Production of Catalyst-Free Hyperpolarised Ethanol Aqueous Solution via Heterogeneous Hydrogenation with Parahydrogen

Science.gov (United States)

Salnikov, Oleg G.; Kovtunov, Kirill V.; Koptyug, Igor V.

2015-09-01

An experimental approach for the production of catalyst-free hyperpolarised ethanol solution in water via heterogeneous hydrogenation of vinyl acetate with parahydrogen and the subsequent hydrolysis of ethyl acetate was demonstrated. For an efficient hydrogenation, liquid vinyl acetate was transferred to the gas phase by parahydrogen bubbling and almost completely converted to ethyl acetate with Rh/TiO2 catalyst. Subsequent dissolution of ethyl acetate gas in water containing OH- ions led to the formation of catalyst- and organic solvent-free hyperpolarised ethanol and sodium acetate. These results represent the first demonstration of catalyst- and organic solvent-free hyperpolarised ethanol production achieved by heterogeneous hydrogenation of vinyl acetate vapour with parahydrogen and the subsequent ethyl acetate hydrolysis.

METHANOLYSIS AND ETHANOLYSIS OF ANIMAL FATS: A COMPARATIVE STUDY OF THE INFLUENCE OF ALCOHOLS

Directory of Open Access Journals (Sweden)

MANUEL GARCÍA

2011-03-01

Full Text Available Biodiesel from animal fats with methanol and ethanol was produced in the presence of sodium methoxide and sodium ethoxide as catalysts. Two samples of pork fats and one natural beef tallow were directly transesterified with a good final product yield: 87.7, 86.7 and 86.3% for methanolysis, and 78.4, 82.6 and 82.7% for ethanolysis, respectively. Methyl ester content was also determined, being higher than 96.5 mass% for all the samples prepared. The presence of natural C17:0 in animal fats makes it necessary to correct the method pro¬posed in the standard EN 14103 (2003. Biodiesel density at 15 C of the samples was between 870 and 876 kg/m3, within the acceptance range of standard EN 14214, and the dynamic viscosity at 40 °C of the produced biodiesels was in the range of 4.5 to 5.16 mm2/s, also fulfilling requirements of EN 14214 standard. The iodine value is much lower than the superior limit established by EN 14214 standard but oxidation stability (OSI is lower than the required limit, 6 h, of the standard, which can be attributed to the lack of natural antioxidants in tallows.

Production of a Biofuel that Keeps the Glycerol as a Monoglyceride by Using Supported KF as Heterogeneous Catalyst

Directory of Open Access Journals (Sweden)

Juan Calero

2014-06-01

Full Text Available This study describes the results obtained in the synthesis of a biofuel that avoids the production of glycerol by applying supported KF as alkaline heterogeneous catalyst, to generate two moles of fatty acid methyl esters and one mole of monoglyceride from one mol of triglyceride. In this respect, the selective transesterification process of sunflower oil with methanol was carried out with KF (10 wt% supported on three different solids, Al2O3, ZnO and MgO. The standard experimental conditions employed in the heterogeneous selective methanolysis reaction were: 12 mL of sunflower oil, 2.7 mL of methanol, 0.8 g of catalyst, at 65 °C temperature and one hour of reaction time. In all cases 100% conversion was obtained, with high selectivity values, greater than 90%, and quite suitable viscosity values, 4.5–8.5 cSt. In this way, the best catalytic behavior in the first use was obtained by using Al2O3 as support. However, although in the five consecutive reuses all catalysts exhibited a continuous decrease in their catalytic activities; the lower one was for KF catalyst using MgO as support. In summary, these three KF supported catalysts are very suitable to obtain a new biofuel, similar to conventional biodiesel, applicable to diesel engines.

Allotropic Carbon Nanoforms as Advanced Metal-Free Catalysts or as Supports

Directory of Open Access Journals (Sweden)

Hermenegildo Garcia

2014-01-01

Full Text Available This perspective paper summarizes the use of three nanostructured carbon allotropes as metal-free catalysts (“carbocatalysts” or as supports of metal nanoparticles. After an introductory section commenting the interest of developing metal-free catalysts and main features of carbon nanoforms, the main body of this paper is focused on exemplifying the opportunities that carbon nanotubes, graphene, and diamond nanoparticles offer to develop advanced catalysts having active sites based on carbon in the absence of transition metals or as large area supports with special morphology and unique properties. The final section provides my personal view on future developments in this field.

Enhancing Biodiesel Production Using Green Glycerol-Enriched Calcium Oxide Catalyst : An Optimization Study

NARCIS (Netherlands)

Avhad, Mangesh R.; Gangurde, L.S.; Sánchez, Marcos; Bouaid, Abderrahim; Aracil, José; Martínez, Mercedes; Marchetti, Jorge M.

2018-01-01

The present article demonstrates a superior catalytic performance of glycerol-enriched calcium oxide for biodiesel production than other calcium-based counterparts. The proficiency of glycerol-enriched calcium oxide in catalyzing the methanolysis of crude Jatropha curcas oil containing high free

Continuous flow hydrogenation using polysilane-supported palladium/alumina hybrid catalysts

Directory of Open Access Journals (Sweden)

Shū Kobayashi

2011-05-01

Full Text Available Continuous flow systems for hydrogenation using polysilane-supported palladium/alumina (Pd/(PSi–Al2O3 hybrid catalysts were developed. Our original Pd/(PSi–Al2O3 catalysts were used successfully in these systems and the hydrogenation of unsaturated C–C bonds and a nitro group, deprotection of a carbobenzyloxy (Cbz group, and a dehalogenation reaction proceeded smoothly. The catalyst retained high activity for at least 8 h under neat conditions.

Solvent-free, catalyst-free aza-Michael addition of cyclohexylamine to diethyl maleate: reaction mechanism and kinetics

Czech Academy of Sciences Publication Activity Database

Bláha, Michal; Trhlíková, Olga; Podešva, Jiří; Abbrent, Sabina; Steinhart, Miloš; Dybal, Jiří; Dušková-Smrčková, Miroslava

2018-01-01

Roč. 74, č. 1 (2018), s. 58-67 ISSN 0040-4020 Institutional support: RVO:61389013 Keywords : Aza-Michael addition * solvent-free * catalyst-free Subject RIV: CD - Macromolecular Chemistry OBOR OECD: Polymer science Impact factor: 2.651, year: 2016

Continuous production of lipase-catalyzed biodiesel in a packed-bed reactor: optimization and enzyme reuse study.

Science.gov (United States)

Chen, Hsiao-Ching; Ju, Hen-Yi; Wu, Tsung-Ta; Liu, Yung-Chuan; Lee, Chih-Chen; Chang, Cheng; Chung, Yi-Lin; Shieh, Chwen-Jen

2011-01-01

An optimal continuous production of biodiesel by methanolysis of soybean oil in a packed-bed reactor was developed using immobilized lipase (Novozym 435) as a catalyst in a tert-butanol solvent system. Response surface methodology (RSM) and Box-Behnken design were employed to evaluate the effects of reaction temperature, flow rate, and substrate molar ratio on the molar conversion of biodiesel. The results showed that flow rate and temperature have significant effects on the percentage of molar conversion. On the basis of ridge max analysis, the optimum conditions were as follows: flow rate 0.1 mL/min, temperature 52.1°C, and substrate molar ratio 1 : 4. The predicted and experimental values of molar conversion were 83.31 ± 2.07% and 82.81 ± .98%, respectively. Furthermore, the continuous process over 30 days showed no appreciable decrease in the molar conversion. The paper demonstrates the applicability of using immobilized lipase and a packed-bed reactor for continuous biodiesel synthesis.

Power generation in microbial fuel cells using platinum group metal-free cathode catalyst: Effect of the catalyst loading on performance and costs.

Science.gov (United States)

Santoro, Carlo; Kodali, Mounika; Herrera, Sergio; Serov, Alexey; Ieropoulos, Ioannis; Atanassov, Plamen

2018-02-28

Platinum group metal-free (PGM-free) catalyst with different loadings was investigated in air breathing electrodes microbial fuel cells (MFCs). Firstly, the electrocatalytic activity towards oxygen reduction reaction (ORR) of the catalyst was investigated by rotating ring disk electrode (RRDE) setup with different catalyst loadings. The results showed that higher loading led to an increased in the half wave potential and the limiting current and to a further decrease in the peroxide production. The electrons transferred also slightly increased with the catalyst loading up to the value of ≈3.75. This variation probably indicates that the catalyst investigated follow a 2x2e - transfer mechanism. The catalyst was integrated within activated carbon pellet-like air-breathing cathode in eight different loadings varying between 0.1 mgcm -2 and 10 mgcm -2 . Performance were enhanced gradually with the increase in catalyst content. Power densities varied between 90 ± 9 μWcm -2 and 262 ± 4 μWcm -2 with catalyst loading of 0.1 mgcm -2 and 10 mgcm -2 respectively. Cost assessments related to the catalyst performance are presented. An increase in catalyst utilization led to an increase in power generated with a substantial increase in the whole costs. Also a decrease in performance due to cathode/catalyst deterioration over time led to a further increase in the costs.

Metal-free carbon materials-catalyzed sulfate radical-based advanced oxidation processes: A review on heterogeneous catalysts and applications.

Science.gov (United States)

Zhao, Qingxia; Mao, Qiming; Zhou, Yaoyu; Wei, Jianhong; Liu, Xiaocheng; Yang, Junying; Luo, Lin; Zhang, Jiachao; Chen, Hong; Chen, Hongbo; Tang, Lin

2017-12-01

In recent years, advanced oxidation processes (AOPs), especially sulfate radical based AOPs have been widely used in various fields of wastewater treatment due to their capability and adaptability in decontamination. Recently, metal-free carbon materials catalysts in sulfate radical production has been more and more concerned because these materials have been demonstrated to be promising alternatives to conventional metal-based catalysts, but the review of metal-free catalysts is rare. The present review outlines the current state of knowledge on the generation of sulfate radical using metal-free catalysts including carbon nanotubes, graphene, mesoporous carbon, activated carbon, activated carbon fiber, nanodiamond. The mechanism such as the radical pathway and non-radical pathway, and factors influencing of the activation of sulfate radical was also be revealed. Knowledge gaps and research needs have been identified, which include the perspectives on challenges related to metal-free catalyst, heterogeneous metal-free catalyst/persulfate systems and their potential in practical environmental remediation. Copyright © 2017 Elsevier Ltd. All rights reserved.

Catalyst-free, III-V nanowire photovoltaics

Science.gov (United States)

Davies, D. G.; Lambert, N.; Fry, P. W.; Foster, A.; Krysa, A. B.; Wilson, L. R.

2014-05-01

We report on room temperature, photovoltaic operation of catalyst-free GaAs p-i-n junction nanowire arrays. Growth studies were first performed to determine the optimum conditions for controlling the vertical and lateral growth of the nanowires. Following this, devices consisting of axial p-i-n junctions were fabricated by planarising the nanowire arrays with a hard baked polymer. We discuss the photovoltaic properties of this proof-of-concept device, and significant improvements to be made during the growth.

Biodiesel production from soybean oil and methanol using hydrotalcites as catalyst

Energy Technology Data Exchange (ETDEWEB)

Silva, Carla Cristina C.M.; Aranda, Donato A.G. [GREENTEC - Laboratory of Green Technologies, Escola de Quimica, Universidade Federal do Rio de Janeiro (UFRJ), Centro de Tecnologia, Bloco E, sala 211, CEP 21941-909, Rio de Janeiro, RJ (Brazil); Ribeiro, Nielson F.P.; Souza, Mariana M.V.M. [LabTecH - Laboratory of Hydrogen Technologies, Escola de Quimica/UFRJ, Centro de Tecnologia, Bloco E, sala 206, CEP 21941-909, Rio de Janeiro, RJ (Brazil)

2010-02-15

Esters of fatty acids, derived from vegetable oils or animal fats, and known as biodiesel, are a promising alternative diesel fuel regarding the limited resources of fossil fuels and the environmental concerns. In this work, methanolysis of soybean oil was investigated using Mg-Al hydrotalcites as heterogeneous catalyst, evaluating the effect of Mg/Al ratio on the basicity and catalytic activity for biodiesel production. The catalysts were prepared with Al/(Mg + Al) molar ratios of 0.20, 0.25 and 0.33, and characterized by X-ray diffraction (XRD), textural analysis (BET method) and temperature-programmed desorption of CO{sub 2} (CO{sub 2}-TPD). When the reaction was carried out at 230 C with a methanol:soybean oil molar ratio of 13:1, a reaction time of 1 h and a catalyst loading of 5 wt.%, the oil conversion was 90% for the sample with Al/(Mg + Al) ratio of 0.33. This sample was the only one to show basic sites of medium strength. We also investigated the reuse of this catalyst, the effect of calcination temperature and made a comparison between refined and acidic oil. (author)

Electrochemical dopamine sensor based on P-doped graphene: Highly active metal-free catalyst and metal catalyst support.

Science.gov (United States)

Chu, Ke; Wang, Fan; Zhao, Xiao-Lin; Wang, Xin-Wei; Tian, Ye

2017-12-01

Heteroatom doping is an effective strategy to enhance the catalytic activity of graphene and its hybrid materials. Despite a growing interest of P-doped graphene (P-G) in energy storage/generation applications, P-G has rarely been investigated for electrochemical sensing. Herein, we reported the employment of P-G as both metal-free catalyst and metal catalyst support for electrochemical detection of dopamine (DA). As a metal-free catalyst, P-G exhibited prominent DA sensing performances due to the important role of P doping in improving the electrocatalytic activity of graphene toward DA oxidation. Furthermore, P-G could be an efficient supporting material for loading Au nanoparticles, and resulting Au/P-G hybrid showed a dramatically enhanced electrocatalytic activity and extraordinary sensing performances with a wide linear range of 0.1-180μM and a low detection limit of 0.002μM. All these results demonstrated that P-G might be a very promising electrode material for electrochemical sensor applications. Copyright © 2017 Elsevier B.V. All rights reserved.

Catalyst retention in continuous flow with supercritical carbon dioxide

NARCIS (Netherlands)

Stouten, S.C.; Noel, T.; Wang, Q.; Hessel, V.

2014-01-01

This review discusses the retention of organometallic catalysts in continuous flow processes utilizing supercritical carbon dioxide. Due to its innovative properties, supercritical carbon dioxide offers interesting possibilities for process intensification. As a result of safety and cost

Methanolysis of Crude Jatropha Oil using Heterogeneous Catalyst from the Seashells and Eggshells as Green Biodiesel

Directory of Open Access Journals (Sweden)

A. N. R. REDDY

2017-07-01

Full Text Available In this work, heterogeneous calcium oxide catalysts gleaned from Polymedosa expansa and eggshell were investigated for the transesterification of crude jatropha oil with methanol, to access their prospective performance in biodiesel production as an alternative green energy resource. The best yield of biodiesel achieved was 96% in 1 h for Step 1 using 0.01:1 ratio of acid catalyst to oil and 0.6:1 ratio of alcohol to oil ratio, together with 2 h of Step 2 using 0.02:1 ratio with base catalyst CaO, derived from P. expansa, to oil ratio and 5:1 ratio of alcohol to oil.  The properties of jatropha biodiesel were analyzed and found to have calorific value of 35.43 MJ/kg, density value of 895 kg/m3 and flash point of 167. The biodiesel was blended with mineral diesel from B0 to B50 for a diesel engine performance test. B20 indicated comparable characteristics with pure mineral diesel, like lowest fuel consumption rate, specific fuel consumption rate, highest brake horsepower and mechanical efficiency.

Continuous wasteless ecologically safe technology of propylenecarbonate production in presence of phthalocyanine catalysts

Science.gov (United States)

Afanasiev, Vladimir Vasilievich [Moscow, RU; Zefirov, Nikolai Serafimovich [Moscow, RU; Zalepugin, Dmitry Yurievich [Moscow, RU; Polyakov, Victor Stanislavovich [Moscow, RU; Tilkunova, Nataliya Alexandrovna [Moscow, RU; Tomilova, Larisa Godvigovna [Moscow, RU

2009-09-08

A continuous method of producing propylenecarbonate includes carboxylation of propylene oxide with carbon dioxide in presence of phthalocyanine catalyst on an inert carrier, using as the phthalocyanine catalyst at least one catalyst selected from the group consisting of not-substituted, methyl, ethyl, butyl, and tret butyl-substituted phthalocyanines of metals, including those containing counterions, and using as the carrier a hydrophobic carrier.

Continuous Production of Lipase-Catalyzed Biodiesel in a Packed-Bed Reactor: Optimization and Enzyme Reuse Study

Directory of Open Access Journals (Sweden)

Hsiao-Ching Chen

2011-01-01

Full Text Available An optimal continuous production of biodiesel by methanolysis of soybean oil in a packed-bed reactor was developed using immobilized lipase (Novozym 435 as a catalyst in a tert-butanol solvent system. Response surface methodology (RSM and Box-Behnken design were employed to evaluate the effects of reaction temperature, flow rate, and substrate molar ratio on the molar conversion of biodiesel. The results showed that flow rate and temperature have significant effects on the percentage of molar conversion. On the basis of ridge max analysis, the optimum conditions were as follows: flow rate 0.1 mL/min, temperature 52.1∘C, and substrate molar ratio 1 : 4. The predicted and experimental values of molar conversion were 83.31±2.07% and 82.81±.98%, respectively. Furthermore, the continuous process over 30 days showed no appreciable decrease in the molar conversion. The paper demonstrates the applicability of using immobilized lipase and a packed-bed reactor for continuous biodiesel synthesis.

Transesterification of jojoba oil, sunflower oil, neem oil, rocket seed oil and linseed oil by tin catalysts

International Nuclear Information System (INIS)

Shah, Mazloom; Tariq, Muhammad; Ali, Saqib; Guo, Qing-Xiang; Fu, Yao

2014-01-01

The methanolysis of jojoba oil has been studied in the presence of tin powder, dibutyltin diacetate (C 4 H 9 ) 2 Sn(OOCCH 3 ) 2 , dioctyltin diacetate (C 8 H 17 ) 2 Sn(OOCCH 3 ) 2 , dibutyltin oxide (C 4 H 9 ) 2 SnO, dioctyltin oxide (C 8 H 17 ) 2 SnO, diphenyltin oxide (C 6 H 5 ) 2 SnO, dibutyltin chloride dihydroxide (C 4 H 9 ) 2 Sn(OH) 2 Cl, butyltinhydroxide hydrate (C 4 H 9 )Sn(=O)OH.xH 2 O, Ni nanoparticles and Pd nanoparticles act as catalysts. Among these, 1 weight % of dibutyltin diacetate shows the maximum conversion. Then, methanolysis of sunflower oil, neem oil, rocket seed oil and linseed oil into methyl esters studied in the presence of 1% dibutyltin diacetate as a catalyst and was compared their percentage conversions. The experimental yield for the conversion of jojoba oil, sunflower oil, neem oil, rocket seed oil and linseed oil into biodiesel was found to be 71%, 51%, 50.78%, 40.90% and 39.66%, respectively. The experimental yield of the conversion of jojoba oil into methyl esters was found to be increased up to 96% by increasing reaction time, without emulsion formation. The synthesis of jojoba seed oil biodiesel (JSOB), soybean oil biodiesel (SOB), neem oil biodiesel (NOB), rocket seed oil biodiesel (RSOB) and linseed oil biodiesel (LSOB) was confirmed by NMR ( 1 H and 13 C) and FT-IR analyses of biodiesel. - Highlights: • Transesterification of jojoba oil into biodiesel by tin and nano catalysts. • 1 weight % dibutyltin diacetate showed highest yield at 60 °C. • Catalytic conversion comparison of five oils using dibutyltin diacetate • The experimental yield of the conversion of jojoba oil increased with time. • FT-IR and NMR ( 1 H and 13 C) characterization

Catalyst-free activation of peroxides under visible LED light irradiation through photoexcitation pathway

Energy Technology Data Exchange (ETDEWEB)

Gao, Yaowen [Department of Environmental Engineering, Wuhan University, Wuhan, 430079 (China); Shenzhen Research Institute of Wuhan University, Shenzhen, 518057 (China); Li, Yixi; Yao, Linyu; Li, Simiao; Liu, Jin [Department of Environmental Engineering, Wuhan University, Wuhan, 430079 (China); Zhang, Hui, E-mail: eeng@whu.edu.cn [Department of Environmental Engineering, Wuhan University, Wuhan, 430079 (China); Shenzhen Research Institute of Wuhan University, Shenzhen, 518057 (China)

2017-05-05

Highlights: • Persulfate could decolorize Rhodamine B (RhB) directly via non-radical reactions. • LED lamps emitting white light were utilized as the visible light source. • Dyes could activate peroxides through photoexcitation pathway. • Decolorization of dyes and production of radicals were achieved simultaneously. • The catalyst-free peroxide/dye/Vis process was effective in a broad pH range. - Abstract: Catalysts are known to activate peroxides to generate active radicals (i.e., hydroxyl radical (·OH) and sulfate radical (SO{sub 4}·{sup −})) under certain conditions, but the activation of peroxides in the absence of catalysts under visible light irradiation has been rarely reported. This work demonstrates a catalyst-free activation of peroxides for the generation of ·OH and/or SO{sub 4}·{sup −} through photoexcited electron transfer from organic dyes to peroxides under visible LED light irradiation, where Rhodamine B (RhB) and Eosin Y (EY) were selected as model dyes. The formation of ·OH and/or SO{sub 4}·{sup −} in the reactions and the electron transfer from the excited dyes to peroxides were validated via electron paramagnetic resonance (EPR), photoluminescence (PL) spectra and cyclic voltammetry (CV). The performance of the peroxide/dye/Vis process was demonstrated to be altered depending on the target substrate. Meanwhile, the peroxide/dye/Vis process was effective for simultaneous decolorization of dyes and production of active radicals under neutral even or basic conditions. The findings of this study clarified a novel photoexcitation pathway for catalyst-free activation of peroxides under visible light irradiation, which could avoid the secondary metal ion (dissolved or leached) pollution from the metal-based catalysts and expand the application range of the peroxide-based catalytic process.

Acidic methanolysis v. alkaline saponification in gas chromatographic characterization of mycobacteria: differentiation between Mycobacterium avium-intracellulare and Mycobacterium gastri.

Science.gov (United States)

Larsson, L

1983-08-01

Mycobacterium avium-intracellulare and M.gastri were analyzed with capillary gas chromatography after each strain had been subjected to acidic methanolysis or to alkaline saponification followed by methylation. Prominent peaks of myristic, palmitoleic, palmitic, oleic, stearic and tuberculostearic acids were found in the chromatograms of both species, whereas 2-octadecanol and 2-eicosanol were detected only in M. avium-intracellulare. In initial runs, both of the derivatization principles yielded virtually identical chromatograms for a given strain. After repeated injections of extracts from alkaline saponification, however, the alcohol peaks showed pronounced tailing and finally almost disappeared from the chromatograms. This disadvantage, which was not observed when only acid methanolysis was used, could be overcome with trifluoroacetylation. Restored peak shape of the underivatized alcohols could be achieved by washing the cross-linked stationary phase in the capillary tubing with organic solvents. The study demonstrated the importance of conditions which enable separation of 2-octadecanol and 2-eicosanol when gas chromatography is used for species identification of mycobacteria.

Ethanol tolerant precious metal free cathode catalyst for alkaline direct ethanol fuel cells

International Nuclear Information System (INIS)

Grimmer, Ilena; Zorn, Paul; Weinberger, Stephan; Grimmer, Christoph; Pichler, Birgit; Cermenek, Bernd; Gebetsroither, Florian; Schenk, Alexander; Mautner, Franz-Andreas

2017-01-01

Highlights: • Selective ORR catalysts are presented for alkaline direct ethanol fuel cells. • Perovskite based cathode catalysts show high tolerance toward ethanol. • A membrane-free alkaline direct ethanol fuel cell is presented. - Abstract: La 0.7 Sr 0.3 (Fe 0.2 Co 0.8 )O 3 and La 0.7 Sr 0.3 MnO 3 −based cathode catalysts are synthesized by the sol-gel method. These perovskite cathode catalysts are tested in half cell configuration and compared to MnO 2 as reference material in alkaline direct ethanol fuel cells (ADEFCs). The best performing cathode is tested in single cell setup using a standard carbon supported Pt 0.4 Ru 0.2 based anode. A backside Luggin capillary is used in order to register the anode potential during all measurements. Characteristic processes of the electrodes are investigated using electrochemical impedance spectroscopy. Physical characterizations of the perovskite based cathode catalysts are performed with a scanning electron microscope (SEM) and by X-ray diffraction showing phase pure materials. In half cell setup, La 0.7 Sr 0.3 MnO 3 shows the highest tolerance toward ethanol with a performance of 614 mA cm −2 at 0.65 V vs. RHE in 6 M KOH and 1 M EtOH at RT. This catalyst outperforms the state-of-the-art precious metal-free MnO 2 catalyst in presence of ethanol. In fuel cell setup, the peak power density is 27.6 mW cm −2 at a cell voltage of 0.345 V and a cathode potential of 0.873 V vs. RHE.

Platinum Group Metal-free Catalysts for Hydrogen Evolution Reaction in Microbial Electrolysis Cells.

Science.gov (United States)

Yuan, Heyang; He, Zhen

2017-07-01

Hydrogen gas is a green energy carrier with great environmental benefits. Microbial electrolysis cells (MECs) can convert low-grade organic matter to hydrogen gas with low energy consumption and have gained a growing interest in the past decade. Cathode catalysts for the hydrogen evolution reaction (HER) present a major challenge for the development and future applications of MECs. An ideal cathode catalyst should be catalytically active, simple to synthesize, durable in a complex environment, and cost-effective. A variety of noble-metal free catalysts have been developed and investigated for HER in MECs, including Nickel and its alloys, MoS 2 , carbon-based catalysts and biocatalysts. MECs in turn can serve as a research platform to study the durability of the HER catalysts. This personal account has reviewed, analyzed, and discussed those catalysts with an emphasis on synthesis and modification, system performance and potential for practical applications. It is expected to provide insights into the development of HER catalysts towards MEC applications. © 2017 The Chemical Society of Japan & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Esterification of free fatty acids in biodiesel production with sulphonated pyrolysed carbohydrate catalysts

DEFF Research Database (Denmark)

Madsen, Anders Theilgaard; Riisager, Anders; Fehrmann, Rasmus

The pre-treatment of free fatty acids in oils and fats in biodiesel production is of pivotal importance, and esterification in acidic medium must be done prior to basic transesterification of glycerides. The free fatty acids may be converted over an acidic catalyst of sulphonated pyrolysed...

Catalyst-free site-specific surface modifications of nanocrystalline diamond films via microchannel cantilever spotting

Czech Academy of Sciences Publication Activity Database

Davydova, Marina; de los Santos Pereira, Andres; Bruns, M.; Kromka, Alexander; Ukraintsev, Egor; Hirtz, M.; Rodriguez-Emmenegger, Cesar

2016-01-01

Roč. 6, č. 63 (2016), s. 57820-57827 ISSN 2046-2069 R&D Projects: GA ČR(CZ) GP14-06054P Institutional support: RVO:68378271 ; RVO:61389013 Keywords : catalysts * nanocrystals * photonic devices * catalyst-free * functionalizations * high reproducibility * micropatterned * multicomponents Subject RIV: BO - Biophysics; CD - Macromolecular Chemistry (UMCH-V) Impact factor: 3.108, year: 2016

Solvent free oxidation of primary alcohols and diols using thymine iron(III) catalyst.

Science.gov (United States)

Al-Hunaiti, Afnan; Niemi, Teemu; Sibaouih, Ahlam; Pihko, Petri; Leskelä, Markku; Repo, Timo

2010-12-28

In this study, we developed an efficient and selective iron-based catalyst system for the synthesis of ketones from secondary alcohols and carboxylic acids from primary alcohol. In situ generated iron catalyst of thymine-1-acetate (THA) and FeCl(3) under solvent-free condition exhibits high activity. As an example, 1-octanol and 2-octanol were oxidized to 1-octanoic acid and 2-octanone with 89% and 98% yields respectively.

Catalyst-free and solvent-free Michael addition of 1,3-dicarbonyl compounds to nitroalkenes by a grinding method

Science.gov (United States)

Xie, Zong-Bo; Wu, Ming-Yu; He, Ting; Le, Zhang-Gao

2012-01-01

Summary An environmentally benign, fast and convenient protocol has been developed for the Michael addition of 1,3-dicarbonyl compounds to β-nitroalkenes in good to excellent yields by a grinding method under catalyst- and solvent-free conditions. PMID:22563352

Silica-Supported Catalyst for Enantioselective Arylation of Aldehydes under Batch and Continuous-Flow Conditions.

Science.gov (United States)

Watanabe, Satoshi; Nakaya, Naoyuki; Akai, Junichiro; Kanaori, Kenji; Harada, Toshiro

2018-05-04

A silica-supported 3-aryl H 8 -BINOL-derived titanium catalyst exhibited high performance in the enantioselective arylation of aromatic aldehydes using Grignard and organolithium reagents not only under batch conditions but also under continuous-flow conditions. Even with a simple pipet reactor packed with the heterogeneous catalyst, the enantioselective production of chiral diarylmethanols could be achieved through a continuous introduction of aldehydes and mixed titanium reagents generated from the organometallic precursors. The pipet reactor could be used repeatedly in different reactions without appreciable deterioration of the activity.

ElectroCat: DOE's approach to PGM-free catalyst and electrode R&D

Energy Technology Data Exchange (ETDEWEB)

Thompson, Simon T.; Wilson, Adria R.; Zelenay, Piotr; Myers, Deborah J.; More, Karren L.; Neyerlin, K. C.; Papageorgopoulos, Dimitrios

2018-06-01

The successful development of high-performance, durable platinum group metal-free (PGM-free) electrocatalysts and electrodes for polymer electrolyte membrane fuel cells (PEMFCs) will ultimately improve the cost-competiveness of fuel cells in a wide range of applications. This is considered to be a critical development especially for automotive fuel cell applications in order to bring the system cost of an automotive fuel cell system down to the $30/kW cost target set by the U.S. Department of Energy (DOE). The platinum group metal (PGM) electrocatalysts are a major contributor to the system cost. Addressing the technical challenges to PGM-free electrocatalyst and electrode development, therefore, represents one of DOE's most pressing research and development (R&D) priorities. ElectroCat was formed by the DOE as part of the Energy Materials Network (EMN) in early 2016, and shares with other EMN consortia the goal of decreasing the time to market for advanced materials related to clean energy technologies, in the context of increasing U.S. fuel cell electric vehicle (FCEV) manufacturing competitiveness. To accomplish this, the consortium performs core research and development and provides universities and companies streamlined access to the unique, world-class set of tools and expertise relevant to early-stage applied PGM-free catalyst R&D of the member national laboratories. Moreover, ElectroCat fosters a systematic methodology by which prospective catalysts and electrodes are prepared and analyzed rapidly and comprehensively using high-throughput, combinatorial methods. Catalyst discovery is augmented by theory as well as foundational electrocatalysis and materials knowledge at the participating national laboratories. Furthermore, ElectroCat has developed a data sharing framework, requisite of all EMN consortia, for disseminating its findings to the public via a searchable database, to further expedite incorporation of PGM-free electrocatalysts into next

Continuous bench-scale slurry catalyst testing direct coal liquefaction rawhide sub-bituminous coal

Energy Technology Data Exchange (ETDEWEB)

Bauman, R.F.; Coless, L.A.; Davis, S.M. [and others

1995-12-31

In 1992, the Department of Energy (DOE) sponsored research to demonstrate a dispersed catalyst system using a combination of molybdenum and iron precursors for direct coal liquefaction. This dispersed catalyst system was successfully demonstrated using Black Thunder sub-bituminous coal at Wilsonville, Alabama by Southern Electric International, Inc. The DOE sponsored research continues at Exxon Research and Development Laboratories (ERDL). A six month continuous bench-scale program using ERDL`s Recycle Coal Liquefaction Unit (RCLU) is planned, three months in 1994 and three months in 1995. The initial conditions in RCLU reflect experience gained from the Wilsonville facility in their Test Run 263. Rawhide sub-bituminous coal which is similar to the Black Thunder coal tested at Wilsonville was used as the feed coal. A slate of five dispersed catalysts for direct coal liquefaction of Rawhide sub-bituminous coal has been tested. Throughout the experiments, the molybdenum addition rate was held constant at 100 wppm while the iron oxide addition rate was varied from 0.25 to 1.0 weight percent (dry coal basis). This report covers the 1994 operations and accomplishments.

A Recyclable Cu-MOF-74 Catalyst for the Ligand-Free O-Arylation Reaction of 4-Nitrobenzaldehyde and Phenol.

Science.gov (United States)

Leo, Pedro; Orcajo, Gisela; Briones, David; Calleja, Guillermo; Sánchez-Sánchez, Manuel; Martínez, Fernando

2017-06-16

The activity and recyclability of Cu-MOF-74 as a catalyst was studied for the ligand-free C-O cross-coupling reaction of 4-nitrobenzaldehyde (NB) with phenol (Ph) to form 4-formyldiphenyl ether (FDE). Cu-MOF-74 is characterized by having unsaturated copper sites in a highly porous metal-organic framework. The influence of solvent, reaction temperature, NB/Ph ratio, catalyst concentration, and basic agent (type and concentration) were evaluated. High conversions were achieved at 120 °C, 5 mol % of catalyst, NB/Ph ratio of 1:2, DMF as solvent, and 1 equivalent of K₂CO₃ base. The activity of Cu-MOF-74 material was higher than other ligand-free copper catalytic systems tested in this study. This catalyst was easily separated and reused in five successive runs, achieving a remarkable performance without significant porous framework degradation. The leaching of copper species in the reaction medium was negligible. The O-arylation between NB and Ph took place only in the presence of Cu-MOF-74 material, being negligible without the solid catalyst. The catalytic advantages of using nanostructured Cu-MOF-74 catalyst were also proven.

Supported Rh-phosphine complex catalysts for continuous gas-phase decarbonylation of aldehydes

DEFF Research Database (Denmark)

Malcho, Phillip; Garcia-Suarez, Eduardo J.; Mentzel, Uffe Vie

2014-01-01

Heterogeneous silica supported rhodium-phosphine complex catalysts are employed for the first time in the catalytic decarbonylation of aldehydes in continuous gas-phase. The reaction protocol is exemplified for the decarbonylation of p-tolualdehyde to toluene and further extended to other aromatic...

Propene and l-octene hydroformylation with silica-supported, ionic liquid-phase (SILP) Rh-phosphine catalysts in continuous fixed-bed mode

DEFF Research Database (Denmark)

Riisager, Anders; Eriksen, Kim Michael; Wasserscheid, Peter

2003-01-01

- and liquid-phase hydroformylation of propene and 1-octene, exhibiting TOFs up to 88 h(-1) for SILP Rh-2 catalysts, while only low selectivities up to 74% n-aldehyde (n/iso ratio of 2.8) were obtained. This is the first example of continuous fixed-bed liquid-phase hydroformylation using SILP catalysts.......Supported ionic liquid-phase (SILP) catalysts were made by immobilizing Rh-monophosphine complexes of bis(m-phenylguanidinium) phenylphosphine 1 and NORBOS 2 ligands in 1-n-butyl-3-methylimidazolium hexafluorophosphate, [BMIM] [PF6], on a silica support. The catalysts were active in continuous gas...

Natrolite zeolite: A natural and reusable catalyst for one-pot synthesis of α-aminophosphonates under solvent-free conditions

Directory of Open Access Journals (Sweden)

Siavash Bahari

2017-02-01

Full Text Available α-Aminophosphonates are synthesized efficiently by one-pot reaction of aldehydes or ketones, amines, trialkyl phosphites in the presence of Natrolite zeolite as a natural catalyst under solvent-free conditions. Furthermore, the catalyst can be reused several times without any significant loss of catalytic activity.

Enzymatic versus Inorganic Oxygen Reduction Catalysts: Comparison of the Energy Levels in a Free-Energy Scheme

DEFF Research Database (Denmark)

Kjærgaard, Christian Hauge; Rossmeisl, Jan; Nørskov, Jens Kehlet

2010-01-01

In this paper, we present a method to directly compare the energy levels of intermediates in enzymatic and inorganic oxygen reduction catalysts. We initially describe how the energy levels of a Pt(111) catalyst, operating at pH = 0, are obtained. By a simple procedure, we then convert the energy...... levels of cytochrome c oxidase (CcO) models obtained at physiological pH = 7 to the energy levels at pH = 0, which allows for comparison. Furthermore, we illustrate how different bias voltages will affect the free-energy landscapes of the catalysts. This allows us to determine the so-called theoretical...

Superior mercury-free catalysts for acetylene hydrochlorination to VCM. Achieving high productivities and long catalyst life-time

Energy Technology Data Exchange (ETDEWEB)

Liebens, A.T.; Piccinini, M. [Solvay S.A., Bruxelles (Belgium)

2013-11-01

New mercury-free catalytic systems based on the use of ionic liquids (IL) and noble metals (e.g. Pd, Au) have been evaluated for the hydrochlorination reaction of acetylene to produce Vinyl Chloride Monomer (VCM). Two different approaches have been investigated: gas-liquid homogeneous catalytic systems in the presence of molten IL/Metal and heterogeneous gas-solid ones using solid materials. For the latter case, very positive results have been obtained using SILP-type catalysts (SILP: Supported Ionic Liquid Phase) where IL/Metal were deposited onto a solid mesoporous support. Remarkably, both systems display very high Space Time Yield (STY) and breakthrough life-time stability. No deactivation is observed even after 500 h on stream indicating the strong advantages of these new materials compared to most investigated Au/C supported systems. The development of heterogeneous catalysts was preferred as the scale-up of gas-liquid technology implies important CAPEX investments to convert current plants from gas-solid to gas-liquid equipment. (orig.)

Recent progress in synthesis and surface functionalization of mesoporous acidic heterogeneous catalysts for esterification of free fatty acid feedstocks: A review

International Nuclear Information System (INIS)

Soltani, Soroush; Rashid, Umer; Al-Resayes, Saud Ibrahim; Nehdi, Imededdine Arbi

2017-01-01

Highlights: • Mesoporous catalysts have potential to esterify the wastes feedstocks. • Surface area of mesoporous catalysts depends on materials synthesis methods. • Hydrophobic surface of sulfonated catalyst causes adsorption on FFA particles. • Mesoporous catalysts have large active sites to trap free fatty acids particles. • Recyclability of mesoporous catalyst is a key feature for biodiesel production. - Abstract: Biodiesel is considered as a sulfur free, non-toxic and biodegradable source of energy and its burning provide less pollution than petroleum based fuels. In case of using fried waste oils, animal’s fats and waste cultivated oil which contain high free fatty acid (FFA), esterification is taking place. Through esterification reaction, catalyst is an integral part which accelerates the FFA conversion to the methyl ester (ME) in shorter reaction time. Although, most of the current catalysts have some defect such as poor recyclability, less surface area and poor porosity. Mesoporous materials have been recently attracted remarkable interests because of its desirable properties, such as large and harmonized surface area, tuneable mesoporous channels with flexible pore size, excellent thermal stability, and post-functionalization surface characteristics. The combination of remarkable physico-chemical and textural properties as well as high activity has proposed them as advanced materials. In this review, it has been attempted to present the details of fundamental properties of mesoporous catalysts, various synthetic methods and formation mechanisms, and surface functionalization methodologies. The effects of various factors (such as surface area, porosity, acidity, post-calcination temperature, and reaction parameters) on esterification of different feedstocks are discussed in detail. Furthermore, the kinetic study of esterification reaction in the presence of mesoporous catalysts is also elaborated. At the end, remarkable challenges and outlooks

Esterification free fatty acid in sludge palm oil using ZrO2/SO42- - rice husk ash catalyst

Science.gov (United States)

Hidayat, Arif; Sutrisno, Bachrun

2017-05-01

Indonesia, as one of the biggest palm oil producers and exporters in the world, is producing large amounts of low-grade oil such as sludge palm oil (SPO) from palm oil industries. The use of SPO can lower the cost of biodiesel production significantly, which makes SPO a highly potential alternative feedstock for biodiesel production. In this paper, the esterification of free fatty acid on sludge palm oil was studied using rice husk ash as heterogeneous solid catalysts. Heterogeneous solid catalysts offer significant advantages of eliminating separation, corrosion, toxicity and environmental problems. In this paper the esterification of SPO, a by-product from palm oil industry, in the presence of modified rice husk ash catalysts was studied. The rice husk ash catalysts were synthesized by impregnating of Zirconia (Zr) on rice husk ash followed by sulfonation. The rice husk ash catalysts were characterized by using different techniques, such as FT-IR, XRD, and porous analysis. The effects of the mass ratio of catalyst to oil (1 - 10%), the molar ratio of methanol to oil (4:1 - 10:1), and the reaction temperature (40 - 60°C) were studied for the conversion of free fatty acids (FFAs) to optimize the reaction conditions. The results showed that the optimal conditions were an methanol to oil molar ratio of 10:1, the amount of catalyst of 10%w, and reaction temperature of 60°C.

One-Pot Syntesis of 3-Functionalized 4-Hydroxycoumarin under Catalyst-Free Conditions

Directory of Open Access Journals (Sweden)

Yang Gao

2018-01-01

Full Text Available A concise and efficient one-pot synthesis of 3-functionalized 4-hydroxycoumarin derivatives via a three-component domino reaction of 4-hydroxycoumarin, phenylglyoxal and 3-arylaminocyclopent-2-enone or 4-arylaminofuran-2(5H-one under catalyst-free and microwave irradiation conditions is described. This synthesis involves a group-assisted purification process, which avoids traditional recrystallization and chromatographic purification methods.

