbulent water. The CSNPs were additionally used as efficient photocatalytic degradation element and were found to be more efficient than pure ZnO nanoparticles (NPs). Also p-NiO/n-ZnO thin film/nanorods pn junctions were synthesized by a two-step synthesis process and were found to act as efficient UV photodetectors. Additionally we show the effect of the morphology of different CuO nanostructures on the efficiency of photo catalytic degradation of Congo red organic dye.

  15. Determination of soluble solid content and acidity of loquats based on FT-NIR spectroscopy*

    PubMed Central

    Fu, Xia-ping; Li, Jian-ping; Zhou, Ying; Ying, Yi-bin; Xie, Li-juan; Niu, Xiao-ying; Yan, Zhan-ke; Yu, Hai-yan

    2009-01-01

    The near infrared (NIR) spectroscopy technique has been applied in many fields because of its advantages of simple preparation, fast response, and non-destructiveness. We investigated the potential of NIR spectroscopy in diffuse reflectance mode for determining the soluble solid content (SSC) and acidity (pH) of intact loquats. Two cultivars of loquats (Dahongpao and Jiajiaozhong) harvested from two orchards (Tangxi and Chun’an, Zhejiang, China) were used for the measurement of NIR spectra between 800 and 2500 nm. A total of 400 loquats (100 samples of each cultivar from each orchard) were used in this study. Relationships between NIR spectra and SSC and acidity of loquats were evaluated using partial least square (PLS) method. Spectra preprocessing options included the first and second derivatives, multiple scatter correction (MSC), and the standard normal variate (SNV). Three separate spectral windows identified as full NIR (800~2500 nm), short NIR (800~1100 nm), and long NIR (1100~2500 nm) were studied in factorial combination with the preprocessing options. The models gave relatively good predictions of the SSC of loquats, with root mean square error of prediction (RMSEP) values of 1.21, 1.00, 0.965, and 1.16 °Brix for Tangxi-Dahongpao, Tangxi-Jiajiaozhong, Chun’an-Dahongpao, and Chun’an-Jiajiaozhong, respectively. The acidity prediction was not satisfactory, with the RMSEP of 0.382, 0.194, 0.388, and 0.361 for the above four loquats, respectively. The results indicate that NIR diffuse reflectance spectroscopy can be used to predict the SSC and acidity of loquat fruit. PMID:19235270

  16. Interaction of acid mine drainage with Ordinary Portland Cement blended solid residues generated from active treatment of acid mine drainage with coal fly ash

    Microsoft Academic Search

    Wilson M. Gitari; Leslie F. Petrik; David L. Key; Charles Okujeni

    2011-01-01

    Fly ash (FA) has been investigated as a possible treatment agent for Acid mine drainage (AMD) and established to be an alternative, cheap and economically viable agent compared to the conventional alkaline agents. However, this treatment option also leads to generation of solid residues (SR) that require disposal and one of the proposed disposal method is a backfill in coal

  17. Pt\\/K–?Al 2O 3 solid electrolyte cell as a “smart electrochemical catalyst” for the effective removal of NO x under wet reaction conditions

    Microsoft Academic Search

    Antonio de Lucas-Consuegra; Ángel Caravaca; Fernando Dorado; José L. Valverde

    2009-01-01

    This study has shown that the phenomenon of electrochemical promotion can be used to activate a metal catalyst for the selective catalytic reduction of nitrogen oxides (NOx) in the presence of water in the feed. The application of different potentials optimized the catalytic performance of the Pt catalyst-working electrode at each reaction temperature range. In addition, the measurement of the

  18. Following solid-acid-catalyzed reactions by MAS NMR spectroscopy in liquid phase--zeolite-catalyzed conversion of cyclohexanol in water.

    PubMed

    Vjunov, Aleksei; Hu, Mary Y; Feng, Ju; Camaioni, Donald M; Mei, Donghai; Hu, Jian Z; Zhao, Chen; Lercher, Johannes A

    2014-01-01

    A microautoclave magic angle spinning NMR rotor is developed enabling in?situ monitoring of solid-liquid-gas reactions at high temperatures and pressures. It is used in a kinetic and mechanistic study of the reactions of cyclohexanol on zeolite HBEA in 130?°C water. The (13) C?spectra show that dehydration of 1-(13) C-cyclohexanol occurs with significant migration of the hydroxy group in cyclohexanol and the double bond in cyclohexene with respect to the (13) C label. A simplified kinetic model shows the E1-type elimination fully accounts for the initial rates of 1-(13) C-cyclohexanol disappearance and the appearance of the differently labeled products, thus suggesting that the cyclohexyl cation undergoes a 1,2-hydride shift competitive with rehydration and deprotonation. Concurrent with the dehydration, trace amounts of dicyclohexyl ether are observed, and in approaching equilibrium, a secondary product, cyclohexyl-1-cyclohexene is formed. Compared to phosphoric acid, HBEA is shown to be a more active catalyst exhibiting a dehydration rate that is 100-fold faster per proton. PMID:24282024

  19. Anaerobic degradation of phthalic acid esters during digestion of municipal solid waste under landfilling conditions.

    PubMed

    Ejlertsson, J; Meyerson, U; Svensson, B H

    1996-08-01

    Anaerobic microorganisms in municipal solid waste samples from laboratory-scale landfill reactors and a pilot-plant biogas digestor were investigated with the aim of assessing their ability to transform four commercially used phthalic acid esters (PAEs) and phthalic acid (PA). The PAEs studied were diethyl phthalate (DEP), butylbenzyl phthalate (BBP), dibutyl phthalate (DBP) and bis(2-ethylhexyl) phthalate (DEHP). No biological transformation of DEHP could be detected in any of the experiments. Together with waste samples from the simulated landfilling conditions, the PAEs (except DEHP) were hydrolytically transformed to their corresponding monoesters. These accumulated as end products, and in most cases they were not further degraded. During incubation with waste from the biogas digestor, the PAEs (except DEHP) were completely degraded to methane and carbon dioxide. The influence of the landfill development phase on the transformations was investigated utilizing PA and DEP as model substances. We found that during both the intense and stable methanogenic (but not the acidogenic) phases, the microorganisms in the samples had the potential to transform PA. A shorter lag phase was observed for the PA transformation in the samples from the stable methanogenic phase as compared with earlier phases. This indicates an increased capacity to degrade PA during the aging phases of the municipal solid waste in landfills. No enhancement of the DEP transformation could be observed as conditions in the methanogenic landfill model changed over a year's time. The results indicate that microorganisms developing in a methanogenic landfill environment have a substantially lower potential to degrade compared with those developing in a biogas reactor. PMID:8987892

  20. Chemical Interactions in Multimetal/Zeolite Catalysts

    SciTech Connect

    Sachtler, Wolfgang M. H.

    2004-04-16

    This two-year project has led to a significant improvement in the fundamental understanding of the catalytic action of zeolite-supported redox catalysts. It turned out to be essential that we could combine four strategies for the preparation of catalysts containing transition metal (TM) ions in zeolite cavities: (1) ion exchange from aqueous solution; (2) chemical vapor deposition (CVD) of a volatile halide onto a zeolite in its acidic form; (3) solid state ion exchange; and (4) hydrothermal synthesis of a zeolite having TM ions in its lattice, followed by a treatment transporting these ions to ''guest positions''. Technique (2) enables us to position more TM ions into cavities than permitted by the conventional technique (1).viz one positive charge per Al centered tetrahedron in the zeolite lattice. The additional charge is compensated by ligands to the TM ions, for instance in oxo-ions such as (GaO){sup +} or dinuclear [Cu-O-Cu]{sup 2+}. While technique (3) is preferred over CVD where volatile halides are not available, technique (4) leads to rather isolated ''ex lattice'' oxo-ions. Such oxo-ions tend to be mono-nuclear, in contrast to technique (2) which preferentially creates dinuclear oxo-ions of the same TM element. A favorable element for the present research was that the PI is also actively engaged in a project on the reduction of nitrogen oxides, sponsored by EMSI program of the National Science Foundation and the US Department of Energy, Office of Science. This combination created a unique opportunity to test and analyze catalysts for the one step oxidation of benzene to phenol and compare them with catalysts for the reduction of nitrogen oxides, using hydrocarbons as the reductant. In both projects catalysts have been used which contain Fe ions or oxo-ions in the cavities the zeolite MFI, often called ZSM-5. With Fe as the TM-element and MFI as the host zeolite we found that catalysts with high Fe content, prepared by technique (2) were optimal for the De-NO{sub x} reaction, but extremely unselective for benzene oxidation to phenol. Conversely, the catalysts prepared with (4) had the highest turnover frequency for benzene oxidation, but performed very poorly for NO{sub x} reduction with so-butane. In fact the Fe concentration in the former catalysts were so low that it was necessary to design a special experimental program for the sole purpose of showing that it is really the Fe which catalyzes the benzene oxidation, not some acid center as has been proposed by other authors. For this purpose we used hydrogen sulfide to selectively poison the Fe sites, without deactivating the acidic sites. In addition we could show that the hydrothermal treatment of catalysts prepared by technique (4) is essential to transform iron ions in the zeolite lattice to ''ex lattice ions'' in guest positions. That line of the work required very careful experimentation, because a hydrothermal treatment of a zeolite containing Fe ions in its cavities can also lead to agglomeration of such ions to nano-particles of iron oxide which lowers the selectivity for the desired formation of phenol. This part of the program showed convincingly that indeed Fe is responsible for the benzene oxidation catalysis. The results and conclusion of this work, including the comparison of different catalysts, was published in a number of papers in the scientific literature, listed in the attached list. In these papers also our analysis of the reaction orders and the possible mechanism of the used test reaction are given.