Conversion of glycerol to polyglycerol over waste duck-bones as a catalyst in solvent free etherification process

Science.gov (United States)

Ayoub, Muhammad; Sufian, Suriati; Mekuria Hailegiorgis, Sintayehu; Ullah, Sami; Uemura, Yoshimitsu

2017-08-01

The alkaline catalyst derived from the duck-bones was used for conversion of glycerol to polyglycerol via solvent free etherification process. The physicochemical properties of prepared materials were duck-bones were systematically investigated as a catalyst by latest techniques of Thermo gravimetric analysis (TGA), X-ray diffraction (XRD), and Brunauer-Emmett-Teller (BET) surface properties. TGA showed different trends of duck-bones decomposition from room temperature to 1000C. XRD pattern showed a clear and sharp peaks of a crystalline phase of CaO. The activity of the catalysts was in line with the basic amount of the strong base sites, surface area, and crystalline phase in the catalysts. The prepared catalyst derived from duck-bones provided high activity (99 %) for glycerol conversion and around 68 % yield for polyglycerol production. These ample wastes of duck-bones have good potential to be used as polyglycerol production catalysts due to have high quantity of Ca compare to other types of bones like cow, chicken and fish bones.

Encaging palladium(0 in layered double hydroxide: A sustainable catalyst for solvent-free and ligand-free Heck reaction in a ball mill

Directory of Open Access Journals (Sweden)

Wei Shi

2017-08-01

Full Text Available In this paper, the synthesis of a cheap, reusable and ligand-free Pd catalyst supported on MgAl layered double hydroxides (Pd/MgAl-LDHs by co-precipitation and reduction methods is described. The catalyst was used in Heck reactions under high-speed ball milling (HSBM conditions at room temperature. The effects of milling-ball size, milling-ball filling degree, reaction time, rotation speed and grinding auxiliary category, which would influence the yields of mechanochemical Heck reactions, were investigated in detail. The characterization results of XRD, ICP–MS and XPS suggest that Pd/MgAl-LDHs have excellent textural properties with zero-valence Pd on its layers. The reaction results indicate that the catalyst could be utilized in HSBM systems to afford a wide range of Heck coupling products in satisfactory yields. Furthermore, this catalyst could be easily recovered and reused for at least five times without significant loss of catalytic activity.

A comparative parametric study of a catalytic plate methane reformer coated with segmented and continuous layers of combustion catalyst for hydrogen production

Science.gov (United States)

Mundhwa, Mayur; Parmar, Rajesh D.; Thurgood, Christopher P.

2017-03-01

A parametric comparison study is carried out between segmented and conventional continuous layer configurations of the coated combustion-catalyst to investigate their influence on the performance of methane steam reforming (MSR) for hydrogen production in a catalytic plate reactor (CPR). MSR is simulated on one side of a thin plate over a continuous layer of nickel-alumina catalyst by implementing an experimentally validated surface microkinetic model. Required thermal energy for the MSR reaction is supplied by simulating catalytic methane combustion (CMC) on the opposite side of the plate over segmented and continuous layer of a platinum-alumina catalyst by implementing power law rate model. The simulation results of both coating configurations of the combustion-catalyst are compared using the following parameters: (1) co-flow and counter-flow modes between CMC and MSR, (2) gas hourly space velocity and (3) reforming-catalyst thickness. The study explains why CPR designed with the segmented combustion-catalyst and co-flow mode shows superior performance not only in terms of high hydrogen production but also in terms of minimizing the maximum reactor plate temperature and thermal hot-spots. The study shows that the segmented coating requires 7% to 8% less combustion-side feed flow and 70% less combustion-catalyst to produce the required flow of hydrogen (29.80 mol/h) on the reforming-side to feed a 1 kW fuel-cell compared to the conventional continuous coating of the combustion-catalyst.

Production of Biodiesel by Esterification of Free Fatty Acid over Solid Catalyst from Biomass Waste

Science.gov (United States)

Mukti, N. I. F.; Sutrisno, B.; Hidayat, A.

2018-05-01

Recently, low cost feedstocks have been utilized to replace vegetable oils in order to improve the economic feasibility of biodiesel. The esterification of free fatty acid (FFA) on Palm Fatty Acid Distillate (PFAD) with methanol using solid catalyst generated from bagasse fly ash is a promising method to convert FFA into biodiesel. In this research, the esterification of FFA on PFAD using the sulfonated bagasse fly ash catalyst was studied. The performances of the catalysts were evaluated in terms of the reaction temperatures, the molar ratios of methanol to PFAD, and the catalyst loading. The effects of the mass ratio of catalyst to oil (1-10%), the molar ratio of methanol to oil (6:1-12:1), and the reaction temperature (40-60°C) were studied for the conversion of PFAD to optimize the reaction conditions. The results showed that the optimum conditions were methanol to PFAD molar ratio of 12:1, the amount of catalyst of 10%wt. of PFAD, and reaction temperature of 6°C. The reusability of the solid acid carbon catalysts was also studied in this work. The catalytic activity decreased up to 38% after third cycle. The significant decline in catalyst esterification activity was due to acid site leaching. The physico-characteristics and acid site densities were analyzed by Nitrogen gas adsorption, surface functional groups by Fourier transform infrared spectroscopy (FT-IR), elemental analysis using X-ray fluorescent (XRF), and acid-base back titration methods for determination of acid density.

Session 4: Combinatorial research of methane catalytic decomposition on supported nitride catalysts for CO-free hydrogen

Energy Technology Data Exchange (ETDEWEB)

Jianghan, Shen; Hua, Wang; Zhongmin, Liu; Hongchao, Liu [Natural Gas Utilization and Applied Catalysis Lab., Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian P. R. (China)

2004-07-01

CO-free Hydrogen production is needed for proton exchange membrane fuel cells (PEMs) because CO strongly poisons the anode-electrocatalysts. Methane directly catalytic decomposition is an attractive way to produce CO-free hydrogen for the large abundance of methane and its high H/C ratio. It is more effective to employ high-throughput screening (HTS) technology in heterogeneous catalysis. In this paper, a combinatorial multi-stream reaction system with online multi-stream mass spectrometer screening (MSMSS) detection technique was applied to study the decomposition of methane over supported MoN{sub x}O{sub y} catalysts (supports = Al{sub 2}O{sub 3}, SiO{sub 2}, SBA-15, ZSM-5,13X, and NaY), which is a catalyst system seldom reported recently. (authors)

Advances in Base-Free Oxidation of Bio-Based Compounds on Supported Gold Catalysts

Directory of Open Access Journals (Sweden)

Robert Wojcieszak

2017-11-01

Full Text Available The oxidation of bio-based molecules in general, and of carbohydrates and furanics in particular, is a highly attractive process. The catalytic conversion of renewable compounds is of high importance. Acids and other chemical intermediates issued from oxidation processes have many applications related, especially, to food and detergents, as well as to pharmaceutics, cosmetics, and the chemical industry. Until now, the oxidation of sugars, furfural, or 5-hydroxymethylfurfural has been mainly conducted through biochemical processes or with strong inorganic oxidants. The use of these processes very often presents many disadvantages, especially regarding products separation and selectivity control. Generally, the oxidation is performed in batch conditions using an appropriate catalyst and a basic aqueous solution (pH 7–9, while bubbling oxygen or air through the slurry. However, there is a renewed interest in working in base-free conditions to avoid the production of salts. Actually, this gives direct access to different acids or diacids without laborious product purification steps. This review focuses on processes applying gold-based catalysts, and on the catalytic properties of these systems in the base-free oxidation of important compounds: C5–C6 sugars, furfural, and 5-hydroxymethylfurfural. A better understanding of the chemical and physical properties of the catalysts and of the operating conditions applied in the oxidation reactions is essential. For this reason, in this review we put emphasis on these most impacting factors.

Research Update: Nickel filling in nanofeatures using supercritical fluid and its application to fabricating a novel catalyst structure for continuous growth of nanocarbon fibers

Directory of Open Access Journals (Sweden)

Mitsuhiro Watanabe

2014-10-01

Full Text Available A novel catalyst structure for continuous growth of nanocarbon fibers is proposed. In this structure, catalyst nanofibers are embedded in a membrane that separates the growth ambient into carbon-supplying and carbon-precipitating environments. The catalyst nanofibers pierce through the membrane so that carbon source gas is supplied only to one end of the catalyst fibers and nanocarbon fibers grow continuously at the other end. To realize this structure, self-supporting anodized alumina was used as a membrane, and its nano-through-holes were filled with catalyst Ni in supercritical CO2 fluid. Direct carbon growth from the Ni nanofibers was confirmed using this catalyst structure.

A new continuous-flow process for catalytic conversion of glycerol to oxygenated fuel additive: Catalyst screening

International Nuclear Information System (INIS)

Nanda, Malaya R.; Yuan, Zhongshun; Qin, Wensheng; Ghaziaskar, Hassan S.; Poirier, Marc-Andre; Xu, Chunbao

2014-01-01

Highlights: • A continuous-flow process for catalytic synthesis of solketal from glycerol. • Six different heterogeneous acid catalysts were studied in the process. • Glycerol conversion and solketal yield of 90% and 88% respectively were achieved. • The process has the potential to be scaled-up for industrial applications. - Abstract: A new continuous-flow reactor was designed for the conversion of glycerol to solketal, an oxygenated fuel additive, through ketalization with acetone. Six heterogeneous catalysts were investigated with respect to their catalytic activity and stability in a flow reactor. The acidity of the catalysts positively influences the catalyst’s activity. Among all the solid acid catalysts tested, the maximum solketal yield from experiments at 40 °C, 600 psi and WHSV of 4 h −1 attained 73% and 88% at the acetone/glycerol molar ratio of 2.0 and 6.0, respectively, with Amberlyst Wet. Based on the solketal yield and glycerol conversion results, the activity of all catalysts tested follows the following order of sequence: Amberlyst Wet ≈ Zeolite ≈ Amberlyst Dry > Zirconium Sulfate > Montmorillonite > Polymax. An increase in acetone/glycerol molar ratio or a decrease in WHSV enhanced the glycerol conversion as expected. This process offers an attractive route for converting glycerol, the main by-product of biodiesel, to solketal – a value-added green product with potential industrial applications as a valuable fuel additive or combustion promoter for gasoline engines

Production of Biodiesel from Roasted Chicken Fat and Methanol: Free Catalyst

OpenAIRE

Jorge Ramírez-Ortiz; Merced Martínez Rosales; Horacio Flores Zúñiga

2014-01-01

Transesterification reactions free of catalyst between roasted chicken fat with methanol were carried out in a batch reactor in order to produce biodiesel to temperatures from 120°C to 140°C. Parameters related to the transesterification reactions, including temperature, time and the molar ratio of chicken fat to methanol also investigated. The maximum yield of the reaction was of 98% under conditions of 140°C, 4 h of reaction time and a molar ratio of chicken fat to meth...

Direct fabrication of metal-free hollow graphene balls with a self-supporting structure as efficient cathode catalysts of fuel cell

Energy Technology Data Exchange (ETDEWEB)

Lu, Yanqi; Liu, Mingda; Nie, Huagui, E-mail: huaguinie@126.com; Gu, Cancan; Liu, Ming; Yang, Zhi, E-mail: yang201079@126.com; Yang, Keqin; Chen, Xi’an; Huang, Shaoming, E-mail: smhuang@wzu.edu.cn [Wenzhou University, Nanomaterials and Chemistry Key Laboratory (China)

2016-06-15

Despite the good progress in developing carbon catalysts for oxygen reduction reaction (ORR), the current metal-free carbon catalysts are still far from satisfactory for large-scale applications of fuel cell. Developing hollow graphene balls with a self-supporting structure is considered to be an ideal method to inhibit graphene stacking and improve their catalytic performance. Herein, we fabricated metal-free hollow graphene balls with a self-supporting structure, through using a new strategy that involves direct metal-free catalytic growth from assembly of SiO{sub 2} spheres. To our knowledge, although much researches involving the synthesis of graphene balls have been reported, investigations into the direct metal-free catalytic growth of hollow graphene balls are rare. Furthermore, the electrocatalytic performance shows that the resulting hollow graphene balls have significantly high catalytic activity. More importantly, such catalysts also possess much improved stability and better methanol tolerance in alkaline media during the ORR compared with commercial Pt/C catalysts. The outstanding performances coupled with an easy and inexpensive preparing method indicated the great potential of the hollow graphene balls with a self-supporting structure in large-scale applications of fuel cell.Graphical AbstractHollow graphene balls with a self-supporting structure have been successfully fabricated, through using a new strategy that involves direct metal-free catalytic growth from 3D assembly of SiO{sub 2} spheres. The hollow graphene balls can exhibit a high catalytic activity, long-term stability, and an excellent methanol tolerance for the oxygen reduction reaction.

Direct fabrication of metal-free hollow graphene balls with a self-supporting structure as efficient cathode catalysts of fuel cell

International Nuclear Information System (INIS)

Lu, Yanqi; Liu, Mingda; Nie, Huagui; Gu, Cancan; Liu, Ming; Yang, Zhi; Yang, Keqin; Chen, Xi’an; Huang, Shaoming

2016-01-01

Despite the good progress in developing carbon catalysts for oxygen reduction reaction (ORR), the current metal-free carbon catalysts are still far from satisfactory for large-scale applications of fuel cell. Developing hollow graphene balls with a self-supporting structure is considered to be an ideal method to inhibit graphene stacking and improve their catalytic performance. Herein, we fabricated metal-free hollow graphene balls with a self-supporting structure, through using a new strategy that involves direct metal-free catalytic growth from assembly of SiO_2 spheres. To our knowledge, although much researches involving the synthesis of graphene balls have been reported, investigations into the direct metal-free catalytic growth of hollow graphene balls are rare. Furthermore, the electrocatalytic performance shows that the resulting hollow graphene balls have significantly high catalytic activity. More importantly, such catalysts also possess much improved stability and better methanol tolerance in alkaline media during the ORR compared with commercial Pt/C catalysts. The outstanding performances coupled with an easy and inexpensive preparing method indicated the great potential of the hollow graphene balls with a self-supporting structure in large-scale applications of fuel cell.Graphical AbstractHollow graphene balls with a self-supporting structure have been successfully fabricated, through using a new strategy that involves direct metal-free catalytic growth from 3D assembly of SiO_2 spheres. The hollow graphene balls can exhibit a high catalytic activity, long-term stability, and an excellent methanol tolerance for the oxygen reduction reaction

Solvent-Free Biginelli Condensation using Tungstate Sulfuric Acid: a Powerful and Reusable Catalyst for Selective Synthesis

Directory of Open Access Journals (Sweden)

Rezvan Rezaee Nasab

2014-07-01

Full Text Available Tungstate sulfuric acid (TSA has been prepared and used as a recyclable catalyst for the Biginelli syn-thesis of some biologically active quinazolinones/thiones under solvent-free conditions. This method has advantages such as the avoidance of organic solvents, high yield of pure products, short reaction times, and operational simplicity.  © 2014 BCREC UNDIP. All rightsReceived: 28th April 2014; Revised: 15th May 2014; Accepted: 26th May 2014[ How to Cite: Nasab, R.R., Karami, B., Khodabakhshi, S. (2014. Selective Solvent‐free Biginelli Condensation using Tungstate Sulfuric Acid as Powerful and Reusable Catalyst. Bulletin of Chemical Reaction Engineering & Catalysis, 9 (2: 142-154. (doi:10.9767/bcrec.9.2.6794.148-154][ Permalink/DOI: http://dx.doi.org/10.9767/bcrec.9.2.6794.148-154

Silica sulfuric acid: a reusable solid catalyst for one pot synthesis of densely substituted pyrrole-fused isocoumarins under solvent-free conditions

Directory of Open Access Journals (Sweden)

Sudipta Pathak

2013-11-01

Full Text Available A convenient and efficient methodology for the synthesis of densely substituted pyrrole-fused isocoumarins, which employs solid-supported silica sulfuric acid (SSA as catalyst, has been developed. When the mixture of ninhydrin adducts of acetylacetone/ethyl acetoacetate and primary amines was heated on the solid surface of SSA under solvent-free conditions, the pyrrole-fused isocoumarins were formed in good yields. This synthetic method has several advantages such as the employment of solvent-free reaction conditions without the use of any toxic reagents and metal catalysts, the ease of product isolation, the use of a recyclable catalyst, the low cost, the easy availability of the starting materials, and the excellent yields of products.

Efficient hydrogenation of biomass-derived furfural and levulinic acid on the facilely synthesized noble-metal-free Cu–Cr catalyst

International Nuclear Information System (INIS)

Yan, Kai; Chen, Aicheng

2013-01-01

Biomass-derived platform intermediate furfural and levulinic acid were efficiently hydrogenated to the value-added furfuryl alcohol and promising biofuel γ-valerolactone, respectively, using a noble-metal-free Cu–Cr catalyst, which was facilely and successfully synthesized by a modified co-precipitation method using the cheap metal nitrates. In the first hydrogenation of furfural, 95% yield of furfuryl alcohol was highly selectively produced at 99% conversion of furfural under the mild conditions. For the hydrogenation of levulinic acid, 90% yield of γ-valerolactone was highly selectively produced at 97.8% conversion. Besides, the physical properties of the resulting Cu–Cr catalysts were studied by XRD (X-ray diffraction), EDX (Energy-dispersive X-ray), TEM (Transmission electron microscopy) and XPS (X-ray photoelectron spectroscopy) to reveal their influence on the catalytic performance. Subsequently, different reaction parameters were studied and it was found that Cu 2+ /Cr 3+ ratios (0.5, 1 and 2), reaction temperature (120–220 °C) and hydrogen pressure (35–70 bar) presented important influence on the catalytic activities. In the end, the stability of the Cu–Cr catalysts was also studied. - Highlights: • A noble-metal-free Cu–Cr catalyst was successfully synthesized using metal nitrates. • Cu–Cr catalysts were highly selective hydrogenation of biomass-derived furfural to FA. • Cu–Cr catalysts were efficient for hydrogenation of biomass-derived LA to biofuel GVL. • The physical properties of the resulting Cu–Cr catalysts were systematically studied. • Reaction parameters and stability in the hydrogenation of furfural were studied in details

Automatic continuity for homomorphisms into free products

DEFF Research Database (Denmark)

Slutsky, Konstantin

2013-01-01

A homomorphism from a completely metrizable topological group into a free product of groups whose image is not contained in a factor of the free product is shown to be continuous with respect to the discrete topology on the range. In particular, any completely metrizable group topology on a free ...

Advancements in rationally designed PGM-free fuel cell catalysts derived from metal–organic frameworks

International Nuclear Information System (INIS)

Barkholtz, Heather M.; Liu, Di-Jia

2016-01-01

Over the past several years, metal-organic framework (MOF)-derived platinum group metal free (PGM-free) electrocatalysts have gained considerable attention due to their high efficiency and low cost as potential replacement for platinum in catalyzing oxygen reduction reaction (ORR). In this review, we summarize the recent advancements in design, synthesis and characterization of MOF-derived ORR catalysts and their performances in acidic and alkaline media. As a result, we also discuss the key challenges such as durability and activity enhancement critical in moving forward this emerging electrocatalyst science.

Magnetic Pd-Fe{sub 3}O{sub 4} heterodimer nanocrystals as recoverable catalysts for ligand-free hiyama cross-coupling reactions

Energy Technology Data Exchange (ETDEWEB)

Lee, Woong Sup; Byun, Sang Moon; Kwon, Jung Min; Kim, B. Moon [Dept. of Chemistry, College of Natural Sciences, Seoul National University, Seoul (Korea, Republic of)

2016-12-15

Ligand-free Hiyama cross-coupling reaction was achieved through the use of Pd-Fe{sub 3}O{sub 4} heterodimeric nanocrystals (1 mol% in Pd) as recyclable catalysts. The nanocrystal catalysts exhibited good activities accommodating a variety of substrates including aryl bromides and iodides with substituents of varying electronic and steric properties. Furthermore, the nanocrystal catalyst could be conveniently recovered with the aid of an external magnet and recycled five times without the loss of catalytic activity to a considerable degree.

A Study of Iron-Nitrogen-Carbon Fuel Cell Catalysts: Chemistry - Nanostructure - Performance

Science.gov (United States)

Workman, Michael J., Jr.

Fuel cells have the potential to be a pollution-free, low-cost, and energy efficient alternative to the internal combustion engine for transportation and small-scale stationary power applications. The current state of fuel cell technology has already achieved two of these three lofty goals. The remaining barrier to wide-scale deployment is the high cost, which is primarily caused by dependence on large amounts of platinum to catalyze the energy conversion reactions. To overcome this barrier and facilitate the integration of fuel cells into mainstream applications, research into a new class of catalyst materials that do not require platinum is needed. There has been a significant amount of research effort directed toward the development of platinum-group metal free (PGM-free) catalysts, yet there is a lack of consensus on both the engineering parameters necessary to improve the technology and the fundamental science that would facilitate rational design. I have engaged in research on PGM-free catalysts based on inexpensive and abundant reagents, specifically: nicarbazin and iron. Catalysts made from these precursors have previously proven to be among the best PGM-free catalysts, but their continued advancement suffered from the same lack of understanding that besets all catalysts in this class. The work I have performed address both engineering concerns and fundamental underlying principles. I present results demonstrating correlations between physical structure, chemical speciation, and synthesis parameters, as well as addressing active site chemistry and likely locations. My research presented herein introduces new morphology analysis techniques and elucidates several key structure-to-property characteristics of catalysts derived from iron and nicarbazin. I discuss the development and application of a new length-scale specific surface analysis technique that allows for analysis of well-defined size ranges from a few nm to several microns. The existing technique of

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

Science.gov (United States)

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

2014-07-01

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.

Esterification free fatty acid in palm fatty acid distillate using sulfonated rice husk ash catalyst

Science.gov (United States)

Hidayat, Arif; Sutrisno, Bachrun

2017-01-01

Indonesia, as one of the biggest palm oil producers and exporters in the world, is producing large amounts of low-grade oil such as Palm Fatty Acid Distillate (PFAD) from palm oil industries. The use of PFAD can reduce the cost of biodiesel production significantly, which makes PFAD a highly potential alternative feedstock for biodiesel production. In this paper, the esterification of free fatty acid (FFA) on PFAD was studied using rice husk ash (RHA) as heterogeneous catalyst. The rice husk ash catalyst was synthesized by sulfonation using concentrated sulfuric acid. The RHA catalyst were characterized by using different techniques, such as porosity analysis, Fourier transform infrared (FT-IR) spectroscopy, total number of acid sites and elemental analysis. The effects of the molar ratio of methanol to PFAD (1-10%), the molar ratio of methanol to PFAD (4:1-10:1), and the reaction temperature (40-60°C) were studied for the conversion of FFA to optimize the reaction conditions. The results showed that the optimal conditions were an methanol to PFAD molar ratio of 10:1, the catalyst amount of 10 wt% of PFAD, and reaction temperature of 60°C.

Bimetallic catalysts for continuous catalytic wet air oxidation of phenol.

Science.gov (United States)

Fortuny, A; Bengoa, C; Font, J; Fabregat, A

1999-01-29

Catalytic wet oxidation has proved to be effective at eliminating hazardous organic compounds, such as phenol, from waste waters. However, the lack of active long-life oxidation catalysts which can perform in aqueous phase is its main drawback. This study explores the ability of bimetallic supported catalysts to oxidize aqueous phenol solutions using air as oxidant. Combinations of 2% of CoO, Fe2O3, MnO or ZnO with 10% CuO were supported on gamma-alumina by pore filling, calcined and later tested. The oxidation was carried out in a packed bed reactor operating in trickle flow regime at 140 degrees C and 900 kPa of oxygen partial pressure. Lifetime tests were conducted for 8 days. The pH of the feed solution was also varied. The results show that all the catalysts tested undergo severe deactivation during the first 2 days of operation. Later, the catalysts present steady activity until the end of the test. The highest residual phenol conversion was obtained for the ZnO-CuO, which was significantly higher than that obtained with the 10% CuO catalyst used as reference. The catalyst deactivation is related to the dissolution of the metal oxides from the catalyst surface due to the acidic reaction conditions. Generally, the performance of the catalysts was better when the pH of the feed solution was increased.

In-situ growing NiCo2O4 nanoplatelets on carbon cloth as binder-free catalyst air-cathode for high-performance microbial fuel cells

International Nuclear Information System (INIS)

Cao, Chun; Wei, Liling; Wang, Gang; Shen, Jianquan

2017-01-01

Highlights: • NiCo 2 O 4 nanoplatelets were in-situ growing on carbon cloth as ORR catalyst in biofuel cells. • Binder-free cathode with the lower internal resistance. • Binder-free cathode was low-cost. • NiCo 2 O 4 -CFC shows better power generation performance than Pt/C. - Abstract: Air-cathode microbial fuel cells (MFCs) was one of most promising sustainable new energy device as well as an advanced sewage treatment technology, and thoroughly studies have been devoted to lower its cost and enhance its power generation. Herein, a binder-free and low-cost catalyst air-cathode was fabricated by in-situ electro-deposition of NiCo 2 O 4 nanoplatelets on carbon cloth, followed by feasible calcinations. The catalytic activity of catalyst air-cathode was optimized by varying the deposition time. And the optimal air-cathode was installed in real MFCs and exhibited distinct maximum out-put power density (645 ± 6 mW m −2 ), which was 12.96% higher than commercial Pt/C (571 ± 11 mW m −2 ). Noted that its remarkable electricity generation performance in MFCs should absolutely attributed to the well catalytic activity for oxygen reduction reaction, and more likely ascribed to its low internal resistance since binder-free catalyst air-cathode can facilitate the electron/charge transfer process. Therefore, it was an efficient strategy to improve the electricity generation performance of MFCs by using this binder-free catalyst air-cathode, which was also potential for application in many other electrochemical devices.

Metaloxide--ZrO2 catalysts for the esterification and transesterification of free fatty acids and triglycerides to obtain bio-diesel

Energy Technology Data Exchange (ETDEWEB)

Kim, Manhoe; Salley, Steven O.; Ng, K. Y. Simon

2016-09-06

Mixed metal oxide catalysts (ZnO, CeO, La2O3, NiO, Al203, SiO2, TiO2, Nd2O3, Yb2O3, or any combination of these) supported on zirconia (ZrO2) or hydrous zirconia are provided. These mixed metal oxide catalysts can be prepared via coprecipitation, impregnation, or sol-gel methods from metal salt precursors with/without a Zirconium salt precursor. Metal oxides/ZrO2 catalyzes both esterification and transesterification of oil containing free fatty acids in one batch or in single stage. In particular, these mixed metal oxides supported or added on zirconium oxide exhibit good activity and selectivity for esterification and transesterification. The low acid strength of this catalyst can avoid undesirable side reaction such as alcohol dehydration or cracking of fatty acids. Metal oxides/ZrO2 catalysts are not sensitive to any water generated from esterification. Thus, esterification does not require a water free condition or the presence of excess methanol to occur when using the mixed metal oxide catalyst. The FAME yield obtained with metal oxides/ZrO2 is higher than that obtained with homogeneous sulfuric acid catalyst. Metal oxides/ZrO2 catalasts can be prepared as strong pellets and in various shapes for use directly in a flow reactor. Furthermore, the pellet has a strong resistance toward dissolution to aqueous or oil phases.

Influence of platinum group metal-free catalyst synthesis on microbial fuel cell performance

Science.gov (United States)

Santoro, Carlo; Rojas-Carbonell, Santiago; Awais, Roxanne; Gokhale, Rohan; Kodali, Mounika; Serov, Alexey; Artyushkova, Kateryna; Atanassov, Plamen

2018-01-01

Platinum group metal-free (PGM-free) ORR catalysts from the Fe-N-C family were synthesized using sacrificial support method (SSM) technique. Six experimental steps were used during the synthesis: 1) mixing the precursor, the metal salt, and the silica template; 2) first pyrolysis in hydrogen rich atmosphere; 3) ball milling; 4) etching the silica template using harsh acids environment; 5) the second pyrolysis in ammonia rich atmosphere; 6) final ball milling. Three independent batches were fabricated following the same procedure. The effect of each synthetic parameters on the surface chemistry and the electrocatalytic performance in neutral media was studied. Rotating ring disk electrode (RRDE) experiment showed an increase in half wave potential and limiting current after the pyrolysis steps. The additional improvement was observed after etching and performing the second pyrolysis. A similar trend was seen in microbial fuel cells (MFCs), in which the power output increased from 167 ± 2 μW cm-2 to 214 ± 5 μW cm-2. X-ray Photoelectron Spectroscopy (XPS) was used to evaluate surface chemistry of catalysts obtained after each synthetic step. The changes in chemical composition were directly correlated with the improvements in performance. We report outstanding reproducibility in both composition and performance among the three different batches.

Controllable synthesis in a continuous mode of unsupported molybdenum catalysts with micro/nano size for heavy oil upgrading

Energy Technology Data Exchange (ETDEWEB)

Wang, J.; Hill, J.M.; Pereira Almao, P.R. [Calgary Univ., AB (Canada)

2004-07-01

Heavy oils contain significant amounts of impurities compared to conventional oils, thereby posing a challenge for hydroprocessing operations at refineries. Hydrodesulfurization is one of the important reactions involved in hydroprocessing. Transition metal sulfides have excellent properties in terms of sulphur removal. Molybdenum based catalysts have been used extensively in the petroleum industry for hydrotreating heavy oil fractions. Supported molybdenum based catalysts suffer strong deactivation in the traditional hydrotreating process due to the deposition of carbonaceous components on the surface of the catalyst when they are used in conventional fixed bed reactors. Unsupported catalysts have higher catalytic activity with better metal dispersion. Laboratory experiments were conducted in which micro/nano size unsupported molybdenum catalysts were synthesized from a water/oil emulsion. The catalysts were prepared in a continuous mode for online application to hydroprocessing or in situ upgrading. Dispersed molybdenum catalysts are more suitable for processing heavier feeds because they are less prone to deactivation. Also, their submicron size ensure high activities due to a large specific surface area. They are also sufficiently small to be readily dispersed in the residual oil. 4 refs., 1 tab., 2 figs.

Continuous synthesis of methanol: heterogeneous hydrogenation of ethylene carbonate over Cu/HMS catalysts in a fixed bed reactor system.

Science.gov (United States)

Chen, Xi; Cui, Yuanyuan; Wen, Chao; Wang, Bin; Dai, Wei-Lin

2015-09-18

Continuous fixed-bed catalytic hydrogenation of ethylene carbonate (EC) to methanol and ethylene glycol (EG), an emerging synthetic process of methanol via indirect conversion of CO2, was successfully performed over Cu/HMS catalysts prepared by the ammonia evaporation (AE) method. The catalysts possessed superb performance with a conversion of 100% and a selectivity to methanol of 74%.

Highly Selective Continuous Gas-Phase Methoxycarbonylation of Ethylene with Supported Ionic Liquid Phase (SILP) Catalysts

DEFF Research Database (Denmark)

Khokarale, Santosh Govind; Garcia Suárez, Eduardo José; Fehrmann, Rasmus

2017-01-01

Supported ionic liquid phase (SILP) technology was applied for the first time to the Pd-catalyzed continuous, gas-phase methoxycarbonylation of ethylene to selectively produce methyl propanoate (MP) in high yields. The influence of catalyst and reaction parameters such as, for example, ionic liquid...

Electrochemical behaviour of PES ionomer and Pt-free catalyst for PEMFCs

Directory of Open Access Journals (Sweden)

STEFANIA GIORDANO

2013-06-01

Full Text Available Proton Exchange Membrane Fuel Cells (PEMFCs represent promising technologies to the world economy, with many applications and low environmental impact. A most important aspect concerning their widespread implementation is the cost of polymeric membranes, typically perfluorinated membranes and platinum-based catalytic electrode materials, all of which are necessary to promote electrode reactions, thus increasing fuel cell energy efficiency. In this work, we present some data about non-fluorinated polyetheresulphone (PES membranes and Pt-free catalysts, as possible substitutes of the above materials. Their electrochemical behaviour in oxygen reduction reaction in acidic media are investigated and compared with available reference materials.

Solvent-free Hydrodeoxygenation of Bio-oil Model Compounds Cyclopentanone and Acetophenone over Flame-made Bimetallic Pt-Pd/ZrO2 Catalysts

Science.gov (United States)

Jiang, Yijiao; Büchel, Robert; Huang, Jun; Krumeich, Frank; Pratsinis, Sotiris E.; Baiker, Alfons

2013-01-01

Bimetallic Pt-Pd/ZrO2 catalysts with different Pt/Pd atomic ratio and homogeneous dispersion of the metal nanoparticles were prepared in a single step by flame-spray pyrolysis. The catalysts show high activity and tuneable product selectivity for the solvent-free hydrodeoxygenation of the bio-oil model compounds cyclopentanone and acetophenone. PMID:22674738

Reaction kinetics of free fatty acids esterification in palm fatty acid distillate using coconut shell biochar sulfonated catalyst

Science.gov (United States)

Hidayat, Arif; Rochmadi, Wijaya, Karna; Budiman, Arief

2015-12-01

Recently, a new strategy of preparing novel carbon-based solid acids has been developed. In this research, the esterification reactions of Palm Fatty Acid Distillate (PFAD) with methanol, using coconut shell biochar sulfonated catalyst from biomass wastes as catalyst, were studied. In this study, the coconut shell biochar sulfonated catalysts were synthesized by sulfonating the coconut shell biochar using concentrated H2SO4. The kinetics of free fatty acid (FFA) esterification in PFAD using a coconut shell biochar sulfonated catalyst was also studied. The effects of the mass ratio of catalyst to oil (1-10%), the molar ratio of methanol to oil (6:1-12:1), and the reaction temperature (40-60°C) were studied for the conversion of PFAD to optimize the reaction conditions. The results showed that the optimal conditions were an methanol to PFAD molar ratio of 12:1, the amount of catalyst of 10%w, and reaction temperature of 60°C. The proposed kinetic model shows a reversible second order reaction and represents all the experimental data satisfactorily, providing deeper insight into the kinetics of the reaction.

Chloro-benquinone Modified on Graphene Oxide as Metal-free Catalyst: Strong Promotion of Hydroxyl Radical and Generation of Ultra-Small Graphene Oxide

Science.gov (United States)

Zhao, He; Wang, Juehua; Zhang, Di; Dai, Qin; Han, Qingzhen; Du, Penghui; Liu, Chenming; Xie, Yongbing; Zhang, Yi; Cao, Hongbin; Fan, Zhuangjun

2017-03-01

Carbon-based metal-free catalyst has attracted more and more attention. It is a big challenge to improve catalytic activity of metal-free catalyst for decomposition of H2O2 to produce hydroxyl radical (HO•). Here, we report chloro-benquinone (TCBQ) modified on graphene oxide (GO) as metal-free catalyst for strong promotion of HO•. By the incorporation of GO, the HO• production by H2O2 and TCBQ is significantly promoted. Based on density functional theory, TCBQ modified GO (GO-TCBQ) is more prone to be nucleophilic attacked by H2O2 to yield HO• via electron transfer acceleration. Furthermore, the generated HO• can cut GO nanosheets into uniform ultra-small graphene oxide (USGO) through the cleavage of epoxy and C-C bonds. Interestingly, the damaged GO and in situ formed GO fragments can further enhance decomposition of H2O2 to produce HO•. Different from other catalytic processes, the GO-TCBQ metal-free catalysis process can be enhanced by GO itself, producing more HO•, and uniform USGO also can be generated. Thus, the metal free catalysis will be considered a fabrication method for uniform USGO, and may be extended to other fields including detoxifying organic pollutants and the application as disinfectants.

Hemoglobin-carbon nanotube derived noble-metal-free Fe5C2-based catalyst for highly efficient oxygen reduction reaction

Science.gov (United States)

Vij, Varun; Tiwari, Jitendra N.; Lee, Wang-Geun; Yoon, Taeseung; Kim, Kwang S.

2016-02-01

High performance non-precious cathodic catalysts for oxygen reduction reaction (ORR) are vital for the development of energy materials and devices. Here, we report an noble metal free, Fe5C2 nanoparticles-studded sp2 carbon supported mesoporous material (CNTHb-700) as cathodic catalyst for ORR, which was prepared by pyrolizing the hybrid adduct of single walled carbon nanotubes (CNT) and lyophilized hemoglobin (Hb) at 700 °C. The catalyst shows onset potentials of 0.92 V in 0.1 M HClO4 and in 0.1 M KOH which are as good as commercial Pt/C catalyst, giving very high current density of 6.34 and 6.69 mA cm-2 at 0.55 V vs. reversible hydrogen electrode (RHE), respectively. This catalyst has been confirmed to follow 4-electron mechanism for ORR and shows high electrochemical stability in both acidic and basic media. Catalyst CNTHb-700 possesses much higher tolerance towards methanol than the commercial Pt/C catalyst. Highly efficient catalytic properties of CNTHb-700 could lead to fundamental understanding of utilization of biomolecules in ORR and materialization of proton exchange membrane fuel cells for clean energy production.

Catalyst-free dehydrative α-alkylation of ketones with alcohols: green and selective autocatalyzed synthesis of alcohols and ketones.

Science.gov (United States)

Xu, Qing; Chen, Jianhui; Tian, Haiwen; Yuan, Xueqin; Li, Shuangyan; Zhou, Chongkuan; Liu, Jianping

2014-01-03

Direct dehydrative α-alkylation reactions of ketones with alcohols are now realized under simple, practical, and green conditions without using external catalysts. These catalyst-free autocatalyzed alkylation methods can efficiently afford useful alkylated ketone or alcohol products in a one-pot manner and on a large scale by CC bond formation of the in situ generated intermediates with subsequent controllable and selective Meerwein-Pondorf-Verley-Oppenauer-type redox processes. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Investigation of heterogeneous solid acid catalyst performance on low grade feedstocks for biodiesel production: A review

International Nuclear Information System (INIS)

Mansir, Nasar; Taufiq-Yap, Yun Hin; Rashid, Umer; Lokman, Ibrahim M.

2017-01-01

Highlights: • Solid acid catalysts are proficient to esterifying high free fatty acid feedstocks to biodiesel. • Heterogeneous catalysts have the advantage of easy separation and reusability. • Heterogeneous basic catalysts have limitations due to high FFA of low cost feedstocks. • Solid catalysts having acid and base sites reveal better catalyst for biodiesel production. - Abstract: The conventional fossil fuel reserves are continually declining worldwide and therefore posing greater challenges to the future of the energy sources. Biofuel alternatives were found promising to replace the diminishing fossil fuels. However, conversion of edible vegetable oils to biodiesel using homogeneous acids and base catalysts is now considered as indefensible for the future particularly due to food versus fuel competition and other environmental problems related to catalyst system and feedstock. This review has discussed the progression in research and growth related to heterogeneous catalysts used for biodiesel production for low grade feedstocks. The heterogeneous base catalysts have revealed effective way to produce biodiesel, but it has the limitation of being sensitive to high free fatty acid (FFA) or low grade feedstocks. Alternatively, solid acid catalysts are capable of converting the low grade feedstocks to biodiesel in the presence of active acid sites. The paper presents a comprehensive review towards the investigation of solid acid catalyst performance on low grade feedstock, their category, properties, advantages, limitations and possible remedy to their drawbacks for biodiesel production.

Ultrasonic promoted catalyst-free N-formylation of amines in neutral ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate

Directory of Open Access Journals (Sweden)

Vinod T. Kamble

2017-05-01

Full Text Available A catalyst-free, simple and efficient protocol for N-formylation of alkyl, aryl, and heteroaryl amines with formic acid under ultrasonic irradiation at room temperature using 1-butyl-3-methylimidazolium tetrafluoroborate [Bmim]BF4 as a neutral medium is described.

Catalyst-free growth of ZnO nanowires on ITO seed/glass by thermal evaporation method: Effects of ITO seed layer thickness

Energy Technology Data Exchange (ETDEWEB)

Alsultany, Forat H., E-mail: foratusm@gmail.com; Ahmed, Naser M. [School of Physics, Universiti Sains Malaysia, 11800 USM, Penang (Malaysia); Hassan, Z. [Institute of Nano-Optoelectronics Research and Technology Laboratory (INOR), Universiti Sains Malaysia, 11800 USM, Penang (Malaysia)

2016-07-19

A seed/catalyst-free growth of ZnO nanowires (ZnO-NWs) on a glass substrate were successfully fabricated using thermal evaporation technique. These nanowires were grown on ITO seed layers of different thicknesses of 25 and 75 nm, which were deposited on glass substrates by radio frequency (RF) magnetron sputtering. Prior to synthesized ITO nanowires, the sputtered ITO seeds were annealed using the continuous wave (CW) CO2 laser at 450 °C in air for 15 min. The effect of seed layer thickness on the morphological, structural, and optical properties of ZnO-NWs were systematically investigated by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and UV-Vis spectrophotometer.

Mechanochemical Solvent-Free and Catalyst-Free One-Pot Synthesis of Pyrano[2,3-d]Pyrimidine-2,4(1H,3H-Diones with Quantitative Yields

Directory of Open Access Journals (Sweden)

M. Reza Naimi-Jamal

2009-01-01

Full Text Available Solvent-free synthesis of pyrano[2,3-d]pyrimidine-2,4(1H,3H-diones by ball-milling and without any catalyst is described. This method provides several advantages such as being environmentally friendly, using a simple workup procedure, and affording high yields.

A Pd/C-CeO2 Anode Catalyst for High-Performance Platinum-Free Anion Exchange Membrane Fuel Cells.

Science.gov (United States)

Miller, Hamish A; Lavacchi, Alessandro; Vizza, Francesco; Marelli, Marcello; Di Benedetto, Francesco; D'Acapito, Francesco; Paska, Yair; Page, Miles; Dekel, Dario R

2016-05-10

One of the biggest obstacles to the dissemination of fuel cells is their cost, a large part of which is due to platinum (Pt) electrocatalysts. Complete removal of Pt is a difficult if not impossible task for proton exchange membrane fuel cells (PEM-FCs). The anion exchange membrane fuel cell (AEM-FC) has long been proposed as a solution as non-Pt metals may be employed. Despite this, few examples of Pt-free AEM-FCs have been demonstrated with modest power output. The main obstacle preventing the realization of a high power density Pt-free AEM-FC is sluggish hydrogen oxidation (HOR) kinetics of the anode catalyst. Here we describe a Pt-free AEM-FC that employs a mixed carbon-CeO2 supported palladium (Pd) anode catalyst that exhibits enhanced kinetics for the HOR. AEM-FC tests run on dry H2 and pure air show peak power densities of more than 500 mW cm(-2) . © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Direct atomic-level insight into the active sites of a high-performance PGM-free ORR catalyst

Science.gov (United States)

Chung, Hoon T.; Cullen, David A.; Higgins, Drew; Sneed, Brian T.; Holby, Edward F.; More, Karren L.; Zelenay, Piotr

2017-08-01

Platinum group metal-free (PGM-free) metal-nitrogen-carbon catalysts have emerged as a promising alternative to their costly platinum (Pt)-based counterparts in polymer electrolyte fuel cells (PEFCs) but still face some major challenges, including (i) the identification of the most relevant catalytic site for the oxygen reduction reaction (ORR) and (ii) demonstration of competitive PEFC performance under automotive-application conditions in the hydrogen (H2)-air fuel cell. Herein, we demonstrate H2-air performance gains achieved with an iron-nitrogen-carbon catalyst synthesized with two nitrogen precursors that developed hierarchical porosity. Current densities recorded in the kinetic region of cathode operation, at fuel cell voltages greater than ~0.75 V, were the same as those obtained with a Pt cathode at a loading of 0.1 milligram of Pt per centimeter squared. The proposed catalytic active site, carbon-embedded nitrogen-coordinated iron (FeN4), was directly visualized with aberration-corrected scanning transmission electron microscopy, and the contributions of these active sites associated with specific lattice-level carbon structures were explored computationally.

Effects of water on the esterification of free fatty acids by acid catalysts

Energy Technology Data Exchange (ETDEWEB)

Park, Ji-Yeon; Kim, Deog-Keun; Lee, Jin-Suk [Korea Institute of Energy Research, 71-2, Jang-dong, Yuseong-gu, Daejeon 305-343 (Korea); Wang, Zhong-Ming [Guangzhou Institute of Energy Conversion, No. 2 Nengyuan Rd, Wushan, Tianhe, Guangzhou 510-640 (China)

2010-03-15

To maximize the production of biodiesel from soybean soapstock, the effects of water on the esterification of high-FFA (free fatty acid) oils were investigated. Oleic acid and high acid acid oil (HAAO) were esterified by reaction with methanol in the presence of Amberlyst-15 as a heterogeneous catalyst or sulfuric acid as a homogeneous catalyst. The yield of fatty acid methyl ester (FAME) was studied at oil to methanol molar ratios of 1:3 and 1:6 and reaction temperatures of 60 and 80 C. The rate of esterification of oleic acid significantly decreased as the initial water content increased to 20% of the oil. The activity of Amberlyst-15 decreased more rapidly than that of sulfuric acid, due to the direct poisoning of acid sites by water. Esterification using sulfuric acid was not affected by water until there was a 5% water addition at a 1:6 molar ratio of oil to methanol. FAME content of HAAO prepared from soapstock rapidly increased for the first 30 min of esterification. Following the 30-min mark, the rate of FAME production decreased significantly due to the accumulation of water. When methanol and Amberlyst-15 were removed from the HAAO after 30 min of esterification and fresh methanol and a catalyst were added, the time required to reach 85% FAME content was reduced from 6 h to 1.8 h. (author)

Continuous Flow Aerobic Alcohol Oxidation Reactions Using a Heterogeneous Ru(OH)x/Al2O3 Catalyst

Science.gov (United States)

2015-01-01

Ru(OH)x/Al2O3 is among the more versatile catalysts for aerobic alcohol oxidation and dehydrogenation of nitrogen heterocycles. Here, we describe the translation of batch reactions to a continuous-flow method that enables high steady-state conversion and single-pass yields in the oxidation of benzylic alcohols and dehydrogenation of indoline. A dilute source of O2 (8% in N2) was used to ensure that the reaction mixture, which employs toluene as the solvent, is nonflammable throughout the process. A packed bed reactor was operated isothermally in an up-flow orientation, allowing good liquid–solid contact. Deactivation of the catalyst during the reaction was modeled empirically, and this model was used to achieve high conversion and yield during extended operation in the aerobic oxidation of 2-thiophene methanol (99+% continuous yield over 72 h). PMID:25620869

Kinetics of methane decomposition to CO{sub x}-free hydrogen and carbon nanofiber over Ni-Cu/MgO catalyst

Energy Technology Data Exchange (ETDEWEB)

Borghei, Maryam; Karimzadeh, Ramin [Chemical Engineering Department, Tarbiat Modares University, Tehran (Iran); Rashidi, Alimorad; Izadi, Nosrat [Research Center of Nanotechnology, Research Institute of Petroleum Industry, Tehran (Iran)

2010-09-15

Kinetic modeling of methane decomposition to CO{sub x}-free hydrogen and carbon nanofiber has been carried out in the temperature range 550-650 C over Ni-Cu/MgO catalyst from CH{sub 4}-H{sub 2} mixtures at atmospheric pressure. Assuming the different mechanisms of the reaction, several kinetic models were derived based on Langmuir-Hinshelwood type. The optimum value of kinetic parameters has been obtained by Genetic Algorithm and statistical analysis has been used for the model discrimination. The suggested kinetic model relates to the mechanism when the dissociative adsorption of methane molecule is the rate-determining stage and the estimated activation energy is 50.4 kJ/mol in agreement with the literature. The catalyst deactivation was found to be dependent on the time, reaction temperature, and partial pressures of methane and hydrogen. Inspection of the behavior of the catalyst activity in relation to time, led to a model of second order for catalyst deactivation. (author)

Identification of Critical Parameters in Liquid Enzyme-Catalyzed Biodiesel Production

DEFF Research Database (Denmark)

Nordblad, Mathias; Silva, Vanessa T. L.; Nielsen, Per Munk

2014-01-01

CalleraTM Trans L, a liquid formulation of Thermomyces lanuginosus lipase, has recently shown great promise as a cost-efficient catalyst for methanolysis of triglyceride substrates, specifically in the BioFAME process. However, identifying the right combination of temperature and concentrations o...

Oxygen-reducing catalyst layer

Science.gov (United States)

O'Brien, Dennis P [Maplewood, MN; Schmoeckel, Alison K [Stillwater, MN; Vernstrom, George D [Cottage Grove, MN; Atanasoski, Radoslav [Edina, MN; Wood, Thomas E [Stillwater, MN; Yang, Ruizhi [Halifax, CA; Easton, E Bradley [Halifax, CA; Dahn, Jeffrey R [Hubley, CA; O'Neill, David G [Lake Elmo, MN

2011-03-22

An oxygen-reducing catalyst layer, and a method of making the oxygen-reducing catalyst layer, where the oxygen-reducing catalyst layer includes a catalytic material film disposed on a substrate with the use of physical vapor deposition and thermal treatment. The catalytic material film includes a transition metal that is substantially free of platinum. At least one of the physical vapor deposition and the thermal treatment is performed in a processing environment comprising a nitrogen-containing gas.

A "catalyst switch" Strategy for the sequential metal-free polymerization of epoxides and cyclic Esters/Carbonate

KAUST Repository

Zhao, Junpeng

2014-06-24

A "catalyst switch" strategy was used to synthesize well-defined polyether-polyester/polycarbonate block copolymers. Epoxides (ethylene oxide and/or 1,2-butylene oxide) were first polymerized from a monoalcohol in the presence of a strong phosphazene base promoter (t-BuP4). Then an excess of diphenyl phosphate (DPP) was introduced, followed by the addition and polymerization of a cyclic ester (ε-caprolactone or δ-valerolactone) or a cyclic carbonate (trimethylene carbonate), where DPP acted as both the neutralizer of phosphazenium alkoxide (polyether chain end) and the activator of cyclic ester/carbonate. This work has provided a one-pot sequential polymerization method for the metal-free synthesis of block copolymers from monomers which are suited for different types of organic catalysts. © 2014 American Chemical Society.

A "catalyst switch" Strategy for the sequential metal-free polymerization of epoxides and cyclic Esters/Carbonate

KAUST Repository

Zhao, Junpeng; Pahovnik, David; Gnanou, Yves; Hadjichristidis, Nikolaos

2014-01-01

A "catalyst switch" strategy was used to synthesize well-defined polyether-polyester/polycarbonate block copolymers. Epoxides (ethylene oxide and/or 1,2-butylene oxide) were first polymerized from a monoalcohol in the presence of a strong phosphazene base promoter (t-BuP4). Then an excess of diphenyl phosphate (DPP) was introduced, followed by the addition and polymerization of a cyclic ester (ε-caprolactone or δ-valerolactone) or a cyclic carbonate (trimethylene carbonate), where DPP acted as both the neutralizer of phosphazenium alkoxide (polyether chain end) and the activator of cyclic ester/carbonate. This work has provided a one-pot sequential polymerization method for the metal-free synthesis of block copolymers from monomers which are suited for different types of organic catalysts. © 2014 American Chemical Society.

Synthesis of biodiesel from waste vegetable oil with large amounts of free fatty acids using a carbon-based solid acid catalyst

Energy Technology Data Exchange (ETDEWEB)

Shu, Qing; Gao, Jixian; Nawaz, Zeeshan; Liao, Yuhui; Wang, Dezheng; Wang, Jinfu [Beijing Key Laboratory of Green Chemical Reaction Engineering and Technology, Department of Chemical Engineering, Tsinghua University, Beijing 100084 (China)

2010-08-15

A carbon-based solid acid catalyst was prepared by the sulfonation of carbonized vegetable oil asphalt. This catalyst was employed to simultaneously catalyze esterification and transesterification to synthesis biodiesel when a waste vegetable oil with large amounts of free fatty acids (FFAs) was used as feedstock. The physical and chemical properties of this catalyst were characterized by a variety of techniques. The maximum conversion of triglyceride and FFA reached 80.5 wt.% and 94.8 wt.% after 4.5 h at 220 C, when using a 16.8 M ratio of methanol to oil and 0.2 wt.% of catalyst to oil. The high catalytic activity and stability of this catalyst was related to its high acid site density (-OH, Broensted acid sites), hydrophobicity that prevented the hydration of -OH species, hydrophilic functional groups (-SO{sub 3}H) that gave improved accessibility of methanol to the triglyceride and FFAs, and large pores that provided more acid sites for the reactants. (author)

A practical and catalyst-free trifluoroethylation reaction of amines using trifluoroacetic acid

Science.gov (United States)

Andrews, Keith G.; Faizova, Radmila; Denton, Ross M.

2017-06-01

Amines are a fundamentally important class of biologically active compounds and the ability to manipulate their physicochemical properties through the introduction of fluorine is of paramount importance in medicinal chemistry. Current synthesis methods for the construction of fluorinated amines rely on air and moisture sensitive reagents that require special handling or harsh reductants that limit functionality. Here we report practical, catalyst-free, reductive trifluoroethylation reactions of free amines exhibiting remarkable functional group tolerance. The reactions proceed in conventional glassware without rigorous exclusion of either moisture or oxygen, and use trifluoroacetic acid as a stable and inexpensive fluorine source. The new methods provide access to a wide range of medicinally relevant functionalized tertiary β-fluoroalkylamine cores, either through direct trifluoroethylation of secondary amines or via a three-component coupling of primary amines, aldehydes and trifluoroacetic acid. A reduction of in situ-generated silyl ester species is proposed to account for the reductive selectivity observed.

OSU-6: A Highly Efficient, Metal-Free, Heterogeneous Catalyst for the Click Synthesis of 5-Benzyl and 5-Aryl-1H-tetrazoles

Directory of Open Access Journals (Sweden)

Baskar Nammalwar

2015-12-01

Full Text Available OSU-6, an MCM-41 type hexagonal mesoporous silica with mild Brönsted acid properties, has been used as an efficient, metal-free, heterogeneous catalyst for the click synthesis of 5-benzyl and 5-aryl-1H-tetrazoles from nitriles in DMF at 90 °C. This catalyst offers advantages including ease of operation, milder conditions, high yields, and reusability. Studies are presented that demonstrate the robust nature of the catalyst under the optimized reaction conditions. OSU-6 promotes the 1,3-dipolar addition of azides to nitriles without significant degradation or clogging of the nanoporous structure. The catalyst can be reused up to five times without a significant reduction in yield, and it does not require treatment with acid between reactions.

Toluene and chlorobenzene dinitration over solid H3PO4/MoO3/SiO2 catalyst

International Nuclear Information System (INIS)

Adamiak, Joanna; Kalinowska-Alichnewicz, Dorota; Szadkowski, Michal; Skupinski, Wincenty

2011-01-01

Highlights: → A novel catalyst H 3 PO 4 /MoO 3 /SiO 2 was characterized and used in nitration. → On the surface domains of phosphomolybdic acid (HPM) are obtained. → Dinitrotoluene is obtained with very high yield i.e. 96 wt.% in mild conditions. → Dinitrochlorobenzene is obtained with only twelve-fold excess of nitric acid. → It is sulfuric acid free and solvent free nitration of aromatic compounds. - Abstract: A new catalyst, H 3 PO 4 /MoO 3 /SiO 2 , was prepared by modification of MoO 3 /SiO 2 using phosphoric acid. The characterization of the catalyst was performed using Infrared and Raman Spectroscopy, potentiometric titration and nitrogen adsorption-desorption methods. Molybdenum oxides were identified along with phosphomolybdic acid and polymolybdates on the modified surface. The suitability of the catalysts for toluene and chlorobenzene nitration in continuous process was examined. Toluene is effectively nitrated to dinitrotoluene (DNT) in one-stage process (96 wt.% of DNT in the product) and in mild conditions i.e. at room temperature and only with ten-fold excess of nitric acid. In chlorobenzene nitration only twelve-fold excess of nitric acid is needed to obtain as high yield as 95 wt.%. Most importantly, the novel catalysts we have developed, provide the opportunity for sulfuric acid- free nitration of aromatic compounds.

Activity targets for nanostructured platinum-group-metal-free catalysts in hydroxide exchange membrane fuel cells

Science.gov (United States)

Setzler, Brian P.; Zhuang, Zhongbin; Wittkopf, Jarrid A.; Yan, Yushan

2016-12-01

Fuel cells are the zero-emission automotive power source that best preserves the advantages of gasoline automobiles: low upfront cost, long driving range and fast refuelling. To make fuel-cell cars a reality, the US Department of Energy has set a fuel cell system cost target of US$30 kW-1 in the long-term, which equates to US$2,400 per vehicle, excluding several major powertrain components (in comparison, a basic, but complete, internal combustion engine system costs approximately US$3,000). To date, most research for automotive applications has focused on proton exchange membrane fuel cells (PEMFCs), because these systems have demonstrated the highest power density. Recently, however, an alternative technology, hydroxide exchange membrane fuel cells (HEMFCs), has gained significant attention, because of the possibility to use stable platinum-group-metal-free catalysts, with inherent, long-term cost advantages. In this Perspective, we discuss the cost profile of PEMFCs and the advantages offered by HEMFCs. In particular, we discuss catalyst development needs for HEMFCs and set catalyst activity targets to achieve performance parity with state-of-the-art automotive PEMFCs. Meeting these targets requires careful optimization of nanostructures to pack high surface areas into a small volume, while maintaining high area-specific activity and favourable pore-transport properties.

Dipyridine cobalt chloride as an efficient and chemoselective catalyst for the synthesis of 1,1-diacetates under solvent-free conditions

Directory of Open Access Journals (Sweden)

Sobhan Rezayati

2014-02-01

Full Text Available 1,1-Diacetates(acylals were prepared by direct condensation of various aldehydes with acetic anhydride using dipyridine cobalt chloride (CoPy2Cl2 as an efficient and green catalyst under solvent-free conditions at room temperature. The important features of this catalyst method are that the catalyst is solid, stable at high temperatures, soluble in water, stable in air, immiscible in common organic solvents, and low toxic and, above all, it is reusable. CoPy2Cl2 can be recycled after a simple work-up and reused at least five runs without appreciable loss of its catalytic activity. High chemo-selectivity toward aldehyde in the presence of ketones is another advantage of the present method which provides selective protection of aldehydes in their mixtures with ketones.

Solvent-free and catalyst-free chemistry: A benign pathway to sustainability

Science.gov (United States)

In the past decade, alternative benign organic methodologies have become an imperative part of organic syntheses and novel chemical reactions. The various new and innovative sustainable organic reactions and methodologies using no solvents or catalysts and employing alternative ...

Solvent-Free Synthesis of Aryl Iodide Using Nano SiO2/HIO4 as a Reusable Acid Catalyst

Directory of Open Access Journals (Sweden)

A. Bamoniri

2014-07-01

Full Text Available An efficient and environmentally benign   method for the synthesis of aryl iodides have been developed by diazotization of aromatic amines with NaNO2 and nanosilica periodic acid (nano-SPIA as a green catalyst via grinding followed by a sandmeyer iodination by KI under solvent-free conditions at room temperature. The ensuing aryl diazonium salts supported on nano-SPIA were sufficiently stable to be kept at room temperature in the dry state. This method is a novel, efficient, eco-friendly route for solvent-free synthesis of aryl iodides.

Influence of process variables on the continuous alkylation of isobutane with 2-butene on superacid sulfated zirconia catalysts

Energy Technology Data Exchange (ETDEWEB)

Corma, A.; Martinez, A.; Martinez, C. [Instituto de Tecnologia Quimica, Valencia (Spain)

1994-09-01

Two sulfated zirconia catalysts have been prepared by impregnation of zirconium hydroxide with H{sub 2}SO{sub 4} 0.3 N and 1 N. Both samples showed superacid sites as shown by a desorption temperature peak in the NH{sub 3} TPD at ca. 813 K. The activity and selectivity of these catalysts have been studied for the alkylation of isobutane with trans-2 butene in a computer-controlled continuous fixed bed reactor coupled with a sampling system which allows to make differential analysis of the products from very short reaction times. In this way, the influence of the main process variables, i.e, time on stream, reaction temperature, olefin WHSV, and isoparaffin/olefin ratio, on the 2-butene conversation and product distribution has been investigated. Cracking of larger carbocations and alkylation of isobutane with 2-butene to give trimethylpentanes were the predominant reactions occurring on the superacid catalyst in the initial stages of the reaction. The alkylation/cracking ratio increased when decreasing reaction temperature. A fast catalyst decay with time on stream was also observed, and this was accompanied by an increase in the oligomerization of butene. 23 refs., 5 figs., 4 tabs.

The utilization of leftover as acid catalyst to catalyse the transesterification and esterification reactions

Science.gov (United States)

Leung, K. K.; Yau, Y. H.

2017-08-01

Biodiesel (Fatty Acid Methyl Ester, FAME) is a green and renewable energy. It is carbon neutral and produces less air pollutants in combustion. In my project, the selected feedstock of biodiesel production is grease trap oil (GTO). It is extracted from restaurants, and needs pre-treatment. The triglycerides and free fatty acid (FFA) are the main components of GTO. Both triglycerides and free fatty acid can be converted to biodiesel (Fatty Acid Methyl Ester) by transesterification and esterification, through reaction with alcohol (methanol) and catalyst. In the processes, acidic catalyst is chosen to speed up the reactions. The catalyst used In the study, a heterogeneous solid acid is applied. It is waste cooked rice (WCR) collected from leftover. The WCR powder is pyrolysed in 400°C furnace 15 hours and blown with nitrogen gas (incomplete carbonization). The WCR black powder is then mixed with concentrated sulphuric acid and heat in 160°C furnace 15 hours and continuous blown with nitrogen gas (sulphonation). This heterogeneous solid acid is used in the both transesterification and esterification to produce FAME. Moreover, in the optimal reaction conditions, this catalyst offers a stable catalytic effect. After 20 times usage in optimal reaction condition, the catalytic activity remains unchanged.

Catalyst free growth of CNTs by CVD on nanoscale rough surfaces of silicon substrates

Science.gov (United States)

Damodar, D.; Sahoo, R. K.; Jacob, C.

2013-06-01

Catalyst free growth of carbon nanotubes (CNT) has been achieved using atmospheric pressure chemical vapor deposition (APCVD) on surface modified Si(111) substrates. The effect of the substrate surface has been observed by partially etching with KOH (potassium hydroxide) solution which is an anisotropic etchant. Scanning electron microscopy (SEM) confirmed the formation of CNTs over most of the area of the substrate where substrates were anisotropically etched. Transmission electron microscopy (TEM) was used to observe the internal structure of the CNTs. Raman spectroscopy further confirmed the formation of the carbon nanostructures and also their graphitic crystallinity.

A Selenium-Based Ionic Liquid as a Recyclable Solvent for the Catalyst-Free Synthesis of 3-Selenylindoles

Directory of Open Access Journals (Sweden)

Eder J. Lenardão

2013-04-01

Full Text Available The ionic liquid 1-butyl-3-methylimidazolium methylselenite, [bmim][SeO2(OCH3], was successfully used as solvent in the catalyst-free preparation of 3-arylselenylindoles by the reaction of indole with ArSeCl at room temperature. The products were obtained selectively in good yields without the need of any additive and the solvent was easily reused for several cycles with good results.

SBA-15-functionalized 3-oxo-ABNO as recyclable catalyst for aerobic oxidation of alcohols under metal-free conditions.

Science.gov (United States)

Karimi, Babak; Farhangi, Elham; Vali, Hojatollah; Vahdati, Saleh

2014-09-01

The nitroxyl radical 3-oxo-9-azabicyclo [3.3.1]nonane-N-oxyl (3-oxo-ABNO) has been prepared using a simple protocol. This organocatalyst is found to be an efficient catalyst for the aerobic oxidation of a wide variety of alcohols under metal-free conditions. In addition, the preparation and characterization of a supported version of 3-oxo-ABNO on ordered mesoporous silica SBA-15 (SABNO) is described for the first time. The catalyst has been characterized using several techniques including simultaneous thermal analysis (STA), transmission electron microscopy (TEM), and nitrogen sorption analysis. This catalyst exhibits catalytic performance comparable to its homogeneous analogue and much superior catalytic activity in comparison with (2,2,6,6-tetramethylpiperidin-1-yl)oxy (TEMPO) for the aerobic oxidation of almost the same range of alcohols under identical reaction conditions. It is also found that SABNO can be conveniently recovered and reused at least 12 times without significant effect on its catalytic efficiency. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Hierarchical hybrid of Ni{sub 3}N/N-doped reduced graphene oxide nanocomposite as a noble metal free catalyst for oxygen reduction reaction

Energy Technology Data Exchange (ETDEWEB)

Zhao, Qi; Li, Yingjun; Li, Yetong [College of Chemistry and Chemical Engineering, Inner Mongolia University, Hohhot 010021 (China); Huang, Keke [State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, College of Chemistry, Jilin University, Changchun 130012 (China); Wang, Qin, E-mail: qinwang@imu.edu.cn [College of Chemistry and Chemical Engineering, Inner Mongolia University, Hohhot 010021 (China); Inner Mongolia Key Lab. of Nanoscience and Nanotechnology, Inner Mongolia University, Hohhot 010021 (China); Zhang, Jun, E-mail: cejzhang@imu.edu.cn [College of Chemistry and Chemical Engineering, Inner Mongolia University, Hohhot 010021 (China); Inner Mongolia Key Lab. of Nanoscience and Nanotechnology, Inner Mongolia University, Hohhot 010021 (China)

2017-04-01

Highlights: • Hybrid of Ni{sub 3}N/N-RGO catalysts are synthesized by using a two-step method. • The catalysts manifest superior catalytic activity towards the ORR. • High activities are attributed to enhanced electron density and synergistic effects. - Abstract: Novel nickel nitride (Ni{sub 3}N) nanoparticles supported on nitrogen-doped reduced graphene oxide nanosheets (N-RGOs) are synthesized via a facile strategy including hydrothermal and subsequent calcination methods, in which the reduced graphene oxide nanosheets (RGOs) are simultaneously doped with nitrogen species. By varying the content of the RGOs, a series of Ni{sub 3}N/N-RGO nanocomposites are obtained. The Ni{sub 3}N/N-RGO-30% hybrid nanocomposite exhibits superior catalytic activity towards oxygen reduction reaction (ORR) under alkaline condition (0.1 M KOH). Furthermore, this hybrid catalyst also demonstrates high tolerance to methanol poisoning. The RGO containing rich N confers the nanocomposite with large specific surface area and high electronic conduction ability, which can enhance the catalytic efficiency of Ni{sub 3}N nanoparticles. The enhanced catalytic activity can be attributed to the synergistic effect between Ni{sub 3}N and nitrogen doped reduced graphene oxide. In addition, the sufficient contact between Ni{sub 3}N nanoparticles and the N-RGO nanosheets simultaneously promotes good nanoparticle dispersion and provides a consecutive activity sites to accelerate electron transport continuously, which further enhance the ORR performance. The Ni{sub 3}N/N-RGO may be further an ideal candidate as efficient and inexpensive noble metal-free ORR electrocatalyst in fuel cells.

Catalyst-free growth of InN nanorods by metal-organic chemical vapor deposition

International Nuclear Information System (INIS)

Kim, Min Hwa; Moon, Dae Young; Park, Jinsub; Nanishi, Yasushi; Yi, Gyu-Chul; Yoon, Euijoon

2012-01-01

We demonstrated the growth of catalyst-free InN nanostructures including nanorods on (0001) Al 2 O 3 substrates using metal-organic chemical vapor deposition. As the growth time increased, growth rate along c-direction increased superlinearly with decreasing c-plane area fractions and increasing side wall areas. It was also found that desorption from the sidewalls of InN nanostructures during the InN nanorods formation was one of essential key parameters of the growth mechanism. We propose a growth model to explain the InN nanostructure evolution by considering the side wall desorption and re-deposition of indium at top c-plane surfaces. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Polymer-bound rhodium hydroformylation catalysts

NARCIS (Netherlands)

Jongsma, Tjeerd

1992-01-01

Homogeneous catalysts are superior in activity, selectivity as well as specificity, but heterogeneous catalyst are often preferred in industrial processes, because of their good recoverability and their applicability in continuous flow reactors. It would be of great environmental, commercial and

CATALYST-FREE REACTIONS UNDER SOLVENT-FEE CONDITIONS: MICROWAVE-ASSISTED SYNTHESIS OF HETEROCYCLIC HYDRAZONES BELOW THE MELTING POINT OF NEAT REACTANTS: JOURNAL ARTICLE

Science.gov (United States)

NRMRL-CIN-1437 Jeselnik, M., Varma*, R.S., Polanc, S., and Kocevar, M. Catalyst-free Reactions under Solvent-fee Conditions: Microwave-assisted Synthesis of Heterocyclic Hydrazones below the Melting Point of Neat Reactants. Published in: Chemical Communications 18:1716-1717 (200...

Hierarchical hybrid peroxidase catalysts for remediation of phenol wastewater

KAUST Repository

Duan, Xiaonan

2014-02-20

We report a new family of hierarchical hybrid catalysts comprised of horseradish peroxidase (HRP)-magnetic nanoparticles for advanced oxidation processes and demonstrate their utility in the removal of phenol from water. The immobilized HRP catalyzes the oxidation of phenols in the presence of H2O2, producing free radicals. The phenoxy radicals react with each other in a non-enzymatic process to form polymers, which can be removed by precipitation with salts or condensation. The hybrid peroxidase catalysts exhibit three times higher activity than free HRP and are able to remove three times more phenol from water compared to free HRP under similar conditions. In addition, the hybrid catalysts reduce substrate inhibition and limit inactivation from reaction products, which are common problems with free or conventionally immobilized enzymes. Reusability is improved when the HRP-magnetic nanoparticle hybrids are supported on micron-scale magnetic particles, and can be retained with a specially designed magnetically driven reactor. The performance of the hybrid catalysts makes them attractive for several industrial and environmental applications and their development might pave the way for practical applications by eliminating most of the limitations that have prevented the use of free or conventionally immobilized enzymes. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Hierarchical hybrid peroxidase catalysts for remediation of phenol wastewater

KAUST Repository

Duan, Xiaonan; Corgié , Sté phane C.; Aneshansley, Daniel J.; Wang, Peng; Walker, Larry P.; Giannelis, Emmanuel P.

2014-01-01

We report a new family of hierarchical hybrid catalysts comprised of horseradish peroxidase (HRP)-magnetic nanoparticles for advanced oxidation processes and demonstrate their utility in the removal of phenol from water. The immobilized HRP catalyzes the oxidation of phenols in the presence of H2O2, producing free radicals. The phenoxy radicals react with each other in a non-enzymatic process to form polymers, which can be removed by precipitation with salts or condensation. The hybrid peroxidase catalysts exhibit three times higher activity than free HRP and are able to remove three times more phenol from water compared to free HRP under similar conditions. In addition, the hybrid catalysts reduce substrate inhibition and limit inactivation from reaction products, which are common problems with free or conventionally immobilized enzymes. Reusability is improved when the HRP-magnetic nanoparticle hybrids are supported on micron-scale magnetic particles, and can be retained with a specially designed magnetically driven reactor. The performance of the hybrid catalysts makes them attractive for several industrial and environmental applications and their development might pave the way for practical applications by eliminating most of the limitations that have prevented the use of free or conventionally immobilized enzymes. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Visible light photocatalytic activities of template free porous graphitic carbon nitride-BiOBr composite catalysts towards the mineralization of reactive dyes

Science.gov (United States)

Kanagaraj, Thamaraiselvi; Thiripuranthagan, Sivakumar; Paskalis, Sahaya Murphin Kumar; Abe, Hideki

2017-12-01

Template free porous g-C3N4 (pGCN) and flower like bismuth oxybromide catalysts were synthesized by poly condensation and precipitation methods respectively. Various weight percentages of porous GCN-BiOBr composite catalysts (x% pGCN-BiOBr where x = 5, 10, 30, 50 & 70 wt% of pGCN) were synthesized by impregnation method. All the synthesized catalysts were characterized by X-Ray diffractometer, Fourier transform infrared spectrophotometer, BET surface area analyzer, UV Visible diffuse reflectance spectrophotometer, X-Ray photoelectron spectrophotometer, SEM with Energy dispersive X-ray analyzer (SEM/EDAX) and elemental mapping, Transmission electron microscope, Photoluminescence spectrophotometer and Electrochemical impedance. Photocatalytic degradation of all the synthesized catalysts were tested towards the harmful reactive dyes such as reactive blue 198 (RB 198), reactive black 5 (RB 5) and reactive yellow 145 (RY 145) in presence of visible irradiation. Among the catalysts 30% pGCN-BiOBr resulted in the highest photocatalytic activity towards the degradation of all the three dyes in presence of UV, visible and solar irradiations. Kinetics studies on the photocatalytic mineralization of dyes indicated that it followed pseudo first order. HPLC, TOC and COD studies confirm that the dyes are mineralized into CO2, water and mineral salts.

Lanthanoid-free perovskite oxide catalyst for dehydrogenation of ethylbenzene working with redox mechanism

Science.gov (United States)

Watanabe, Ryo; Ikushima, Maiko; Mukawa, Kei; Sumomozawa, Fumitaka; Ogo, Shuhei; Sekine, Yasushi

2013-01-01

For the development of highly active and robust catalysts for dehydrogenation of ethylbenzene (EBDH) to produce styrene; an important monomer for polystyrene production, perovskite-type oxides were applied to the reaction. Controlling the mobility of lattice oxygen by changing the structure of Ba1 − xSrxFeyMn1 − yO3 − δ (0 ≤ x ≤ 1, 0.2 ≤ y ≤ 0.8), perovskite catalyst showed higher activity and stability on EBDH. The optimized Ba/Sr and Fe/Mn molar ratios were 0.4/0.6 and 0.6/0.4, respectively. Comparison of the dehydrogenation activity of Ba0.4Sr0.6Fe0.6Mn0.4O3 − δ catalyst with that of an industrial potassium promoted iron (Fe–K) catalyst revealed that the Ba0.4Sr0.6Fe0.6Mn0.4O3 − δ catalyst showed higher initial activity than the industrial Fe–K oxide catalyst. Additionally, the Ba0.4Sr0.6Fe0.6Mn0.4O3 − δ catalyst showed high activity and stability under severe conditions, even at temperatures as low as 783 K, or at the low steam/EB ratio of 2, while, the Fe–K catalyst showed low activity in such conditions. Comparing reduction profiles of the Ba0.4Sr0.6Fe0.6Mn0.4O3 − δ and the Fe–K catalysts in a H2O/H2 atmosphere, reduction was suppressed by the presence of H2O over the Ba0.4Sr0.6Fe0.6Mn0.4O3 − δ catalyst while the Fe–K catalyst was reduced. In other words, Ba0.4Sr0.6Fe0.6Mn0.4O3 − δ catalyst had higher potential for activating the steam than the Fe–K catalyst. The lattice oxygen in perovskite-structure was consumed by H2, subsequently the consumed lattice oxygen was regenerated by H2O. So the catalytic performance of Ba0.4Sr0.6Fe0.6Mn0.4O3 − δ was superior to that of Fe–K catalyst thanks to the high redox property of the Ba0.4Sr0.6Fe0.6Mn0.4O3 − δ perovskite oxide. PMID:24790949

Lanthanoid-free perovskite oxide catalyst for dehydrogenation of ethylbenzene working with redox mechanism

Directory of Open Access Journals (Sweden)

Ryo eWatanabe

2013-10-01

Full Text Available For the development of highly active and robust catalysts for dehydrogenation of ethylbenzene (EBDH to produce styrene; an important monomer for polystyrene production, perovskite-type oxides were applied to the reaction. Controlling the mobility of lattice oxygen by changing the structure of Ba1–xSrxFeyMn1–yO3–d(0 ≤ x≤ 1, 0.2 ≤ y≤ 0.8, perovskite catalyst showed higher activity and stability on EBDH. The optimized Ba/Sr and Fe/Mn molar ratios were 0.4/0.6 and 0.6/0.4, respectively. Comparison of the dehydrogenation activity of Ba0.4Sr0.6Fe0.6Mn0.4O3–d catalyst with that of an industrial potassium promoted iron (Fe–K catalyst revealed that the Ba0.4Sr0.6Fe0.6Mn0.4O3–d catalyst showed higher initial activity than the industrial Fe–K oxide catalyst. Additionally, the Ba0.4Sr0.6Fe0.6Mn0.4O3–d catalyst showed high activity and stability under severe conditions, even at temperatures as low as 783 K, or at the low steam/EB ratio of 2, while, the Fe–K catalyst showed low activity in such conditions. Comparing reduction profiles of the Ba0.4Sr0.6Fe0.6Mn0.4O3–d and the Fe–K catalysts in aH2O/H2 atmosphere, reduction was suppressed by the presence of H2O over the Ba0.4Sr0.6Fe0.6Mn0.4O3–d catalyst while the Fe–K catalyst was reduced. In other words, Ba0.4Sr0.6Fe0.6Mn0.4O3–d catalyst had higher potential for activating the steam than the Fe–K catalyst. The lattice oxygen in perovskite-structure was consumed by H2, subsequently the consumed lattice oxygen was regenerated by H2O. So the catalytic performance of Ba0.4Sr0.6Fe0.6Mn0.4O3–d was superior to that of Fe–K catalyst thanks to the high redox property of the Ba0.4Sr0.6Fe0.6Mn0.4O3–d perovskite oxide.

Lanthanoid-free perovskite oxide catalyst for dehydrogenation of ethylbenzene working with redox mechanism

Science.gov (United States)

Watanabe, Ryo; Ikushima, Maiko; Mukawa, Kei; Sumomozawa, Fumitaka; Ogo, Shuhei; Sekine, Yasushi

2013-10-01

For the development of highly active and robust catalysts for dehydrogenation of ethylbenzene (EBDH) to produce styrene; an important monomer for polystyrene production, perovskite-type oxides were applied to the reaction. Controlling the mobility of lattice oxygen by changing the structure of Ba1-xSrxFeyMn1-yO3-d(0 ≤ x≤ 1, 0.2 ≤ y≤ 0.8), perovskite catalyst showed higher activity and stability on EBDH. The optimized Ba/Sr and Fe/Mn molar ratios were 0.4/0.6 and 0.6/0.4, respectively. Comparison of the dehydrogenation activity of Ba0.4Sr0.6Fe0.6Mn0.4O3-d catalyst with that of an industrial potassium promoted iron (Fe-K) catalyst revealed that the Ba0.4Sr0.6Fe0.6Mn0.4O3-d catalyst showed higher initial activity than the industrial Fe-K oxide catalyst. Additionally, the Ba0.4Sr0.6Fe0.6Mn0.4O3-d catalyst showed high activity and stability under severe conditions, even at temperatures as low as 783 K, or at the low steam/EB ratio of 2, while, the Fe-K catalyst showed low activity in such conditions. Comparing reduction profiles of the Ba0.4Sr0.6Fe0.6Mn0.4O3-d and the Fe-K catalysts in aH2O/H2 atmosphere, reduction was suppressed by the presence of H2O over the Ba0.4Sr0.6Fe0.6Mn0.4O3-d catalyst while the Fe-K catalyst was reduced. In other words, Ba0.4Sr0.6Fe0.6Mn0.4O3-d catalyst had higher potential for activating the steam than the Fe-K catalyst. The lattice oxygen in perovskite-structure was consumed by H2, subsequently the consumed lattice oxygen was regenerated by H2O. So the catalytic performance of Ba0.4Sr0.6Fe0.6Mn0.4O3-d was superior to that of Fe-K catalyst thanks to the high redox property of the Ba0.4Sr0.6Fe0.6Mn0.4O3-d perovskite oxide.

Lanthanoid-free perovskite oxide catalyst for dehydrogenation of ethylbenzene working with redox mechanism.

Science.gov (United States)

Watanabe, Ryo; Ikushima, Maiko; Mukawa, Kei; Sumomozawa, Fumitaka; Ogo, Shuhei; Sekine, Yasushi

2013-01-01

For the development of highly active and robust catalysts for dehydrogenation of ethylbenzene (EBDH) to produce styrene; an important monomer for polystyrene production, perovskite-type oxides were applied to the reaction. Controlling the mobility of lattice oxygen by changing the structure of Ba1 - x SrxFe y Mn1 - y O3 - δ (0 ≤ x ≤ 1, 0.2 ≤ y ≤ 0.8), perovskite catalyst showed higher activity and stability on EBDH. The optimized Ba/Sr and Fe/Mn molar ratios were 0.4/0.6 and 0.6/0.4, respectively. Comparison of the dehydrogenation activity of Ba0.4Sr0.6Fe0.6Mn0.4O3 - δ catalyst with that of an industrial potassium promoted iron (Fe-K) catalyst revealed that the Ba0.4Sr0.6Fe0.6Mn0.4O3 - δ catalyst showed higher initial activity than the industrial Fe-K oxide catalyst. Additionally, the Ba0.4Sr0.6Fe0.6Mn0.4O3 - δ catalyst showed high activity and stability under severe conditions, even at temperatures as low as 783 K, or at the low steam/EB ratio of 2, while, the Fe-K catalyst showed low activity in such conditions. Comparing reduction profiles of the Ba0.4Sr0.6Fe0.6Mn0.4O3 - δ and the Fe-K catalysts in a H2O/H2 atmosphere, reduction was suppressed by the presence of H2O over the Ba0.4Sr0.6Fe0.6Mn0.4O3 - δ catalyst while the Fe-K catalyst was reduced. In other words, Ba0.4Sr0.6Fe0.6Mn0.4O3 - δ catalyst had higher potential for activating the steam than the Fe-K catalyst. The lattice oxygen in perovskite-structure was consumed by H2, subsequently the consumed lattice oxygen was regenerated by H2O. So the catalytic performance of Ba0.4Sr0.6Fe0.6Mn0.4O3 - δ was superior to that of Fe-K catalyst thanks to the high redox property of the Ba0.4Sr0.6Fe0.6Mn0.4O3 - δ perovskite oxide.

Synthesis of solid catalyst from egg shell waste and clay for biodiesel production

Science.gov (United States)

Setiadji, S.; Sundari, C. D. D.; Munir, M.; Fitriyah, S.

2018-05-01

Until now, energy consumption in Indonesia is almost entirely fulfilled by fossil fuels, thus, its availability will be limited and continue to decrease. To overcome these problems, development and utilization of renewable energy are required, one of which is biodiesel. Biodiesel can be prepared through transesterification reaction of vegetable oil using catalyst. In this research, a solid catalyst for biodiesel synthesis was prepared from chicken egg shell waste and clay. Optimization of the transesterification reaction of coconut (Cocos nucifera) oil to obtain biodiesel was also carried out. The formation of CaO/kaolin catalyst was confirmed based on the results of XRD and SEM-EDS. This catalyst is suitable for biodiesel synthesis from vegetable oils with lower FFA (free fatty acid) levels, i.e. coconut oil with FFA level of 0.18%. Based on FTIR result, FFA level and flame tests, it was found that biodiesel was successfully formed. Synthesis of biodiesel has the optimum conditions on reaction time of 16 hours and temperature of 64 °C, with oil: methanol ratio of 1: 15 and CaO/kaolin catalyst concentration of 0.9% in a reflux system.

Ester versus polyketone formation in the palladium-diphosphine catalyzed carbonylation of ethene.