  1. Cu-Mn-Ce ternary mixed-oxide catalysts for catalytic combustion of toluene.

    PubMed

    Lu, Hanfeng; Kong, Xianxian; Huang, Haifeng; Zhou, Ying; Chen, Yinfei

    2015-06-01

    Cu-Mn, Cu-Mn-Ce, and Cu-Ce mixed-oxide catalysts were prepared by a citric acid sol-gel method and then characterized by XRD, BET, H2-TPR and XPS analyses. Their catalytic properties were investigated in the toluene combustion reaction. Results showed that the Cu-Mn-Ce ternary mixed-oxide catalyst with 1:2:4 mole ratios had the highest catalytic activity, and 99% toluene conversion was achieved at temperatures below 220°C. In the Cu-Mn-Ce catalyst, a portion of Cu and Mn species entered into the CeO2 fluorite lattice, which led to the formation of a ceria-based solid solution. Excess Cu and Mn oxides existed on the surface of the ceria-based solid solution. The coexistence of Cu-Mn mixed oxides and the ceria-based solid solution resulted in a better synergetic interaction than the Cu-Mn and Cu-Ce catalysts, which promoted catalyst reducibility, increased oxygen mobility, and enhanced the formation of abundant active oxygen species. PMID:26040736

  2. Photosynthetic hydrogen evolution with volatile organic acids derived from the fermentation of source selected municipal solid wastes

    Microsoft Academic Search

    E. Fascetti; E. D'Addario; O. Todini; A. Robertiello

    1998-01-01

    Rhodobacter sphaeroides RV cells were cultivated on lactate containing solutions derived from the acidogenesis of source selected municipal solid wastes. Cells were also used for the phototrophic hydrogen evolution using the same substrate. Batch-wise and continuous experiments showed that the acidic aqueous stream obtained from such refuse is quite a good substrate for the growth of R. sphaeroides RV without

  3. 10th International Conference on Chemometrics in Analytical Chemistry OP35 Simultaneuosly Calibrating Solids, Sugars and Acidity of Tomato

    E-print Network

    Ferreira, Márcia M. C.

    10th International Conference on Chemometrics in Analytical Chemistry OP35 Simultaneuosly Calibrating Solids, Sugars and Acidity of Tomato Products Using PLS2 and NIR Spectroscopy André M. K. Pedro* 1(SP), 13271-450, Brazil, 2 Universidade Estadual de Campinas (UNICAMP), Chemistry Institute, Physical

  4. GC-MS QUANTIFICATION OF THE METHANOL AND ACETIC ACID CONTENT OF PECTIN USING HEADSPACE SOLID-PHASE MICROEXTRACTION

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A simple, fast, and direct procedure was developed for the simultaneous determination of the methanol and acetic acid present as esters in the plant cell wall polysaccharide pectin. After base-hydrolysis of esters and acidification of pectin samples, headspace solid-phase microextraction was perfor...

  5. SCREENING FOR VOLATILE ORGANIC FATTY ACIDS IN AGRICULTURAL AIR USING SOLID-PHASE MICROEXTRACTION AND GAS CHROMATOGRAPHY-MASS SPECTROMETRY

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Volatile fatty acids (VFAs) are a major component of odorous gases associated with agricultural sources. Because of typically low VFA air concentrations, conventional air sampling methods including sorbent tubes and vacuum canisters are often not sensitive enough to detect them. Solid phase microe...

  6. The effect of isosaccharinic acid (ISA) on the mobilization of metals in municipal solid waste incineration (MSWI) dry scrubber residue

    Microsoft Academic Search

    Malin Svensson; Magnus Berg; Karin Ifwer; Rolf Sjöblom; Holger Ecke

    2007-01-01

    Co-landfilling of incineration ash and cellulose might facilitate the alkaline degradation of cellulose. A major degradation product is isosaccharinic acid (ISA), a complexing agent for metals. The impact of ISA on the mobility of Pb, Zn, Cr, Cu and Cd from a municipal solid waste incineration dry scrubber residue was studied at laboratory using a reduced 25?1 factorial design. Factors

  7. Molecular Structure of Glutaric acid

    NSDL National Science Digital Library

    2004-11-10

    Glutaric acid is a colorless liquid and white crystals as a solid occurring in plants and animal tissues. It is used in organic synthesis and as an intermediate for the manufacture of polymers such as polyamides and polyesters, ester plasticizers and corrosion inhibitors. It is also useful in the application of decreasing polymer elasticity and in a variety of industrial applications. In addition glutaric acid plays an important role as an intermediary in the Krebs cycle and is used in medication against a large number of viruses and in animal diabetes. Glutaric acid can be prepared from cyclopentanone by oxidative ring fission with nitric acid and in the presence of a catalyst. Glutaric acid has the lowest melting point among dicarboxylic acids (98 C); it is very soluble in water and the solution in water is a medium strong acid. Short-term exposure to glutaric acid may cause irritation to the eyes, skin and the respiratory tract.

  8. The conversion of CO2 and CH4 to acetic acid over the Au-exchanged ZSM-5 catalyst: a density functional theory study.

    PubMed

    Panjan, Wasinee; Sirijaraensre, Jakkapan; Warakulwit, Chompunuch; Pantu, Piboon; Limtrakul, Jumras

    2012-12-28

    The direct conversion of methane and carbon dioxide to acetic acid is one of the most challenging research topics. Using the density functional theory (M06-L) the study reveals the catalytic activity of the Au(I)-ZSM-5 zeolite in this reaction. The Au(I)-ZSM-5 is represented by a 34T quantum cluster model. The activation of the C-H bond over the Au-ZSM-5 zeolite would readily take place via the homolytic ?-bond activation with an energy barrier of 10.5 kcal mol(-1), and subsequent proton transfer from the Au cation to the zeolitic oxygen, yielding the stable methyl-gold complex adsorbed on the zeolite Brønsted acid. The conversion of CO(2) on this bi-functional catalyst involves the Brønsted acid site playing a role in the protonation of CO(2) and the methyl-gold complex acting as a methylating agent. The activation energy of 52.9 kcal mol(-1) is predicted. PMID:22903398

  9. In situ FTIR investigation of acetic acid electrooxidation on carbon supported Pt-Sn based trimetallic catalysts: Influence of the nature of the third metal

    NASA Astrophysics Data System (ADS)

    Beyhan, Seden; Léger, Jean-Michel; Kad?rgan, Figen

    2014-12-01

    The effect of adding a third metal (Ni, Co, Pd, Rh) to Pt-Sn/C catalyst has been investigated for the adsorption and oxidation of acetic acid in acidic medium using in situ Fourier transform infrared (FTIR) spectroscopy. The results showed that the decomposition of acetic acid on the surface leads to the formation of different intermediate species and products such as acetate, acetyl, carbonate, CO and CO2. The reaction pathway of CO2 production proceeds via the formation of acetyl or carbonate through surface acetate species. It has been found that the selectivity of the acetate was enhanced by the addition of any third metal. However, the presence of Pd or Co increases the relative intensity of IR band for CO2. This is probably due to success in facilitating of the Csbnd C bond cleavage of acetyl. On the other hand, the conversion of acetate to carbonate is strongly affected by the adsorbed water, as is evident from the pronounced changes in the OH stretching region with the presence of Pd or Ni.

  10. Modeling of anaerobic degradation of solid slaughterhouse waste: inhibition effects of long-chain fatty acids or ammonia.

    PubMed

    Lokshina, L Y; Vavilin, V A; Salminen, E; Rintala, J

    2003-01-01

    The anaerobic bioconversion of solid poultry slaughterhouse wastes was kinetically investigated. The modified version of simulation model was applied for description of experimental data in mesophilic laboratory digester and assays. Additionally, stages of formation and consumption of long chain fatty acids (LCFA) were included in the model. Batch data on volatile solids, ammonium, acetate, butyrate, propionate, LCFA concentrations, pH level, cumulative volume, and methane partial pressure were used for model calibration. As a reference, the model was used to describe digestion of solid sorted household waste. Simulation results showed that an inhibition of polymer hydrolysis by volatile fatty acids and acetogenesis by NH3 or LCFA could be responsible for the complex system dynamics during degradation of lipid- and protein-rich wastes. PMID:12794281

  11. Metal chelate catalysts for fuel cells

    NASA Astrophysics Data System (ADS)

    Darby, R.; Yamana, M.; Dhar, H.; White, R.

    1982-10-01

    Various modified forms of several organometallic chelate compounds were synthesized and tested for their activity and stability as oxygen reduction electrocatalysts in sulfuric acid electrolyte. The most active catalysts found were cobalt tetraazaannulene (CoTAA), iron phthalocyanine (FePc) and cobalt tetraphenylporphyrin (CoTPP). However, these catalysts have limited stability in strong acids.

  12. Metal chelate catalysts for fuel cells

    Microsoft Academic Search

    R. Darby; M. Yamana; H. Dhar; R. White

    1982-01-01

    Various modified forms of several organometallic chelate compounds were synthesized and tested for their activity and stability as oxygen reduction electrocatalysts in sulfuric acid electrolyte. The most active catalysts found were cobalt tetraazaannulene (CoTAA), iron phthalocyanine (FePc) and cobalt tetraphenylporphyrin (CoTPP). However, these catalysts have limited stability in strong acids.

  13. Solids

    NSDL National Science Digital Library

    worthent

    2006-03-31

    Findingsurface area and volume of solids. These sites a have drills for learning surface area and volume, Volume of Rec. Prism Surface Area This site allows you to change the surface area and volume of a prism. This site allows you to change the surface area and volume of a prism. This site has a quiz for you to do. Quiz Geodesic domes Geodesic domes ...

  14. Hydrodewaxing with mixed zeolite catalysts

    SciTech Connect

    Chester, A.W.; McHale, W.D.; Yen, J.H.

    1986-03-11

    A process is described for catalytically dewaxing a hydrocarbon lubricating oil feedstock comprising contacting the feedstock with a dewaxing catalyst, the dewaxing catalyst comprising, in combination: (a) a zeolite catalyst having a Constraint Index not less than 1, (b) an acidic catalytic material selected from the group consisting of Mordenite, TEA Mordenite, Dealuminized Y, Ultrastable Y, Rare Earth Y, amorphous silica-alumina chlorinated alumina, ZSM-4 and ZSM-20, and (c) a hydrogenation component, and recovering a dewaxed product. A process is also described for catalytically dewaxing a hydrocarbon lubricating oil feedstock comprising contacting the feedstock with a dewaxing catalyst, the dewaxing catalyst comprising, in combinations: (a) a first zeolite catalyst selected from the group consisting of ZSM-5, ZMS-11, ZSM-12, ZSM-22, ZSM-23, ZSM-34, ZSM-35, ZSM-38, ZSM-48, TMA Offretite and Erionite, (b) a second catalyst selected from the group consisting of ZSM-12, ZSM-22, ZSM-38 and ZSM-48, the second zeolite catalyst being different from the first zeolite catalyst, and (c) a hydrogenation component, and recovering a dewaxed product.

  15. Preparation and characterization of core–shell structured catalysts using Pt x Pd y as active shell and nano-sized Ru as core for potential direct formic acid fuel cell application

    Microsoft Academic Search

    Haili Gao; Shijun Liao; Jianhuang Zeng; Yichun Xie; Dai Dang

    2011-01-01

    Carbon-supported core–shell structured Ru@PtxPdy\\/C catalysts with PtxPdy as shell and nano-sized Ru as core are prepared by a successive reduction procedure. The catalysts are extensively characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The formic acid oxidation activity of Ru@PtxPdy\\/C varies with the varying Pt:Pd atomic ratio. The peak oxidation potential on Ru@Pt1Pd2\\/C shifts

  16. Characterization and catalytic activity of differently pretreated Pd\\/Al 2O 3 catalysts: the role of acid sites and of palladium–alumina interactions

    Microsoft Academic Search

    M. Skotak; Z. Karpi?ski; W. Juszczyk; J. Pielaszek; L. K?pi?ski; D. V. Kazachkin; V. I. Kovalchuk; J. L. d'Itri

    2004-01-01

    The effect of catalyst pretreatment on the performance of chlorine-free ?-alumina-supported palladium catalysts with metal loadings in the range of 0.3 to 2.77 wt% has been investigated in the hydroconversion of n-hexane (nH) and 2,2-dimethylbutane (22DMB) at 290?°C and atmospheric pressure. The catalyst properties were modified by varying the catalyst pretreatment: low-temperature reduction (LTR) at 300?°C; high-temperature reduction (HTR) at

  17. Increased Selectivity in the Formation of the Phenoxy Ether of Methyl Lesquerolate over Chloroalkyl-modified SBA-15-SO3H Catalysts

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A novel synthetic catalysis was developed for selective modification of useful bioproducts from the oil of Lesquerella fendlerii, an agricultural commodity of increasing importance. Modification of the surface of the solid acid catalyst SBA-15-SO3H with the chloroalkyl groups CH2CH2Cl has improved ...

  18. Activity of Pt anode catalyst modified by underpotential deposited Pb in a direct formic acid fuel cell

    Microsoft Academic Search

    Sunghyun Uhm; Sung Taik Chung; Jaeyoung Lee

    2007-01-01

    We characterized the electrocatalytic activity of platinum electrode modified by underpotential deposited lead (PtPbupd) for a formic acid (HCOOH) oxidation and investigated the influence on the power performance of direct formic acid fuel cells (DFAFC). Based on the electrochemical analysis using cyclic voltammetry and chronoamperometry, PtPbupd electrode modified by underpotential deposition (UPD) exhibited significantly enhanced catalytic activity for HCOOH oxidation

  19. CATALYSTS NHI Thermochemical Systems FY 2009 Year-End Report

    Microsoft Academic Search

    Daniel M. Ginosar

    2009-01-01

    Fiscal Year 2009 work in the Catalysts project focused on advanced catalysts for the decomposition of sulfuric acid, a reaction common to both the Sulfur-Iodine (S-I) cycle and the Hybrid Sulfur cycle. Prior years effort in this project has found that although platinum supported on titanium oxide will be an acceptable catalyst for sulfuric acid decomposition in the integrated laboratory

  20. Solid solutions of Ni and Co molybdates in silica-dispersed and bulk catalysts prepared by sol–gel and citrate methods

    Microsoft Academic Search

    Andrea Maione; Michel Devillers

    2004-01-01

    Silica-dispersed catalysts based on cobalt, nickel and mixed Ni–Co molybdates of various compositions are prepared by a sol–gel procedure from silicon alkoxides, metal nitrates and ammonium heptamolybdate. For comparative purposes, the corresponding bulk molybdates are obtained by the citrate route. The polymorphism and the textural properties of these catalysts are investigated by means of X-ray diffraction, UV–visible diffuse reflectance spectroscopy

  1. Process for fatty acid methyl esters by dual reactive distillation

    Microsoft Academic Search

    Alexandre C. Dimian; Florin Omota; Anton A. Kiss

    2007-01-01

    Fatty acid methyl esters (FAME) , valuable oleo-chemicals and main constituent of biodiesel, can be manufactured in a continuous process based on reactive distillation and solid catalyst. A central problem is the effective water removal. In this work we propose a novel approach, namely dual esterification with a mixture of methanol and long-chain alcohol, as 2-ethylhexanol, which plays the role

  2. Bio-inspired amino acid oxidation by a non-heme iron catalyst modeling the action of 1-aminocyclopropane-1-carboxylic acid oxidase.