Science.gov (United States)

Zuidema, Erik; Bo, Carles; van Leeuwen, Piet W N M

2007-04-04

The origin of the chemoselectivity of palladium catalysts containing bidentate phosphine ligands toward either methoxycarbonylation of ethene or the copolymerization of ethene and carbon monoxide was investigated using density functional theory based calculations. For a palladium catalyst containing the electron-donating bis(dimethylphosphino)ethane (dmpe) ligand, the rate determining step for chain propagation is shown to be the insertion of ethene into the metal-acyl bond. The high barrier for chain propagation is attributed to the low stability of the ethene intermediate, (dmpe)Pd(ethene)(C(O)CH3). For the competing methanolysis process, the most likely pathway involves the formation of (dmpe)Pd(CH3OH)(C(O)CH3) via dissociative ligand exchange, followed by a solvent mediated proton-transfer/reductive- elimination process. The overall barrier for this process is higher than the barrier for ethene insertion into the palladium-acetyl bond, in line with the experimentally observed preference of this type of catalyst toward the formation of polyketone. Electronic bite angle effects on the rates of ethene insertion and ethanoyl methanolysis were evaluated using four electronically and sterically related ligands (Me)2P(CH2)nP(Me)2 (n = 1-4). Steric effects were studied for larger tert-butyl substituted ligands using a QM/MM methodology. The results show that ethene coordination to the metal center and subsequent insertion into the palladium-ethanoyl bond are disfavored by the addition of steric bulk around the metal center. Key intermediates in the methanolysis mechanism, on the other hand, are stabilized because of electronic effects caused by increasing the bite angle of the diphosphine ligand. The combined effects explain successfully which ligands give polymer and which ones give methyl propionate as the major products of the reaction.

European workshop on spent catalysts. Book of abstracts

Energy Technology Data Exchange (ETDEWEB)

NONE

2006-07-01

In 1999 and 2002 two well attended workshops on recycling, regeneration, reuse and disposal of spent catalysts took place in Frankfurt. This series has been continued in Berlin. The workshop was organized in collaboration with DGMK, the German Society for Petroleum and Coal Science and Technology. Contributions were in the following areas of catalyst deactivation: recycling of spent catalysts in chemical and petrochemical industry, recycling of precious metal catalysts and heterogenous base metal catalysts, legal aspects of transboundary movements, catalyst regeneration, quality control, slurry catalysts, commercial reactivation of hydrotreating catalysts. (uke)

Experimental study of simultaneous Athabasca bitumen recovery and upgrading using ultradispersed catalysts injection

Energy Technology Data Exchange (ETDEWEB)

Hashemi, R.; Pereira, P. [University of Calgary (Canada)

2011-07-01

As the demand for oil is continuously increasing, the need for unconventional resources is rising. Oil extraction from bitumen and heavy oil reservoirs requires advanced techniques in order to decrease the viscosity of the oil. To increase the recovered original oil in place (OOIP) of a reservoir and decrease refining costs, new techniques to upgrade oil in situ are being developed. The current study investigates the use of ultra-dispersed (UD) submicronic catalysts to decrease oil viscosity. The experiment involved the injection of the catalyst and hydrogen gas in a sand pack saturated with Athabasca bitumen. Analysis was carried out by building recovery curves, and by comparing the oil recovery from the catalyzed process with that of catalyst-free processes. The study demonstrated that the oil recovered from the new technique had higher API gravity and lower viscosity, indicating the success of the in situ upgrading process.

Design of Highly Selective Platinum Nanoparticle Catalysts for the Aerobic Oxidation of KA-Oil using Continuous-Flow Chemistry.

Science.gov (United States)

Gill, Arran M; Hinde, Christopher S; Leary, Rowan K; Potter, Matthew E; Jouve, Andrea; Wells, Peter P; Midgley, Paul A; Thomas, John M; Raja, Robert

2016-03-08

Highly active and selective aerobic oxidation of KA-oil to cyclohexanone (precursor for adipic acid and ɛ-caprolactam) has been achieved in high yields using continuous-flow chemistry by utilizing uncapped noble-metal (Au, Pt & Pd) nanoparticle catalysts. These are prepared using a one-step in situ methodology, within three-dimensional porous molecular architectures, to afford robust heterogeneous catalysts. Detailed spectroscopic characterization of the nature of the active sites at the molecular level, coupled with aberration-corrected scanning transmission electron microscopy, reveals that the synthetic methodology and associated activation procedures play a vital role in regulating the morphology, shape and size of the metal nanoparticles. These active centers have a profound influence on the activation of molecular oxygen for selective catalytic oxidations. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Carbon-free H2 production from ammonia triggered at room temperature with an acidic RuO2/γ-Al2O3 catalyst.

Science.gov (United States)

Nagaoka, Katsutoshi; Eboshi, Takaaki; Takeishi, Yuma; Tasaki, Ryo; Honda, Kyoko; Imamura, Kazuya; Sato, Katsutoshi

2017-04-01

Ammonia has been suggested as a carbon-free hydrogen source, but a convenient method for producing hydrogen from ammonia with rapid initiation has not been developed. Ideally, this method would require no external energy input. We demonstrate hydrogen production by exposing ammonia and O 2 at room temperature to an acidic RuO 2 /γ-Al 2 O 3 catalyst. Because adsorption of ammonia onto the catalyst is exothermic, the catalyst bed is rapidly heated to the catalytic ammonia autoignition temperature, and subsequent oxidative decomposition of ammonia produces hydrogen. A differential calorimeter combined with a volumetric gas adsorption analyzer revealed a large quantity of heat evolved both with chemisorption of ammonia onto RuO 2 and acidic sites on the γ-Al 2 O 3 and with physisorption of multiple ammonia molecules.

Direct synthesis of Pt-free catalyst on gas diffusion layer of fuel cell and usage of high boiling point fuels for efficient utilization of waste heat

International Nuclear Information System (INIS)

Nandan, Ravi; Goswami, Gopal Krishna; Nanda, Karuna Kar

2017-01-01

Graphical abstract: Direct-grown boron-doped carbon nanotubes on gas-diffusion layer as efficient Pt-free cathode catalyst for alcohol fuel cells, high boiling point fuels used to obtain hot fuels for the enhancement of cell performance that paves the way for the utilization of waste heat. Display Omitted -- Highlights: •One-step direct synthesis of boron-doped carbon nanotubes (BCNTs) on gas diffusion layer (GDL). •Home built fuel-cell testing using BCNTs on GDL as Pt-free cathode catalyst. •BCNTs exhibit concentration dependent oxygen reduction reaction and the cell performance. •Effective utilization of waste heat to raise the fuel temperature. •Fuel selectivity to raise the fuel temperature and the overall performance of the fuel cells. -- Abstract: Gas diffusion layers (GDL) and electrocatalysts are integral parts of fuel cells. It is, however, a challenging task to grow Pt-free robust electrocatalyst directly on GDL for oxygen reduction reaction (ORR) – a key reaction in fuel cells. Here, we demonstrate that boron-doped carbon nanotubes (BCNTs) grown directly on gas-diffusion layer (which avoid the need of ionomer solution used for catalyst loading) can be used as efficient Pt-free catalyst in alcohol fuel cells. Increase in boron concentration improves the electrochemical ORR activity in terms of onset and ORR peak positions, half-wave potentials and diffusion-limited current density that ensure the optimization of the device performance. The preferential 4e − pathway, excellent cell performance, superior tolerance to fuel crossover and long-term stability makes directly grown BCNTs as an efficient Pt-free cathode catalyst for cost-effective fuel cells. The maximum power density of the fuel cell is found to increase monotonically with boron concentration. In addition to the application of BCNTs in fuel cell, we have introduced the concept of hot fuels so that waste heat can effectively be used and external power sources can be avoided. The fuel

Continuous hydrogenation of ethyl levulinate to γ-valerolactone and 2-methyl tetrahydrofuran over alumina doped Cu/SiO2 catalyst: the potential of commercialization

Science.gov (United States)

Zheng, Junlin; Zhu, Junhua; Xu, Xuan; Wang, Wanmin; Li, Jiwen; Zhao, Yan; Tang, Kangjian; Song, Qi; Qi, Xiaolan; Kong, Dejin; Tang, Yi

2016-01-01

Hydrogenation of levulinic acid (LA) and its esters to produce γ-valerolactone (GVL) and 2-methyl tetrahydrofuran (2-MTHF) is a key step for the utilization of cellulose derived LA. Aiming to develop a commercially feasible base metal catalyst for the production of GVL from LA, with satisfactory activity, selectivity, and stability, Al2O3 doped Cu/SiO2 and Cu/SiO2 catalysts were fabricated by co-precipitation routes in parallel. The diverse physio-chemical properties of these two catalysts were characterized by XRD, TEM, dissociative N2O chemisorptions, and Py-IR methods. The catalytic properties of these two catalysts were systematically assessed in the continuous hydrogenation of ethyl levulinate (EL) in a fixed-bed reactor. The effect of acidic property of the SiO2 substrate on the catalytic properties was investigated. To justify the potential of its commercialization, significant attention was paid on the initial activity, proper operation window, by-products control, selectivity, and stability of the catalyst. The effect of reaction conditions, such as temperature and pressure, on the performance of the catalyst was also thoroughly studied. The development of alumina doped Cu/SiO2 catalyst strengthened the value-chain from cellulose to industrially important chemicals via LA and GVL. PMID:27377401

Reverse microemulsion prepared Ni–Pt catalysts for methane cracking to produce COx-free hydrogen

KAUST Repository

Zhou, Lu

2017-09-08

A monodispersed 15 nm Ni9Pt1 catalyst synthesized via a reverse microemulsion method, shows a lower activation energy than both Ni and Pt catalysts during the methane cracking reaction. Thanks to the synergic effect of Ni–Pt alloy, this catalyst presents a stable H2 formation rate at 700 °C, and forms carbon nanotubes, anchoring the catalyst particles on top.

Reverse microemulsion prepared Ni–Pt catalysts for methane cracking to produce COx-free hydrogen

KAUST Repository

Zhou, Lu; Harb, Moussab; Enakonda, Linga Reddy; Al Mana, Noor; Hedhili, Mohamed N.; Basset, Jean-Marie

2017-01-01

A monodispersed 15 nm Ni9Pt1 catalyst synthesized via a reverse microemulsion method, shows a lower activation energy than both Ni and Pt catalysts during the methane cracking reaction. Thanks to the synergic effect of Ni–Pt alloy, this catalyst presents a stable H2 formation rate at 700 °C, and forms carbon nanotubes, anchoring the catalyst particles on top.

Biodiesel production from esterification of free fatty acid over PA/NaY solid catalyst

International Nuclear Information System (INIS)

Liu, Wei; Yin, Ping; Zhang, Jiang; Tang, Qinghua; Qu, Rongjun

2014-01-01

Highlights: • Biodiesel production from esterification of oleic acid was catalyzed by PA/NaY. • The influences of the process operating parameters were studied. • RSM was employed to optimize the experimental conditions. • The kinetic equation of the esterification reaction was investigated. - Abstract: Because of the incitements from increasing petroleum prices, diminishing petroleum reserves and the environmental consequences of exhaust gases from petroleum fueled engines, biodiesel has been used as a substitute of the regular diesel in recent years. In this paper, biodiesel production from the esterification of the free fatty oil oleic acid with ethanol catalyzed by PA/NaY (PA = organic phosphonic acid) was investigated, and the effect of reaction conditions such as PA loading, catalyst amount, molar ratio of alcohol to acid, reaction temperature and reaction time on the esterification reaction was examined. The process optimization using response surface methodology (RSM) was performed and the interactions between the operational variables were elucidated. The optimum values for maximum conversion ratio of oleic acid could be obtained by using a Box–Behnken center-united design with a minimum of experimental work. The oleic acid conversion reached 79.51 ± 0.68% with the molar ratio of alcohol to oleic acid being 7:1 and 1.7 g PA/NaY catalyst (20 ml of PA loading) at 105 °C for 7 h. Moreover, a kinetic model for the esterification catalyzed by PA/NaY catalyst was established. By fitting the kinetic model with the experimental results, the reaction order n = 2, activation energy of the positive reaction Ea + = 43.41 kJ/mol and that of the reverse reaction Ea − = 59.74 kJ/mol were obtained

Toluene and chlorobenzene dinitration over solid H{sub 3}PO{sub 4}/MoO{sub 3}/SiO{sub 2} catalyst

Energy Technology Data Exchange (ETDEWEB)

Adamiak, Joanna, E-mail: jadamiak@ch.pw.edu.pl [Warsaw University of Technology, Faculty of Chemistry, Division of High Energetic Materials, Noakowskiego 3, 00-664 Warsaw (Poland); Kalinowska-Alichnewicz, Dorota; Szadkowski, Michal; Skupinski, Wincenty [Warsaw University of Technology, Faculty of Chemistry, Division of High Energetic Materials, Noakowskiego 3, 00-664 Warsaw (Poland)

2011-11-15

Highlights: {yields} A novel catalyst H{sub 3}PO{sub 4}/MoO{sub 3}/SiO{sub 2} was characterized and used in nitration. {yields} On the surface domains of phosphomolybdic acid (HPM) are obtained. {yields} Dinitrotoluene is obtained with very high yield i.e. 96 wt.% in mild conditions. {yields} Dinitrochlorobenzene is obtained with only twelve-fold excess of nitric acid. {yields} It is sulfuric acid free and solvent free nitration of aromatic compounds. - Abstract: A new catalyst, H{sub 3}PO{sub 4}/MoO{sub 3}/SiO{sub 2}, was prepared by modification of MoO{sub 3}/SiO{sub 2} using phosphoric acid. The characterization of the catalyst was performed using Infrared and Raman Spectroscopy, potentiometric titration and nitrogen adsorption-desorption methods. Molybdenum oxides were identified along with phosphomolybdic acid and polymolybdates on the modified surface. The suitability of the catalysts for toluene and chlorobenzene nitration in continuous process was examined. Toluene is effectively nitrated to dinitrotoluene (DNT) in one-stage process (96 wt.% of DNT in the product) and in mild conditions i.e. at room temperature and only with ten-fold excess of nitric acid. In chlorobenzene nitration only twelve-fold excess of nitric acid is needed to obtain as high yield as 95 wt.%. Most importantly, the novel catalysts we have developed, provide the opportunity for sulfuric acid- free nitration of aromatic compounds.

Continuous fabrication of a MnS/Co nanofibrous air electrode for wide integration of rechargeable zinc-air batteries.

Science.gov (United States)

Wang, Yang; Fu, Jing; Zhang, Yining; Li, Matthew; Hassan, Fathy Mohamed; Li, Guang; Chen, Zhongwei

2017-10-26

Exploring highly efficient bifunctional electrocatalysts toward the oxygen reduction and evolution reactions is essential for the realization of high-performance rechargeable zinc-air batteries. Herein, a novel nanofibrous bifunctional electrocatalyst film, consisting of metallic manganese sulfide and cobalt encapsulated by nitrogen-doped carbon nanofibers (CMS/NCNF), is prepared through a continuous electrospinning method followed by carbonization treatment. The CMS/NCNF bifunctional catalyst shows both comparable ORR and OER performances to those of commercial precious metal-based catalysts. Furthermore, the free-standing CMS/NCNF fibrous thin film is directly used as the air electrode in a solid-state zinc-air battery, which exhibits superior flexibility while retaining stable battery performance at different bending angles. This study provides a versatile design route for the rational design of free-standing bifunctional catalysts for direct use as the air electrode in rechargeable zinc-air batteries.

Highly effective ionic liquids for biodiesel production from waste vegetable oils

Directory of Open Access Journals (Sweden)

Fathy A. Yassin

2015-03-01

Full Text Available As conventional energy sources deplete, the need for developing alternative energy resources which are environment friendly becomes more imperative. Vegetable oils are attracting increased interest in this purpose. The methanolysis of vegetable oil to produce a fatty acid methyl ester (FAME, i.e., biodiesel fuel was catalyzed by commercial ionic liquid and its chloride modification. The imidazolium chloride ionic liquid was frequently chosen for the synthesis of biodiesel. The dual-functionalized’ ionic liquid is prepared by a direct combination reaction between imidazolium cation and various metal chlorides such as CoCl2, CuCl2, NiCl2, FeCl3 and AlCl3. Imidazolium tetrachloroferrate was proved to be a selective catalyst for the methanolysis reaction at a yield of 97% when used at 1:10, catalyst: oil ratio for 8 h at 55 °C. Operational simplicity, reusability of the used catalyst for 8 times at least, high yields and no saponification are the key features of this methodology. The dynamic viscosity and density of the upgraded vegetable oil decreased from 32.1 cP and 0.9227 g/cm3 to 10.2 cP and 0.9044 g/cm3 respectively, compared to those of the base vegetable oil. The objective of this study was the synthesis and characterization of biodiesel using commercial ionic liquid and its chloride modification. The ionic liquid catalysts were characterized using FTIR, Raman spectroscopy, DSC, TG and UV.

Sulfidization of an aluminocobaltomolybdenum catalyst using the 35S radioisotope

International Nuclear Information System (INIS)

Isagulyants, G.V.; Greish, A.A.; Kogan, V.M.

1987-01-01

It has been established that in aluminocobaltomolybdenum catalyst sulfidized with elemental sulfur there are two types of sulfur, free and bound. The maximum amount of bound sulfur in ACM catalyst is 6.6 wt. %, which corresponds to practically complete sulfidation of the ACM catalyst. In the presence of hydrogen an equilibrium distribution of bound sulfur is achieved in a granule of ACM catalyst irrespective of the temperature of sulfidation. In a nitrogen atmosphere it is primarily the surface layers of the catalyst that are sulfured

Optimisation of Lab-Scale Continuous Alcohol-Free Beer Production

Czech Academy of Sciences Publication Activity Database

Lehnert, R.; Novák, Pavel; Macieira, F.; Kuřec, M.; Teixeira, J.A.; Brányik, T.

2009-01-01

Roč. 27, č. 4 (2009), s. 267-275 ISSN 1212-1800 Institutional research plan: CEZ:AV0Z40720504 Keywords : alcohol-free beer * continuous reactor * immobilised yeast Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 0.602, year: 2009

Surface modification of g-C3N4 by hydrazine: Simple way for noble-metal free hydrogen evolution catalysts

KAUST Repository

Chen, Yin

2015-11-02

The graphitic carbon nitride (g-C3N4) usually is thought to be an inert material and it’s difficult to have the surface terminated NH2 groups functionalized. By modifying the g-C3N4 surface with hydrazine, the diazanyl group was successfully introduced onto the g-C3N4 surface, which allows the introduction with many other function groups. Here we illustrated that by reaction of surface hydrazine group modified g-C3N4 with CS2 under basic condition, a water electrolysis active group C(=S)SNi can be implanted on the g-C3N4 surface, and leads to a noble metal free hydrogen evolution catalyst. This catalyst has 40% hydrogen evolution efficiency compare to the 3 wt% Pt photo precipitated g-C3N4, with only less than 0.2 wt% nickel.

Surface modification of g-C3N4 by hydrazine: Simple way for noble-metal free hydrogen evolution catalysts

KAUST Repository

Chen, Yin; Lin, Bin; Wang, Hong; Yang, Yong; Zhu, Haibo; Yu, Weili; Basset, Jean-Marie

2015-01-01

The graphitic carbon nitride (g-C3N4) usually is thought to be an inert material and it’s difficult to have the surface terminated NH2 groups functionalized. By modifying the g-C3N4 surface with hydrazine, the diazanyl group was successfully introduced onto the g-C3N4 surface, which allows the introduction with many other function groups. Here we illustrated that by reaction of surface hydrazine group modified g-C3N4 with CS2 under basic condition, a water electrolysis active group C(=S)SNi can be implanted on the g-C3N4 surface, and leads to a noble metal free hydrogen evolution catalyst. This catalyst has 40% hydrogen evolution efficiency compare to the 3 wt% Pt photo precipitated g-C3N4, with only less than 0.2 wt% nickel.

Toluene and chlorobenzene dinitration over solid H3PO4/MoO3/SiO2 catalyst.

Science.gov (United States)

Adamiak, Joanna; Kalinowska-Alichnewicz, Dorota; Szadkowski, Michał; Skupiński, Wincenty

2011-11-15

A new catalyst, H(3)PO(4)/MoO(3)/SiO(2), was prepared by modification of MoO(3)/SiO(2) using phosphoric acid. The characterization of the catalyst was performed using Infrared and Raman Spectroscopy, potentiometric titration and nitrogen adsorption-desorption methods. Molybdenum oxides were identified along with phosphomolybdic acid and polymolybdates on the modified surface. The suitability of the catalysts for toluene and chlorobenzene nitration in continuous process was examined. Toluene is effectively nitrated to dinitrotoluene (DNT) in one-stage process (96 wt.% of DNT in the product) and in mild conditions i.e. at room temperature and only with ten-fold excess of nitric acid. In chlorobenzene nitration only twelve-fold excess of nitric acid is needed to obtain as high yield as 95 wt.%. Most importantly, the novel catalysts we have developed, provide the opportunity for sulfuric acid- free nitration of aromatic compounds. Copyright © 2011 Elsevier B.V. All rights reserved.

Homogeneous deuterium exchange using rhenium and platinum chloride catalysts

International Nuclear Information System (INIS)

Fawdry, R.M.

1979-01-01

Previous studies of homogeneous hydrogen isotope exchange are mostly confined to one catalyst, the tetrachloroplatinite salt. Recent reports have indicated that chloride salts of iridium and rhodium may also be homogeneous exchange catalysts similar to the tetrachloroplatinite, but with much lower activities. Exchange by these homogeneous catalysts is frequently accompanied by metal precipitation with the termination of homogeneous exchange, particularly in the case of alkane exchange. The studies presented in this thesis describe two different approaches to overcome this limitation of homogeneous hydrogen isotope exchange catalysts. The first approach was to improve the stability of an existing homogeneous catalyst and the second was to develop a new homogeneous exchange catalyst which is free of the instability limitation

The asymmetric Schrock olefin metathesis catalysts. A computational study

NARCIS (Netherlands)

Goumans, T.P.M.; Ehlers, A.W.; Lammertsma, K.

2005-01-01

The mechanism of the transition metal catalyzed olefin metathesis reaction with the Schrock catalyst is investigated with pure (BP86) and hybrid (B3LYP) density functional theory. On the free-energy surface there is no adduct between ethylene and model catalyst (MeO)

Synthesis of 2-Substituted Benzofurans from o-Iodophenols and Terminal Alkynes with a Recyclable Palladium Catalyst Supported on Nano-sized Carbon Balls under Copper- and Ligand-Free Conditions

Energy Technology Data Exchange (ETDEWEB)

Yum, Eul Kgun; Yang, Okkyung; Kim, Jieun; Park, Hee Jank [Chungnam National Univ., Daejeon (Korea, Republic of)

2013-09-15

We have developed a one-step synthesis of benzofurans from o-iodophenol and various terminal alkynes, by using Pd catalyst supported on nano-sized carbon balls (NCB) under copper- and ligand free conditions. This recyclable catalyst could be reused more than 5 times in the same heteroannulation reaction. The results have demonstrated that diverse 2-substituted benzofurans with tolerant functional groups can be prepared simply and conveniently under these conditions.

Synthesis of 2-Substituted Benzofurans from o-Iodophenols and Terminal Alkynes with a Recyclable Palladium Catalyst Supported on Nano-sized Carbon Balls under Copper- and Ligand-Free Conditions

International Nuclear Information System (INIS)

Yum, Eul Kgun; Yang, Okkyung; Kim, Jieun; Park, Hee Jank

2013-01-01

We have developed a one-step synthesis of benzofurans from o-iodophenol and various terminal alkynes, by using Pd catalyst supported on nano-sized carbon balls (NCB) under copper- and ligand free conditions. This recyclable catalyst could be reused more than 5 times in the same heteroannulation reaction. The results have demonstrated that diverse 2-substituted benzofurans with tolerant functional groups can be prepared simply and conveniently under these conditions

Epoxidation catalyst and process

Science.gov (United States)

Linic, Suljo; Christopher, Phillip

2010-10-26

Disclosed herein is a catalytic method of converting alkenes to epoxides. This method generally includes reacting alkenes with oxygen in the presence of a specific silver catalyst under conditions suitable to produce a yield of the epoxides. The specific silver catalyst is a silver nanocrystal having a plurality of surface planes, a substantial portion of which is defined by Miller indices of (100). The reaction is performed by charging a suitable reactor with this silver catalyst and then feeding the reactants to the reactor under conditions to carry out the reaction. The reaction may be performed in batch, or as a continuous process that employs a recycle of any unreacted alkenes. The specific silver catalyst has unexpectedly high selectivity for epoxide products. Consequently, this general method (and its various embodiments) will result in extraordinarily high epoxide yields heretofore unattainable.

Co-catalyst free Titanate Nanorods for improved Hydrogen ...

Indian Academy of Sciences (India)

Herein, we report a simplified method for the preparation of photo-active titanate nanorods catalyst .... The TEM images were taken with Philips Technai G2 FEI F12 trans- mission electron microscope operating at 80-100 kV. Optical properties were measured in DRS ..... Chen X, Shen S, Guo L and Mao S S 2010 Chem. Rev ...

Graphene supported heterogeneous catalysts for Li–O{sub 2} batteries

Energy Technology Data Exchange (ETDEWEB)

Alaf, M., E-mail: mirac.alaf@bilecik.edu.tr [Bilecik Seyh Edebali University, Engineering Faculty, Department of Metallurgy and Materials Engineering, Gulumbe Campus, Bilecik 11210 (Turkey); Tocoglu, U.; Kartal, M.; Akbulut, H. [Sakarya University, Engineering Faculty, Department of Metallurgy and Materials Engineering, Esentepe Campus, Sakarya 54187 (Turkey)

2016-09-01

Graphical abstract: - Highlights: • Free-standing and flexible electrodes were prepared for Li–air batteries. • α-MnO{sub 2} nanorods, Pt nanoparticles and graphene were used. • α-MnO{sub 2} and Pt catalyst improved OER/ORR kinetics. - Abstract: In this study production and characterization of free-standing and flexible (i) graphene, (ii) α-MnO{sub 2}/graphene, (iii) Pt/graphene (iv) α-MnO{sub 2}/Pt/graphene composite cathodes for Li–air batteries were reported. Graphene supported heterogeneous catalysts were produced by a facile method. In order to prevent aggregation of graphene sheets and increase not only interlayer distance but also surface area, a trace amount multi-wall carbon nano tube (MWCNT) was introduced to the composite structure. The obtained composite catalysts were characterized by SEM, X-ray diffraction, N{sub 2} adsorption–desorption analyze and Raman spectroscopy. The electrochemical characterization tests including galvanostatic charge/discharge and electrochemical impedance spectroscopy (EIS) measurement of catalyst were carried out by using an ECC-Air test cell. These highly active graphene supported heterogeneous composite catalysts provide competitive properties relative to other catalyst materials for Li–air batteries.

Oxidation catalysts on alkaline earth supports

Science.gov (United States)

Mohajeri, Nahid

2017-03-21

An oxidation catalyst includes a support including particles of an alkaline earth salt, and first particles including a palladium compound on the support. The oxidation catalyst can also include precious metal group (PMG) metal particles in addition to the first particles intermixed together on the support. A gas permeable polymer that provides a continuous phase can completely encapsulate the particles and the support. The oxidation catalyst may be used as a gas sensor, where the first particles are chemochromic particles.

A Collision-Free G2 Continuous Path-Smoothing Algorithm Using Quadratic Polynomial Interpolation

Directory of Open Access Journals (Sweden)

Seong-Ryong Chang

2014-12-01

Full Text Available Most path-planning algorithms are used to obtain a collision-free path without considering continuity. On the other hand, a continuous path is needed for stable movement. In this paper, the searched path was converted into a G2 continuous path using the modified quadratic polynomial and membership function interpolation algorithm. It is simple, unique and provides a good geometric interpretation. In addition, a collision-checking and improvement algorithm is proposed. The collision-checking algorithm can check the collisions of a smoothed path. If collisions are detected, the collision improvement algorithm modifies the collision path to a collision-free path. The collision improvement algorithm uses a geometric method. This method uses the perpendicular line between a collision position and the collision piecewise linear path. The sub-waypoint is added, and the QPMI algorithm is applied again. As a result, the collision-smoothed path is converted into a collision-free smooth path without changing the continuity.

Application of Heterogeneous Copper Catalyst in a Continuous Flow Process: Dehydrogenation of Cyclohexanol

Science.gov (United States)

Glin´ski, Marek; Ulkowska, Urszula; Iwanek, Ewa

2016-01-01

In this laboratory experiment, the synthesis of a supported solid catalyst (Cu/SiO2) and its application in the dehydrogenation of cyclohexanol performed under flow conditions was studied. The experiment was planned for a group of two or three students for two 6 h long sessions. The copper catalyst was synthesized using incipient wetness…

Nano Fe{sub 2}O{sub 3,} clinoptilolite and H{sub 3}PW{sub 12}O{sub 40} as efficient catalysts for solvent-free synthesis of 5(4H)-isoxazolone under microwave irradiation conditions

Energy Technology Data Exchange (ETDEWEB)

Fozooni, Samieh, E-mail: samieh.fozooni@uk.ac.ir, E-mail: s_fozooni@yahoo.com [Shahid Bahonar University, Kerman (Iran, Islamic Republic of). Mining Engineering Department. Zarand High Education Center; Hosseinzadeh, Nasrin Gholam; Akhgar, Mohammad Reza [Islamic Azad University, Kerman (Iran, Islamic Republic of). Department of Chemistry; Hamidian, Hooshang [Payame Noor University (PNU), Tehran (Iran, Islamic Republic of). Department of Chemistry

2013-10-15

A quick and solvent-free approach involving the exposure of neat reactants to microwave irradiation in conjunction with the use of clinoptilolite, H{sub 3}PW{sub 12}O{sub 40} and Fe{sub 2}O{sub 3} nanoparticle catalysts is described. In this work, condensation of hydroxylamine hydrochloride, sodium acetate, acetoacetic or benzoyl acetic ethyl ester and appropriate aldehydes by employing catalysts gave 5(4H)-isoxazolone only in one step. Catalyst amount, temperature effects and catalysts reusability were monitored. Among the catalysts, Fe{sub 2}O{sub 3} nanoparticles had better performance than other catalysts from viewpoint of yield and reaction time. The present protocol offers several advantages, such as short reaction time, reasonable yield, mild reaction condition and recycling catalysts with a very easy workup. (author)

: Recyclable, ligand free palladium(II) catalyst for Heck reaction

Indian Academy of Sciences (India)

well as heterogeneous palladium catalysts, generated from either palladium(0) compounds or palladium(II) acetate or chloride salts.6 Several ligands such as phosphines, phoshites, carbenes, thioethers have been successfully employed for this reaction.7 However, homogeneous catalysis results in problems of recovery.

Coatings of active and heat-resistant cobalt-aluminium xerogel catalysts.

Science.gov (United States)

Schubert, Miriam; Schubert, Lennart; Thomé, Andreas; Kiewidt, Lars; Rosebrock, Christopher; Thöming, Jorg; Roessner, Frank; Bäumer, Marcus

2016-09-01

The application of catalytically coated metallic foams in catalytic processes has a high potential for exothermic catalytic reactions such as CO2 methanation or Fischer-Tropsch synthesis due to good heat conductivity, improved turbulent flow properties and high catalyst efficiencies. But the preparation of homogenous catalyst coats without pore blocking is challenging with conventional wash coating techniques. Here, we report on a stable and additive free colloidal CoAlOOH suspension (sol) for the preparation of catalytically active Co/Al2O3 xerogel catalysts and coatings. Powders with 18wt% Co3O4 prepared from this additive free synthesis route show a catalytic activity in Fischer-Tropsch synthesis and CO2 methanation which is similar to a catalyst prepared by incipient wetness impregnation (IWI) after activating the material under flowing hydrogen at 430°C. Yet, the xerogel catalyst exhibits a much higher thermal stability as compared to the IWI catalyst, as demonstrated in catalytic tests after different heat agings between 430°C and 580°C. It was also found that the addition of polyethylene glycol (PEG) to the sol influences the catalytic properties of the formed xerogels negatively. Only non-reducible cobalt spinels were formed from a CoAlOOH sol with 20wt% PEG. Metallic foams with pores sizes between 450 and 1200μm were coated with the additive free CoAlOOH sol, which resulted in homogenous xerogel layers. First catalytic tests of the coated metal foams (1200μm) showed good performance in CO2 methanation. Copyright © 2016 Elsevier Inc. All rights reserved.

B2O3/Al2O3 as a new, highly efficient and reusable heterogeneous catalyst for the selective synthesis of β-enamino ketones and esters under solvent-free conditions

International Nuclear Information System (INIS)

Chen, Jiu-Xi; Gao, Wen-Xia; Jin, Hui-Le; Ding, Jin-Chang; Wu, Hua-Yue

2010-01-01

Boron oxide adsorbed on alumina (B 2 O 3 /Al 2 O 3 ) has been found to be a new and highly efficient heterogeneous catalyst for the synthesis of β-enamino ketones and esters by the enamination of various primary and secondary amines with β-dicarbonyl compounds under solvent-free conditions. The important features of this methodology are broad substrate scope, high yield, no requirement of metal catalysts, high regio- and chemoselectivity and environmental friendliness. In addition, the catalyst could be recovered easily after the reactions and reused without evident loss of reactivity. (author)

Sulfated polyborate: A mild, efficient catalyst for synthesis of N-tert ...

Indian Academy of Sciences (India)

chemsci

trityl protected amides via Ritter reaction of nitriles with tertiary alcohols in the presence of a sulfated polyborate catalyst under solvent-free conditions is described. The catalyst has the advantage of Lewis as well as Bronsted acidity and.

Large-scale uniform ZnO tetrapods on catalyst free glass substrate by thermal evaporation method

Energy Technology Data Exchange (ETDEWEB)

Alsultany, Forat H., E-mail: foratusm@gmail.com [School of Physics, USM, 11800 Penang (Malaysia); Hassan, Z. [Institute of Nano-Optoelectronics Research and Technology Laboratory (INOR), USM, 11800 Penang (Malaysia); Ahmed, Naser M. [School of Physics, USM, 11800 Penang (Malaysia)

2016-07-15

Highlights: • Investigate the growth of ZnO-Ts on glass substrate by thermal evaporation method. • Glass substrate without any catalyst or a seed layer. • The morphology was controlled by adjusting the temperature of the material and the substrate. • Glass substrate was placed vertically in the quartz tube. - Abstract: Here, we report for the first time the catalyst-free growth of large-scale uniform shape and size ZnO tetrapods on a glass substrate via thermal evaporation method. Three-dimensional networks of ZnO tetrapods have needle–wire junctions, an average leg length of 2.1–2.6 μm, and a diameter of 35–240 nm. The morphology and structure of ZnO tetrapods were investigated by controlling the preparation temperature of each of the Zn powder and the glass substrate under O{sub 2} and Ar gases. Studies were carried out on ZnO tetrapods using X-ray diffraction, field emission scanning electron microscopy, UV–vis spectrophotometer, and a photoluminescence. The results showed that the sample grow in the hexagonal wurtzite structure with preferentially oriented along (002) direction, good crystallinity and high transmittance. The band gap value is about 3.27 eV. Photoluminescence spectrum exhibits a very sharp peak at 378 nm and a weak broad green emission.

Alum an Efficient Catalyst for Erlenmeyer Synthesis

African Journals Online (AJOL)

NICO

this paper we describe the use of alum as a catalyst in the. Erlenmeyer reaction, under solvent-free condition using ultra- sonic irradiation. The application of solvent-free reaction conditions in organic chemistry has been explored extensively within the last decade. It was shown to be an efficient technique for various organic.

Theoretical Study on Free Fatty Acid Elimination Mechanism for Waste Cooking Oils to Biodiesel over Acid Catalyst.

Science.gov (United States)

Wang, Kai; Zhang, Xiaochao; Zhang, Jilong; Zhang, Zhiqiang; Fan, Caimei; Han, Peide

2016-05-01

A theoretical investigation on the esterification mechanism of free fatty acid (FFA) in waste cooking oils (WCOs) has been carried out using DMol(3) module based on the density functional theory (DFT). Three potential pathways of FFA esterification reaction are designed to achieve the formation of fatty acid methyl ester (FAME), and calculated results show that the energy barrier can be efficiently reduced from 88.597kcal/mol to 15.318kcal/mol by acid catalyst. The molar enthalpy changes (ΔrHm°) of designed pathways are negative, indicating that FFA esterification reaction is an exothermic process. The obtained favorable energy pathway is: H(+) firstly activates FFA, then the intermediate combines with methanol to form a tetrahedral structure, and finally, producing FAME after removing a water molecule. The rate-determining step is the combination of the activated FFA with methanol, and the activation energy is about 11.513kcal/mol at 298.15K. Our results should provide basic and reliable theoretical data for further understanding the elimination mechanism of FFA over acid catalyst in the conversion of WCOs to biodiesel products. Copyright © 2016 Elsevier Inc. All rights reserved.

Catalysts for conversion of syngas to liquid motor fuels

Science.gov (United States)

Rabo, Jule A.; Coughlin, Peter K.

1987-01-01

Synthesis gas comprising carbon monoxide and hydrogen is converted to C.sub.5.sup.+ hydrocarbons suitable for use as liquid motor fuels by contact with a dual catalyst composition capable of ensuring the production of only relatively minor amounts of heavy products boiling beyond the diesel oil range. The catalyst composition, having desirable stability during continuous production operation, employs a Fischer-Tropsch catalyst, together with a co-catalyst/support component. The latter component is a steam-stabilized zeolite Y catalyst of hydrophobic character, desirably in acid-extracted form.

Silica nanoparticles as a highly efficient catalyst for the one-pot ...

African Journals Online (AJOL)

Silica nanoparticles as a highly efficient catalyst for the one-pot synthesis of sterically congested ... Bulletin of the Chemical Society of Ethiopia ... 42 nm) as a catalyst under solvent free conditions at room temperature is described. The ease of ...

Extended Catalyst Longevity Via Supercritical Isobutane Regeneration of a Partially Deactivated USY Alkylation Catalyst

Energy Technology Data Exchange (ETDEWEB)

Daniel M. Ginosar; David N. Thompson; Kyle C. Burch; David J. Zalewski

2005-05-01

Off-line, in situ activity recovery of a partially deactivated USY zeolite catalyst used for isobutane/butene alkylation was examined in a continuous-flow reaction system employing supercritical isobutane. Catalyst samples were deactivated in a controlled manner by running them to either to a fixed butene conversion level of 95% or a fixed time on stream of three hours, and then exposing the catalyst to supercritical isobutane to restore activity. Activity recovery was determined by comparing alkylation activity before and after the regeneration step. Both single and multiple regenerations were performed. Use of a 95% butene conversion level criterion to terminate the reaction step afforded 86% activity recovery for a single regeneration and provided nine sequential reaction steps for the multiple regeneration studies. Employing a fixed 3 h time on stream criterion resulted in nearly complete activity recovery for a single regeneration, and 24 reaction steps were demonstrated in sequence for the multiple regeneration process, producing only minor product yield declines per step. This resulted in a 12-fold increase in catalyst longevity versus unregenerated catalyst.

In-situ Electrodeposition of Highly Active Silver Catalyst on Carbon Fiber Papers as Binder Free Cathodes for Aluminum-air Battery

OpenAIRE

Hong, Qingshui; Lu, Huimin

2017-01-01

Carbon fiber papers supported Ag catalysts (Ag/CFP) with different coverage of electro-active site are prepared by electrochemical deposition and used as binder free cathodes in primary aluminum-air (Al-air) battery. Scanning Electron Microscopy and X-ray Diffraction studies are carried out to characterize the as-prepared Ag/CFP air cathodes. Oxygen reduction reaction (ORR) activities on these air cathodes in alkaline solutions are systematic studied. A newly designed aluminum-air cell is use...

L^p-continuity of solutions to parabolic free boundary problems

Directory of Open Access Journals (Sweden)

Abdeslem Lyaghfouri

2015-07-01

Full Text Available In this article, we consider a class of parabolic free boundary problems. We establish some properties of the solutions, including L^infinity-regularity in time and a monotonicity property, from which we deduce strong L^p-continuity in time.

Using Pd-salen complex as an efficient catalyst for the copper- and solvent-free coupling of acyl chlorides with terminal alkynes under aerobic conditions

Institute of Scientific and Technical Information of China (English)

Mohammad

2010-01-01

The palladium-salen complex palladium(Ⅱ) N,N'-bis{[5-(triphenylphosphonium)-methyl]salicylidene}-l,2-ethanediamine chloride was found to be a highly active catalyst for the copper- and solvent-free coupling reaction of terminal alkynes with different acyl chlorides in the presence of triethylamine as base, giving excellent ynones under aerobic conditions.

A green synthetic approach toward the synthesis of structurally diverse spirooxindole derivative libraries under catalyst-free conditions.

Science.gov (United States)

Kausar, Nazia; Masum, Abdulla Al; Islam, Md Maidul; Das, Asish R

2017-05-01

A catalyst-free green methodology for the synthesis of pharmacologically important spirooxindole derivatives has been developed by a three-component domino reaction between isatin, various amino compounds, and 1,3-dicarbonyl or 3-phenylisoxazolone compounds in ethyl L-lactate medium at room temperature. This new efficient synthetic method facilitated the formation of a wide range of biologically significant spirooxindole derivatives (including 17 new spirooxindoles) under very mild conditions. The cytotoxic activity of one of the isoxazole-fused spirooxindoles was evaluated in MDA-MB 468 breast cancer cell line. It was found that cell survivability decreases with increasing concentration of the selected compound in MDA-MB 468 breast cancer cells.