    PubMed

    Baráth, Gábor; Kaizer, József; Pap, József Sándor; Speier, Gábor; El Bakkali-Taheri, Nadia; Simaan, A Jalila

    2010-10-21

    In this communication we describe the first example of a biomimetic mononuclear iron complex, [Fe(III)(Salen)Cl] (Salen = N,N'-bis(salicylidene)-ethylenediaminato), that highly selectively and efficiently catalyzes the oxidation of 1-aminocyclopropane-1-carboxylic acid (ACCH), ?-aminoisobutyric acid (AIBH), and alanine (ALAH) to ethylene or the corresponding carbonyl compounds, mimicking the action of the non-heme iron enzyme 1-aminocyclopropane-1-carboxylic acid oxidase (ACCO). PMID:20830340

  3. Catalytic performance of Fe3O4-CoO/Al2O3 catalyst in ozonation of 2-(2,4-dichlorophenoxy)propionic acid, nitrobenzene and oxalic acid in water.

    PubMed

    Tong, Shaoping; Shi, Rui; Zhang, Hua; Ma, Chunan

    2010-01-01

    Fe3O4-CoO/Al2O3 catalyst was prepared by incipient wetness impregnation using Fe(NO3)3 x 9H2O and Co(NO3)2 x 6H2O as the precursors, and its catalytic performance was investigated in ozonation of 2-(2,4-dichlorophenoxy)propionic acid (2,4-DP), nitrobenzene and oxalic acid. The experimental results indicated that Fe3O4-CoO/Al2O3 catalyst enabled an interesting improvement of ozonation efficiency during the degradation of each organic pollutant, and the Fe3O4-CoO/Al2O3 catalytic ozonation system followed a radical-type mechanism. The kinetics of ozonation alone and Fe3O4-CoO/Al2O3 catalytic ozonation of three organic pollutants in aqueous solution were discussed under the mere consideration of direct ozone reaction and OH radical reaction to well investigate its performance. In the catalytic ozonation of 2,4-DP, the apparent reaction rate constants (k) were determined to be 1.456 x 10(-2) min(-1) for ozonation alone and 4.740 x 10(-2) min(-1) for O3/Fe3O4-CoO/Al203. And O3/Fe3O4-CoO/Al2O3 had a larger R(ct) (6.614 x 10(-9)) calculated by the relative method than O3 did (1.800 x 10(-9)), showing O3/Fe3O4-CoO/Al2O3 generated more hydroxyl radical. Similar results were also obtained in the catalytic ozonation of nitrobenzene and oxalic acid. The above results demonstrated that the catalytic performance of Fe3O4-CoO/Al2O3 in ozonation of studied organic substance was universal to a certain degree. PMID:21235195

  4. Amino acid modified Ni catalyst exhibits reversible H2 oxidation/production over a broad pH range at elevated temperatures

    PubMed Central

    Dutta, Arnab; DuBois, Daniel L.; Roberts, John A. S.; Shaw, Wendy J.

    2014-01-01

    Hydrogenases interconvert H2 and protons at high rates and with high energy efficiencies, providing inspiration for the development of molecular catalysts. Studies designed to determine how the protein scaffold can influence a catalytically active site have led to the synthesis of amino acid derivatives of [Ni(P2RN2R?)2]2+ complexes, [Ni(P2CyN2Amino?acid)2]2+ (CyAA). It is shown that these CyAA derivatives can catalyze fully reversible H2 production/oxidation at rates approaching those of hydrogenase enzymes. The reversibility is achieved in acidic aqueous solutions (pH = 0–6), 1 atm 25% H2/Ar, and elevated temperatures (tested from 298 to 348 K) for the glycine (CyGly), arginine (CyArg), and arginine methyl ester (CyArgOMe) derivatives. As expected for a reversible process, the catalytic activity is dependent upon H2 and proton concentrations. CyArg is significantly faster in both directions (?300 s?1 H2 production and 20 s?1 H2 oxidation; pH = 1, 348 K, 1 atm 25% H2/Ar) than the other two derivatives. The slower turnover frequencies for CyArgOMe (35 s?1 production and 7 s?1 oxidation under the same conditions) compared with CyArg suggests an important role for the COOH group during catalysis. That CyArg is faster than CyGly (3 s?1 production and 4 s?1 oxidation) suggests that the additional structural features imparted by the guanidinium groups facilitate fast and reversible H2 addition/release. These observations demonstrate that outer coordination sphere amino acids work in synergy with the active site and can play an important role for synthetic molecular electrocatalysts, as has been observed for the protein scaffold of redox active enzymes. PMID:25368196

  5. A column-based `flush and flow' system for the asymmetric a-chlorination of acid halides

    E-print Network

    Lectka, Thomas

    alkaloid based reagent/catalyst solid-phase promotes the asymmetric a-chlorination of acid chlorides for the enantioselective chlorination of acid halides, in which resin beads derivatized with a cinchona alkaloid serve, the cinchona alkaloid-derived beads can be completely regenerated. Given the robustness of the beads

  6. Naturally occurring alkaline amino acids function as efficient catalysts on Knoevenagel condensation at physiological pH: a mechanistic elucidation.

    PubMed

    Li, Weina; Fedosov, Sergey; Tan, Tianwei; Xu, Xuebing; Guo, Zheng

    2014-05-01

    To maintain biological functions, thousands of different reactions take place in human body at physiological pH (7.0) and mild conditions, which is associated with health and disease. Therefore, to examine the catalytic function of the intrinsically occurring molecules, such as amino acids at neutral pH, is of fundamental interests. Natural basic ?-amino acid of L-lysine, L-arginine, and L-histidine neutralized to physiological pH as salts were investigated for their ability to catalyze Knoevenagel condensation of benzaldehyde and ethyl cyanoacetate. Compared with their free base forms, although neutralized alkaline amino acid salts reduced the catalytic activity markedly, they were still capable to perform an efficient catalysis at physiological pH as porcine pancreatic lipase (PPL), one of the best enzymes that catalyze Knoevenagel condensation. In agreement with the fact that the three basic amino acids were well neutralized, stronger basic amino acid Arg and Lys showed more obvious variation in NH bend peak from the FTIR spectroscopy study. Study of ethanol/water system and quantitative kinetic analysis suggested that the microenvironment in the vicinity of amino acid salts and protonability/deprotonability of the amine moiety may determine their catalytic activity and mechanism. The kinetic study of best approximation suggested that the random binding might be the most probable catalytic mechanism for the neutralized alkaline amino acid salt-catalyzed Knoevenagel condensation. PMID:24682854

  7. Control of product selectivity using solid acids for the catalytic addition of phenol to hydroxy fatty acids

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The acid catalyzed reactions of hydroxy fatty acids, such as ricinoleic and lesquerolic, in the presence of phenolics can lead to four products or product groups. These include simple dehydration to dienoic acids, cyclization to epoxides, Friedel-Crafts alkylations of the double bonds, or ether for...

  8. Bifunctional TiO2 Catalysts for Efficient Cr(VI) Photoreduction Under Solar Light Irradiation Without Addition of Acids

    NASA Astrophysics Data System (ADS)

    Shi, Fu-cheng; Wang, Wen-dong; Huang, Wei-xin

    2012-04-01

    Bifunctional TiO2 photocatalysts co-doped with nitrogen and sulfur were prepared by the controlled thermal decomposition of ammonium titanyl sulfate precursor. They have both photocatalytic activity and Brønsted acidity, and thus are active in the photoreduction of Cr(VI) under solar light irradiation without the addition of acids. The activity is superior to that of Degussa P25 in the acidified suspension at the same pH adjusted by H2SO4.

  9. High temperature acid hydrolysis of biomass using an engineering - scale plug flow reactor. Results of low testing solids

    SciTech Connect

    Brennan, A.H.; Hoagland, W.; Schell, D.J.; Scott, C.D. (ed.)

    1986-01-01

    An engineering-scale experiment at the Solar Energy Research Institute investigating dilute acid hydrolysis of lignocellulosic biomass using a 3.8-cm (1.5-in) diameter plug flow to 900 kg/h (2000 lb/h) at 200-260 degrees and 4-20 seconds residence time. Initial experiments operated with 10 weight percent solids slurries to verify that yields obtained in bench-scale experiments could be maintained at a larger scale. The results of these tests can serve as a baseline for research addressing prehydrolysis of the slurry, high solids pumping, pretreatment requirements, and fermentability.

  10. Polymorphism in sulfadimidine/4-aminosalicylic acid cocrystals: solid-state characterization and physicochemical properties.

    PubMed

    Grossjohann, Christine; Serrano, Dolores R; Paluch, Krzysztof J; O'Connell, Peter; Vella-Zarb, Liana; Manesiotis, Panagiotis; Mccabe, Thomas; Tajber, Lidia; Corrigan, Owen I; Healy, Anne Marie

    2015-04-01

    Polymorphism of crystalline drugs is a common phenomenon. However, the number of reported polymorphic cocrystals is very limited. In this work, the synthesis and solid-state characterization of a polymorphic cocrystal composed of sulfadimidine (SD) and 4-aminosalicylic acid (4-ASA) is reported for the first time. By liquid-assisted milling, the SD:4-ASA 1:1 form I cocrystal, the structure of which has been previously reported, was formed. By spray drying, a new polymorphic form (form II) of the SD:4-ASA 1:1 cocrystal was discovered which could also be obtained by solvent evaporation from ethanol and acetone. Structure determination of the form II cocrystal was calculated using high-resolution X-ray powder diffraction. The solubility of the SD:4-ASA 1:1 cocrystal was dependent on the pH and predicted by a model established for a two amphoteric component cocrystal. The form I cocrystal was found to be thermodynamically more stable in aqueous solution than form II, which showed transformation to form I. Dissolution studies revealed that the dissolution rate of SD from both cocrystals was enhanced when compared with a physical equimolar mixture and pure SD. © 2015 Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci 104:1385-1398, 2015. PMID:25605031

  11. Chemo-Enzymatic Synthesis of Each Enantiomer of Orthogonally-Protected 4,4-Difluoroglutamic Acid – A Candidate Monomer for Chiral Brønsted-Acid Peptide-Based Catalysts

    PubMed Central

    Li, Yang

    2011-01-01

    We have accomplished an asymmetric synthesis of each enantiomer of 4,4-difluoroglutamic acid. This ?-amino acid has been of interest in medicinal chemistry circles. Key features of the synthesis include highly scalable procedures, a Reformatsky-based coupling reaction, and straightforward functional group manipulations to make the parent amino acid. Enantioenrichment derives from an enzymatic resolution of the synthetic material. Conversion of the optically enriched compounds to orthogonally protected forms allows selective formation of peptide bonds. 4,4- Difluoroglutamic acid, in a suitably protected form, is also shown to exhibit enhanced catalytic activity in both an oxidation reaction and a reduction reaction, in comparison to the analogous glutamic acid derivative. PMID:22039908

  12. 7 CFR 51.1178 - Maximum anhydrous citric acid permissible for corresponding total soluble solids.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ...2010-01-01 false Maximum anhydrous citric acid permissible for corresponding total soluble... § 51.1178 Maximum anhydrous citric acid permissible for corresponding total soluble...the maximum permissible anhydrous citric acid content in relation to...

  13. Solid solutions of Ni and Co molybdates in silica-dispersed and bulk catalysts prepared by sol-gel and citrate methods

    NASA Astrophysics Data System (ADS)

    Maione, Andrea; Devillers, Michel

    2004-07-01

    Silica-dispersed catalysts based on cobalt, nickel and mixed Ni-Co molybdates of various compositions are prepared by a sol-gel procedure from silicon alkoxides, metal nitrates and ammonium heptamolybdate. For comparative purposes, the corresponding bulk molybdates are obtained by the citrate route. The polymorphism and the textural properties of these catalysts are investigated by means of X-ray diffraction, UV-visible diffuse reflectance spectroscopy and Raman spectroscopy. Their surface and textural characteristics are investigated by X-ray photoelectron spectroscopy and nitrogen or krypton physisorption. In the sol-gel prepared catalysts, the ?-phase of Ni 1- xCo xMoO 4, which is the most active phase in the oxidative dehydrogenation of light alkanes, is stabilized over the whole composition range. In the analogous bulk catalysts prepared by the citrate method, this phase is stabilized only at high Co content ( x?0.55). Dispersion of the active phase in silica is shown to improve the propene productivity in comparison with bulk catalysts obtained by citrate or coprecipitation methods.

  14. Fundamental studies of the mechanism of catalytic reactions with catalysts effective in the gasification of carbon solids and the oxidative coupling of methane

    SciTech Connect

    Heinemann, H.; Somorjai, G.A.; Perry, D.L.

    1992-03-01

    Work will continue on the oxidative coupling reaction of methane over ternary oxide catalysts to produce C{sub 2}, C{sub 3} and C{sub 4} hydrocarbons and particularly olefins with high selectivity. The work which has shown that close to 100% selectivity can be obtained has received wide attention and has resulted in collaborative efforts with industry (CRADA) towards the development of a commercial process. An immediate purpose of additional work is to increase the conversion without diminishing the extremely high selectivity of the reaction and also to permit operation at higher space velocity to reduce equipment size. The mechanism of this reaction is not understood and much additional work is needed to explain the role of carbon formation and of water as intermediates in the reaction and to investigate whether carbon oxides are intermediates. It has been found that oxides other than calcium-nickel-potassium oxides can be useful catalysts for this reaction in the presence of steam and at relatively low temperatures and long contact times. Better definition of the class of binary metal oxides is required and better catalyst characterization is needed to ensure reproducibility of catalyst preparation and operational results. Pretreatment of the catalyst should be shortened and higher space velocities must be obtained. Close collaboration with Orion ACT is required to advance the project toward the pilot plant stage. In the area of coal and char catalytic steam gasification, the large volume of data obtained at atmospheric pressure will be extended to operations at higher pressures.

  15. Recycling GTL catalysts—A new challenge

    Microsoft Academic Search

    Andreas Brumby; Michel Verhelst; Daniel Cheret

    2005-01-01

    The Fischer Tropsch synthesis of motor fuel from natural gas on a large scale may become significant in the near future for economic and environmental reasons. This process requires solid-phase catalysts containing large amounts of cobalt (catalyst) and traces of platinum group metals or rhenium (promoter). The economic data presented in this paper shows why recycling of those metals will

  16. Use of solid-state 13C NMR in structural studies of humic acids and humin from Holocene sediments

    USGS Publications Warehouse

    Hatcher, P.G.; VanderHart, D.L.; Earl, W.L.

    1980-01-01

    13C NMR spectra of solid humic substances in Holocene sediments have been obtained using cross polarization with magic-angle sample spinning techniques. The results demonstrate that this technique holds great promise for structural characterizations of complex macromolecular substances such as humin and humic acids. Quantifiable distinctions can be made between structural features of aquatic and terrestrial humic substances. The aliphatic carbons of the humic substances are dominant components suggestive of input from lipid-like materials. An interesting resemblance is also noted between terrestrial humic acid and humin spectra. ?? 1980.

  17. TiO2 and Al2O3 promoted Pt/C nanocomposites as low temperature fuel cell catalysts for electro oxidation of methanol in acidic media

    NASA Astrophysics Data System (ADS)

    Naeem, Rabia; Ahmed, Riaz; Shahid Ansari, Muhammad

    2014-06-01

    Carbon corrosion and platinum dissolution are the two major catalyst layer degradation problems in polymer electrolyte membrane fuel cells (PEMFC). Ceramic addition can reduce the corrosion of carbon and increase the stability of catalysts. Pt/TiO2, Pt/TiO2-C, Pt/Al2O3 and Pt/Al2O3-C catalysts were synthesized and characterized. Electrochemical surface area of Pt/TiO2-C and Pt/Al2O3-C nanocomposite catalysts was much higher than the Pt/TiO2 and Pt/Al2O3 catalysts. Peak current, specific activity and mass activity of the catalysts was also determined by cyclic voltammetry and were much higher for the carbon nanocomposites. Exchange current densities were determined from Tafel plots. Heterogeneous rates of reaction of electro oxidation of methanol were determined for all the catalysts and were substantially higher for titania catalysts as compared to alumina added catalysts. Mass activity of Pt/TiO2-C was much higher than mass activity of Pt/Al2O3-C. Stability studies showed that addition of ceramics have increased the catalytic activity and durability of the catalysts considerably.