Hybrid Pd/Fe{sub 3}O{sub 4} nanowires: Fabrication, characterization, optical properties and application as magnetically reusable catalyst for the synthesis of N-monosubstituted ureas under ligand-free conditions

Energy Technology Data Exchange (ETDEWEB)

Nasrollahzadeh, Mahmoud, E-mail: mahmoudnasr81@gmail.com [Department of Chemistry, Faculty of Science, University of Qom, Qom 37185-359 (Iran, Islamic Republic of); Azarian, Abbas [Department of Physics, University of Qom, Qom (Iran, Islamic Republic of); Ehsani, Ali [Department of Chemistry, Faculty of Science, University of Qom, Qom 37185-359 (Iran, Islamic Republic of); Sajadi, S.Mohammad [Department of Petroleum Geoscience, Faculty of Science, Soran University, PO Box 624, Soran, Kurdistan Regional Government (Iraq); Babaei, Ferydon [Department of Physics, University of Qom, Qom (Iran, Islamic Republic of)

2014-07-01

Highlights: • Preparation of Pd/Fe{sub 3}O{sub 4} nanowires as magnetically reusable catalysts. • The optical properties of the catalyst were studied using Gans theory. • N-arylation of benzylurea and in situ hydrogenolysis of 1-benzyl-3-arylureas. - Abstract: This paper reports the synthesis and use of Pd/Fe{sub 3}O{sub 4} nanowires, as magnetically separable catalysts for ligand-free amidation coupling reactions of aryl halides with benzylurea under microwave irradiation. Then, the in situ hydrogenolysis of the products was performed to afford the N-monosubstituted ureas from good to excellent yields. This method has the advantages of high yields, simple methodology and easy work up. The catalyst can be recovered by using a magnet and reused several times without significant loss of its catalytic activity. The catalyst was characterized using the powder XRD, SEM, EDS and UV–vis spectroscopy. Experimental absorbance spectra was compared with results from the Gans theory.

In-situ Electrodeposition of Highly Active Silver Catalyst on Carbon Fiber Papers as Binder Free Cathodes for Aluminum-air Battery.

Science.gov (United States)

Hong, Qingshui; Lu, Huimin

2017-06-13

Carbon fiber papers supported Ag catalysts (Ag/CFP) with different coverage of electro-active site are prepared by electrochemical deposition and used as binder free cathodes in primary aluminum-air (Al-air) battery. Scanning Electron Microscopy and X-ray Diffraction studies are carried out to characterize the as-prepared Ag/CFP air cathodes. Oxygen reduction reaction (ORR) activities on these air cathodes in alkaline solutions are systematic studied. A newly designed aluminum-air cell is used to further determine the cathodes performance under real operation condition and during the test, the Ag/CFP electrodes show outstanding catalytic activity for ORR in concentrated alkaline electrolyte, and no obvious activity degradation is observed after long-time discharge. The electrochemical test results display the dependence of coverage of the electro-active Ag on the catalytic performance of the air cathodes. The resulting primary Al-air battery made from the best-performing cathode shows an impressive discharge peak power density, outperforming that of using commercial nano-manganese catalyst air electrodes.

Continuous-flow hydration–condensation reaction: Synthesis of α,β-unsaturated ketones from alkynes and aldehydes by using a heterogeneous solid acid catalyst

Directory of Open Access Journals (Sweden)

Magnus Rueping

2011-12-01

Full Text Available A simple, practical and efficient continuous-flow hydration–condensation protocol was developed for the synthesis of α,β-unsaturated ketones starting from alkynes and aldehydes by employing a heterogeneous catalyst in a flow microwave. The procedure presents a straightforward and convenient access to valuable differently substituted chalcones and can be applied on multigram scale.

Process for the regeneration of metallic catalysts

Science.gov (United States)

Katzer, James R.; Windawi, Hassan

1981-01-01

A method for the regeneration of metallic hydrogenation catalysts from the class consisting of Ni, Rh, Pd, Ir, Pt and Ru poisoned with sulfur, with or without accompanying carbon deposition, comprising subjecting the catalyst to exposure to oxygen gas in a concentration of about 1-10 ppm. intermixed with an inert gas of the group consisting of He, A, Xe, Kr, N.sub.2 and air substantially free of oxygen to an extent such that the total oxygen molecule throughout is in the range of about 10 to 20 times that of the hydrogen sulfide molecular exposure producing the catalyst poisoning while maintaining the temperature in the range of about 300.degree. to 500.degree. C.

Supported chromium-molybdenum and tungsten sulfide catalysts

International Nuclear Information System (INIS)

Chianelli, R.R.; Jacobson, A.J.; Young, A.R.

1988-01-01

This patent describes the process for preparing a supported hydroprocessing catalyst. The process comprising compositing a quantity of a particulate, porous catalyst support material comprising one or more refactory oxides with one or more catalyst precursor salts and heating the composite at elevated temperature of at least about 200/sup 0/C up to about 600/sup 0/, in the presence of a sulfur-bearing compound in an amount whereby sulfur in the form of the sulfur-bearing compound in an amount whereby sulfur in the form of the sulfur bearing compound is present in excess of that contained in the catalyst precursor and under oxygen-free conditions for a time sufficient to form the catalyst. The catalyst precursor salt contains a tetrathiometallate anion of Mo, W or mixture therof and a cation comprising trivalent chromium or a mixture of trivalent chromium with one or more divalent promoter metals selected from the group consisting of Fe, Ni, Co, Mn, Cu and a mixture thereof wherein the trivalent chromium and divalent promoter metals are chelated by at least one neutral, nitrogen-containing polydentate ligand, L

Facile, eco-friendly, catalyst-free synthesis of polyfunctionalized quinoxalines.

Science.gov (United States)

Zhang, Yaohong; Luo, Mengqiang; Li, Yan; Wang, Hai; Ren, Xiaorong; Qi, Chenze

2018-02-01

A novel, facile and eco-friendly synthesis of quinoxalines from [Formula: see text] and 1,2-diamines was developed. An attractive feature of this protocol is that the desired products could be generated efficiently in water and without any catalyst, which is in accordance with the aim of green chemistry. A plausible mechanism has been proposed.

Phosphorene Co-catalyst Advancing Highly Efficient Visible-Light Photocatalytic Hydrogen Production.

Science.gov (United States)

Ran, Jingrun; Zhu, Bicheng; Qiao, Shi-Zhang

2017-08-21

Transitional metals are widely used as co-catalysts boosting photocatalytic H 2 production. However, metal-based co-catalysts suffer from high cost, limited abundance and detrimental environment impact. To date, metal-free co-catalyst is rarely reported. Here we for the first time utilized density functional calculations to guide the application of phosphorene as a high-efficiency metal-free co-catalyst for CdS, Zn 0.8 Cd 0.2 S or ZnS. Particularly, phosphorene modified CdS shows a high apparent quantum yield of 34.7 % at 420 nm. This outstanding activity arises from the strong electronic coupling between phosphorene and CdS, as well as the favorable band structure, high charge mobility and massive active sites of phosphorene, supported by computations and advanced characterizations, for example, synchrotron-based X-ray absorption near edge spectroscopy. This work brings new opportunities to prepare highly-active, cheap and green photocatalysts. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Temperature dependence of stacking faults in catalyst-free GaAs nanopillars.

Science.gov (United States)

Shapiro, Joshua N; Lin, Andrew; Ratsch, Christian; Huffaker, D L

2013-11-29

Impressive opto-electronic devices and transistors have recently been fabricated from GaAs nanopillars grown by catalyst-free selective-area epitaxy, but this growth technique has always resulted in high densities of stacking faults. A stacking fault occurs when atoms on the growing (111) surface occupy the sites of a hexagonal-close-pack (hcp) lattice instead of the normal face-centered-cubic (fcc) lattice sites. When stacking faults occur consecutively, the crystal structure is locally wurtzite instead of zinc-blende, and the resulting band offsets are known to negatively impact device performance. Here we present experimental and theoretical evidence that indicate stacking fault formation is related to the size of the critical nucleus, which is temperature dependent. The difference in energy between the hcp and fcc orientation of small nuclei is computed using density-function theory. The minimum energy difference of 0.22 eV is calculated for a nucleus with 21 atoms, so the population of nuclei in the hcp orientation is expected to decrease as the nucleus grows larger. The experiment shows that stacking fault occurrence is dramatically reduced from 22% to 3% by raising the growth temperature from 730 to 790 ° C. These data are interpreted using classical nucleation theory which dictates a larger critical nucleus at higher growth temperature.

Flexible, highly graphitized carbon aerogels based on bacterial cellulose/lignin: Catalyst-free synthesis and its application in energy storage devices

KAUST Repository

Xu, Xuezhu

2015-04-15

Currently, most carbon aerogels are based on carbon nanotubes (CNTs) or graphene, which are produced through a catalyst-assisted chemical vapor deposition method. Biomass based organic aerogels and carbon aerogels, featuring low cost, high scalability, and small environmental footprint, represent an important new research direction in (carbon) aerogel development. Cellulose and lignin are the two most abundant natural polymers in the world, and the aerogels based on them are very promising. Classic silicon aerogels and available organic resorcinol-formaldehyde (RF) or lignin-resorcinol-formaldehyde (LRF) aerogels are brittle and fragile; toughening of the aerogels is highly desired to expand their applications. This study reports the first attempt to toughen the intrinsically brittle LRF aerogel and carbon aerogel using bacterial cellulose. The facile process is catalyst-free and cost-effective. The toughened carbon aerogels, consisting of blackberry-like, core-shell structured, and highly graphitized carbon nanofibers, are able to undergo at least 20% reversible compressive deformation. Due to their unique nanostructure and large mesopore population, the carbon materials exhibit an areal capacitance higher than most of the reported values in the literature. This property makes them suitable candidates for flexible solid-state energy storage devices. Besides energy storage, the conductive interconnected nanoporous structure can also find applications in oil/water separation, catalyst supports, sensors, and so forth. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Catalyst free growth of ZnO nanowires on graphene and graphene oxide and its enhanced photoluminescence and photoresponse

International Nuclear Information System (INIS)

Biroju, Ravi K; Giri, P K; Tilak, Nikhil; Rajender, Gone; Dhara, S

2015-01-01

We demonstrate the graphene assisted catalyst free growth of ZnO nanowires (NWs) on chemical vapor deposited (CVD) and chemically processed graphene buffer layers at a relatively low growth temperature (580 °C) in the presence and absence of ZnO seed layers. In the case of CVD graphene covered with rapid thermal annealed ZnO buffer layer, the growth of vertically aligned ZnO NWs takes place, while the direct growth on CVD graphene, chemically derived graphene (graphene oxide and graphene quantum dots) without ZnO seed layer resulted in randomly oriented sparse ZnO NWs. Growth mechanism was studied from high resolution transmission electron microscopy and Raman spectroscopy of the hybrid structure. Further, we demonstrate strong UV, visible photoluminescence (PL) and enhanced photoconductivity (PC) from the CVD graphene–ZnO NWs hybrids as compared to the ZnO NWs grown without the graphene buffer layer. The evolution of crystalinity in ZnO NWs grown with ZnO seed layer and graphene buffer layer is correlated with the Gaussian line shape of UV and visible PL. This is further supported by the strong Raman mode at 438 cm −1 significant for the wurtzite phase of the ZnO NWs grown on different graphene substrates. The effect of the thickness of ZnO seed layers and the role of graphene buffer layers on the aligned growth of ZnO NWs and its enhanced PC are investigated systematically. Our results demonstrate the catalyst free growth and superior performance of graphene–ZnO NW hybrid UV photodetectors as compared to the bare ZnO NW based photodetectors. (paper)

Theoretical modeling of structure and function of cathode catalyst layers in PEMFC

International Nuclear Information System (INIS)

Wang, Q.; Eikerling, M.; Song, D.; Liu, Z.

2004-01-01

'Full text:' In this work, we first investigate transport and reaction kinetics in single agglomerates of cathode catalyst layers in proton exchange fuel cells. Two types of spherical agglomerates are evaluated, which represent limiting structures that can be obtained by distinct synthetic procedures. One type consists of a mixture of carbon/catalyst particles and proton conducting perfluorosulfonated ionomer (PFSI). The other type consists of carbon/catalyst particles and water-filled pores. Performance of the former type is rationalized on the basis of the well-known Thiele-modulus. Characteristics of the latter type are studied using Nernst-Planck and Poisson equations. Aspects of current conversion, reactant and current distributions, and catalyst utilization are explored. In general, the PFSI-filled agglomerates exhibit more homogeneous distributions of reaction rates. Effectiveness factors for them are close to one. However, it was found that proton penetration depths in waterflooded agglomerates could be quite significant as well under certain conditions, resulting in unexpectedly high catalyst utilization. The effects of agglomerate radius and of boundary conditions at the agglomerate surface are studied. Moreover, using the same approach, we evaluate the performance of a flat PFSI-free catalyst layer with water-filled pore space. Compared with conventional composite catalyst layers impregnated with PFSI, the PFSI-free layer exhibits better performance and high Pt utilization for thicknesses less than 0.1 μm. The significance of these results for the optimization catalyst layers in view of operation conditions and synthesis methods is discussed. (author)

Microwave assisted esterification of free fatty acid over a heterogeneous catalyst for biodiesel production

International Nuclear Information System (INIS)

Liu, Wei; Yin, Ping; Liu, Xiguang; Chen, Wen; Chen, Hou; Liu, Chunping; Qu, Rongjun; Xu, Qiang

2013-01-01

Highlights: • Microwave assisted esterification of stearic acid with ethanol was catalyzed by D418. • D418 exhibited remarkable catalytic performance for ethyl stearate formation. • It proved possible to prepare biodiesel rapidly and with good conversions by microwave heating. • The relative catalytic kinetics study has been conducted and modeled. - Abstract: Biodiesel fuel is gaining significant attention in recent years because of its environmental benefits and the growing interest in finding new resources and alternatives for conventional fuels. Biodiesel production from waste cooking oil with high free fatty acids usually requires esterification step to produce fatty acid methyl/ethyl ester. In the present work, the heterogeneous catalyst aminophosphonic acid resin D418 has been successfully utilized in the energy-efficient microwave-assisted esterification reaction of fatty acid ethyl ester (FAEE) from free fatty acid (FFA) stearic acid with short-chain alcohol ethanol. Under the reaction conditions of 9 wt% D418 and 11: 1 M ratio of ethanol to stearic acid at 353 K and atmospheric pressure, more than 90% conversion of the esterification was achieved in 7 h by microwave heating, while it took about 12 h by conventional heating. Moreover, the kinetics of this esterification reaction has been studied, and the relevant values of activation energy and pre-exponential factor were obtained

The Role of Mg(OH)2 in the So-Called "Base-Free" Oxidation of Glycerol with AuPd Catalysts.

Science.gov (United States)

Fu, Jile; He, Qian; Miedziak, Peter J; Brett, Gemma L; Huang, Xiaoyang; Pattisson, Samuel; Douthwaite, Mark; Hutchings, Graham J

2018-02-16

Mg(OH) 2 - and Mg(OH) 2 -containing materials can provide excellent performance as supports for AuPd nanoparticles for the oxidation of glycerol in the absence of base, which is considered to be a result of additional basic sites on the surface of the support. However, its influence on the reaction solution is not generally discussed. In this paper, we examine the relationship between the basic Mg(OH) 2 support and AuPd nanoparticles in detail using four types of catalyst. For these reactions, the physical interaction between Mg(OH) 2 and AuPd was adjusted. It was found that the activity of the AuPd nanoparticles increased with the amount of Mg(OH) 2 added under base-free conditions, regardless of its interaction with the noble metals. In order to investigate how Mg(OH) 2 affected the glycerol oxidation, detailed information about the performance of AuPd/Mg(OH) 2 , physically mixed (AuPd/C+Mg(OH) 2 ) and (AuPd/C+NaHCO 3 ) was obtained and compared. Furthermore, NaOH and Mg(OH) 2 were added during the reaction using AuPd/C. All these results indicate that the distinctive and outstanding performance of Mg(OH) 2 supported catalysts in base-free condition is in fact directly related to its ability to affect the pH during the reaction and as such, assists with the initial activation of the primary alcohol, which is considered to be the rate determining step in the reaction. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Propene Hydroformylation by Supported Aqueous-phase Rh-NORBOS Catalysts

DEFF Research Database (Denmark)

Riisager, Anders; Eriksen, Kim Michael; Hjortkjær, Jes

2003-01-01

The gas-phase hydroformylation reaction of propene using supported aqueous-phase (SAP) Rh-NORBOS modified catalysts in a continuous flow reactor has been examined. SAP catalysts supported on six different support materials were made by wet impregnation using solutions of the precursor complex Rh(...

Continuous-Flow O-Alkylation of Biobased Derivatives with Dialkyl Carbonates in the Presence of Magnesium-Aluminium Hydrotalcites as Catalyst Precursors.

Science.gov (United States)

Cattelan, Lisa; Perosa, Alvise; Riello, Piero; Maschmeyer, Thomas; Selva, Maurizio

2017-04-10

The base-catalysed reactions of OH-bearing biobased derivatives (BBDs) including glycerol formal, solketal, glycerol carbonate, furfuryl alcohol and tetrahydrofurfuryl alcohol with non-toxic dialkyl carbonates (dimethyl and diethyl carbonate) were explored under continuous-flow (CF) conditions in the presence of three Na-exchanged Y- and X-faujasites (FAUs) and four Mg-Al hydrotalcites (HTs). Compared to previous etherification protocols mediated by dialkyl carbonates, the reported procedure offers substantial improvements not only in terms of (chemo)selectivity but also for the recyclability of the catalysts, workup, ease of product purification and, importantly, process intensification. Characterisation studies proved that both HT30 and KW2000 hydrotalcites acted as catalyst precursors: during the thermal activation pre-treatments, the typical lamellar structure of the hydrotalcite was broken down gradually into a MgO-like phase (periclase) or rather a magnesia-alumina solid solution, which was the genuine catalytic phase. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Sulfated polyborate: A mild, efficient catalyst for synthesis of N-tert ...

Indian Academy of Sciences (India)

Rapid, efficient and inexpensive method for synthesis of N-tert-butyl/N-trityl protected amides via Ritter reaction of nitriles with tertiary alcohols in the presence of a sulfated polyborate catalyst under solvent-free conditions is described. The catalyst has the advantage of Lewis as well as Bronsted acidity and recyclability ...

Preparation of biodiesel from soybean oil by using heterogeneous catalyst

Energy Technology Data Exchange (ETDEWEB)

Ferdous, Kaniz; Rakib Uddin, M.; Islam, M.A. [Department of Chemical Engineering and Polymer Science, Shah Jalal University of Science and Technology, Sylhet 3114 (Bangladesh); Khan, Maksudur R. [Department of Chemical Engineering and Polymer Science, Shah Jalal University of Science and Technology, Sylhet 3114 (Bangladesh); Faculty of Chemical and Natural Resources Engineering, University Malaysia Pahang, 26300 Gambang, Kuantan, Pahang (Malaysia)

2013-07-01

The predicted shortage of fossil fuels and related environmental concerns has recently attracted significant attention to search alternative fuel. Biodiesel is one of the alternatives to fossil fuel. Now-a-days, most biodiesel is produced by the transesterification of oils using methanol and a homogeneous base catalyst. The use of homogeneous catalysts is normally limited to batch mode processing followed by a catalyst separation step. The immiscible glycerol phase, which accumulates during the course of the reaction, solubilizes the homogeneous base catalyst and therefore, withdraws from the reaction medium. Moreover, other difficulties of using homogeneous base catalysts relate to their sensitivity to free fatty acid (FFA) and water and resulting saponification phenomenon. High energy consumption and costly separation of the catalyst from the reaction mixture have inspired the use of heterogeneous catalyst. The use of heterogeneous catalysts does not lead to the formation of soaps through neutralization of FFA and saponification of oil. In the present paper, biodiesel was prepared from crude (soybean) oil by transesterification reaction using heterogeneous base catalyst name calcium oxide (CaO). Various reaction parameters were optimized and the biodiesel properties were evaluated.

Morphology Engineering of Co3O4 Nanoarrays as Free-Standing Catalysts for Lithium-Oxygen Batteries.

Science.gov (United States)

He, Mu; Zhang, Peng; Xu, Shan; Yan, Xingbin

2016-09-14

The effective shape-controlled synthesis of Co3O4 nanoarrays on nickel foam substrates has been achieved through a simple hydrothermal strategy. When they served as the binder- and conductive-agent-free porous cathodes for nonaqueous Li-O2 batteries, they sufficiently reflect the favorable catalytic characteristic of Co3O4 and alleviate the problems of serious pore blocking and surface passivation caused by insoluble and insulating discharge products. In particular, Co3O4 rectangular nanosheets exhibit superior electrocatalytic performance comparing with Co3O4 nanowires and hexagonal nanosheets, leading to higher specific capacity and better cycling stability over 54 cycles at 100 mA g(-1), which relate to their good pore structure, large specific surface area, and highly active {112} exposed plane, effectively promoting the mass transport and reversible formation and decomposition of discharge products in the cathode. These comparisons further indicate the morphology effect of nanostructured Co3O4 on their performances as free-standing catalysts for Li-O2 batteries, which also have been proved through the further analysis of discharge products on different shapes of Co3O4 nanoarrays electrodes.

Robust Chemiresistive Sensor for Continuous Monitoring of Free Chlorine Using Graphene-like Carbon.

Science.gov (United States)

Aryasomayajula, Aditya; Wojnas, Caroline; Divigalpitiya, Ranjith; Selvaganapathy, Ponnambalam Ravi; Kruse, Peter

2018-02-23

Free chlorine is widely used in industry as a bleaching and oxidizing agent. Its concentration is tightly monitored to avoid environmental contamination and deleterious human health effects. Here, we demonstrate a solid state chemiresistive sensor using graphene like carbon (GLC) to detect free chlorine in water. A 15-20 nm thick GLC layer on a PET substrate was modified with a redox-active aniline oligomer (phenyl-capped aniline tetramer, PCAT) to increase sensitivity, improve selectivity, and impart fouling resistance. Both the bare GLC sensor and the PCAT-modified GLC sensor can detect free chlorine continuously and, unlike previous chemiresistive sensors, do not require a reset. The PCAT-modified sensor showed a linear response with a slope of 13.89 (mg/L) -1 to free chlorine concentrations between 0.2 and 0.8 mg/L which is relevant for free chlorine monitoring for drinking water and wastewater applications. The PCAT-modified GLC sensors were found to be selective and showed less than 0.5% change in current in response to species such as nitrates, phosphates and sulfates in water. They also were resistant to fouling from organic material and showed only a 2% loss in signal. Tap water samples from residential area were tested using this sensor which showed good agreement with standard colorimetric measurement methods. The GLC and PCAT-GLC sensors show high sensitivity and excellent selectivity to free chlorine and can be used for continuous automated monitoring of free chlorine.

A novel continuous process for synthesis of carbon nanotubes using iron floating catalyst and MgO particles for CVD of methane in a fluidized bed reactor

Energy Technology Data Exchange (ETDEWEB)

Maghsoodi, Sarah; Khodadadi, Abasali [Catalysis and Nanostructured Materials Research Laboratory, School of Chemical Engineering, University of Tehran, Tehran (Iran, Islamic Republic of); Mortazavi, Yadollah, E-mail: mortazav@ut.ac.ir [Nanoelectronics Centre of Excellence, University of Tehran, POB 11365-4563, Tehran (Iran, Islamic Republic of)

2010-02-15

A novel continuous process is used for production of carbon nanotubes (CNTs) by catalytic chemical vapor deposition (CVD) of methane on iron floating catalyst in situ deposited on MgO in a fluidized bed reactor. In the hot zone of the reactor, sublimed ferrocene vapors were contacted with MgO powder fluidized by methane feed to produce Fe/MgO catalyst in situ. An annular tube was used to enhance the ferrocene and MgO contacting efficiency. Multi-wall as well as single-wall CNTs was grown on the Fe/MgO catalyst while falling down the reactor. The CNTs were continuously collected at the bottom of the reactor, only when MgO powder was used. The annular tube enhanced the contacting efficiency and improved both the quality and quantity of CNTs. The SEM and TEM micrographs of the products reveal that the CNTs are mostly entangled bundles with diameters of about 10-20 nm. Raman spectra show that the CNTs have low amount of amorphous/defected carbon with I{sub G}/I{sub D} ratios as high as 10.2 for synthesis at 900 deg. C. The RBM Raman peaks indicate formation of single-walled carbon nanotubes (SWNTs) of 1.0-1.2 nm diameter.

The Dependence of CNT Aerogel Synthesis on Sulfur-driven Catalyst Nucleation Processes and a Critical Catalyst Particle Mass Concentration.

Science.gov (United States)

Hoecker, Christian; Smail, Fiona; Pick, Martin; Weller, Lee; Boies, Adam M

2017-11-06

The floating catalyst chemical vapor deposition (FC-CVD) process permits macro-scale assembly of nanoscale materials, enabling continuous production of carbon nanotube (CNT) aerogels. Despite the intensive research in the field, fundamental uncertainties remain regarding how catalyst particle dynamics within the system influence the CNT aerogel formation, thus limiting effective scale-up. While aerogel formation in FC-CVD reactors requires a catalyst (typically iron, Fe) and a promotor (typically sulfur, S), their synergistic roles are not fully understood. This paper presents a paradigm shift in the understanding of the role of S in the process with new experimental studies identifying that S lowers the nucleation barrier of the catalyst nanoparticles. Furthermore, CNT aerogel formation requires a critical threshold of Fe x C y  > 160 mg/m 3 , but is surprisingly independent of the initial catalyst diameter or number concentration. The robustness of the critical catalyst mass concentration principle is proved further by producing CNTs using alternative catalyst systems; Fe nanoparticles from a plasma spark generator and cobaltocene and nickelocene precursors. This finding provides evidence that low-cost and high throughput CNT aerogel routes may be achieved by decoupled and enhanced catalyst production and control, opening up new possibilities for large-scale CNT synthesis.

Ni Catalysts Supported on Modified Alumina for Diesel Steam Reforming

Directory of Open Access Journals (Sweden)

Antonios Tribalis

2016-01-01

Full Text Available Nickel catalysts are the most popular for steam reforming, however, they have a number of drawbacks, such as high propensity toward coke formation and intolerance to sulfur. In an effort to improve their behavior, a series of Ni-catalysts supported on pure and La-, Ba-, (La+Ba- and Ce-doped γ-alumina has been prepared. The doped supports and the catalysts have been extensively characterized. The catalysts performance was evaluated for steam reforming of n-hexadecane pure or doped with dibenzothiophene as surrogate for sulphur-free or commercial diesel, respectively. The undoped catalyst lost its activity after 1.5 h on stream. Doping of the support with La improved the initial catalyst activity. However, this catalyst was completely deactivated after 2 h on stream. Doping with Ba or La+Ba improved the stability of the catalysts. This improvement is attributed to the increase of the dispersion of the nickel phase, the decrease of the support acidity and the increase of Ni-phase reducibility. The best catalyst of the series doped with La+Ba proved to be sulphur tolerant and stable for more than 160 h on stream. Doping of the support with Ce also improved the catalytic performance of the corresponding catalyst, but more work is needed to explain this behavior.

TEM characterization of catalyst- and mask-free grown GaN nanorods

International Nuclear Information System (INIS)

Schowalter, M; Aschenbrenner, T; Kruse, C; Hommel, D; Rosenauer, A

2010-01-01

Catalyst- and mask-free grown GaN nanorods have been investigated using transmission electron microscopy (TEM), scanning transmission electron microscopy (STEM) and energy filtered transmission electron microscopy (EFTEM). The nanorods were grown on nitridated r-plane sapphire substrates in a molecular beam epitaxy reactor. We investigated samples directly after the nitridation and after the overgrowth of the structure with GaN. High resolution transmission electron microscopy (HRTEM) and EFTEM revealed that AlN islands have formed due to nitridation. After overgrowth, the AlN islands could not be observed any more, neither by EFTEM nor by Z-contrast imaging. Instead, a smooth layer consisting of AlGaN was found. The investigation of the overgrown sample revealed that an a-plane GaN layer and GaN nanorods on top of the a-plane GaN have formed. The nanorods reduced from top of the a-plane GaN towards the a-plane GaN/sapphire interface suggesting that the nanorods originate at the AlN islands found after nitridation. However, this could not be shown unambiguously. The number of threading dislocations in the nanorods was very low. The analysis of the epitaxial relationship to the a-plane GaN showed that the nanorods grew along the [000-1] direction, and the [1-100] direction of the rods was parallel to the [0001] direction of the a-plane GaN.

One-pot synthesis of linear- and three-arm star-tetrablock quarterpolymers via sequential metal-free ring-opening polymerization using a "catalyst switch" strategy

KAUST Repository

Zhao, Junpeng; Pahovnik, David; Gnanou, Yves; Hadjichristidis, Nikolaos

2014-01-01

A "catalyst switch" strategy has been used to sequentially polymerize four different heterocyclic monomers. In the first step, epoxides (1,2-butylene oxide and ethylene oxide) were successively polymerized from a monohydroxy or trihydroxy initiator in the presence of a strong phosphazene base promoter (t-BuP4). Then, an excess of diphenyl phosphate (DPP) was introduced, followed by addition and polymerization of a cyclic carbonate (trimethylene carbonate) and a cyclic ester (δ-valerolactone or ε-caprolactone). DPP acted as both neutralizer of the phosphazenium alkoxide (polyether chain end) and activator of the cyclic carbonate/ester. Using this method, linear- and star-tetrablock quarterpolymers were prepared in one pot. This work is emphasizing the strength of the previously developed catalyst switch strategy for the facile metal-free synthesis of complex macromolecular architectures. © 2014 Wiley Periodicals, Inc.

One-pot synthesis of linear- and three-arm star-tetrablock quarterpolymers via sequential metal-free ring-opening polymerization using a "catalyst switch" strategy

KAUST Repository

Zhao, Junpeng

2014-08-06

A "catalyst switch" strategy has been used to sequentially polymerize four different heterocyclic monomers. In the first step, epoxides (1,2-butylene oxide and ethylene oxide) were successively polymerized from a monohydroxy or trihydroxy initiator in the presence of a strong phosphazene base promoter (t-BuP4). Then, an excess of diphenyl phosphate (DPP) was introduced, followed by addition and polymerization of a cyclic carbonate (trimethylene carbonate) and a cyclic ester (δ-valerolactone or ε-caprolactone). DPP acted as both neutralizer of the phosphazenium alkoxide (polyether chain end) and activator of the cyclic carbonate/ester. Using this method, linear- and star-tetrablock quarterpolymers were prepared in one pot. This work is emphasizing the strength of the previously developed catalyst switch strategy for the facile metal-free synthesis of complex macromolecular architectures. © 2014 Wiley Periodicals, Inc.

Molybdenum oxide supported on silica (MoO3/SiO2): an efficient and reusable catalyst for the synthesis of 1,8-dioxodecahydroacridines under solvent-free conditions

International Nuclear Information System (INIS)

Khojastehnezhad, A.; Vafaei, M.; Moeinpour, F.

2014-01-01

Silica supported molybdenum oxide (MoO 3 /SiO 2 ) was found to be and efficient, eco-friendly and heterogeneous catalyst for the multicomponent reaction of aromatic aldehydes, dimedone and ammonium acetate or aromatic amines under solvent-free conditions to afford the corresponding 1,8-dioxodecahydroacridines in high yields. The catalyst can be easily recovered and reused for several times without considerable loss of activity. Furthermore, the present method offers several advantages, such as an easy experimental and work-up procedures, short reaction times and good to excellent yields. For the characterization were used: Fourier transform infrared spectroscopy (Ft-IR), X-ray diffraction and scanning electron microscopy analyses. (Author)

NO formation during burnoff of spent hydroprocessing catalysts

Energy Technology Data Exchange (ETDEWEB)

Furimsky, E.; Zaitlin, L.; Laugher, R. (CANMET, Ottawa, ON (Canada). Energy Research Laboratories)

1993-11-01

Temperature-programmed oxidation (from room temperature to 600[degree]C) was performed on operating forms of aged CoMo (extrudate) and NiMo (chestnut bur-like) as well as powder forms, with continuous on-line analysis for NO, CO, CO[sub 2] and SO[sub 2]. For all catalysts, NO formation was delayed by that of CO and CO[sub 2], indicating either a strong interaction of nitrogen-containing compounds with the catalyst surface or a lower reactivity of nitrogen during burnoff compared with that of carbon. The existence of diffusion effects during burnoff was quite evident. These effects were influenced by the catalyst structure and the level of catalyst deactivation. 18 refs., 6 figs., 1 tab.

Production of ethyl ester from crude palm oil by two-step reaction using continuous microwave system

Directory of Open Access Journals (Sweden)

Sukritthira Ratanawilai

2011-02-01

Full Text Available The esterification of free fatty acids (FFA in vegetable oils with alcohol using an acid catalyst is a promising methodto convert FFA into valuable ester and obtain a FFA-free oil that can be further transesterified using alkali bases. In thiswork, the direct esterification reaction of FFA in crude palm oil to ethyl ester by continuous microwave was studied and theeffects of the main variables involved in the process, amount of catalyst, reaction time and the molar ratio oil/ alcohol, wereanalyzed. The optimum condition for the continuous esterification process was carried out with a molar ratio of oil to ethanol1:6, using 1.25%wt of H2SO4/oil as a catalyst, microwave power of 78 W and a reaction time 90 min. This esterification processshows that the amount of FFA was reduced from 7.5%wt to values around 1.4 %wt. Similar results were obtained followingconventional heating at 70°C, but only after a reaction time of 240 min. The esterified crude palm oil is suitable to perform thetransesterification process. Transesterification of the esterified palm oil has been accomplished with a molar ratio of oil toethanol of 1:8.5, 2.5%wt of KOH as a catalyst, a microwave power of 78 W, and a reaction time of 7 min. In addition, theproblem of glycerin separation was solved by mixing 10%wt of pure glycerin into the ethyl ester to induce the glycerin fromthe reaction to separated. This two-step esterification and transesterification process provided a yield of 78%wt with anester content of 97.4%wt. The final ethyl ester product met with the specifications stipulated by ASTM D6751-02.

Glycerol valorization: dehydration to acrolein over silica-supported niobia catalysts

NARCIS (Netherlands)

Shiju, N.R.; Brown, D.R.; Wilson, K.; Rothenberg, G.

2010-01-01

The catalytic dehydration of glycerol to acrolein is investigated over silica-supported niobia catalysts in a continuous fixed-bed gas-phase reactor. Various supported niobia catalysts are prepared and characterized using surface analysis and spectroscopic methods (XRD, UV-Vis, XPS, N2 adsorption),

Single Atomic Iron Catalysts for Oxygen Reduction in Acidic Media: Particle Size Control and Thermal Activation

Energy Technology Data Exchange (ETDEWEB)

Zhang, Hanguang; Hwang, Sooyeon; Wang, Maoyu; Feng, Zhenxing; Karakalos, Stavros; Luo, Langli; Qiao, Zhi; Xie, Xiaohong; Wang, Chongmin; Su, Dong; Shao, Yuyan; Wu, Gang (BNL); (Oregon State U.); (SC); (PNNL); (Buffalo)

2017-09-26

It remains a grand challenge to replace platinum group metal (PGM) catalysts with earth-abundant materials for the oxygen reduction reaction (ORR) in acidic media, which is crucial for large-scale deployment of proton exchange membrane fuel cells (PEMFCs). Here, we report a high-performance atomic Fe catalyst derived from chemically Fe-doped zeolitic imidazolate frameworks (ZIFs) by directly bonding Fe ions to imidazolate ligands within 3D frameworks. Although the ZIF was identified as a promising precursor, the new synthetic chemistry enables the creation of well-dispersed atomic Fe sites embedded into porous carbon without the formation of aggregates. The size of catalyst particles is tunable through synthesizing Fe-doped ZIF nanocrystal precursors in a wide range from 20 to 1000 nm followed by one-step thermal activation. Similar to Pt nanoparticles, the unique size control without altering chemical properties afforded by this approach is able to increase the number of PGM-free active sites. The best ORR activity is measured with the catalyst at a size of 50 nm. Further size reduction to 20 nm leads to significant particle agglomeration, thus decreasing the activity. Using the homogeneous atomic Fe model catalysts, we elucidated the active site formation process through correlating measured ORR activity with the change of chemical bonds in precursors during thermal activation up to 1100 °C. The critical temperature to form active sites is 800 °C, which is associated with a new Fe species with a reduced oxidation number (from Fe3+ to Fe2+) likely bonded with pyridinic N (FeN4) embedded into the carbon planes. Further increasing the temperature leads to continuously enhanced activity, linked to the rise of graphitic N and Fe–N species. The new atomic Fe catalyst has achieved respectable ORR activity in challenging acidic media (0.5 M H2SO4), showing a half-wave potential of 0.85 V vs RHE and leaving only a 30 mV gap with Pt/C (60 μgPt/cm2). Enhanced stability

Novel Nano-Composite Catalysts for Renewable Energy Storage Applications

Science.gov (United States)

Devaguptapu, Surya Vamsi

Spinel NiCo2O4 catalysts are considered the promising precious metal-free catalyst for oxygen reactions. Significant efforts are mainly explore optimal chemical doping and substituent to tune its electronic structures for enhanced performance. Here, we focuses on morphology control and determine the morphology-dependent activity for bifunctional oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). In particular, three types of spinel NiCo2O4 were prepared using temple-free, SiO 2 hard template, and Pluronic-123 soft template hydrothermal methods, showing significantly different morphologies, respectively. In particular, template-free method yield dense structures. Sold-template method assists the formation of porous and hollow structures. Importantly, the soft template is effective to prepare a unique nanoflower morphology containing abundant rose petal (needle) like structures. The effect of the utilization of templates, both soft and hard as well as a template free synthesis on the morphology as well as the activity and stability of the final catalyst is investigated. Compared to others, the nanoflower-like NiCo2O4 exhibited the highest bifunctional catalytic activity simultaneously for ORR and OER, likely due to the facile absorption of oxygen molecules on increased surface areas with efficient mass transfer. The nanoflower NiCo2O 4 also exhibited an onset and half-wave potentials of 0.94 and 0.82 V for the ORR in alkaline media. Although it is still inferior to state of the art Pt, the new type of spinel NiCo2O4 catalyst represents the best activity compared to reported carbon-free oxides. Meanwhile, OER activity and stability were achieved with an onset potential of 1.48 V generating a current density of 14 mA/cm2 at 1.6 V. The OER activity does not declined after 10,000 potential cycles demonstrating excellent stability, which is superior to the benchmark of Ir for the OER. This work provides an effective solution to enhance catalytic activity

Size-controlled growth of ZnO nanowires by catalyst-free high-pressure pulsed laser deposition and their optical properties

Directory of Open Access Journals (Sweden)

W. Z. Liu

2011-06-01

Full Text Available Single crystalline ZnO nanowires were fabricated on Si (100 substrates by catalyst-free high-pressure pulsed laser deposition. It is found that the nanowires start to form when the substrate temperature and growth pressure exceed the critical values of 700 oC and 700 Pa, and their size strongly depends on these growth conditions. That is, the aspect ratio of the nanowires decreases with increasing temperature or decreasing pressure. Such a size dependence on growth conditions was discussed in terms of surface migration and scattering of ablated atoms. Room-temperature photoluminescence spectrum of ZnO nanowires shows a dominant near-band-edge emission peak at 3.28 eV and a visible emission band centered at 2.39 eV. Temperature-dependent photoluminescence studies reveal that the former consists of the acceptor-bound exciton and free exciton emissions; while the latter varies in intensity with the aspect ratio of the nanowires and is attributed to the surface-mediated deep level emission.

“Flash” Solvent-free Synthesis of Triazoles Using a Supported Catalyst

Directory of Open Access Journals (Sweden)

Ibtissem Jlalia

2009-01-01

Full Text Available A solvent-free synthesis of 1,4-disubstituted-1,2,3-triazoles using neat azides and alkynes and a copper(I polymer supported catalyst (Amberlyst® A21•CuI is presented herein. As it provides the products in high yields and purities within minutes, this method thus being characterized as a "flash" synthesis, and was exemplified through the synthesis of a 24-compound library on a small scale.

Highly efficient nonprecious metal catalyst prepared with metal–organic framework in a continuous carbon nanofibrous network

Science.gov (United States)

Shui, Jianglan; Chen, Chen; Grabstanowicz, Lauren; Zhao, Dan; Liu, Di-Jia

2015-01-01

Fuel cell vehicles, the only all-electric technology with a demonstrated >300 miles per fill travel range, use Pt as the electrode catalyst. The high price of Pt creates a major cost barrier for large-scale implementation of polymer electrolyte membrane fuel cells. Nonprecious metal catalysts (NPMCs) represent attractive low-cost alternatives. However, a significantly lower turnover frequency at the individual catalytic site renders the traditional carbon-supported NPMCs inadequate in reaching the desired performance afforded by Pt. Unconventional catalyst design aiming at maximizing the active site density at much improved mass and charge transports is essential for the next-generation NPMC. We report here a method of preparing highly efficient, nanofibrous NPMC for cathodic oxygen reduction reaction by electrospinning a polymer solution containing ferrous organometallics and zeolitic imidazolate framework followed by thermal activation. The catalyst offers a carbon nanonetwork architecture made of microporous nanofibers decorated by uniformly distributed high-density active sites. In a single-cell test, the membrane electrode containing such a catalyst delivered unprecedented volumetric activities of 3.3 A⋅cm−3 at 0.9 V or 450 A⋅cm−3 extrapolated at 0.8 V, representing the highest reported value in the literature. Improved fuel cell durability was also observed. PMID:26261338

Active carbon catalyst for heavy oil upgrading

Energy Technology Data Exchange (ETDEWEB)

Fukuyama, Hidetsugu; Terai, Satoshi [Technology Research Center, Toyo Engineering Corporation, 1818 Azafujimi, Togo, Mobara-shi, Chiba 297-00017 (Japan); Uchida, Masayuki [Business Planning and Exploring Department, Overseas Business Development and Marketing Division, Toyo Engineering Corporation, 2-8-1 Akanehama, Narashino-shi, Chiba 275-0024 (Japan); Cano, Jose L.; Ancheyta, Jorge [Maya Crude Treatment Project, Instituto Mexicano del Petroleo, Eje Central Lazaro Cardenas No. 152, Col. San Bartolo Atepehuacan, Mexico D.F. 07730 (Mexico)

2004-11-24

The active carbon (AC) catalyst was studied by hydrocracking of Middle Eastern vacuum residue (VR) for heavy oil upgrading. It was observed that the active carbon has the affinity to heavy hydrocarbon compounds and adsorption selectivity to asphaltenes, and exhibits better ability to restrict the coke formation during the hydrocracking reaction of VR. The mesopore of active carbon was thought to play an important role for effective conversion of heavy hydrocarbon compounds into lighter fractions restricting carbon formation. The performance of the AC catalyst was examined by continuous hydrocracking by CSTR for the removal of such impurities as sulfur and heavy metals (nickel and vanadium), which are mostly concentrated in the asphaltenes. The AC catalyst was confirmed to be very effective for the removal of heavy metals from Middle Eastern VR, Maya/Istmo VR and Maya VR. The extruded AC catalysts were produced by industrial manufacturing method. The application test of the extruded AC catalyst for ebullating-bed reactor as one of the commercially applicable reactors was carried out at the ebullating-bed pilot plant for 500h. The ebullition of the extruded AC catalyst was successfully traced and confirmed by existing {gamma}-ray density meter. The extruded AC catalyst showed stable performance with less sediment formation at an equivalent conversion by conventional alumina catalyst at commercial ebullating-bed unit. The degradation of the AC catalyst at the aging test was observed to be less than that of the conventional alumina catalyst. Thus, the AC catalyst was confirmed to be effective and suitable for upgrading of heavy oil, especially such heavy oils as Maya, which contains much heavy metals.

Two-step microalgal biodiesel production using acidic catalyst generated from pyrolysis-derived bio-char

International Nuclear Information System (INIS)

Dong, Tao; Gao, Difeng; Miao, Chao; Yu, Xiaochen; Degan, Charles; Garcia-Pérez, Manuel; Rasco, Barbara; Sablani, Shyam S.; Chen, Shulin

2015-01-01

Highlights: • Highly active catalyst was prepared using bio-char co-produced in Auger pyrolysis. • Catalyst inhibitors in crude oil were effectively removed by a practical refinery process. • Free fatty acids (FFA) content in refined microalgal oil was reduced to less than 0.5%. • A total fatty acid methyl ester (FAME) yield of 99% was obtained via a two-step process. • The inexpensive bio-char catalyst is superior to Amberlyst-15 in pre-esterification. - Abstract: An efficient process for biodiesel production from fast-refined microalgal oil was demonstrated. A low cost catalyst prepared from pyrolysis-derived bio-char, was applied in pre-esterification to reduce free fatty acid (FFA) content. Results showed that the bio-char catalyst was highly active in esterification; however, the performance of the catalyst significantly reduced when crude microalgal oil was used as feedstock. To solve the problem caused by catalyst-fouling, a fast and scalable crude oil refinery procedure was carried out to remove chlorophyll and phospholipids that might degrade the catalyst and the quality of biodiesel. The activity and reusability of bio-char catalyst were remarkably improved in the fast-refined oil. FFA content in the refined microalgal oil was reduced to less than 0.5% after pre-esterification. The bio-char catalyst could be reused for 10 cycles without dramatic loss in activity. The pre-esterification fits the first-order kinetic reaction with activation energy of 42.16 kJ/mol. The activity of bio-char catalyst was superior to commercial Amberlyst-15 under the same reaction condition. A total fatty acid methyl ester (FAME, namely biodiesel) yield of 99% was obtained following the second-step CaO-catalyzed transesterification. The cost-effective bio-char catalyst has great potential for biodiesel production using feedstocks having high FFA content.

SELECTIVE HYDROGENOLYSIS OF GLYCEROL TO PROPYLENE GLYCOL IN A CONTINUOUS FLOW TRICKLE BED REACTOR USING COPPER CHROMITE AND Cu/Al2O3 CATALYSTS

Directory of Open Access Journals (Sweden)

Jorge Sepúlveda

Full Text Available The glycerol hydrogenolysis reaction was performed in a continuous flow trickle bed reactor using a water glycerol feed and both copper chromite and Cu/Al2O3 catalysts. The commercial copper chromite had a higher activity than the laboratory prepared Cu/Al2O3 and was used for most of the tests. Propylene glycol was the main product with both catalysts, acetol being the main by-product. It was found that temperature is the main variable influencing the conversion of glycerol. When the state of the glycerol-water reactant mixture was completely liquid, at temperatures lower than 190 ºC, conversion was low and deactivation was observed. At reaction temperatures of 210-230 ºC the conversion of glycerol was complete and the selectivity to propylene glycol was stable at about 60-80% all throughout the reaction time span of 10 h, regardless of the hydrogen pressure level (1 to 20 atm. These optimal values could not be improved significantly by using other different reaction conditions or increasing the catalyst acidity. At higher temperatures (245-250 ºC the conversion was also 100%. Under reaction conditions at which copper chromite suffered deactivation, light by-products and surface deposits were formed. The deposits could be completely burned at 250 ºC and the catalyst activity fully recovered.

Treatment of a non-azo dye aqueous solution by CWAO in continuous reactor using a Ni catalyst derived from hydrotalcite-like precursor

International Nuclear Information System (INIS)

Vallet, Ana; Besson, Michèle; Ovejero, Gabriel; García, Juan

2012-01-01

Highlights: ► Ni supported over hydrotalcite calcined precursors as catalyst. ► Catalytic wet air oxidation in trickle bed reactor for Basic Yellow 11 removal. ► Dye removal depends on temperature, initial dye concentration and flow rate. ► The catalyst proved to be stable and efficient for the dye degradation. - Abstract: Catalytic wet air oxidation (CWAO) of a Basic Yellow 11 (BY11) aqueous solution, chosen as a model of a hardly biodegradable non-azo dye was carried out in a continuous-flow trickle-bed reactor, using nickel supported over hydrotalcite precursor calcined at 550 °C. An increase in the reaction temperature (120–180 °C), and a decrease in dye concentration (1000–3000 ppm) or liquid flow rate (0.1–0.7 mL min −1 ) enhanced the CWAO performance in a 30 and 19% for the variation of the temperature and concentration respectively. After a small leaching observed within the first hours, the catalyst proved to be very stable during the 65-day reaction. The CWAO process was found to be very efficient, achieving BY11 conversion up to 95% and TOC conversion up to 85% at 0.1 mL min −1 and 180 °C under 5 MPa air.

Oxidation catalyst

Science.gov (United States)

Ceyer, Sylvia T.; Lahr, David L.

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.

Optimization of sunflower oil methanolysis for the production of biodiesel and its characterization with spectroscopic techniques (abstract)

International Nuclear Information System (INIS)

Tariq, M.; Ali, S.; Khalid, N.; Naureen, R.; Rafique, U.

2011-01-01

Esters from vegetable oils have attracted a great deal of interest as substitute for petrodiesel to reduce dependence on imported petroleum and provide an alternate and sustainable source for fuel with more benign environmental properties. In the present study biodiesel was prepared from sunflower seed oil by transesterification by alkali-catalyzed methanolysis. The fuel properties like kinematic viscosity, density, specific gravity, flash point, pour point, cloud point, acid number and colour comparison of sunflower oil biodiesel (SOB) were determined and discussed in the light of ASTM D6751 standards for biodiesel. The SOB was chemically characterized with analytical techniques like FT-IR, NMR (/sup 1/H and /sup 13/C). The chemical composition of SOB was determined by GC-MS. Various fatty acid methyl esters (FAMEs) were identified by retention time data and verified by mass fragmentation patterns. The identified FAMEs were methyl dodecanoate (C/sub 12:0/), methyl tetradecanoate(C/sub 14:0/), methyl hexadecanoate (C/sub 16:0/), methyl 8,11-octadecadienoate (C/sub 18:2/), methyl 9-octadecenoate (C/sub 18:1/), methyl octadecanoate (C/sub 18:0/), methyl 11-eicosenoate (C/sub 20:1/), methyl eicosanoate (C/sub 20:0/), methyl 13-docosenoate(C/sub 22:1/), methyl docosenoate(C/sub 22:0/) and methyl tetracosanoate (C/sub 24:0/). The percentage conversion of triglycerides to corresponding methyl esters determined by /sup 1/H-NMR was 87.33 % which was quite in good agreement with the practically observed yield of 85.1 %. (author)

Al- or Si-decorated graphene oxide: A favorable metal-free catalyst for the N2O reduction

International Nuclear Information System (INIS)

Esrafili, Mehdi D.; Sharifi, Fahimeh; Nematollahi, Parisa

2016-01-01

Highlights: • The reduction of N 2 O by CO molecule is investigated over Al- and Si-decorated graphene oxides (Al-/Si-GO). • The N 2 O decomposition process can take place with a negligible activation energy over both surfaces. • Al-GO and Si-GO can be used as an efficient metal-free catalyst for the reduction of N 2 O molecule at ambient conditions. - Abstract: The structural and catalytic properties of Al- or Si-decorated graphene oxide (Al-/Si-GO) are studied by means of density functional theory calculations. The relatively large adsorption energy together with the small Al−O or Si−O binding distances indicate that the epoxy groups over the GO surface can strongly stabilize the single Al or Si atom. Hence, Al-GO and Si-GO are stable enough to be utilized in catalytic reduction of N 2 O by CO molecule. It is found that the adsorption and decomposition of N 2 O molecule over Si-GO is more favorable than over Al-GO, due to its larger adsorption energy (E ads ) and charge transfer (q CT ) values. On the other hand, the CO molecule is physically adsorbed over both surfaces, with relatively small E ads and q CT values. Therefore, at the presence of N 2 O and CO molecules as the reaction gas, the Al or Si atom of the surface should be dominantly covered by N 2 O molecule. Our results indicate that the N 2 O decomposition process can take place with a negligible activation energy over Al-/Si-GO surface, where the N 2 molecule can be easily released from the surface. Then, the activated oxygen atom (O ads ) which remains over the surface reacts with the CO molecule to form the CO 2 molecule via the reaction O ads + CO → CO 2 . Based on the calculated activation energies, it is suggested that both Al-GO and Si-GO can be used as an efficient metal-free catalyst for the reduction of N 2 O molecule at ambient conditions.

Solid Catalysts and theirs Application in Biodiesel Production

Directory of Open Access Journals (Sweden)

Ramli Mat

2012-12-01

Full Text Available The reduction of oil resources and increasing petroleum price has led to the search for alternative fuel from renewable resources such as biodiesel. Currently biodiesel is produced from vegetable oil using liquid catalysts. Replacement of liquid catalysts with solid catalysts would greatly solve the problems associated with expensive separation methods and corrosion problems, yielding to a cleaner product and greatly decreasing the cost of biodiesel production. In this paper, the development of solid catalysts and its catalytic activity are reviewed. Solid catalysts are able to perform trans-esterification and esterification reactions simultaneously and able to convert low quality oils with high amount of Free Fatty Acids. The parameters that effect the production of biodiesel are discussed in this paper. Copyright © 2012 by BCREC UNDIP. All rights reservedReceived: 6th April 2012, Revised: 24th October 2012, Accepted: 24th October 2012[How to Cite: R. Mat, R.A. Samsudin, M. Mohamed, A. Johari, (2012. Solid Catalysts and Their Application in Biodiesel Production. Bulletin of Chemical Reaction Engineering & Catalysis, 7(2: 142-149. doi:10.9767/bcrec.7.2.3047.142-149] [How to Link / DOI: http://dx.doi.org/10.9767/bcrec.7.2.3047.142-149 ] | View in 

Online screening of homogeneous catalyst performance using reaction detection mass spectrometry

NARCIS (Netherlands)

Martha, C.T.; Elders, N.; Krabbe, J.G.; Kool, J.; Niessen, W.M.A.; Orru, R.V.A.; Irth, H.

2008-01-01

An integrated online screening system was developed to rapidly screen homogeneous catalysts for activity toward a selected synthesis. The continuous-flow system comprises standard HPLC pumps for the delivery of substrates, an HPLC autosampler for the injection of homogeneous catalysts, a

Continuous Heterogeneous Photocatalysis in Serial Micro-Batch Reactors.

Science.gov (United States)

Pieber, Bartholomäus; Shalom, Menny; Antonietti, Markus; Seeberger, Peter H; Gilmore, Kerry

2018-01-29

Solid reagents, leaching catalysts, and heterogeneous photocatalysts are commonly employed in batch processes but are ill-suited for continuous-flow chemistry. Heterogeneous catalysts for thermal reactions are typically used in packed-bed reactors, which cannot be penetrated by light and thus are not suitable for photocatalytic reactions involving solids. We demonstrate that serial micro-batch reactors (SMBRs) allow for the continuous utilization of solid materials together with liquids and gases in flow. This technology was utilized to develop selective and efficient fluorination reactions using a modified graphitic carbon nitride heterogeneous catalyst instead of costly homogeneous metal polypyridyl complexes. The merger of this inexpensive, recyclable catalyst and the SMBR approach enables sustainable and scalable photocatalysis. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

A Combined Synthetic and DFT Study on the Catalyst-Free and Solvent-Assisted Synthesis of 1,3,4-Oxadiazole-2-thiol Derivatives

Directory of Open Access Journals (Sweden)

Mohammad Soleiman-Beigi

2013-01-01

Full Text Available A novel practical and efficient catalyst-free method for the synthesis of 5-substituted 1,3,4-oxadiazole-2-thiols has been developed, which is assisted by reaction solvent (DMF. The solvent effects on product selectivity were studied based on Onsager’s reaction field theory of electrostatic solvation. The ab initio theoretical studies on the effect of solvents on the process also supported the suitability of DMF as the reaction medium for the preparation of 1,3,4-oxadiazole-2-thiol derivatives.

A two-step acid-catalyzed process for the production of biodiesel from rice bran oil

Energy Technology Data Exchange (ETDEWEB)

Zullaikah, S.; Lai, Chao Chin; Vali, S.R.; Ju, Yi Hsu [National Taiwan Univ. of Science and Technology, Taipei (China). Dept. of Chemical Engineering

2005-11-15

A study was undertaken to examine the effect of temperature, moisture and storage time on the accumulation of free fatty acid in the rice bran. Rice bran stored at room temperature showed that most triacylglyceride was hydrolyzed and free fatty acid (FFA) content was raised up to 76% in six months. A two-step acid-catalyzed methanolysis process was employed for the efficient conversion of rice bran oil into fatty acid methyl ester (FAME). The first step was carried out at 60 {sup o}C. Depending on the initial FFA content of oil, 55-90% FAME content in the reaction product was obtained. More than 98% FFA and less than 35% of TG were reacted in 2 h. The organic phase of the first step reaction product was used as the substrate for a second acid-catalyzed methanolysis at 100 {sup o}C. By this two-step methanolysis reaction, more than 98% FAME in the product can be obtained in less than 8 h. Distillation of reaction product gave 99.8% FAME (biodiesel) with recovery of more than 96%. The residue contains enriched nutraceuticals such as {gamma}-oryzanol (16-18%), mixture of phytosterol, tocol and steryl ester (19-21%). (author)

Highly Durable Direct Methanol Fuel Cell with Double-Layered Catalyst Cathode

Directory of Open Access Journals (Sweden)

Jing Liu

2015-01-01

Full Text Available Polymer electrolyte membrane (PEM is one of the key components in direct methanol fuel cells. However, the PEM usually gets attacked by reactive oxygen species during the operation period, resulting in the loss of membrane integrity and formation of defects. Herein, a double-layered catalyst cathode electrode consisting of Pt/CeO2-C as inner catalyst and Pt/C as outer catalyst is fabricated to extend the lifetime and minimize the performance loss of DMFC. Although the maximum power density of membrane electrode assembly (MEA with catalyst cathode is slightly lower than that of the traditional one, its durability is significantly improved. No obvious degradation is evident in the MEA with double-layered catalyst cathode within durability testing. These results indicated that Pt/CeO2-C as inner cathode catalyst layer greatly improved the stability of MEA. The significant reason for the improved stability of MEA is the ability of CeO2 to act as free-radical scavengers.

A palladium-doped ceria@carbon core-sheath nanowire network: a promising catalyst support for alcohol electrooxidation reactions

Science.gov (United States)

Tan, Qiang; Du, Chunyu; Sun, Yongrong; Du, Lei; Yin, Geping; Gao, Yunzhi

2015-08-01

A novel palladium-doped ceria and carbon core-sheath nanowire network (Pd-CeO2@C CSNWN) is synthesized by a template-free and surfactant-free solvothermal process, followed by high temperature carbonization. This hierarchical network serves as a new class of catalyst support to enhance the activity and durability of noble metal catalysts for alcohol oxidation reactions. Its supported Pd nanoparticles, Pd/(Pd-CeO2@C CSNWN), exhibit >9 fold increase in activity toward the ethanol oxidation over the state-of-the-art Pd/C catalyst, which is the highest among the reported Pd systems. Moreover, stability tests show a virtually unchanged activity after 1000 cycles. The high activity is mainly attributed to the superior oxygen-species releasing capability of Pd-doped CeO2 nanowires by accelerating the removal of the poisoning intermediate. The unique interconnected one-dimensional core-sheath structure is revealed to facilitate immobilization of the metal catalysts, leading to the improved durability. This core-sheath nanowire network opens up a new strategy for catalyst performance optimization for next-generation fuel cells.A novel palladium-doped ceria and carbon core-sheath nanowire network (Pd-CeO2@C CSNWN) is synthesized by a template-free and surfactant-free solvothermal process, followed by high temperature carbonization. This hierarchical network serves as a new class of catalyst support to enhance the activity and durability of noble metal catalysts for alcohol oxidation reactions. Its supported Pd nanoparticles, Pd/(Pd-CeO2@C CSNWN), exhibit >9 fold increase in activity toward the ethanol oxidation over the state-of-the-art Pd/C catalyst, which is the highest among the reported Pd systems. Moreover, stability tests show a virtually unchanged activity after 1000 cycles. The high activity is mainly attributed to the superior oxygen-species releasing capability of Pd-doped CeO2 nanowires by accelerating the removal of the poisoning intermediate. The unique

Continuous protein concentration via free-flow moving reaction boundary electrophoresis.

Science.gov (United States)

Kong, Fanzhi; Zhang, Min; Chen, Jingjing; Fan, Liuyin; Xiao, Hua; Liu, Shaorong; Cao, Chengxi

2017-07-28

In this work, we developed the model and theory of free-flow moving reaction boundary electrophoresis (FFMRB) for continuous protein concentration for the first time. The theoretical results indicated that (i) the moving reaction boundary (MRB) can be quantitatively designed in free-flow electrophoresis (FFE) system; (ii) charge-to-mass ratio (Z/M) analysis could provide guidance for protein concentration optimization; and (iii) the maximum processing capacity could be predicted. To demonstrate the model and theory, three model proteins of hemoglobin (Hb), cytochrome C (Cyt C) and C-phycocyanin (C-PC) were chosen for the experiments. The experimental results verified that (i) stable MRBs with different velocities could be established in FFE apparatus with weak acid/weak base neutralization reaction system; (ii) proteins of Hb, Cyt C and C-PC were well concentrated with FFMRB; and (iii) a maximum processing capacity and recovery ratio of Cyt C enrichment were 126mL/h and 95.5% respectively, and a maximum enrichment factor was achieved 12.6 times for Hb. All of the experiments demonstrated the protein concentration model and theory. In contrast to other methods, the continuous processing ability enables FFMRB to efficiently enrich diluted protein or peptide in large volume solution. Copyright © 2017 Elsevier B.V. All rights reserved.

Process Intensification of Alkynol Semihydrogenation in a Tube Reactor Coated with a Pd/ZnO Catalyst

Directory of Open Access Journals (Sweden)

Nikolay Cherkasov

2017-11-01

Full Text Available Semihydrogenation of 2-methyl-3-butyn-2-ol (MBY was studied in a 5 m tube reactor wall-coated with a 5 wt% Pd/ZnO catalyst. The system allowed for the excellent selectivity towards the intermediate alkene of 97.8 ± 0.2% at an ambient H2 pressure and a MBY conversion below 90%. The maximum alkene yield reached 94.6% under solvent-free conditions and 96.0% in a 30 vol % MBY aqueous solution. The reactor stability was studied for 80 h on stream with a deactivation rate of only 0.07% per hour. Such a low deactivation rate provides a continuous operation of one month with only a two-fold decrease in catalyst activity and a metal leaching below 1 parts per billion (ppb. The excellent turn-over numbers (TON of above 105 illustrates a very efficient utilisation of the noble metal inside catalyst-coated tube reactors. When compared to batch operation at 70 °C, the reaction rate in flow reactor can be increased by eight times at a higher reaction temperature, keeping the same product decomposition of about 1% in both cases.

H2O2 sensing using HRP modified catalyst-free ZnO nanorods synthesized by RF sputtering

Science.gov (United States)

Srivastava, Amit; Kumar, Naresh; Singh, Priti; Singh, Sunil Kumar

2017-06-01

Catalyst-free ( 00 l) oriented ZnO nanorods (NRs) -based biosensor for the H2O2 sensing has been reported. The (002) oriented ZnO NRs as confirmed by X-ray diffraction were successfully grown on indium tin oxide (ITO) coated glass substrate by radio frequency (RF) sputtering technique without using any catalyst. Horseradish peroxidase (HRP) enzyme was immobilized on ZnO NRs by physical adsorption technique to prepare the biosensor. In this HRP/ZnO NR/ITO bioelectrode, nafion solution was added to form a tight membrane on surface. The prepared bioelectrode has been used for biosensing measurements by electrochemical analyzer. The electrochemical studies reveal that the prepared HRP/ZnO NR/ITO biosensor is highly sensitive to the detection of H2O2 over a linear range of 0.250-10 μM. The ZnO NR-based biosensor showed lower value of detection limit (0.125 μM) and higher sensitivity (13.40 µA/µM cm2) towards H2O2. The observed value of higher sensitivity attributed to larger surface area of ZnO nanostructure for effective loading of HRP besides its high electron communication capability. In addition, the biosensor also shows lower value of enzyme's kinetic parameter (Michaelis-Menten constant, K m) of 0.262 μM which indicates enhanced enzyme affinity of HRP to H2O2. The reported biosensor may be useful for various applications in biosensing, clinical, food, and beverage industry.

Supported sub-nanometer Ta oxide clusters as model catalysts for the selective epoxidation of cyclooctene

KAUST Repository

Zwaschka, Gregor; Rondelli, Manuel; Krause, Maximilian; Rö tzer, Marian David; Hedhili, Mohamed N.; Heiz, Ulrich; Basset, Jean-Marie; Schweinberger, Florian; D'Elia, Valerio

2018-01-01

The preparation of organic ligands-free, isolated tantalum oxide atoms (Ta1) and small clusters (Tan>1) on flat silicate supports was accomplished by ultra-high vacuum (UHV) techniques followed by oxidation in air. The resulting surface complexes were thoroughly characterized and tested as supported catalysts for the epoxidation of cycloalkenes. The observed catalytic performance highlights the potential of the applied method for the production of active catalysts and the study of well-defined, ligand-free metal oxide moieties.

Supported sub-nanometer Ta oxide clusters as model catalysts for the selective epoxidation of cyclooctene

KAUST Repository

Zwaschka, Gregor

2018-01-22

The preparation of organic ligands-free, isolated tantalum oxide atoms (Ta1) and small clusters (Tan>1) on flat silicate supports was accomplished by ultra-high vacuum (UHV) techniques followed by oxidation in air. The resulting surface complexes were thoroughly characterized and tested as supported catalysts for the epoxidation of cycloalkenes. The observed catalytic performance highlights the potential of the applied method for the production of active catalysts and the study of well-defined, ligand-free metal oxide moieties.

Molybdenum oxide supported on silica (MoO{sub 3}/SiO{sub 2}): an efficient and reusable catalyst for the synthesis of 1,8-dioxodecahydroacridines under solvent-free conditions

Energy Technology Data Exchange (ETDEWEB)

Khojastehnezhad, A.; Vafaei, M. [Islamic Azad University, Mashhad Branch, Department of Chemistry, Mashhad (Iran, Islamic Republic of); Moeinpour, F., E-mail: akhojastehnezhad@yahoo.com [Islamic Azad University, Bandar Abbas Branch, Department of Chemistry, Bandar Abbas (Iran, Islamic Republic of)

2014-07-01

Silica supported molybdenum oxide (MoO{sub 3}/SiO{sub 2}) was found to be and efficient, eco-friendly and heterogeneous catalyst for the multicomponent reaction of aromatic aldehydes, dimedone and ammonium acetate or aromatic amines under solvent-free conditions to afford the corresponding 1,8-dioxodecahydroacridines in high yields. The catalyst can be easily recovered and reused for several times without considerable loss of activity. Furthermore, the present method offers several advantages, such as an easy experimental and work-up procedures, short reaction times and good to excellent yields. For the characterization were used: Fourier transform infrared spectroscopy (Ft-IR), X-ray diffraction and scanning electron microscopy analyses. (Author)

Cationic Zn-Porphyrin Polymer Coated onto CNTs as a Cooperative Catalyst for the Synthesis of Cyclic Carbonates.

Science.gov (United States)

Jayakumar, Sanjeevi; Li, He; Chen, Jian; Yang, Qihua

2018-01-24

The development of solid catalysts containing multiple active sites that work cooperatively is very attractive for biomimetic catalysis. Herein, we report the synthesis of bifunctional catalysts by supporting cationic porphyrin-based polymers on carbon nanotubes (CNTs) using the direct reaction of 5,10,15,20-tetrakis(4-pyridyl)porphyrin zinc(II), di(1H-imidazol-1-yl)methane, and 1,4-bis(bromomethyl)benzene in the presence of CNTs. The bifunctional catalysts could efficiently catalyze the cycloaddition reaction of epoxides and CO 2 under solvent-free conditions with porphyrin zinc(II) as the Lewis acid site and a bromine anion as a nucleophilic agent working in a cooperative way. Furthermore, a relative amount of porphyrin zinc(II) and quaternary ammonium bromide could be facilely adjusted for facilitating cooperative behavior. The bifunctional catalyst with a TOF up to 2602 h -1 is much more active than the corresponding homogeneous counterpart and is one of the most active heterogeneous catalysts ever reported under cocatalyst-free conditions. The high activity is mainly attributed to the enhanced cooperation effect of the bifunctional catalyst. With a wide substrate scope, the bifunctional catalyst could be stably recycled. This work demonstrates a new approach for the generation of a cooperative activation effect for solid catalysts.

Investigation and comparison of GaN nanowire nucleation and growth by the catalyst-assisted and self-induced approaches

Energy Technology Data Exchange (ETDEWEB)

Cheze, Caroline

2010-03-04

{sub x}N{sub y} layer leads to the massive nucleation of GaN islands that are free of the substrate lattice constraint and therefore form in the wurtzite (WZ) structure. In the catalyst-assisted approach, Ga strongly reacts with the catalyst Ni particles whose crystal structure and phases are decisive for the NW growth. In the catalyst-free approach, N forms an interfacial layer with Si before the intense nucleation of GaN starts, and the lattice-mismatch to the substrate plays the most important role. Both approaches are viable to produce NWs within the same range of substrate temperatures and V/III ratios, provided the latter is larger than one (N-excess). Both yield monocrystalline GaN NWs of WZ structure, which grow in the Ga-polar direction. However, strong differences are also observed. First, the catalyst-assisted NWs are longer than the catalyst-free ones after growth under identical conditions (duration, substrate temperature and V/III ratio), and the former grow at the rate of the supplied N. In contrast, the selfinduced NWs grow with an intermediate rate between the supplied Ga- and N-rates. Second, the catalyst-assisted approach provides GaN NWs that contain many stacking faults, while the catalyst-free ones are largely free of defects. Third, the photoluminescence (PL) of the catalyst-free NWs is narrower and much more intense than the one of the catalyst-assisted NWs. The seed captures Ga atoms arriving at the NW tip more efficiently than the bare top facet in the catalyst-free approach. (orig.)

Molybdenum-containing acidic catalysts to convert cellulosic biomass to glycolic acid

KAUST Repository

Han, Yu

2014-09-30

Embodiments of the present invention include methods and compositions related to catabolic conversion of cellulosic biomass to glycolic acid using molybdenum-containing acidic catalysts. The invention includes the use of heteropoly and isopoly acids and salts as the molybdenum-containing multi-functional catalysts for biomass conversion. In embodiments of the invention, the reactions employ successive hydrolysis, retro-aldol fragmentation, and selective oxidation in a noble metal-free system.

Treatment of a non-azo dye aqueous solution by CWAO in continuous reactor using a Ni catalyst derived from hydrotalcite-like precursor

Energy Technology Data Exchange (ETDEWEB)

Vallet, Ana, E-mail: avallet@quim.ucm.es [Grupo de Catalisis y Procesos de Separacion (CyPS), Departamento de Ingenieria Quimica, Facultad de Ciencias Quimicas, Universidad Complutense de Madrid, Avda. Complutense s/n, 28040 Madrid (Spain); Besson, Michele, E-mail: michele.besson@ircelyon.univ-lyon1.fr [IRCELYON, Institut de recherches sur la catalyse et l' environnement de Lyon, UMR5256 CNRS-Universite Lyon1, 2 Avenue Albert Einstein, F-69626 Villeurbanne Cedex (France); Ovejero, Gabriel; Garcia, Juan [Grupo de Catalisis y Procesos de Separacion (CyPS), Departamento de Ingenieria Quimica, Facultad de Ciencias Quimicas, Universidad Complutense de Madrid, Avda. Complutense s/n, 28040 Madrid (Spain)

2012-08-15

Highlights: Black-Right-Pointing-Pointer Ni supported over hydrotalcite calcined precursors as catalyst. Black-Right-Pointing-Pointer Catalytic wet air oxidation in trickle bed reactor for Basic Yellow 11 removal. Black-Right-Pointing-Pointer Dye removal depends on temperature, initial dye concentration and flow rate. Black-Right-Pointing-Pointer The catalyst proved to be stable and efficient for the dye degradation. - Abstract: Catalytic wet air oxidation (CWAO) of a Basic Yellow 11 (BY11) aqueous solution, chosen as a model of a hardly biodegradable non-azo dye was carried out in a continuous-flow trickle-bed reactor, using nickel supported over hydrotalcite precursor calcined at 550 Degree-Sign C. An increase in the reaction temperature (120-180 Degree-Sign C), and a decrease in dye concentration (1000-3000 ppm) or liquid flow rate (0.1-0.7 mL min{sup -1}) enhanced the CWAO performance in a 30 and 19% for the variation of the temperature and concentration respectively. After a small leaching observed within the first hours, the catalyst proved to be very stable during the 65-day reaction. The CWAO process was found to be very efficient, achieving BY11 conversion up to 95% and TOC conversion up to 85% at 0.1 mL min{sup -1} and 180 Degree-Sign C under 5 MPa air.

Development of Ultra-Low Platinum Alloy Cathode Catalysts for PEM Fuel Cells

Energy Technology Data Exchange (ETDEWEB)

Popov, Branko N. [Univ. of South Carolina, Columbia, SC (United States). Dept. of Chemical Engineering; Weidner, John [Univ. of South Carolina, Columbia, SC (United States)

2016-01-07

The goal of this project is to synthesize a low cost PEM fuel cell cathode catalyst and support with optimized average mass activity, stability of mass activity, initial high current density performance under H₂/air (power density), and catalyst and support stability able to meet 2017 DOE targets for electrocatalysts for transportation applications. Pt*/ACCS-2 catalyst was synthesized according to a novel methodology developed at USC through: (i) surface modification, (ii) metal catalyzed pyrolysis and (iii) chemical leaching to remove excess meal used to dope the support. Pt* stands for suppressed platinum catalyst synthesized with Co doped platinum. The procedure results in increasing carbon graphitization, inclusion of cobalt in the bulk and formation of non-metallic active sites on the carbon surface. Catalytic activity of the support shows an onset potential of 0.86 V for the oxygen reduction reaction (ORR) with well-defined kinetic and mass transfer regions and 2.5% H₂O₂ production. Pt*/ACCS-2 catalyst durability under 0.6-1.0 V potential cycling and support stability under 1.0-1.5 V potential cycling was evaluated. The results indicated excellent catalyst and support performance under simulated start-up/shut down operating conditions (1.0 – 1.5 V, 5000 cycles) which satisfy DOE 2017 catalyst and support durability and activity. The 30% Pt*/ACCS-2 catalyst showed high initial mass activity of 0.34 A/mg_PGM at 0.9 ViR-free and loss of mass activity of 45% after 30,000 cycles (0.6-1.0 V). The catalyst performance under H₂-air fuel cell operating conditions showed only 24 mV (iR-free) loss at 0.8 A/cm² with an ECSA loss of 42% after 30,000 cycles (0.6-1.0 V). The support stability under 1.0-1.5 V potential cycling showed mass activity loss of 50% and potential loss of 8 mV (iR-free) at 1.5 A/cm². The ECSA loss was 22% after 5,000 cycles. Furthermore, the Pt*/ACCS-2 catalyst showed an

Novel bimetallic dispersed catalysts for temperature-programmed coal liquefaction

Energy Technology Data Exchange (ETDEWEB)

Chunshan, Song; Kirby, S.; Schmidt, E. [Pennsylvania State Univ., University Park, PA (United States)] [and others

1995-12-31

The objective of this project is to explore bimetallic dispersed catalysts for more efficient coal liquefaction. Coal liquefaction involves cleavage of methylene, dimethylene and ether bridges connecting various aromatic units and the reactions of various oxygen functional groups. This paper describes recent results on (1) hydrodeoxygenation of O-containing polycyclic model compounds using novel organometallic catalyst precursors; and (2) activity and selectivity of dispersed Fe catalysts from organometallic and inorganic precursors for hydrocracking of 4-(1-naphthylmethyl) bibenzyl. The results showed that some iron containing catalysts have higher activity in the sulfur-free form, contrary to conventional wisdom. Adding sulfur to Fe precursors with Cp-ligands decreased the activity of the resulting catalyst. This is in distinct contrast to the cases with iron pentacarbonyl and superfine Fe{sub 2}O{sub 3}, where S addition increased their catalytic activity substantially. A positive correlation between sulfur addition and increased activity can be seen, but a reversed trend between Fe cluster size and hydrocracking conversion could be observed, for carbonyl-type Fe precursors. It is apparent that the activity and selectivity of Fe catalysts for NMBB conversion depends strongly on both the type of ligand environment, the oxidation state and the number of intermetal bonds in the molecular precursor.

Removal of free fatty acid in Palm Fatty Acid Distillate using sulfonated carbon catalyst derived from biomass wastefor biodiesel production

Science.gov (United States)

Hidayat, Arif; Rochmadi; Wijaya, Karna; Budiman, Arief

2016-01-01

In this research, the esterification of PFAD using the sulfonatedcoconut shell biochar catalyst was studied. Carbon solid catalysts were prepared by a sulfonation of carbonized coconut shells. The performances of the catalysts were evaluated in terms of the reaction temperatures, the molar ratios of methanol to PFAD, the catalyst loading and the reaction times. The reusability of the solid acid carbon catalysts was also studied in this work. The results indicated that the FFA conversion was significantly increased with increasing catalyst loading and reaction times. It can be concluded that the optimal conditions were an PFAD to methanol molar ratio of 1:12, the amount of catalyst of 10%w, and reaction temperature of 60oC.At this optimum condition, the conversion to biodieselreached 88%.

Thiamine hydrochloride: An efficient catalyst for one-pot synthesis of ...

Indian Academy of Sciences (India)

thiamine hydrochloride (VB1) as an inexpensive, non-toxic and metal ion free catalyst at ambient temperature. Keywords. ... from practical applications due to environmental and economic ... filtered and purified by column chromatography on.

Regeneration of a deactivated USY alkylation catalyst using supercritical isobutane

Energy Technology Data Exchange (ETDEWEB)

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.

Mechanism of nucleation and growth of catalyst-free self-organized GaN columns by MOVPE

Science.gov (United States)

Wang, Xue; Li, Shunfeng; Fündling, Sönke; Wehmann, Hergo-H.; Strassburg, Martin; Lugauer, Hans-Jürgen; Steegmüller, Ulrich; Waag, Andreas

2013-05-01

The growth mechanism of catalyst-free self-organized GaN nuclei and three-dimensional columns on sapphire by metal organic vapour phase epitaxy (MOVPE) is investigated. Temperature- and time-dependent growth is performed. The growth behaviour can be characterized by two different kinetic regimes: mass-transport-limited growth and thermodynamically limited growth. The sum of activation energies for thermodynamic barrier of nucleation and for surface diffusion/mass-transport limitation, i.e. Whet +Ed, is 0.57 eV in the ‘low’-temperature region and 2.43 eV in the ‘high’-temperature region. GaN columns grown under the same conditions have very comparable height, which is not dependent on their diameter or the distance to other columns. Therefore, the growth rate is presumably limited by the incorporation rate on the top surface of columns. The height and diameter at the top of the GaN columns increase linearly with time and no height limit is observed. The GaN columns can reach more than 40 µm in height. Moreover, the investigated GaN columns are Ga-polar.

Separation of deuterium by H2/H2O reaction with hydrophobic platinum catalyst

International Nuclear Information System (INIS)

Kitamoto, A.; Takashima, Y.; Shimizu, M.

The separation performance of a trickle bed exchange column packed with a hydrophobic or waterproof catalyst is related to operating conditions such as hydrogen surface velocity, water flow rate, and temperature. The optimum carrier type and catalyst platinum content were determined. The continuous injection of roughly 10 3 ppm O 2 regenerates the catalyst effectively. The ratio of hydrophobic catalyst to hydrophilic packing is an important factor in increasing the exchange rate in deuterium extraction

Self-regenerative function of the intelligent automotive catalyst

International Nuclear Information System (INIS)

Tanaka, Hirohisa; Nishihata, Yasuo

2007-01-01

Intelligent catalyst, in which noble metals are used as an active part of automotive catalyst, has been considered for keeping up their sufficient activity. The noble metals have a function of cleaning up the exhaust gas as well as that of self-regeneration. In 2002, a Pd system has been put to practical use, and continuously Rh and Pt systems have been commercialized. Now the catalyst has been used in more than three million vehicles. In this report, the atomic level mechanism of the catalyst and its self-regeneration function getting from analyses using synchrotron radiation are introduced. By the analysis using the Spring-8, the mechanism of keeping the active state of the Pd Perovskite Oxide without degradation was identified. The DXAFS (Dispersive X-ray Absorption Fine Structure) analysis in the ESRF (European Synchrotron Radiation Facility) made clear the self-regeneration mechanism of the Pd Perovskite Oxide. This knowledge could lead to the practical development of the Rh and Pt systems. The catalyst technology is counted on balancing resources of the noble metal and environmental sustainability. (A.H.)

Solvent Free Preparation of p-Cymene from Limonene Using Vietnamese Montmorillonite

DEFF Research Database (Denmark)

Nguyen, Thao-Tran Thi; Duus, Fritz; Le, Thach Ngoc

2013-01-01

p-Cymene, an important intermediate in industrial chemistry, has been prepared in good yields by thermally induced dehydrogenation of limonene under solvent-free reaction conditions using Vietnamese montmorillonite as an efficient green catalyst.......p-Cymene, an important intermediate in industrial chemistry, has been prepared in good yields by thermally induced dehydrogenation of limonene under solvent-free reaction conditions using Vietnamese montmorillonite as an efficient green catalyst....

First-Row-Transition Ion Metals(II-EDTA Functionalized Magnetic Nanoparticles as Catalysts for Solvent-Free Microwave-Induced Oxidation of Alcohols

Directory of Open Access Journals (Sweden)

Nuno M. R. Martins

2017-11-01

Full Text Available A series of first-row transition-metals combined with ethylenediamine tetraacetic acid (EDTA, as metal-based N,O-chelating ligands, at the surface of ferrite magnetic nanoparticles (MNPs was prepared by a co-precipitation method. Those EDTA functionalized MNPs with general formula Fe3O4@EDTA-M2+ [M = Mn2+ (1, Fe2+ (2, Co2+ (3, Ni2+ (4, Cu2+ (5 or Zn2+ (6] were characterized by FTIR (Fourier Transform Infrared spectroscopy, powder XRD (X-ray Diffraction, SEM (Scanning Electron Microscope, EDS (Energy Dispersive Spectrometer, VSM (Vibrating Sample Magnetometer and TGA (Thermal Gravity Analysis. The application of the magnetic NPs towards the microwave-assisted oxidation of several alcohol substrates in a solvent-free medium was evaluated. The influence of reaction parameters such as temperature, time, type of oxidant, and presence of organic radicals was investigated. This study demonstrates that these MNPs can act as efficient catalysts for the conversion of alcohols to the corresponding ketones or aldehydes with high selectivity and yields up to 99% after 2 h of reaction at 110 °C using t-BuOOH as oxidant. Moreover, they have the advantage of being magnetically recoverable catalysts that can be easily recycled in following runs.

Pt Nanostructures/N-Doped Carbon hybrid, an Efficient Catalyst for Hydrogen Evolution/Oxidation Reactions: Enhancing its Base Media Activity through Bifunctionality of the Catalyst.