  18. CATALYSTS FOR HIGH CETANE ETHERS AS DIESEL FUELS

    SciTech Connect

    Kamil Klier; Richard G. Herman; James G.C. Shen; Qisheng Ma

    2000-08-31

    A novel 1,2-ethanediol, bis(hydrogen sulfate), disodium salt precursor-based solid acid catalyst with a zirconia substrate was synthesized and demonstrated to have significantly enhanced activity and high selectivity in producing methyl isobutyl ether (MIBE) or isobutene from methanol-isobutanol mixtures. The precursor salt was synthesized and provided by Dr. T. H. Kalantar of the M.E. Pruitt Research Center, Dow Chemical Co., Midland, MI 48674. Molecular modeling of the catalyst synthesis steps and of the alcohol coupling reaction is being carried out. A representation of the methyl transfer from the surface activated methanol molecule (left) to the activated oxygen of the isobutanol molecule (right) to form an ether linkage to yield MIBE is shown.

  19. X-ray data for the substitutional solid solution of the binary system ammonium dihydrogen phosphate with boric acid

    Microsoft Academic Search

    M. L. N. Madhu Mohan; C. Haranadh

    1994-01-01

    X-ray powder diffraction data for the binary system ammonium dihydrogen phosphate with boric acid is studied and it is inferred\\u000a that the binary belongs to tetragonal system and forms a substitutional solid phase. On the basis of the space group the binary\\u000a is predicted to exhibit electrooptic property along with piezoelectric and electrostriction properties. It is proposed that\\u000a the phosphorus

  20. Comparison of citric acid production by solid-state fermentation in flask, column, tray, and drum bioreactors

    Microsoft Academic Search

    Luciana P. S. Vandenberghe; Carlos R. Soccol; F. C. Prado; Ashok Pandey

    2004-01-01

    Studies were conducted to evaluate citric acid production by solid-state fermentation (SSF) using cassava bagasse as substrate\\u000a employing a fungal culture of Aspergillus niger LPB 21 at laboratory and semipilot scale. Optimization of the process parameters temperature, pH, initial humidity, aeration,\\u000a and nutritive composition was conducted in flasks and column fermentors. The results showed that thermal treatment of cassava\\u000a bagasse

  1. Distribution of organophosphoric acid triesters between water and sediment at a sea-based solid waste disposal site

    Microsoft Academic Search

    Yasunori Kawagoshi; Isao Fukunaga; Hisao Itoh

    1999-01-01

    Organophosphoric acid triester (OPE) concentration levels in water and bottom sediment at the Osaka North Port Sea-Based Solid\\u000a Waste Disposal Site were investigated, and the behavior of OPEs in the water environment of the waste disposal site was examined.\\u000a The more highly water-soluble OPEs were frequently detected in raw water. Of the OPEs detected, TCEP and TCPP showed very\\u000a high

  2. Catalyzed pyrolysis of grape and olive bagasse. Influence of catalyst type and chemical treatment

    SciTech Connect

    Encinar, J.M.; Beltran, F.J.; Ramiro, A.; Gonzalez, J.F. [Univ. de Extremadura, Badajoz (Spain). Dept. de Ingenieria Quimica y Energetica] [Univ. de Extremadura, Badajoz (Spain). Dept. de Ingenieria Quimica y Energetica

    1997-10-01

    Catalyzed pyrolysis of grape and olive bagasse under different experimental conditions has been studied. Variables investigated were temperature and type and concentration of catalysts. Experiments were carried out in an isothermal manner. Products of pyrolysis are gases (H{sub 2}, CO, CO{sub 2}, and CH{sub 4}), liquids (methanol, acetone, furfurylic alcohol, phenol, furfural, naphthalene, and o-cresol), and solids (chars). Temperature is a significant variable, yielding increases of fixed carbon content, gases, and to a lesser extent, ash percentage. Catalyst presence also yields increases of solid phase content, but the amount of liquid components decrease. Among catalysts applied those of Fe and Zn are the most advisable to obtain gases. Chemical treatment of bagasses with sulfuric or phosphoric acid washing leads to lower char yields, although fixed carbon content is higher and ash presence diminishes with respect to catalyst pyrolysis without chemical pretreatment. A pyrolysis kinetic study based on gas generation from thermal decomposition of residues has been carried out. From the model proposed, rate constants for the formation of each gas, reaction order of the catalyst, and activation energies were determined.

  3. Generation of ricinoleic acid from castor oil using the lipase from ground oat ( Avena sativa L.) seeds as a catalyst

    Microsoft Academic Search

    George J. Piazza; Harold M. Farrell

    1991-01-01

    Summary The lipase found in oat seeds acts upon castor oil in organic solvent, yielding approximately 90% ricinoleic acid. Initial velocity is a poor predictor of the time required for complete lipolysis except at low oil concentrations. Equations were developed to estimate kinetic parameters necessary to accurately predict the degree of lipolysis.

  4. Effect of total solids content on methane and volatile fatty acid production in anaerobic digestion of food waste.

    PubMed

    Liotta, Flavia; d'Antonio, Giuseppe; Esposito, Giovanni; Fabbricino, Massimiliano; van Hullebusch, Eric D; Lens, Piet N L; Pirozzi, Francesco; Pontoni, Ludovico

    2014-10-01

    This work investigates the role of the moisture content on anaerobic digestion of food waste, as representative of rapidly biodegradable substrates, analysing the role of volatile fatty acid production on process kinetics. A range of total solids from 4.5% to 19.2% is considered in order to compare methane yields and kinetics of reactors operated under wet to dry conditions. The experimental results show a reduction of the specific final methane yield of 4.3% and 40.8% in semi-dry and dry conditions compared with wet conditions. A decreasing trend of the specific initial methane production rate is observed when increasing the total solids concentration. Because of lack of water, volatile fatty acids accumulation occurs during the first step of the process at semi-dry and dry conditions, which is considered to be responsible for the reduction of process kinetic rates. The total volatile fatty acids concentration and speciation are proposed as indicators of process development at different total solids content. PMID:25281663

  5. Investigating fatty acids inserted into magnetically aligned phospholipid bilayers using EPR and solid-state NMR spectroscopy.

    PubMed

    Nusair, Nisreen A; Tiburu, Elvis K; Dave, Paresh C; Lorigan, Gary A

    2004-06-01

    This is the first time (2)H solid-state NMR spectroscopy and spin-labeled EPR spectroscopy have been utilized to probe the structural orientation and dynamics of a stearic acid incorporated into magnetically aligned phospholipid bilayers or bicelles. The data gleaned from the two different techniques provide a more complete description of the bilayer membrane system. Both methods provided similar qualitative information on the phospholipid bilayer, high order, and low motion for the hydrocarbon segment close to the carboxyl groups of the stearic acid and less order and more rapid motion at the end towards the terminal methyl groups. However, the segmental order parameters differed markedly due to the different orientations that the nitroxide and C-D bond axes transform with the various stearic acid acyl chain conformations, and because of the difference in dynamic sensitivity between NMR and EPR over the timescales examined. 5-, 7-, 12-, and 16-doxylstearic acids spin-labels were used in the EPR experiments and stearic acid-d(35) was used in the solid-state NMR experiments. The influence of the addition of cholesterol and the variation of temperature on the fatty acid hydrocarbon chain ordering in the DMPC/DHPC phospholipid bilayers was also studied. Cholesterol increased the degree of ordering of the hydrocarbon chains. Conversely, as the temperature of the magnetically aligned phospholipid bilayers increased, the order parameters decreased due to the higher random motion of the acyl chain of the stearic acid. The results indicate that magnetically aligned phospholipid bilayers are an excellent model membrane system and can be used for both NMR and EPR studies. PMID:15140432

  6. Filter Paper-based Nucleic Acid Storage in High-throughput Solid Tumor Genotyping.

    PubMed

    Stachler, Matthew; Jia, Yonghui; Sharaf, Nematullah; Wade, Jacqueline; Longtine, Janina; Garcia, Elizabeth; Sholl, Lynette M