Science.gov (United States)

Barman, Sudip; Kundu, Manas; Bhowmik, Tanmay; Mishra, Ranjit

2018-06-04

Design and synthesis of active catalyst for HER/HOR are important for the development of hydrogen based renewable technologies. We report synthesis of Pt nanostructures-N-doped carbon hybrid (Pt-(PtO2)-NSs/C) for HER/HOR applications. The HER activity of this Pt-(PtOx)-NSs/C catalyst is 4 and 6.5 times better than commercial Pt/C in acid and base. The catalyst exhibits a current density of 10 mA/cm2 at overpotentials of 5 and 51 mV with tafel slopes of 29 and 64mV/dec in in 0.5 M H2SO4 and 0.5 M KOH. This catalyst also showed superior HOR activity at all pH values. The HER/HOR activity of Pt-(PtOx)-NSs/C and PtOx-free Pt-Nanostructures/C (PtNSs/C) catalysts are comparable in acid. The presence of PtOx in Pt-(PtOx)-NSs/C makes this Pt-catalyst more HER/HOR active in base media. The activity of Pt-(PtOx)NSs/C catalyst is 5 fold higher than that of PtNSs/C catalyst in basic medium although their activity is comparable in acid. Hydrogen binding energy and oxophilicity are the two equivalent descriptors for HER/HOR in basic media. We propose a bi-functional mechanism for the enhanced alkaline HER/HOR activity of Pt(PtOx)-NSs/C catalyst. In bi-functional Pt-(PtOx)-NSs/C catalyst, PtOx provide an active site for OH- adsorption to form OHads which reacts with hydrogen intermediate (Hads), present at neighbouring Pt sites to form H2O leading to enhancement of HOR activity in basic medium This work may provide opportunity to develop catalysts for various renewable energy technologies. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Catalyst for Carbon Monoxide Oxidation

Science.gov (United States)

Davis, Patricia; Brown, Kenneth; VanNorman, John; Brown, David; Upchurch, Billy; Schryer, David; Miller, Irvin

2010-01-01

In many applications, it is highly desirable to operate a CO2 laser in a sealed condition, for in an open system the laser requires a continuous flow of laser gas to remove the dissociation products that occur in the discharge zone of the laser, in order to maintain a stable power output. This adds to the operating cost of the laser, and in airborne or space applications, it also adds to the weight penalty of the laser. In a sealed CO2 laser, a small amount of CO2 gas is decomposed in the electrical discharge zone into corresponding quantities of CO and O2. As the laser continues to operate, the concentration of CO2 decreases, while the concentrations of CO and O2 correspondingly increase. The increasing concentration of O2 reduces laser power, because O2 scavenges electrons in the electrical discharge, thereby causing arcing in the electric discharge and a loss of the energetic electrons required to boost CO2 molecules to lasing energy levels. As a result, laser power decreases rapidly. The primary object of this invention is to provide a catalyst that, by composition of matter alone, contains chemisorbed water within and upon its structure. Such bound moisture renders the catalyst highly active and very long-lived, such that only a small quantity of it needs to be used with a CO2 laser under ambient operating conditions. This object is achieved by a catalyst that consists essentially of about 1 to 40 percent by weight of one or more platinum group metals (Pt, Pd, Rh, Ir, Ru, Os, Pt being preferred); about 1 to 90 percent by weight of one or more oxides of reducible metals having multiple valence states (such as Sn, Ti, Mn, Cu, and Ce, with SnO2 being preferred); and about 1 to 90 percent by weight of a compound that can bind water to its structure (such as silica gel, calcium chloride, magnesium sulfate, hydrated alumina, and magnesium perchlorate, with silica gel being preferred). Especially beneficial results are obtained when platinum is present in the

Conical nano-structure arrays of Platinum cathode catalyst for enhanced cell performance in PEMFC (proton exchange membrane fuel cell)

International Nuclear Information System (INIS)

Khan, Aziz; Nath, Bhabesh Kumar; Chutia, Joyanti

2015-01-01

Conical nanostructure arrays of Pt (Platinum) as cathode catalyst are developed using a novel integrated plasma sputtering technique. The integration method involves successive deposition of Pt catalyst arrays one upon another maintaining a uniform time gap. Deposition by integrated approach results in the formation of dense arrays of Pt nanostructure as compared to continuous deposition. These high number density integrated arrays with low Pt loading of 0.10 mg cm −2 at the cathode provide enhanced performance compared to non-integrated cathode catalyst prepared by continuous deposition and standard commercial electrodes with Pt loadings of 1 mg cm −2 . The performance is compared on the basis of polarization curve measurements and the calculated power density values. PEM fuel cell with dual integrated cathode showed an improved power density of 0.90 W cm −2 , which is higher than continuously deposited cathode catalyst with maximum power density of 0.67 W cm −2 for the same Pt loading of 0.10 mg cm −2 . - Highlights: • Conical nanostructures with high number density are prepared by a novel integrated deposition technique. • Electrode with such catalyst shows maximum performance of 0.9 W cm −2 . • Integrated catalyst performs better than continuously prepared nanostructure catalyst.

Optimization of catalyst-free production of biodiesel from Ceiba pentandra (kapok) oil with high free fatty acid contents

International Nuclear Information System (INIS)

Ong, Lu Ki; Effendi, Chintya; Kurniawan, Alfin; Lin, Chun Xiang; Zhao, Xiu Song; Ismadji, Suryadi

2013-01-01

Catalyst-free biodiesel production from non-edible Ceiba pentandra (kapok) oil via supercritical methanol transesterification was demonstrated in this work. The supercritical transesterification experiments were performed in a batch reactor at temperatures of 250–350 °C, pressures of 10–18 MPa, reaction times of 120–600 s, and methanol to oil molar ratios of 15:1–35:1. Response surface methodology (RSM) and four-way analysis of variance (ANOVA) were applied for the design and optimization of the experiments with respect to temperature, pressure, reaction time, and molar ratio of methanol to oil simultaneously. The response (i.e., FAME yield) was fitted by a quadratic polynomial regression model using least square analysis in a five-level-four-factor central composite design (CCD). The optimum conditions were found as follows: methanol to oil molar ratio of 30:1, temperature of 322 °C, pressure of 16.7 MPa, and reaction time of 476 s with FAME (fatty acid methyl ester) yield of 95.5%. The significance of the reaction parameters toward FAME yield was in the order of methanol to oil molar ratio > reaction time > pressure > temperature. - Highlights: • Transesterification of non-edible kapok oil into biodiesel via a non-catalytic route. • Methanol to oil molar ratio, temperature, pressure, and reaction time were optimized. • Experimental design in a five-level-four-factor central composite design. • Application of quadratic polynomial model for fitting the response (FAME yield)

Process for Making a Noble Metal on Tin Oxide Catalyst

Science.gov (United States)

Davis, Patricia; Miller, Irvin; Upchurch, Billy

2010-01-01

To produce a noble metal-on-metal oxide catalyst on an inert, high-surface-area support material (that functions as a catalyst at approximately room temperature using chloride-free reagents), for use in a carbon dioxide laser, requires two steps: First, a commercially available, inert, high-surface-area support material (silica spheres) is coated with a thin layer of metal oxide, a monolayer equivalent. Very beneficial results have been obtained using nitric acid as an oxidizing agent because it leaves no residue. It is also helpful if the spheres are first deaerated by boiling in water to allow the entire surface to be coated. A metal, such as tin, is then dissolved in the oxidizing agent/support material mixture to yield, in the case of tin, metastannic acid. Although tin has proven especially beneficial for use in a closed-cycle CO2 laser, in general any metal with two valence states, such as most transition metals and antimony, may be used. The metastannic acid will be adsorbed onto the high-surface-area spheres, coating them. Any excess oxidizing agent is then evaporated, and the resulting metastannic acid-coated spheres are dried and calcined, whereby the metastannic acid becomes tin(IV) oxide. The second step is accomplished by preparing an aqueous mixture of the tin(IV) oxide-coated spheres, and a soluble, chloride-free salt of at least one catalyst metal. The catalyst metal may be selected from the group consisting of platinum, palladium, ruthenium, gold, and rhodium, or other platinum group metals. Extremely beneficial results have been obtained using chloride-free salts of platinum, palladium, or a combination thereof, such as tetraammineplatinum (II) hydroxide ([Pt(NH3)4] (OH)2), or tetraammine palladium nitrate ([Pd(NH3)4](NO3)2).

One-Pot Conversion of Epoxidized Soybean Oil (ESO into Soy-Based Polyurethanes by MoCl2O2 Catalysis

Directory of Open Access Journals (Sweden)

Vincenzo Pantone

2017-02-01

Full Text Available An innovative and eco-friendly one-pot synthesis of bio-based polyurethanes is proposed via the epoxy-ring opening of epoxidized soybean oil (ESO with methanol, followed by the reaction of methoxy bio-polyols intermediates with 2,6-tolyl-diisocyanate (TDI. Both synthetic steps, methanolysis and polyurethane linkage formation, are promoted by a unique catalyst, molybdenum(VI dichloride dioxide (MoCl2O2, which makes this procedure an efficient, cost-effective, and environmentally safer method amenable to industrial scale-up.

Practical, economical, and eco-friendly starch-supported palladium catalyst for Suzuki coupling reactions.

Science.gov (United States)

Baran, Talat

2017-06-15

In catalytic systems, the support materials need to be both eco friendly and low cost as well as having high thermal and chemical stability. In this paper, a novel starch supported palladium catalyst, which had these outstanding properties, was designed and its catalytic activity was evaluated in a Suzuki coupling reaction under microwave heating with solvent-free and mild reaction conditions. The starch supported catalyst gave remarkable reaction yields after only 5min as a result of the coupling reaction of the phenyl boronic acid with 23 different substrates, which are bearing aril bromide, iodide, and chloride. The longevity of the catalyst was also investigated, and the catalyst could be reused for 10 runs. The starch supported Pd(II) catalyst yielded remarkable TON (up to 25,000) and TOF (up to 312,500) values by using a simple, fast and eco-friendly method. In addition, the catalytic performance of the catalyst was tested against different commercial palladium catalysts, and the green starch supported catalyst had excellent selectivity. The catalytic tests showed that the novel starch based palladium catalyst proved to be an economical and practical catalyst for the synthesis of biaryl compounds. Copyright © 2017 Elsevier Inc. All rights reserved.

Studies on recycling and utilization of spent catalysts. Preparation of active hydrodemetallization catalyst compositions from spent residue hydroprocessing catalysts

Energy Technology Data Exchange (ETDEWEB)

Marafi, Meena; Stanislaus, Antony [Petroleum Refining Department, Petroleum Research and Studies Center, Kuwait Institute for Scientific Research, P.O. Box 24885, Safat (Kuwait)

2007-02-15

Spent catalysts form a major source of solid wastes in the petroleum refining industries. Due to environmental concerns, increasing emphasis has been placed on the development of recycling processes for the waste catalyst materials as much as possible. In the present study the potential reuse of spent catalysts in the preparation of active new catalysts for residual oil hydrotreating was examined. A series of catalysts were prepared by mixing and extruding spent residue hydroprocessing catalysts that contained C, V, Mo, Ni and Al{sub 2}O{sub 3} with boehmite in different proportions. All prepared catalysts were characterized by chemical analysis and by surface area, pore volume, pore size and crushing strength measurements. The hydrodesulfurization (HDS) and hydrodemetallization (HDM) activities of the catalysts were evaluated by testing in a high pressure fixed-bed microreactor unit using Kuwait atmospheric residue as feed. A commercial HDM catalyst was also tested under similar operating conditions and their HDS and HDM activities were compared with that of the prepared catalysts. The results revealed that catalyst prepared with addition of up to 40 wt% spent catalyst to boehmite had fairly high surface area and pore volume together with large pores. The catalyst prepared by mixing and extruding about 40 wt% spent catalyst with boehmite was relatively more active for promoting HDM and HDS reactions than a reference commercial HDM catalyst. The formation of some kind of new active sites from the metals (V, Mo and Ni) present in the spent catalyst is suggested to be responsible for the high HDM activity of the prepared catalyst. (author)

Selectivity and Activity of Iron Molybdate Catalysts in Oxidation of Methanol

OpenAIRE

Khalid Khazzal Hummadi; Karim H. Hassan; Phillip C.H. Mitchell

2009-01-01

The selectivity and activity of iron molybdate catalysts prepared by different methods are compared with those of a commercial catalyst in the oxidation of methanol to formaldehyde in a continuous tubular bed reactor at 200-350 oC (473-623 oK), 10 atm (1013 kPa), with a methanol-oxygen mixture fixed at 5.5% by volume methanol: air ratio. The iron(III) molybdate catalyst prepared by co-precipitation and filtration had a selectivity towards formaldehyde in methanol oxidation comparable with a c...

Silver-Copper Nanoalloy Catalyst Layer for Bifunctional Air Electrodes in Alkaline Media.

Science.gov (United States)

Wu, Xiaoqiang; Chen, Fuyi; Jin, Yachao; Zhang, Nan; Johnston, Roy L

2015-08-19

A carbon-free and binder-free catalyst layer composed of a Ag-Cu nanoalloy on Ni foam was used as the air cathode in a zinc-air battery for the first time. The Ag-Cu catalyst was prepared using pulsed laser deposition. The structures of the catalysts were found to consist of crystalline Ag-Cu nanoalloy particles with an average size of 2.58 nm embedded in amorphous Cu films. As observed in the X-ray photoelectron spectra, the Ag 3d core levels shifted to higher binding energies, whereas the Cu 2p core levels shifted to lower binding energies, indicating alloying of the silver and copper. Rotating disk electrode measurements indicated that the oxygen reduction reaction (ORR) proceeded through a four-electron pathway on the Ag50Cu50 and Ag90Cu10 nanoalloy catalysts in alkaline solution. Moreover, the catalytic activity of Ag50Cu50 in the ORR is more efficient than that of Ag90Cu10. By performing charge and discharge cycling measurements, the Ag50Cu50 catalyst layer was confirmed to have a maximum power density of approximately 86.3 mW cm(-2) and an acceptable cell voltage at 0.863 V for current densities up to 100 mA cm(-2) in primary zinc-air batteries. In addition, a round-trip efficiency of approximately 50% at a current density of 20 mA cm(-2) was also obtained in the test.

Catalyst-Free Synthesis of Hollow-Sphere-Like ZnO and Its Photoluminescence Property

Directory of Open Access Journals (Sweden)

Junye Cheng

2014-01-01

Full Text Available Hollow-sphere-like ZnO was successfully prepared by a facile combustion route at 950°C, and no external catalysts or additives were introduced. The morphology and structure of the hollow-sphere-like ZnO were characterized by X-ray diffraction (XRD, scanning electron microscopy (SEM, high-resolution transmission electron microscopy (HRTEM, and energy dispersive spectrometer (EDS. The possible growth mechanism was discussed in detail. In addition, the as-obtained hollow-sphere-like ZnO exhibited a strong green emission at 518 nm and a weak UV emission at 385 nm. We believe that the hollow-sphere-like ZnO material may be a good candidate for application in optical devices and catalyst systems.

Catalyst inks and method of application for direct methanol fuel cells

Science.gov (United States)

Zelenay, Piotr; Davey, John; Ren, Xiaoming; Gottesfeld, Shimshon; Thomas, Sharon C.

2004-02-24

Inks are formulated for forming anode and cathode catalyst layers and applied to anode and cathode sides of a membrane for a direct methanol fuel cell. The inks comprise a Pt catalyst for the cathode and a Pt--Ru catalyst for the anode, purified water in an amount 4 to 20 times that of the catalyst by weight, and a perfluorosulfonic acid ionomer in an amount effective to provide an ionomer content in the anode and cathode surfaces of 20% to 80% by volume. The inks are prepared in a two-step process while cooling and agitating the solutions. The final solution is placed in a cooler and continuously agitated while spraying the solution over the anode or cathode surface of the membrane as determined by the catalyst content.

Catalysts, methods of making catalysts, and methods of use

KAUST Repository

Renard, Laetitia; El Eter, Mohamad; Caps, Valerie; Basset, Jean-Marie

2014-01-01

Embodiments of the present disclosure provide for catalysts, methods of making catalysts, methods of using catalysts, and the like. In an embodiment, the method of making the catalysts can be performed in a single step with a metal nanoparticle precursor and a metal oxide precursor, where a separate stabilizing agent is not needed.

Catalysts, methods of making catalysts, and methods of use

KAUST Repository

Renard, Laetitia

2014-03-06

Embodiments of the present disclosure provide for catalysts, methods of making catalysts, methods of using catalysts, and the like. In an embodiment, the method of making the catalysts can be performed in a single step with a metal nanoparticle precursor and a metal oxide precursor, where a separate stabilizing agent is not needed.

Gas chromatography and silver-ion high-performance liquid chromatography analysis of conjugated linoleic acid isomers in free fatty acid form using sulphuric acid in methanol as catalyst.

Science.gov (United States)

Luna, Pilar; Juárez, Manuela; de la Fuente, Miguel Angel

2008-09-12

This study used GC and silver-ion HPLC to examine the effects of temperature and time on methylation of individual and mixtures of conjugated linoleic acid (CLA) isomers in free fatty acid form using sulphuric acid as catalyst. In the conditions tested (temperatures between 20 and 50 degrees C and times between 10 and 60 min) methylation was complete while avoiding isomerization of conjugated dienes and the formation of artefacts that could interfere with chromatographic determinations. An analytical method using solvent extraction of the lipids followed by selective elution of the free fatty acids from aminopropyl bonded phase columns and methylation with H(2)SO(4) in mild conditions was then applied to determine the CLA isomers in free fatty acid form in rumen fluid, and the results were evaluated.

Optimization of transesterification of rubber seed oil using heterogeneous catalyst calcium oxide

Science.gov (United States)

Inggrid, Maria; Kristanto, Aldi; Santoso, Herry

2015-12-01

Biodiesel is an alternative fuel manufactured with the help of alkali hydroxide catalyst through transesterification reaction of vegetable oil. This study aims to examine methods and the most suitable conditions for transesterification reaction producing biodiesel from crude rubber seed oil by varying process parameters such as the molar ratio of alcohol, CaO amount as the alkaline catalyst, and reaction time. The rubber seed oil has a high level of free fatty acid content, which means the use of homogenous alkaline catalyst gives some technological problems such as soap formation which leaded in difficulty in the separation and purification of the product. Calcium oxide (CaO) is one of the most favorable heterogeneous base catalysts because it's reusable, noncorrosive, and low cost. Pre-treatment was performed by acid esterification with H2SO4 as the catalyst to decrease the content of free fatty acid in the rubber seed oil, in this pretreatment process the 12% FFA of crude oil could be reduced to below 3% FFA. The product after esterification process was then transesterified by alkaline transesterification by varying process parameters to convert triglyceride into biodiesel. The study found that maximum curvature for biodiesel yield occurred at 9:1 molar ratio of alcohol, 5%w catalyst loading, and 3 hours reaction time. Design expert software is used to determine the optimum point from experimental data. The result showed that the optimum yield of methyl ester from transesterification was 73.5 % by mass with 0.69 degree of desirability. The yielded methyl ester was tested for its density, viscosity, acid number, and solubility to meet SNI requirement standards.

Tuning CNT Properties for Metal-Free Environmental Catalytic Applications

Directory of Open Access Journals (Sweden)

Raquel P. Rocha

2016-06-01

Full Text Available The application of carbon nanotubes (CNTs as metal-free catalysts is a novel approach for heterogeneous liquid phase catalytic systems. Textural and chemical modifications by liquid/gas phase or mechanical treatments, as well as solid state reactions, were successfully applied to obtain carbon nanotubes with different surface functionalities. Oxygen, nitrogen, and sulfur are the most common heteroatoms introduced on the carbon surface. This short-review highlights different routes used to develop metal-free carbon nanotube catalysts with enhanced properties for Advanced Oxidation Processes.

Understanding the Performance and Stability of Supported Ni-Co-Based Catalysts in Phenol HDO

Directory of Open Access Journals (Sweden)

Thuan M. Huynh

2016-11-01

Full Text Available Performances of bimetallic catalysts (Ni-Co supported on different acidic carriers (HZSM-5, HBeta, HY, ZrO2 and corresponding monometallic Ni catalysts in aqueous phase hydrodeoxygenation of phenol were compared in batch and continuous flow modes. The results revealed that the support acidity plays an important role in deoxygenation as it mainly controls the oxygen-removing steps in the reaction network. At the same time, sufficient hydrothermal stability of a solid catalyst is essential. Batch experiments revealed 10Ni10Co/HZSM-5 to be the best-performing catalyst in terms of conversion and cyclohexane yield. Complementary continuous runs provided more insights into the relationship between catalyst structure, efficiency and stability. After 24 h on-stream, the catalyst still reveals 100% conversion and a slight loss (from 100% to 90% in liquid hydrocarbon selectivity. The observed alloy of Co with Ni increased dispersion and stability of Ni-active sites, and combination with HZSM-5 resulted in a well-balanced ratio of metal and acid sites which promoted all necessary steps in preferred pathways. This was proved by studies of fresh and spent catalysts using various characterization techniques (N2 physisorption, X-ray diffraction (XRD, X-ray photoelectron spectroscopy (XPS, transmission electron microscopy (TEM and infrared spectroscopy of adsorbed pyridine (pyr-IR.

Single-Site Palladium(II) Catalyst for Oxidative Heck Reaction: Catalytic Performance and Kinetic Investigations

Energy Technology Data Exchange (ETDEWEB)

Duan, Hui; Li, Mengyang; Zhang, Guanghui; Gallagher, James R.; Huang, Zhiliang; Sun, Yu; Luo, Zhong; Chen, Hongzhong; Miller, Jeffrey T.; Zou, Ruqiang; Lei, Aiwen; Zhao, Yanli

2015-01-01

ABSTRACT: The development of organometallic single-site catalysts (SSCs) has inspired the designs of new heterogeneous catalysts with high efficiency. Nevertheless, the application of SSCs in certain modern organic reactions, such as C-C bond formation reactions, has still been less investigated. In this study, a single-site Pd(II) catalyst was developed, where 2,2'-bipyridine-grafted periodic mesoporous organosilica (PMO) was employed as the support of a Pd(II) complex. The overall performance of the single-site Pd(II) catalyst in the oxidative Heck reaction was then investigated. The investigation results show that the catalyst displays over 99% selectivity for the product formation with high reaction yield. Kinetic profiles further confirm its high catalytic efficiency, showing that the rate constant is nearly 40 times higher than that for the free Pd(II) salt. X-ray absorption spectroscopy reveals that the catalyst has remarkable lifetime and recyclability.

SYNTHESIS OF OXIMES WITH THE DOPED POTASSIUM FLUORIDE ANIMAL BONE MEAL AS A CATALYST

Directory of Open Access Journals (Sweden)

M. AIT TALEB

2017-12-01

Full Text Available The potassium fluoride doped Animal Bone Meal (KF/ABM was prepared and characterized using several techniques to identify the structural properties. After, it has been used as a new and eco-friendly catalyst for the preparation of from aldehydes and ketones oximes under solvent-free conditions. It is clearly shown that this reaction (using this catalyst can lead to the corresponding oximes in good yields (80 % to excellent yields (96 %. In the case of dissymmetric aldehydes and ketones, this catalyst can lead to a mixture of Z- and E- isomers (Z/E = 86/14–90/10. The remarkable advantages of this catalyst are high conversion, short reaction times, cleaner reaction profiles, reusability up to 8 times without significant loss of activity, and reduction in catalyst toxicity.

Deactivation-resistant catalyst for selective catalyst reduction of NOx

DEFF Research Database (Denmark)

2011-01-01

The present invention relates to a catalyst for selective catalytic reduction of NOx in alkali metal containing flue gas using ammonia as reductant, the catalyst comprising a surface with catalytically active sites, wherein the surface is at least partly coated with a coating comprising at least...... one metal oxide. In another aspect the present invention relates to the use of said catalyst and to a method of producing said catalyst. In addition, the present invention relates to a method of treating an catalyst for conferring thereon an improved resistance to alkali poisoning....

Ni2+ supported on hydroxyapatite-core@shell γ-Fe2O3 nanoparticles as new and green catalyst for the synthesis of 3,4-dihydropyrimidin-2(1H-ones under solvent-free condition

Directory of Open Access Journals (Sweden)

Eshagh Rezaee Nezhad

2013-10-01

Full Text Available The aim of this research is to study Ni2+ supported on hydroxyapatite-core-shell magnetic γ-Fe2O3 nanoparticles (γ-Fe2O3@HAp-Ni2+ as a green and recyclable catalyst for the Biginelli reaction under solvent-free conditions. One-pot multi-component condensation of 1,3-dicarbonyl compounds, urea and aldehydes at 80 oC affords the corresponding compounds in high yields and in short reaction times using γ-Fe2O3@HAp-Ni2+. The catalyst can be readily isolated using an external magnet and no obvious loss of activity was observed when the catalyst was reused in seven consecutive runs. The mean size and the surface morphology of the nanoparticles were characterized by transmission electron microscopy, scanning electron microscope, vibrating sample magnetometry, X-ray powder diffraction and Fourier transform infrared techniques.

In situ doping of catalyst-free InAs nanowires with Si: Growth, polytypism, and local vibrational modes of Si

Energy Technology Data Exchange (ETDEWEB)

Dimakis, Emmanouil; Ramsteiner, Manfred; Huang, Chang-Ning; Trampert, Achim; Riechert, Henning; Geelhaar, Lutz [Paul-Drude-Institut für Festkörperelektronik, Hausvogteiplatz 5-7, 10117 Berlin (Germany); Davydok, Anton; Biermanns, Andreas; Pietsch, Ullrich [Festkörperphysik, Universität Siegen, Walter-Flex-Str. 3, 57072 Siegen (Germany)

2013-09-30

Growth and structural aspects of the in situ doping of InAs nanowires with Si have been investigated. The nanowires were grown catalyst-free on Si(111) substrates by molecular beam epitaxy. The supply of Si influenced the growth kinetics, affecting the nanowire dimensions, but not the degree of structural polytypism, which was always pronounced. As determined by Raman spectroscopy, Si was incorporated as substitutional impurity exclusively on In sites, which makes it a donor. Previously unknown Si-related Raman peaks at 355 and 360 cm{sup −1} were identified, based on their symmetry properties in polarization-dependent measurements, as the two local vibrational modes of an isolated Si impurity on In site along and perpendicular, respectively, to the c-axis of the wurtzite InAs crystal.

Biodiesel fuel production from waste cooking oil using radiation-grafted fibrous catalysts

Science.gov (United States)

Ueki, Yuji; Saiki, Seiichi; Hoshina, Hiroyuki; Seko, Noriaki

2018-02-01

Waste cooking oil, which can be used as a raw material for biodiesel fuel (BDF), contains two kinds of oil components: triglycerides (TGs) and free fatty acids (FFAs). Therefore, both alkaline-type and acid-type catalysts are needed to produce BDF from waste cooking oil. In this study, an alkaline-type grafted fibrous catalyst bearing OH- ions was synthesized by radiation-induced emulsion grafting of 4-chloromethylstyrene onto a polyethylene-coated polypropylene (PE/PP) nonwoven fabric, amination with trimethylamine, and further treatment with NaOH. Furthermore, an acid-type catalyst bearing H+ ions was synthesized by radiation-induced emulsion grafting of ethyl p-styrenesulfonate onto a PE/PP nonwoven fabric, saponification with NaOH, and protonation with HNO3. The OH- and H+ densities of the grafted fibrous catalysts were controlled by the grafting yield. The maximum OH- and H+ densities of the catalysts were 3.6 mmol-OH-/g-catalyst and 3.4 mmol-H+/g-catalyst, respectively. The performances of the catalysts were evaluated in the batchwise transesterification of TGs and ethanol, and the batchwise esterification of FFAs and ethanol. In both cases, TGs and FFAs were gradually converted into BDF. The mixed oil and four actual waste cooking oils, which contained both TGs and FFAs, were completely converted into BDF by sequential catalytic reactions with the acid-type grafted fibrous catalyst and then the alkaline-type grafted fibrous catalyst.

Session 4: High-throughput screening of supported catalysts for CO{sub x}-free hydrogen production from ammonia

Energy Technology Data Exchange (ETDEWEB)

Hongchao, Liu; Hua, Wang; Zhongmin, Liu; Jianghan, Shen [Natural Gas Utilization and Applied Catalysis Laboratory, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, P. R. (China)

2004-07-01

In this paper, we used a multi-stream mass spectrometer screening (MSMSS) technique and a multi-stream reactor to select promising candidates from supported transition metal catalyst library, and then combinatorially nitrided and tested silica and SAB-15 supported Mo catalysts for hydrogen production from ammonia. (authors)

Magnetic nanoparticle supported phosphotungstic acid: An efficient catalyst for the synthesis of xanthene derivatives

Science.gov (United States)

Patel, Nipun; Katheriya, Deepak; Dadhania, Harsh; Dadhania, Abhishek

2018-05-01

Magnetic nanoparticle supported phosphotungstic acid (Fe3O4@SiO2-HPW) was applied as a highly efficient catalyst for the synthesis of 14H-dibenzoxanthene derivatives via condensation reaction of 2-naphthol and aryl aldehydes. The catalyst was found highly efficient for the synthesis of xanthene derivatives under solvent free condition. The catalyst showed high activity and stability during the reaction and provided excellent yield of the corresponding products in short reaction time. All the synthesized compounds were characterized through FT-IR, 1H-NMR and 13C-NMR spectroscopic techniques. Furthermore, the catalyst is magnetically recoverable and can be reused several times without significant loss of its catalytic activity.

Continuous proline catalysis via leaching of solid proline

Directory of Open Access Journals (Sweden)

Suzanne M. Opalka

2011-12-01

Full Text Available Herein, we demonstrate that a homogeneous catalyst can be prepared continuously via reaction with a packed-bed of a catalyst precursor. Specifically, we perform continuous proline catalyzed α-aminoxylations using a packed-bed of L-proline. The system relies on a multistep sequence in which an aldehyde and thiourea additive are passed through a column of solid proline, presumably forming a soluble oxazolidinone intermediate. This transports a catalytic amount of proline from the packed-bed into the reactor coil for subsequent combination with a solution of nitrosobenzene, affording the desired optically active α-aminooxy alcohol after reduction. To our knowledge, this is the first example in which a homogeneous catalyst is produced continuously using a packed-bed. We predict that the method will not only be useful for other L-proline catalyzed reactions, but we also foresee that it could be used to produce other catalytic species in flow.

Reactivation of a Tin-Oxide-Containing Catalyst

Science.gov (United States)

Hess, Robert; Sidney, Barry; Schryer, David; Miller, Irvin; Miller, George; Upchurch, Bill; Davis, Patricia; Brown, Kenneth

2010-01-01

The electrons in electric-discharge CO2 lasers cause dissociation of some CO2 into O2 and CO, and attach themselves to electronegative molecules such as O2, forming negative O2 ions, as well as larger negative ion clusters by collisions with CO or other molecules. The decrease in CO2 concentration due to dissociation into CO and O2 will reduce the average repetitively pulsed or continuous wave laser power, even if no disruptive negative ion instabilities occur. Accordingly, it is the primary object of this invention to extend the lifetime of a catalyst used to combine the CO and O2 products formed in a laser discharge. A promising low-temperature catalyst for combining CO and O2 is platinum on tin oxide (Pt/SnO2). First, the catalyst is pretreated by a standard procedure. The pretreatment is considered complete when no measurable quantity of CO2 is given off by the catalyst. After this standard pretreatment, the catalyst is ready for its low-temperature use in the sealed, high-energy, pulsed CO2 laser. However, after about 3,000 minutes of operation, the activity of the catalyst begins to slowly diminish. When the catalyst experiences diminished activity during exposure to the circulating gas stream inside or external to the laser, the heated zone surrounding the catalyst is raised to a temperature between 100 and 400 C. A temperature of 225 C was experimentally found to provide an adequate temperature for reactivation. During this period, the catalyst is still exposed to the circulating gas inside or external to the laser. This constant heating and exposing the catalyst to the laser gas mixture is maintained for an hour. After heating and exposing for an appropriate amount of time, the heated zone around the catalyst is allowed to return to the nominal operating temperature of the CO2 laser. This temperature normally resides in the range of 23 to 100 C. Catalyst activity can be measured as the percentage conversion of CO to CO2. In the specific embodiment

The synthesis of nanostructured, phase pure catalysts by hydrodynamic cavitation

Energy Technology Data Exchange (ETDEWEB)

Moser, W.R.; Sunstrom, J.E.; Marshik-Geurts, B.J. [Worcester Polytechnic Institute, Worcester, MA (United States)

1995-12-01

A new process for the synthesis of advanced catalytic materials based on performing the synthesis under hydrodynamic cavitation conditions has been discovered. This continuous process for catalyst synthesis resulted in the formation of both supported and unsupported catalysts. The advantage of the process over classical methods of synthesis is that it permits the formation of a wide variety of nanostructured catalysts in exceptionally high phase purities. The synthesis of platinum and palladium catalysts supported on alumina and other supports resulted in high dispersions of the noble metals. The synthesis of alpha, beta- and gamma-bismuth molybdates resulted in catalysts having superior phase purities as compared to several other classical methods of synthesis. The beta-bismuth molybdate was synthesized directly onto Cabosil. These studies showed that the particle size of the active component could be varied from a few manometers to much larger grains. The process enabled the synthesis of other complex metal oxides like perovskites as pure phases. The process uses a commercially available Microfluidizer.

A clean method for solvent-free nitration of toluene over sulfated titania promoted by ceria catalysts.

Science.gov (United States)

Mao, Wei; Ma, Hongzhu; Wang, Bo

2009-08-15

A mild simple method for nitration of aromatic compounds, various solid acids as catalysts, the air treated with the corona discharge generator as nitrating agent, the liquid-phase nitration of toluene, at ambient temperature and atmospheric pressure without solvent has been investigated. The results show that SO(4)(2-)/TiO(2) (ST) and SO(4)(2-)/TiO(2) doped with CeO(2) (STC) catalysts displayed good nitration activity in the experiments. It is an attractive method for the environmentally friendly synthesis of nitroaromatic compounds. Moreover, only mononitrotoluenes were detected in the products, and the ratio of para-nitrotoluene and ortho-nitrotoluene was approximately 1:1 with various catalysts. A maximum yield of about 11.4% was achieved for mononitrotoluenes in STC reaction system in 3h.

Performance characterization of hydrogen isotope exchange and recombination catalysts for tritium processing

International Nuclear Information System (INIS)

Suppiah, S.; Ryland, D.; Marcinkowska, K.; Boniface, H.; Everatt, A.

2010-01-01

AECL's hydrogen isotope exchange catalyst and recombination catalysts have been successfully applied to a wide range of industrial tritium-removal applications. The catalysts are used for Liquid Phase Catalytic Exchange (LPCE) and for gas-phase and trickle-bed recombination of hydrogen isotopes and have led to process simplification, improved safety and operational advantages. Catalyst performance design equations derived from laboratory testing of these catalysts have been validated against performance under industrial conditions. In a Combined Electrolysis and Catalytic Exchange (CECE) demonstration plant analyses of LPCE and recombiner efficiency were carried out as a function of catalyst activity over a wide range of operation. A steady-state process simulation used to model and design the hydrogen-water isotopic exchange processes, such as the CECE detritiation plant, was validated using the results of this demonstration. Catalyst development for isotope-exchange and recombination applications has continued over the last decade. As a result, significant improvements in catalyst performance have been achieved for these applications. This paper outlines the uniqueness of AECL's specialized catalysts and process designs for these applications with examples from laboratory and industrial case studies.

Two-Stage Conversion of High Free Fatty Acid Jatropha curcas Oil to Biodiesel Using Brønsted Acidic Ionic Liquid and KOH as Catalysts

Directory of Open Access Journals (Sweden)

Subrata Das

2014-01-01

Full Text Available 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.

Cost analysis of simulated base-catalyzed biodiesel production processes

International Nuclear Information System (INIS)

Tasić, Marija B.; Stamenković, Olivera S.; Veljković, Vlada B.

2014-01-01

Highlights: • Two semi-continuous biodiesel production processes from sunflower oil are simulated. • Simulations were based on the kinetics of base-catalyzed methanolysis reactions. • The total energy consumption was influenced by the kinetic model. • Heterogeneous base-catalyzed process is a preferable industrial technology. - Abstract: The simulation and economic feasibility evaluation of semi-continuous biodiesel production from sunflower oil were based on the kinetics of homogeneously (Process I) and heterogeneously (Process II) base-catalyzed methanolysis reactions. The annual plant’s capacity was determined to be 8356 tonnes of biodiesel. The total energy consumption was influenced by the unit model describing the methanolysis reaction kinetics. The energy consumption of the Process II was more than 2.5 times lower than that of the Process I. Also, the simulation showed the Process I had more and larger process equipment units, compared with the Process II. Based on lower total capital investment costs and biodiesel selling price, the Process II was economically more feasible than the Process I. Sensitivity analysis was conducted using variable sunflower oil and biodiesel prices. Using a biodiesel selling price of 0.990 $/kg, Processes I and II were shown to be economically profitable if the sunflower oil price was 0.525 $/kg and 0.696 $/kg, respectively

Outstanding low temperature HC-SCR of NOx over platinum-group catalysts supported on mesoporous materials expecting diesel-auto emission regulation

International Nuclear Information System (INIS)

Komatsu, Tamikuni; Tomokuni, Keizou; Yamada, Issaku

2006-01-01

Outstanding low temperature HC-SCR of NOx over platinum-group catalysts supported on mesoporous materials, which does not rely on the conventional NOx-absorption-reduction-catalysts, is presented for the purpose of de-NOx of diesel-auto emissions. The established catalysts basically consist of mesoporous silica or metal-substituted mesoporous silicates for supports and platinum for active species, which is operated under lean- and rich-conditions. The new catalysts are very active at 150-200 o C and free from difficult problems of SOx-deactivation and hydrothermal ageing of the NOx-absorption-reduction catalyst. (author)

Strontium cobaltite oxygen sponge catalyst and methods of use

Energy Technology Data Exchange (ETDEWEB)

Lee, Ho Nyung; Jeen, Hyoungjeen; Choi, Woo Seok; Biegalski, Michael; Folkman, Chad M.; Tung, I-Cheng; Fong, Dillon D.; Freeland, John W.; Shin, Dongwon; Ohta, Hiromichi; Chisholm, Matthew F.

2017-01-24

Rapid, reversible redox activity may be accomplished at significantly reduced temperatures, as low as about 200.degree. C., from epitaxially stabilized, oxygen vacancy ordered SrCoO.sub.2.5 and thermodynamically unfavorable perovskite SrCoO.sub.3-.delta.. The fast, low temperature redox activity in SrCoO.sub.3-.delta. may be attributed to a small Gibbs free energy difference between the two topotactic phases. Epitaxially stabilized thin films of strontium cobaltite provide a catalyst adapted to rapidly transition between oxidation states at substantially low temperatures. Methods of transitioning a strontium cobaltite catalyst from a first oxidation state to a second oxidation state are described.

Engelhard and IFP/Procatalyse set up worldwide catalysts venture

International Nuclear Information System (INIS)

Hunter, D.

1992-01-01

The new joint venture between Engelhard (Iselin, N) and Procatalyse (Paris), jointly owned by process licenser Institut Francais de Petrole (IFP; Rueil Malmaison, France) and Rhone-Poulenc (RP; Paris), marks the latest episode in the worldwide catalyst industry's restructuring. The operation will combine Engelhard's catalyst line, apart from its fluid catalytic cracking (FCC) and emission catalysts, with Procatalyse's offering. To be launched at the beginning of 1993, the venture will have annual sales of about $75 million. Reforming catalysts will be the biggest part of the venture's lineup at the outset, making it number three in the US, behind UOP - which dominates the sector - and Criterion. IFP is starting to establish a presence in North America with its reforming technology. But flat gasoline demand and reductions on aromatics in gasoline limit requirements for new reforming units, comments one competitor. Although lower sulfur specifications are putting some new demand into the hydrodesulfurization (HDS) catalyst market, both partners play down their prospects. The sector, whose leaders are Akzo and Crtierion, is continuing to suffer from severe overcapacity. Procatalyse's HDS business is mainly linked to IFP licensees, while Engelhard is due to mothball its Salt Lake City HDS catalyst plant by year-end, transferring output to Elyria

Enhanced protection of PDMS-embedded palladium catalysts by co-embedding of sulphide-scavengers.

Science.gov (United States)

Comandella, Daniele; Ahn, Min Hyung; Kim, Hojeong; Mackenzie, Katrin

2017-12-01

For Pd-containing hydrodechlorination catalysts, coating with poly(dimethyl siloxane) (PDMS) was proposed earlier as promising protection scheme against poisoning. The PDMS coating can effectively repel non-permeating poisons (such as SO 3 2- ) retaining the hydrodechlorination Pd activity. In the present study, the previously achieved protection efficiency was enhanced by incorporation of sulphide scavengers into the polymer. The embedded scavengers were able to bind permeating non-ionic poisons (such as H 2 S) during their passage through PDMS prior to Pd contact which ensured an extended catalyst lifetime. Three scavenger types forming non-permeable sulphur species from H 2 S - alkaline, oxidative or iron-based compounds - were either incorporated into single-layer coats around individual Pd/Al 2 O 3 particles or into a second layer above Pd-containing PDMS films (Pd-PDMS). Hydrodechlorination and hydrogenation were chosen as model reactions, carried out in batch and continuous-flow reactors. Batch tests with all scavenger-containing catalysts showed extended Pd protection compared to scavenger-free catalysts. Solid alkaline compounds (Ca(OH) 2 , NaOH, CaO) and MnO 2 showed the highest instantaneous scavenger efficiencies (retained Pd activity=30-60%), while iron-based catalysts, such as nano zero-valent iron (nZVI) or ferrocene (FeCp 2 ), proved less efficient (1-10%). When stepwise poisoning was applied, the protection efficiency of iron-based and oxidizing compounds was higher in the long term than that of alkaline solids. Long-term experiments in mixed-flow reactors were performed with selected scavengers, revealing the following trend of protection efficiency: CaO 2 >Ca(OH) 2 >FeCp 2 . Under field-simulating conditions using a fixed-bed reactor, the combination of sulphide pre-oxidation in the water phase by H 2 O 2 and local scavenger-enhanced Pd protection was successful. The oxidizing agent H 2 O 2 does not disturb the Pd-catalysed reduction, while the

Layered double hydroxide catalyst for the conversion of crude vegetable oils to a sustainable biofuel

Science.gov (United States)

Mollaeian, Keyvan

Over the last two decades, the U.S. has developed the production of biodiesel, a mixture of fatty acid methyl esters, using chiefly vegetable oils as feedstocks. However, there is much concern about the availability of high-quality vegetable oils for longterm biodiesel production. Problems have also risen due to the production of glycerol, an unwanted byproduct, as well as the need for process wash water. Therefore, this study was initiated to produce not only fatty acid methyl esters (FAMEs) but also fatty acid glycerol carbonates (FAGCs) by replacing methanol with dimethyl carbonate (DMC). The process would have no unnecessary byproducts and would be a simplified process compared to traditional biodiesel. In addition, this altering of the methylating agent could convert triglycerides, free fatty acids, and phospholipids to a sustainable biofuel. In this project, Mg-Al Layered Double Hydroxide (LDH) was optimized by calcination in different temperature varied from 250°C to 450°C. The gallery between layers was increased by intercalating sodium dodecylsulfate (SDS). During catalyst preparation, the pH was controlled ~10. In our experiment, triazabicyclodecene (TBD) was attached with trimethoxysilane (3GPS) as a coupling agent, and N-cetyl-N,N,N-trimethylammonium bromide (CTAB) was added to remove SDS from the catalyst. The catalyst was characterized by XRD, FTIR, and Raman spectroscopy. The effect of the heterogeneous catalyst on the conversion of canola oil, corn oil, and free fatty acids was investigated. To analyze the conversion of lipid oils to biofuel an in situ Raman spectroscopic method was developed. Catalyst synthesis methods and a proposed mechanism for converting triglycerides and free fatty acids to biofuel will be presented.