    2015-01-01

    Molecular testing of tumors from formalin-fixed paraffin-embedded (FFPE) tissue blocks is central to clinical practice; however, it requires histology support and increases test turnaround time. Prospective fresh frozen tissue collection requires special handling, additional storage space, and may not be feasible for small specimens. Filter paper-based collection of tumor DNA reduces the need for histology support, requires little storage space, and preserves high-quality nucleic acid. We investigated the performance of tumor smears on filter paper in solid tumor genotyping, as compared with paired FFPE samples. Whatman FTA Micro Card (FTA preps) smears were prepared from 21 fresh tumor samples. A corresponding cytology smear was used to assess tumor cellularity and necrosis. DNA was isolated from FTA preps and FFPE core samples using automated methods and quantified using SYBR green dsDNA detection. Samples were genotyped for 471 mutations on a mass spectrophotometry-based platform (Sequenom). DNA concentrations from FTA preps and FFPE correlated for untreated carcinomas but not for mesenchymal tumors (Spearman ?=0.39 and ?=-0.1, respectively). Average DNA concentrations were lower from FTA preps as compared with FFPE, but DNA quality was higher with less fragmentation. Seventy-six percent of FTA preps and 86% of FFPE samples generated adequate DNA for genotyping. FTA preps tended to perform poorly for collection of DNA from pretreated carcinomas and mesenchymal neoplasms. Of the 16 paired DNA samples that were genotyped, 15 (94%) gave entirely concordant results. Filter paper-based sample preservation is a feasible alternative to FFPE for use in automated, high-throughput genotyping of carcinomas. PMID:25221956

  7. Citric Acid Production from Orange Peel Wastes by Solid-State Fermentation

    PubMed Central

    Torrado, Ana María; Cortés, Sandra; Manuel Salgado, José; Max, Belén; Rodríguez, Noelia; Bibbins, Belinda P.; Converti, Attilio; Manuel Domínguez, José

    2011-01-01

    Valencia orange (Citrus sinensis) peel was employed in this work as raw material for the production of citric acid (CA) by solid-state fermentation (SSF) of Aspergillus niger CECT-2090 (ATCC 9142, NRRL 599) in Erlenmeyer flasks. To investigate the effects of the main operating variables, the inoculum concentration was varied in the range 0.5·103 to 0.7·108 spores/g dry orange peel, the bed loading from 1.0 to 4.8 g of dry orange peel (corresponding to 35-80 % of the total volume), and the moisture content between 50 and 100 % of the maximum water retention capacity (MWRC) of the material. Moreover, additional experiments were done adding methanol or water in different proportions and ways. The optimal conditions for CA production revealed to be an inoculum of 0.5·106 spores/g dry orange peel, a bed loading of 1.0 g of dry orange peel, and a humidification pattern of 70 % MWRC at the beginning of the incubation with posterior addition of 0.12 mL H2O/g dry orange peel (corresponding to 3.3 % of the MWRC) every 12 h starting from 62 h. The addition of methanol was detrimental for the CA production. Under these conditions, the SSF ensured an effective specific production of CA (193 mg CA/g dry orange peel), corresponding to yields of product on total initial and consumed sugars (glucose, fructose and sucrose) of 376 and 383 mg CA/g, respectively. These results, which demonstrate the viability of the CA production by SSF from orange peel without addition of other nutrients, could be of interest to possible, future industrial applications. PMID:24031646

  8. omega-Amino acid:pyruvate transaminase from Alcaligenes denitrificans Y2k-2: a new catalyst for kinetic resolution of beta-amino acids and amines.

    PubMed

    Yun, Hyungdon; Lim, Seongyop; Cho, Byung-Kwan; Kim, Byung-Gee

    2004-04-01

    Alcaligenes denitrificans Y2k-2 was obtained by selective enrichment followed by screening from soil samples, which showed omega-amino acid:pyruvate transaminase activity, to kinetically resolve aliphatic beta-amino acid, and the corresponding structural gene (aptA) was cloned. The gene was functionally expressed in Escherichia coli BL21 by using an isopropyl-beta-D-thiogalactopyranoside (IPTG)-inducible pET expression system (9.6 U/mg), and the recombinant AptA was purified to show a specific activity of 77.2 U/mg for L-beta-amino-n-butyric acid (L-beta-ABA). The enzyme converts various beta-amino acids and amines to the corresponding beta-keto acids and ketones by using pyruvate as an amine acceptor. The apparent K(m) and V(max) for L-beta-ABA were 56 mM and 500 U/mg, respectively, in the presence of 10 mM pyruvate. In the presence of 10 mM L-beta-ABA, the apparent K(m) and V(max) for pyruvate were 11 mM and 370 U/mg, respectively. The enzyme exhibits high stereoselectivity (E > 80) in the kinetic resolution of 50 mM D,L-beta-ABA, producing optically pure D-beta-ABA (99% enantiomeric excess) with 53% conversion. PMID:15066855

  9. Influence of nature\\/concentration of halide promoters and oxidation state on the direct oxidation of H 2 to H 2O 2 over Pd\\/ZrO 2 catalysts in aqueous acidic medium

    Microsoft Academic Search

    V. R. Choudhary; C. Samanta; T. V. Choudhary

    2007-01-01

    The nature\\/concentration of halide promoters and influence of the Pd oxidation state on the promoted reaction system has been investigated on the direct H2O2 process over a 2.5wt.% Pd\\/ZrO2 catalyst in an aqueous acidic reaction medium. The oxidation state of Pd had a profound influence on the H2O2 synthesis process. Interestingly, the nature of the halide determined the magnitude\\/type of

  10. Selective oxidation of light alkanes over hydrothermally synthesized Mo-V-M-O (M=Al, Ga, Bi, Sb, and Te) oxide catalysts

    Microsoft Academic Search

    Wataru Ueda; Kenzo Oshihara

    2000-01-01

    Selective oxidations of ethane to ethene and acetic acid and of propane to acrylic acid were carried out over hydrothermally synthesized Mo-V-M-O (M=Al, Ga, Bi, Sb, and Te) complex metal oxide catalysts. All the synthesized solids were rod-shaped crystallites and gave a common XRD peak corresponding to 4.0Å d-spacing. From the different XRD patterns at low angle region below 10°

  11. The new esterification catalysts and the nature of reactions proceeding at esterification of synthetic naphthenic acids in their presence

    Microsoft Academic Search

    A. H. Azizov; G. I. Amanullayeva; R. V. Aliyeva; B. M. Aliyev; N. R. Bektashi

    2011-01-01

    There have been synthesized the novel sulfocationites on the basis of graft copolymers of polystyrene with oligostyrene, and their metal-polymer composites based on the titanium-containing compound with the grafted ionic-liquid type ligands. Esterifacation reaction of synthetic naphthen acid (SNA) fraction with heptyl alcohol as a model reaction has been investigated in the presence of the novel sulfocationites and Ti-containing metal-polymer

  12. Influence of Au contents of AuPt anode catalyst on the performance of direct formic acid fuel cell

    Microsoft Academic Search

    Jae Kwang Lee; Jaeyoung Lee; Jonghee Han; Tae-Hoon Lim; Yung-Eun Sung; Yongsug Tak

    2008-01-01

    We reported that various compositions of AuPt nanoparticles synthesized as an anode material for formic acid fuel cell were investigated. Its surface characteristics were systematically analyzed using XRD and TEM and anodic electrocatalytic activity was studied using a linear sweep voltammetry technique in 0.5M H2SO4+1M HCOOH. In addition, the voltage–current curve and power density of home-made AuPt-based membrane–electrode-assembly (MEA) and

  13. Mathematical Modeling of the Poly(lactic acid) Ring-Opening Polymerization using Stannous Octoate as a Catalyst

    Microsoft Academic Search

    Rajeev Mehta; Vineet Kumar; S. N. Upadhyay

    2007-01-01

    A novel and simple mathematical model to get the polymerization rate constants for the ring-opening polymerization of poly(lactic acid) is described. The model permits evaluation of the degree of polymerization versus monomer-to-initiator ratio curves. The predicted results are compared with the reported experimental data. The value of rate constants for initiation, propagation, and different modes of termination, are also obtained.

  14. Synthesis of ferromagnetic nanoparticles, formic acid oxidation catalyst nanocomposites, and late-transition metal-boride intermetallics by unique synthetic methods and single-source precursors

    NASA Astrophysics Data System (ADS)

    Wellons, Matthew S.

    The design, synthesis, and characterization of magnetic alloy nanoparticles, supported formic acid oxidation catalysts, and superhard intermetallic composites are presented. Ferromagnetic equatomic alloy nanoparticles of FePt, FePd, and CoPt were synthesized utilizing single-source heteronuclear organometallic precursors supported on an inert water-soluble matrix. Direct conversion of the precursor-support composite to supported ferromagnetic nanoparticles occurs under elevated temperatures and reducing conditions with metal-ion reduction and minimal nanoparticle coalescence. Nanoparticles were easily extracted from the support by addition of water and characterized in structure and magnetic properties. Palladium and platinum based nanoparticles were synthesized with microwave-based and chemical metal-ion reduction strategies, respectively, and tested for catalytic performance in a direct formic acid fuel cell (DFAFC). A study of palladium carbide nanocomposites with various carbonaceous supports was conducted and demonstrated strong activity comparable to commercially available palladium black, but poor catalytic longevity. Platinum-lead alloy nanocomposites synthesized with chemical reduction and supported on Vulcan carbon demonstrated strong activity, excellent catalytic longevity, and were subsequently incorporated into a prototype DFAFC. A new method for the synthesis of superhard ceramics on polymer substrates called Confined Plasma Chemical Deposition (CPCD) was developed. The CPCD method utilizes a tuned Free Electron Laser to selectively decompose the single-source precursor, Re(CO)4(B3H8), in a plasma-like state resulting in the superhard intermetallic ReB2 deposited on polymer substrates. Extension of this method to the synthesis of other hard of superhard ceramics; WB4, RuB2, and B4C was demonstrated. These three areas of research show new synthetic methods and novel materials of technological importance, resulting in a substantial advance in their respective fields.

  15. Amino acid modified Ni catalyst exhibits reversible H2 oxidation/production over a broad pH range at elevated temperatures

    SciTech Connect

    Dutta, Arnab; DuBois, Daniel L.; Roberts, John A.; Shaw, Wendy J.

    2014-11-18

    Hydrogenases interconvert H2 and protons at high rates and with high energy efficiencies, providing inspiration for the development of molecular catalysts. Studies designed to determine how the protein scaffold can influence a catalytically active site has led to the synthesis of amino acid derivatives, [Ni(PCy2NAmino acid2)2]2+ (CyAA), of [Ni(PR2NR'2)2]2+ complexes. It is shown that these CyAA derivatives can catalyze fully reversible H2 production/oxidation, a feature reminiscent of enzymes. The reversibility is achieved in acidic aqueous solutions, 0.25% H2/Ar, and elevated temperatures (tested up to 348 K) for the glycine (CyGly), arginine (CyArg), and arginine methyl ester (CyArgOMe) derivatives. As expected for a reversible process, the activity is dependent upon H2 and proton concentration. CyArg is significantly faster in both directions than the other two derivatives (~300 s-1 H2 production and 20 s-1 H2 oxidation; pH=1, 348 K). The significantly slower rates for CyArgOMe (35 s-1 production and 7 s-1 oxidation) compared to CyArg suggests an important role for the COOH group during catalysis. That CyArg is faster than CyGly (3 s-1 production and 4 s-1 oxidation under the same conditions) suggests that the additional structural features imparted by the guanidinium groups facilitate fast and reversible H2 addition/release. These observations demonstrate that appended, outer coordination sphere amino acids work in synergy with the active site and can play an equally important role for synthetic molecular electrocatalysts as the protein scaffold does for redox active enzymes. This work was funded by the Office of Science Early Career Research Program through the US DOE, BES (AD, WJS), and the Center for Molecular Electrocatalysis, an Energy Frontier Research Center funded by the US DOE, BES (DLD, JASR). PNNL is operated by Battelle for the US DOE.

  16. Investigation of a dual-particle liquid-solid circulating fluidized bed bioreactor for extractive fermentation of lactic acid.

    PubMed

    Patel, Manoj; Bassi, Amarjeet S; Zhu, Jesse J-X; Gomaa, Hassan

    2008-01-01

    A dual-particle liquid-solid circulating fluidized bed (DP-LSCFB) bioreactor has been constructed and investigated for the simultaneous production and extraction of lactic acid using immobilized Lactobacillus bulgaricus and ion-exchange resins. The apparatus consisted of a downer fluidized bed, 13 cm I.D. and 4.75 m tall, and a riser fluidized bed, 3.8 cm I.D. and 5.15 m in height. The lactic acid production and removal was carried out in the downer, while the riser was used for the recovery of lactic acid. A continuously recirculating bed of ion-exchange resin was used for adsorption of the produced acid as well as for maintaining optimum pH for bioconversion, thus eliminating the need for costly and complex chemical control approach used in conventional techniques. Studies using lactic acid aqueous solution as feed and sodium hydroxide solution as regeneration stream showed 93% lactic acid removal from the downer and 46% recovery in the riser under the conditions investigated. Such results prove the functionality of using the newly developed bioreactor design for the continuous production and recovery of products of biotechnological significance. PMID:19194893

  17. Reactions of atomic hydrogen with formic acid and carbon monoxide in solid parahydrogen II: Deuterated reaction studies.

    PubMed

    Wonderly, William R; Anderson, David T

    2014-09-11

    It is difficult to determine whether the measured rate constant for reaction of atomic hydrogen with formic acid reported in Part 1 reflects the H atom quantum diffusion rate or the rate constant for the tunneling reaction step. In Part 2 of this series, we present kinetic studies of the postphotolysis H atom reactions with deuterated formic acid (DCOOD) to address this ambiguity. Short duration 193 nm in situ photolysis of DCOOD trapped in solid parahydrogen results in partial depletion of the DCOOD precursor and photoproduction of primarily CO, CO2, DOCO, HCO and mobile H atoms. At 1.9 K we observe post-irradiation growth in the concentrations of DOCO and HCO that can be explained by H atom tunneling reactions with DCOOD and CO, respectively. Conducting experiments with different deuterium isotopomers of formic acid (DCOOD, DCOOH, HCOOD and HCOOH) provides strong circumstantial evidence the reaction involves H atom abstraction from the alkyl group of formic acid. Further, the anomalous temperature dependence measured for the H + HCOOH reaction in Part 1 is also observed for the analogous reactions with deuterated formic acid. The rate constants extracted for H atom reactions with DCOOD and HCOOH are equivalent to within experimental uncertainty. This lack of a kinetic isotope effect in the measured rate constant is interpreted as evidence the reactions are diffusion limited; the measured rate constant reflects the H atom diffusion rate and not the tunneling reaction rate. Whether or not H atom reactions with chemical species in solid parahydrogen are diffusion limited is one of the outstanding questions in this field, and this work makes significant strides toward showing the reaction kinetics with formic acid are diffusion limited. PMID:25113062

  18. REVIEW ARTICLE: Nanoassembled model catalysts

    Microsoft Academic Search

    Ueli Heiz; Wolf-Dieter Schneider

    2000-01-01

    The present review outlines, on the basis of specific examples taken from our laboratory, the most important steps in (i) preparing supported nanoassembled model catalysts and (ii) investigating their size-dependent catalytic properties. We describe the cluster generation and present evidence for softlanding of the clusters onto solid surfaces. Subsequently, the growth and the characterization of the cluster support material, thin

  19. CCMR: Environmentally Benign Iron Catalysts

    NSDL National Science Digital Library

    Brown, Kristi L.

    2007-08-29

    A new para substituted iPrPDI ligand was synthesized using methods previously described1. iPrPDI-CH2TMS, a bright yellow solid was isolated in moderate yields. An iron catalyst, iPrPDI-(CH2TMS)FeBr2 was synthesized and tested in a polymerization reaction with preliminary success.

  20. Aromatization of n-heptane over H-AlMFI, Ga\\/H-AlMFI, H-GaMFI and H-GaAlMFI zeolite catalysts: influence of zeolitic acidity and non-framework gallium

    Microsoft Academic Search

    V. R Choudhary; S. A. R Mulla; S Banerjee

    2003-01-01

    Influence of zeolite acidity (strong acid sites measured in terms of the pyridine chemisorbed at 400 °C) and non-framework Ga-species present in the zeolite channels on the conversion (total and to aromatics) and selectivity in the aromatization of n-heptane at 500 °C over the H-AlMFI (H-ZSM-5), Ga\\/ H-AlMFI, H-GaMFI and H-GaAlMFI zeolite catalysts (GHSV=3400 and 13,600 h?1) has been investigated.