An introduction to catalyst

International Nuclear Information System (INIS)

Jeon, Hak Je

1988-11-01

This book explains basic conception of catalyst such as definition, velocity of chemical reaction and velocity of catalyst reaction, absorption with absorption energy and chemical absorption, pore structure with the role of pore and measurement of pore structure, catalyst activity on solid structure, electrical property on catalyst activity, choice and design of catalyst, catalytic reaction with reaction velocity and chemical equilibrium and reaction velocity model, measurement of reaction velocity and material analysis, catalyst for mixed compound, catalyst for solid acid and catalyst for supported metal.

Selective methane chlorination to methyl chloride by zeolite Y-based catalysts

Science.gov (United States)

Joo, Hyeonho; Kim, Daeho; Lim, Kwang Soo; Choi, Yong Nam; Na, Kyungsu

2018-03-01

The CH4 chlorination over Y zeolites was investigated to produce CH3Cl in a high yield. Three different catalytic systems based on Y zeolite were tested for enhancement of CH4 conversion and CH3Cl selectivity: (i) HY zeolites in H+-form having various Si/Al ratios, (ii) Pt/HY zeolites supporting Pt metal nanoparticles, (iii) Pt/NaY zeolites in Na+-form supporting Pt metal nanoparticles. The reaction was carried out using the gas mixture of CH4 and Cl2 with the respective flow rates of 15 and 10 mL min-1 at 300-350 °C using a fixed-bed reactor under a continuous gas flow condition (gas hourly space velocity = 3000 mL g-1 h-1). Above the reaction temperature of 300 °C, the CH4 chlorination is spontaneous even in the absence of catalyst, achieving 23.6% of CH4 conversion with 73.4% of CH3Cl selectivity. Under sufficient supplement of thermal energy, Cl2 molecules can be dissociated to two chlorine radicals, which triggered the C-H bond activation of CH4 molecule and thereby various chlorinated methane products (i.e., CH3Cl, CH2Cl2, CHCl3, CCl4) could be produced. When the catalysts were used under the same reaction condition, enhancement in the CH4 conversion was observed. The Pt-free HY zeolite series with varied Si/Al ratios gave around 27% of CH4 conversion, but there was a slight decrease in CH3Cl selectivity with about 64%. Despite the difference in acidity of HY zeolites having different Si/Al ratios, no prominent effect of the Si/Al ratios on the catalytic performance was observed. This suggests that the catalytic contribution of HY zeolites under the present reaction condition is not strong enough to overcome the spontaneous CH4 chlorination. When the Pt/HY zeolite catalysts were used, the CH4 conversion reached further up to 30% but the CH3Cl selectivity decreased to 60%. Such an enhancement of CH4 conversion could be attributed to the strong catalytic activity of HY and Pt/HY zeolite catalysts. However, both catalysts induced the radical cleavage of Cl2

Mechanisms of catalytic activity in heavily coated hydrocracking catalysts

Energy Technology Data Exchange (ETDEWEB)

Millan, M.; Adell, C.; Hinojosa, C.; Herod, A.A.; Kandiyoti, R. [University of London Imperial College Science Technology & Medicine, London (United Kingdom). Dept. of Chemical Engineering

2008-01-15

Catalyst deactivation by coke deposition has a direct impact on the economic viability of heavy hydrocarbon upgrading processes, such as coal liquefaction and oil residue hydroprocessing. Coke deposition is responsible for rapid loss of catalytic activity and it mostly takes place in the early stages of hydrocracking. The effect of carbonaceous deposition on the catalytic activity of a chromium pillared montmorillonite has been studied in the present work. Its catalytic activity in hydrocracking a coal extract was evaluated based on the boiling point distributions of feed and products obtained by thermogravimetric analysis (TGA), and their characterisation by size exclusion chromatography (SEC) and UV-Fluorescence spectroscopy (UV-F). A large deposition on the catalyst was observed after two successive 2-hour long runs in which the catalyst recovered from the first run was reused in the second. The pillared clay retained its activity even though it showed high carbon loading, a large drop in surface area and complete apparent pore blockage. Some observations may contribute to explain this persistent catalytic activity. First, there is evidence suggesting the dynamic nature of the carbonaceous deposits, which continuously exchange material with the liquid, allowing catalytic activity to continue. Secondly, Scanning Electron Microscopy (SEM) on the used Cr montmorillonite has shown preferential deposition on some regions of the catalyst, which leaves a fraction of the surface relatively exposed. Finally, evidence from SEM coupled to X-ray microanalysis also suggest that deposits are thinner in areas where the active phase of the catalyst is present in higher concentrations. Hydrogenation on the active sites would make the deposits more soluble in the liquid cleaning of surrounding area from deposits.

Engineering Single-Atom Cobalt Catalysts toward Improved Electrocatalysis.

Science.gov (United States)

Wan, Gang; Yu, Pengfei; Chen, Hangrong; Wen, Jianguo; Sun, Cheng-Jun; Zhou, Hua; Zhang, Nian; Li, Qianru; Zhao, Wanpeng; Xie, Bing; Li, Tao; Shi, Jianlin

2018-04-01

The development of cost-effective catalysts to replace noble metal is attracting increasing interests in many fields of catalysis and energy, and intensive efforts are focused on the integration of transition-metal sites in carbon as noble-metal-free candidates. Recently, the discovery of single-atom dispersed catalyst (SAC) provides a new frontier in heterogeneous catalysis. However, the electrocatalytic application of SAC is still subject to several theoretical and experimental limitations. Further advances depend on a better design of SAC through optimizing its interaction with adsorbates during catalysis. Here, distinctive from previous studies, favorable 3d electronic occupation and enhanced metal-adsorbates interactions in single-atom centers via the construction of nonplanar coordination is achieved, which is confirmed by advanced X-ray spectroscopic and electrochemical studies. The as-designed atomically dispersed cobalt sites within nonplanar coordination show significantly improved catalytic activity and selectivity toward the oxygen reduction reaction, approaching the benchmark Pt-based catalysts. More importantly, the illustration of the active sites in SAC indicates metal-natured catalytic sites and a media-dependent catalytic pathway. Achieving structural and electronic engineering on SAC that promotes its catalytic performances provides a paradigm to bridge the gap between single-atom catalysts design and electrocatalytic applications. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Deactivation by carbon of iron catalysts for indirect liquefaction

Energy Technology Data Exchange (ETDEWEB)

Bartholomew, C.H.

1990-10-11

This report describes recent progress in a fundamental, three-year investigation of carbon formation and its effects on the activity and selectivity of promoted iron catalysts for Fischer-Tropsch (FT) synthesis, the objectives of which are: determine rates and mechanisms of carbon deactivation of unsupported Fe and Fe/K catalysts during CO hydrogenation over a range of CO concentrations, CO:H{sub 2} ratios, and temperatures; model the rates of deactivation of the same catalysts in fixed-bed reactors. During the thirteenth quarter design of software for a computer-automated reactor system to be used in the kinetic and deactivation studies was continued. Further progress was made toward the completion of the control language, control routines, and software for operating this system. Progress was also made on the testing of the system hardware and software. H{sub 2} chemisorption capacities and activity selectivity data were also measured for three iron catalysts promoted with 1% alumina. 47 refs., 8 figs., 1 tab.

Synthesis and characterization of hydrotalcite-hydroxyapatite material doped with carbon nanotubes and its application in catalysis of transesterification reaction

International Nuclear Information System (INIS)

Rodrigues, E.; Barros, T.; Pereira, C.; Almeida, O.; Brasil, H.; Reis, M.A L. dos

2018-01-01

The aim of this study was to synthesize and characterize hydrotalcite-hydroxyapatite (HTHAp) material doped with three different proportions (1, 5 and 15% w/w) of carbon nanotubes (NTC) in order to evaluate its potential as a heterogeneous catalyst in the soybean oil methanolysis reaction. The synthesis of the HTHAp material was performed by the co-precipitation method (10≤pH≤ 11) with ultrasonic homogenization and hydrothermal treatment at 80 °C. XRD, SEM/EDS, FT-IR, Raman, N 2 physisorption and TG/DTA were the characterization techniques performed. The sample HTHAp1NTC, doped at 1% w/w, was tested as a catalyst under two temperature conditions (180 and 240 °C), 4 h reaction time, 2.5% catalyst loading and alcohol:oil ratio of 12:1. Doping contributed to improve structural, morphological and thermal stability properties of HTHAp material. The yield results achieved 35.2% (180 °C) and 40.5% (240 °C) qualifying the HTHAp material doped with CNT as a potential catalyst in the transesterification reaction. (author)

Fischer-Tropsch Cobalt Catalyst Activation and Handling Through Wax Enclosure Methods

Science.gov (United States)

Klettlinger, Jennifer L. S.; Yen, Chia H.; Nakley, Leah M.; Surgenor, Angela D.

2016-01-01

Fischer-Tropsch (F-T) synthesis is considered a gas to liquid process which converts syn-gas, a gaseous mixture of hydrogen and carbon monoxide, into liquids of various hydrocarbon chain length and product distributions. Cobalt based catalysts are used in F-T synthesis and are the focus of this paper. One key concern with handling cobalt based catalysts is that the active form of catalyst is in a reduced state, metallic cobalt, which oxidizes readily in air. In laboratory experiments, the precursor cobalt oxide catalyst is activated in a fixed bed at 350 ?C then transferred into a continuous stirred tank reactor (CSTR) with inert gas. NASA has developed a process which involves the enclosure of active cobalt catalyst in a wax mold to prevent oxidation during storage and handling. This improved method allows for precise catalyst loading and delivery into a CSTR. Preliminary results indicate similar activity levels in the F-T reaction in comparison to the direct injection method. The work in this paper was supported by the NASA Fundamental Aeronautics Subsonics Fixed Wing Project.

PdRu/C catalysts for ethanol oxidation in anion-exchange membrane direct ethanol fuel cells

Science.gov (United States)

Ma, Liang; He, Hui; Hsu, Andrew; Chen, Rongrong

2013-11-01

Carbon supported PdRu catalysts with various Pd:Ru atomic ratios were synthesized by impregnation method, and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), electrochemical half-cell tests, and the anion-exchange membrane direct ethanol fuel cell (AEM-DEFC) tests. XRD results suggest that the PdRu metal exists on carbon support in an alloy form. TEM study shows that the bimetallic PdRu/C catalysts have slightly smaller average particle size than the single metal Pd/C catalyst. Lower onset potential and peak potential and much higher steady state current for ethanol oxidation in alkaline media were observed on the bimetallic catalysts (PdxRuy/C) than on the Pd/C, while the activity for ethanol oxidation on the pure Ru/C was not noticeable. By using Pd/C anode catalysts and MnO2 cathode catalysts, AEM-DEFCs free from the expensive Pt catalyst were assembled. The AEM DEFC using the bimetallic Pd3Ru/C anode catalyst showed a peak power density as high as 176 mW cm-2 at 80 °C, about 1.8 times higher than that using the single metal Pd/C catalyst. The role of Ru for enhancing the EOR activity of Pd/C catalysts is discussed.

Engineering New Catalysts for In-Process Elimination of Tars

Energy Technology Data Exchange (ETDEWEB)

Felix, Larry G. [Gas Technology Inst., Des Plaines, IL (United States)

2012-09-30

and integrated (bulk) catalysts via a glass-ceramic processing route which were shown to exhibit excellent catalytic activity and superior resistance to attrition deactivation. With the discovery of these active, robust, glass-based catalysts, and with the permission of the project officer, the investigation of waste-based materials as originally proposed for Task 3 and pilot-scale testing proposed in Task 5 were deferred indefinitely in favor of further investigation of the glass-ceramic based catalyst materials. This choice was justified in part because during FY 2006 and through FY 2007, funding restrictions imposed by congressional budget choices significantly reduced funding for DOE biomass-related projects. Funding for this project was limited to what had been authorized which slowed the pace of project work at GTI so that our project partners could continue in their work. Thereafter, project work was allowed to resume and with restored funding, the project continued and concentrated on the development and testing of glass-ceramic catalysts in bulk or supported formats. Work concluded with a final development devoted to increasing the surface area of glass-ceramic catalysts in the form of microspheres. Following that development, project reporting was completed and the project was concluded.

Methods and catalysts for making biodiesel from the transesterification and esterification of unrefined oils

Science.gov (United States)

Yan, Shuli [Detroit, MI; Salley, Steven O [Grosse Pointe Park, MI; Ng, K Y. Simon [West Bloomfield, MI

2012-04-24

A method of forming a biodiesel product and a heterogeneous catalyst system used to form said product that has a high tolerance for the presence of water and free fatty acids (FFA) in the oil feedstock is disclosed. This catalyst system may simultaneously catalyze both the esterification of FAA and the transesterification of triglycerides present in the oil feedstock. The catalyst system according to one aspect of the present disclosure represents a class of zinc and lanthanum oxide heterogeneous catalysts that include different ratios of zinc oxide to lanthanum oxides (Zn:La ratio) ranging from about 10:0 to 0:10. The Zn:La ratio in the catalyst is believed to have an effect on the number and reactivity of Lewis acid and base sites, as well as the transesterification of glycerides, the esterification of fatty acids, and the hydrolysis of glycerides and biodiesel.

Mechanochemical synthesis of TiO2/NiFe2O4 magnetic catalysts for operation under RF field

International Nuclear Information System (INIS)

Houlding, Thomas K.; Gao, Pengzhao; Degirmenci, Volkan; Tchabanenko, Kirill; Rebrov, Evgeny V.

2015-01-01

Highlights: • Novel NiFe 2 O 4 –TiO 2 composite magnetic catalysts have been prepared by mechanochemical synthesis. • The synthesis time of 30 min provides the highest specific absorption rate (SAR) in RF heating. • Formation of NiTiO 3 phase during calcination decreases the SAR of the catalysts. • High stability of the NiFe 2 O 4 –TiO 2 catalyst was observed in a continuous amide bond synthesis under RF heating. - Abstract: Composite NiFe 2 O 4 –TiO 2 magnetic catalysts were prepared by mechanochemical synthesis from a mixture of titania supported nickel ferrite nanoparticles and P25 titania (Evonic). The former provides fast and efficient heating under radiofrequency field, while the latter serves as an active catalyst or catalyst support. The highest heating rate was observed over a catalyst prepared for a milling time of 30 min. The catalytic activity was measured over the sulfated composite catalysts in the condensation of aniline and 3-phenylbutyric acid in a stirred tank reactor and in a continuous RF heated flow reactor in the 140–170 °C range. The product yield of 47% was obtained over the sulfated P25 titania catalyst in the flow reactor

Oxidative dehydrogenation of ethane on rare-earth oxide-based catalysts

Energy Technology Data Exchange (ETDEWEB)

Buyevskaya, O.; Baerns, M. [Institut fuer Angewandte Chemie Berlin-Adlershof e.V., Berlin (Germany)

1998-12-31

Results on the oxidative dehydrogenation of ethane on rare-earth oxide (REO) based catalysts (Na-P-Sm-O, Sm-Sr(Ca)-O, La-Sr-O and Nd-Sr-O) are described. Oxygen adsorption was found to be a key factor which determines the activity of this type of catalysts. Continuous flow experiments in the presence of catalysts which reveal strong oxygen adsorption showed that the reaction mixture is ignited resulting in an enhanced heat generation at the reactor inlet. The heat produced by the oxidative reactions was sufficient under the conditions chosen for the endothermic thermal pyrolysis which takes place preferentially in the gas phase. Ignition of the reaction mixture is an important catalyst function. Contrary to non-catalytic oxidative dehydrogenation, reaction temperatures above 700 C could be achieved without significant external heat input. Ethylene yields of up to 34-45% (S=66-73%) were obtained on REO-based catalysts under non-isothermal conditions (T{sub max}=810-865 C) at contact times in the order of 30 to 40 ms. (orig.)

Polarity driven simultaneous growth of free-standing and lateral GaAsP epitaxial nanowires on GaAs (001) substrate

International Nuclear Information System (INIS)

Sun, Wen; Xu, Hongyi; Guo, Yanan; Gao, Qiang; Hoe Tan, Hark; Jagadish, Chennupati; Zou, Jin

2013-01-01

Simultaneous growth of 〈111〉 B free-standing and ±[110] lateral GaAsP epitaxial nanowires on GaAs (001) substrates were observed and investigated by electron microscopy and crystallographic analysis. It was found that the growth of both free-standing and lateral ternary nanowires via Au catalysts was driven by the fact that Au catalysts prefer to maintain low-energy (111) B interfaces with surrounding GaAs(P) materials: in the case of free-standing nanowires, Au catalysts maintain (111) B interfaces with their underlying GaAsP nanowires; while in the case of lateral nanowires, each Au catalyst remain their side (111) B interfaces with the surrounding GaAs(P) material during the lateral nanowire growth

Impeded solid state reactions and transformations in ceramic catalysts supports and catalysts

Directory of Open Access Journals (Sweden)

Ernő E. Kiss

2012-12-01

Full Text Available Impeded chemical reactions and impeded polymorphous transformation in materials are discussed, as desired effects, for stabilization of ceramic catalyst supports and ceramic based catalysts. This paper gives a short overview about the possibilities of slowing down the aging processes in ceramic catalyst supports and catalysts. Special attention is given to alumina and titania based catalysts.

High Performance and Cost-Effective Direct Methanol Fuel Cells: Fe-N-C Methanol-Tolerant Oxygen Reduction Reaction Catalysts.

Science.gov (United States)

Sebastián, David; Serov, Alexey; Artyushkova, Kateryna; Gordon, Jonathan; Atanassov, Plamen; Aricò, Antonino S; Baglio, Vincenzo

2016-08-09

Direct methanol fuel cells (DMFCs) offer great advantages for the supply of power with high efficiency and large energy density. The search for a cost-effective, active, stable and methanol-tolerant catalyst for the oxygen reduction reaction (ORR) is still a great challenge. In this work, platinum group metal-free (PGM-free) catalysts based on Fe-N-C are investigated in acidic medium. Post-treatment of the catalyst improves the ORR activity compared with previously published PGM-free formulations and shows an excellent tolerance to the presence of methanol. The feasibility for application in DMFC under a wide range of operating conditions is demonstrated, with a maximum power density of approximately 50 mW cm(-2) and a negligible methanol crossover effect on the performance. A review of the most recent PGM-free cathode formulations for DMFC indicates that this formulation leads to the highest performance at a low membrane-electrode assembly (MEA) cost. Moreover, a 100 h durability test in DMFC shows suitable applicability, with a similar performance-time behavior compared to common MEAs based on Pt cathodes. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The use of niobium based catalysts for liquid fuel production

Directory of Open Access Journals (Sweden)

Reguera Frank Martin

2004-01-01

Full Text Available The catalytic properties of niobium based catalysts were investigated in the conversion of oleic acid to liquid fuels at atmospheric pressure and at 623 K. The catalytic tests were performed in a fixed bed and continuous flow reactor using an acid to catalyst ratio equal to 4 and N2 as carrier gas. The reaction products were analyzed by gas chromatography and acidity measurements. NH3 temperature programmed desorption, N2 adsorption-desorption (BET method and Xray diffraction were also performed in order to determine the structural and acidic properties of the catalysts. From the catalytic tests, it was detected the formation of compounds in the range of gasoline, diesel and lubricant oils. Higher catalytic activity and selectivity for diesel fuel were observed for the catalysts NbOPO4 and H3PO4/Nb2O5 that possesses higher acidities and surface areas.

Carbon-supported cubic CoSe2 catalysts for oxygen reduction reaction in alkaline medium

International Nuclear Information System (INIS)

Feng Yongjun; Alonso-Vante, Nicolas

2012-01-01

Highlights: ► Cubic CoSe 2 a non-precious metal electrocatalyst for oxygen reduction in KOH. ► The catalyst shows four-electron transfer pathway in overall reaction. ► Catalyst has higher methanol tolerance than commercial Pt/C catalyst. - Abstract: A Carbon-supported CoSe 2 nanocatalyst has been developed as an alternative non-precious metal electrocatalyst for oxygen reduction reaction (ORR) in alkaline medium. The catalyst was prepared via a surfactant-free route and its electrocatalytic activity for the ORR has been investigated in detail in 0.1 M KOH electrolyte at 25 °C using rotating disk electrode (RDE) and rotating ring-disk electrode (RRDE) techniques. The prepared catalyst showed promising catalytic activity towards ORR in a four-electron transfer pathway and higher tolerance to methanol compared to commercial Pt/C catalyst in 0.1 M KOH. To some extent, the increase of CoSe 2 loading on the electrode favors a faster reduction of H 2 O 2 intermediate to H 2 O.

Synthesis, characterization and application of a nano-manganese-catalyst as an efficient solid catalyst for solvent free selective oxidation of ethylbenzene, cyclohexene, and benzylalcohol

Science.gov (United States)

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.

Catalyst support structure, catalyst including the structure, reactor including a catalyst, and methods of forming same

Science.gov (United States)

Van Norman, Staci A.; Aston, Victoria J.; Weimer, Alan W.

2017-05-09

Structures, catalysts, and reactors suitable for use for a variety of applications, including gas-to-liquid and coal-to-liquid processes and methods of forming the structures, catalysts, and reactors are disclosed. The catalyst material can be deposited onto an inner wall of a microtubular reactor and/or onto porous tungsten support structures using atomic layer deposition techniques.

Ruthenium Dioxide Catalysts for the Selective Oxidation of Benzylamine to Benzonitrile: Investigating the Effect of Ruthenium Loading on Physical and Catalytic Properties

DEFF Research Database (Denmark)

Nordvang, Emily Catherine; Schill, Leonhard; Riisager, Anders

2017-01-01

The oxidative dehydrogenation of benzylamine to benzonitrile was studied in batch and continuous flow processes using ruthenium dioxide catalysts with varying ruthenium loadings. Increased conversions were observed in the continuous flow process compared with the batch process (up to 100% in the ......The oxidative dehydrogenation of benzylamine to benzonitrile was studied in batch and continuous flow processes using ruthenium dioxide catalysts with varying ruthenium loadings. Increased conversions were observed in the continuous flow process compared with the batch process (up to 100......% in the flow process compared with up to 92% in the batch process), with increased selectivity to benzonitrile (82 and 65%, respectively) and benzonitrile yields (84 and 58%, respectively). The major by-product was N-benzylidenebenzylamine. The ruthenium loading in the catalyst was successfully optimised...... and the most active catalyst had a ruthenium loading of 2.5-3.5 wt%....

Hydrogen evolution by a metal-free electrocatalyst

KAUST Repository

Zheng, Yao

2014-04-28

Electrocatalytic reduction of water to molecular hydrogen via the hydrogen evolution reaction may provide a sustainable energy supply for the future, but its commercial application is hampered by the use of precious platinum catalysts. All alternatives to platinum thus far are based on nonprecious metals, and, to our knowledge, there is no report about a catalyst for electrocatalytic hydrogen evolution beyond metals. Here we couple graphitic-carbon nitride with nitrogen-doped graphene to produce a metal-free hybrid catalyst, which shows an unexpected hydrogen evolution reaction activity with comparable overpotential and Tafel slope to some of well-developed metallic catalysts. Experimental observations in combination with density functional theory calculations reveal that its unusual electrocatalytic properties originate from an intrinsic chemical and electronic coupling that synergistically promotes the proton adsorption and reduction kinetics. © 2014 Macmillan Publishers Limited. All rights reserved.

Determination of the stability constants for cobalt, nickel and palladium homogeneous catalyst complexes containing triphenylphosphine ligands

NARCIS (Netherlands)

Djekic, T.; Zivkovic, Z.; van der Ham, Aloysius G.J.; de Haan, A.B.

2006-01-01

Homogeneous catalysts are complex compounds that are always in equilibrium with their free metal, free ligand and other forms of complexes. The ratios between different species are defined by the stability constants, which are influenced by different parameters such as the type of metal, ligand,

Alum as a Catalyst for the Synthesis of Bispyrazole Derivatives

Directory of Open Access Journals (Sweden)

Mohammad Ali Zolfigol

2016-01-01

Full Text Available Compounds with pyrazolemoieties as nitrogen-containing heterocyclic systems have received attention owing to their diverse biological activities. Alum (KAl(SO42∙12H2O is an inexpensive, reusable and nontoxic catalyst used to synthesize 1H-pyrazole derivatives via the reaction of 3-methyl-1-phenyl-1H-pyrazol-5(4H-one and carbonyl compound under solvent-free conditions at 60 °C. The proposed method has been used for the preparation of 1H-pyrazole derivatives to yield green products for cleaning-in-place and to avoid toxic catalysts and hazardous solvents in accordance with the philosophy of sustainable chemistry.

Efficient room temperature oxidation of cyclohexane over highly active hetero-mixed WO3/V2O5 oxide catalyst

CSIR Research Space (South Africa)

Makgwane, PR

2014-09-01

Full Text Available catalytic activity to initiate the free-radical oxyfunctionalization of cyclohexane to afford up to 90% conversions within 6 h. The KA selectivity was found to depend on reaction time and the amount of catalyst. The WO(sub3)/V(sub2)O(sub5) catalyst...

Ionic Liquid as a Solvent and Catalyst for Acylation of Maltodextrin

Science.gov (United States)

Catalyst-free esterification of maltodextrin was carried out in ionic liquid. Stearate esters of maltodextrin were obtained in various degree of substitution (DS) when vinyl stearate or stearic acid was heated with maltodextrin in ionic liquid, 1-butyl-3-methylimidazolium cyanamide (bmim[dca]). Re...

Further studies on hydration of alkynes by the PtCl4-CO catalyst

Energy Technology Data Exchange (ETDEWEB)

Israelsohn, Osnat; Vollhardt, K. Peter C.; Blum, Jochanan

2002-01-18

Under CO atmosphere, between 80 and 120 C, a glyme solution of PtCl{sub 4} forms a carbonyl compound that promotes hydration of internal as well as terminal alkynes to give aldehyde-free ketones. The catalytic process depends strongly on the electronic and steric nature of the substrates. Part of the carbonyl functions of the catalyst can be replaced by phosphine ligands. Chiral DIOP reacts with the PtCl{sub 4}-CO compound to give a catalyst that promotes partial kinetic resolution of a racemic alkyne. Replacement of part of the CO by polystyrene-bound diphenylphosphine enables to attach the catalyst to the polymeric support. Upon entrapment of the platinum compound in a silica sol-gel matrix, it reacts as a partially recyclable catalyst. A reformulated mechanism for the PdCl{sub 4}-CO catalyzed hydration is suggested on the basis of the present study.

Cobalt oxide-based catalysts deposited by cold plasma for proton exchange membrane fuel cells

Energy Technology Data Exchange (ETDEWEB)

Kazimierski, P.; Jozwiak, L.; Sielski, J.; Tyczkowski, J., E-mail: jacek.tyczkowski@p.lodz.pl

2015-11-02

In proton exchange membrane fuel cells (PEMFC), both the anodic hydrogen oxidation reaction and the cathodic oxygen reduction reaction (ORR) require appropriate catalysts. So far, platinum-based catalysts are still the best option for this purpose. However, because these catalysts are too expensive for making commercially viable fuel cells, extensive research over the past decade has focused on developing noble metal-free alternative catalysts. In this paper, an approach based on cobalt oxide films fabricated by plasma-enhanced metal-organic chemical vapor deposition is presented. Such a material can be used to prepare catalysts for ORR in PEMFC. The films containing CoO{sub X} were deposited on a carbon paper thereby forming the electrode. Morphology and atomic composition of the films were investigated by scanning electron microscopy and energy-dispersive X-ray spectroscopy, respectively. The possibility of their application as the electro-catalyst for ORR in PEMFC was investigated and the electro-catalytic activities were evaluated by the electrochemical measurements and single cell tests. It was found that the fuel cell with Pt as the anode catalyst and CoO{sub X} deposit as the cathode catalyst was characterized by the open circuit voltage of 635 mV, Tafel slope of approx. 130 mV/dec and the maximum power density of 5.3 W/m{sup 2}. - Highlights: • Cobalt oxide catalyst for proton exchange membrane fuel cells was plasma deposited. • The catalyst exhibits activity for the oxygen reduction reaction. • Morphology and atomic composition of the catalyst were determined.

Continuous esterification for biodiesel production from palm fatty acid distillate using economical process

Energy Technology Data Exchange (ETDEWEB)

Chongkhong, S.; Tongurai, C.; Chetpattananondh, P. [Department of Chemical Engineering, Faculty of Engineering, Prince of Songkla University, Hat-Yai, Songkhla 90112 (Thailand)

2009-04-15

An overflow system for continuous esterification of palm fatty acid distillate (PFAD) using an economical process was developed using a continuous stirred tank reactor (CSTR). Continuous production compared to batch production at the same condition had higher product purity. The optimum condition for the esterification process was a 8.8:1:0.05 molar ratio of methanol to PFAD to sulfuric acid catalyst, 60 min of residence time at 75 C under its own pressure. The free fatty acid (FFA) content in the PFAD was reduced from 93 to less than 1.5%wt by optimum esterification. The esterified product had to be neutralized with 10.24%wt of 3 M sodium hydroxide in water solution at a reaction temperature of 80 C for 20 min to reduce the residual FFA and glycerides. The components and properties of fatty acid methyl ester (FAME) could meet the standard requirements for biodiesel fuel. Eventually the production costs were calculated to disclose its commercialization. (author)

Turbostratic carbon supported palladium as an efficient catalyst for reductive purification of water from trichloroethylene

Directory of Open Access Journals (Sweden)

Emil Kowalewski

2017-12-01

Full Text Available This work investigates the catalytic properties of turbostratic carbon supported Pd catalyst in hydrodechlorination of trichloroethylene (TCE HDC in aqueous phase. 1.57 wt% Pd/C was thoroughly characterized by BET, TPHD, CO chemisorption, PXRD, STEM, XPS and used as the catalyst in removal of trichloroethylene from drinking water in batch and continuous-flow reactors. The studies showed that catalytic performance of Pd/C depended on the hydrophobicity and textural properties of carbon support, which influenced noble metal dispersion and increased catalyst tolerance against deactivation by chlorination. Palladium in the form of uniformly dispersed small (~3.5 nm nanoparticles was found to be very active and stable in purification of water from TCE both in batch and continuous-flow operation.

Design of heterogeneous catalysts

DEFF Research Database (Denmark)

Frey, Anne Mette

was inspired by a computational screening, suggesting that alloys such as Ni-Fe, Co-Ni, and Co-Fe should show superior activity to the industrially used nickel catalyst. Especially the Ni-Fe system was considered to be interesting, since such alloy catalysts should be both more active and cheaper than the Ni...... catalyst. The results from the screening were experimentally verified for CO hydrogenation, CO2 hydrogenation, and simultaneous CO and CO2 hydrogenation by bimetallic Ni-Fe catalysts. These catalysts were found to be highly active and selective. The Co-Ni and Co-Fe systems were investigated for CO...... well, and the best catalyst prepared had a C5+ yield almost a factor of two higher than a standard air calcined Co catalyst. In the NH3-SCR reaction it is desirable to develop an active and stable catalyst for NOx removal in automotive applications, since the traditionally used vanadium-based catalyst...

STUDY ON THE CONCENTRATION EFFECT OF Nb2O5-ZAA CATALYST TOWARDS TOTAL CONVERSION OF BIODIESEL IN TRANSESTERIFICATION OF WASTED COOKING OIL

Directory of Open Access Journals (Sweden)

Astuti Tri Padmaningsih

2010-06-01

Full Text Available Study on the concentration effect of Nb2O5-ZAA catalyst towards total conversion of biodiesel has been conducted. The natural zeolite (ZA was activated by dipping in NH4Cl solution and was calcined using N2 atmosphere at 500 °C for 5h to produce the ZAA sample. The Nb2O5-ZAA catalyst was made by mixing the activated natural zeolite (ZAA, Nb2O5 3 % (w/w and oxalic acid 10 % (w/w solution, until the paste was formed, followed by drying and calcining the catalyst for 3 h at 500 °C under N2 atmosphere. Catalyst characterizations were conducted by measuring acidity with NH3 gas using gravimetric method and porosimetric analysis using N2 gas adsorption based on the BET equation by surface area analyzer instrument. The Nb2O5-ZAA catalyst was then used as an acid catalyst in free fatty acid esterification reaction of wasted cooking oil in methanol medium with variation of catalyst concentration: 1.25%; 2.5%; 3.75% and 5% towards the weight of oil+methanol. The reaction was continued by transesterification of triglyceride in the used cooking oil using NaOH catalyst in methanol medium. For comparison, the esterification reaction using H2SO4 catalyst 1.25% towards the weight of oil+methanol has been conducted as well. Methyl ester (biodiesel product was analyzed using Gas Chromatography (GC and Gas Chromatography-Mass Spectrometry (GC-MS. The characters of biodiesel were analyzed using American Society for Testing and Materials (ASTM method. The results showed that modification of ZAA by impregning Nb2O5 3% (w/w increased the total catalyst acidity from 5.00 mmol/g to 5.65 mmol/g. The Nb2O5-ZAA catalyst has specific surface area of 60.61 m2/g, total pore volume of 37.62x10-3 cc/g and average pore radius of 12.41 Å. The Nb2O5-ZAA catalyst with concentration of 1.25%-5% produced higher total conversion of biodiesel than that of H2SO4 catalyst 1.25%. The Nb2O5-ZAA catalyst with concentration of 3.75% produced the highest total conversion of biodiesel, i

A micro alkaline direct ethanol fuel cell with platinum-free catalysts

Science.gov (United States)

Verjulio, R. W.; Alcaide, F.; Álvarez, G.; Sabaté, N.; Torres-Herrero, N.; Esquivel, J. P.; Santander, J.

2013-11-01

This paper presents the fabrication and characterization of a micro alkaline direct ethanol fuel cell. The device has been conceived as a feasibility demonstrator, using microtechnologies for the fabrication of the current collectors and traditional techniques for the membrane electrode assembly production. The fuel cell works in passive mode, as expected for the simplicity required for micro power systems. Non-noble catalysts have been used in order to implement the main advantage of alkaline systems, showing the feasibility of such a device as a potential very-low-cost power device at mini- and micro scales.

Evaluation of the Optimal Reaction Conditions for the Methanolysis and Ethanolysis of Castor Oil Catalyzed by Immobilized Enzymes

DEFF Research Database (Denmark)

Andrade, Thalles Allan; Al-Kabalawi, Ibrahim F.; Errico, Massimiliano

:1 methanol-to-oil molar ratio, 5 wt% of enzymes, 7.5 wt% of water, 50 wt% n-hexane, at 50 °C. The fatty acid methyl esters content was 96.8 % and 1.0 % FFA. Regarding the reactions with ethanol, 98.0 % fatty acid ethyl ester was obtained and 1.3 % FFA, when the reaction was carried out at 60 °C, 4:1 ethanol......As an alternative to the use of chemical catalysts, immobilized enzyme Lipozyme 435 was evaluated as catalyst for biodiesel production, comparing its efficiency in the castor oil transesterification with methanol and ethanol. Different reaction conditions were assessed and optimized, including...... the reaction temperature (35 – 60 °C), alcohol-to-oil molar ratio (from 3:1 to 6:1), amount of catalyst (from 3 to 15 wt% by weight of oil), addition of water (0 – 15 wt%), and use of n-hexane as a solvent (0 – 75 wt%). For the transesterification with methanol, the optimal reaction conditions were 3...

Iron ore catalysts for methane decomposition to make CO x free hydrogen and carbon nano material

KAUST Repository

Zhou, Lu

2018-03-27

In this work, for the first time, iron ores with 91.7%–96.2% FeO, 1.3%–2.3% AlO, 1.2%–4.5% SiO, 1.3%–3.9% NaO, were studied directly as bulk catalysts for methane decomposition. By hydrogen pre-reduction at 850 °C, FeO species on iron ores were gradually reduced into FeO, FeO and then finally into Fe species. After reduction of 1.6 g of iron ore catalysts of 50 µm particle size with 100 mL/min pure H for 3.5 h at 850 °C, CMD life testing was conducted at 850 °C and GHSV of 3.75 L/g h and the catalyst showed a stable methane conversion for 5 h. When methane decomposition proceeded on Fe sites, FeC species would be formed to deposit graphite around themselves to finally form carbon nano onions. This carbon nano onions material showed excellent application for wastewater purification. All samples were fully characterized with XRF, XRD, H-TPR, TEM and Raman.

Pt-based Thin Films as Efficient and Stable Catalysts for Oxygen Electroreduction

DEFF Research Database (Denmark)

Zamburlini, Eleonora

at the cathode of Polymer Electrolyte Membrane Fuel Cells (PEMFCs). Herein the fabrication method, which consists of co-sputtering of thin films, is presented in detail, explaining the challenges one must face in order to fabricate oxygen-free Pt-lanthanides and Pt-early transition metals alloys......This thesis presents the fabrication and characterization of Pt-based thin film catalysts for Oxygen Reduction Reaction (ORR). Gadolinium and Yttrium have been used as alloying materials, in preparation for the replacement of the traditional but economically disadvantageous pure Pt catalysts......, and the proposed solutions. The characterization of the catalysts focused mainly on the electrochemical testing using a Rotating Ring Disk Electrode (RRDE) setup, and includes X-ray Diffraction (XRD), X-ray Photoemission Spectroscopy (XPS), Angle-Resolved X-ray Photoelectron Spectroscopy (AR-XPS), Scanning...

Fluorine-doped carbon nanotubes as an efficient metal-free catalyst for destruction of organic pollutants in catalytic ozonation.

Science.gov (United States)

Wang, Jing; Chen, Shuo; Quan, Xie; Yu, Hongtao

2018-01-01

Metal-free carbon materials have been presented to be potential alternatives to metal-based catalysts for heterogeneous catalytic ozonation, yet the catalytic performance still needs to be enhanced. Doping carbon with non-metallic heteroatoms (e.g., N, B, and F) could alter the electronic structure and electrochemical properties of original carbon materials, has been considered to be an effective method for improving the catalytic activity of carbon materials. Herein, fluorine-doped carbon nanotubes (F-CNTs) were synthesized via a facile method and characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. The as-synthesized F-CNTs exhibited notably enhanced catalytic activity towards catalytic ozonation for the degradation of organic pollutants. The oxalic acid removal efficiency of optimized F-CNTs was approximately two times as much as that of pristine CNTs, and even exceeded those of four conventional metal-based catalysts (ZnO, Al 2 O 3 , Fe 2 O 3 , and MnO 2 ). The XPS and Raman studies confirmed that the covalent CF bonds were formed at the sp 3 C sites instead of sp 2 C sites on CNTs, not only resulting in high positive charge density of C atoms adjacent to F atoms, but remaining the delocalized π-system with intact carbon structure of F-CNTs, which then favored the conversion of ozone molecules (O 3 ) into reactive oxygen species (ROS) and contributed to the high oxalic acid removal efficiency. Furthermore, electron spin resonance (ESR) studies revealed that superoxide radicals (O 2 - ) and singlet oxygen ( 1 O 2 ) might be the dominant ROS that responsible for the degradation of oxalic acid in these catalytic systems. Copyright © 2017 Elsevier Ltd. All rights reserved.

Highly dispersed metal catalyst

Science.gov (United States)

Xiao, Xin; West, William L.; Rhodes, William D.

2016-11-08

A supported catalyst having an atomic level single atom structure is provided such that substantially all the catalyst is available for catalytic function. A process of forming a single atom catalyst unto a porous catalyst support is also provided.

Hydroformylation and kinetics of 1-hexene over ruthenium, cobalt and rhodium zerolite catalysts

International Nuclear Information System (INIS)

Wang, C.; Wei, W.

1989-01-01

In this paper, six kinds of catalysts were prepared by cation exchange with rhodium, ruthenium and cobalt chloropentaamino dichoride and zeolites. Effects such as support materials, PPH 3 to metal ratio, reaction temperature, total pressure, H 2 /CO ratio, reaction time and solvents have been investigated in an autoclave. The most favorable results of 1-hexene hydroformylation were obtained in the temperature range 100-150 degrees C at a pressure of 5.0MPa (H 2 /CO=1:1) and the addition of free PPh 3 . The bimetallic catalysts showed high catalytic activing for hydroformylation because of the synergistic effect of bimetallic systems. This paper reports the results of experiments and catalysts characterization by means of IR and XRD spectroscopy

Efficient and Highly Selective Solvent-Free Oxidation of Primary Alcohols to Aldehydes Using Bucky Nanodiamond.

Science.gov (United States)

Lin, Yangming; Wu, Kuang-Hsu Tim; Yu, Linhui; Heumann, Saskia; Su, Dang Sheng

2017-09-11

Selective oxidation of alcohols to aldehydes is widely applicable to the synthesis of various green chemicals. The poor chemoselectivity for complicated primary aldehydes over state-of-the-art metal-free or metal-based catalysts represents a major obstacle for industrial application. Bucky nanodiamond is a potential green catalyst that exhibits excellent chemoselectivity and cycling stability for the selective oxidation of primary alcohols in diverse structures (22 examples, including aromatic, substituted aromatic, unsaturated, heterocyclic, and linear chain alcohols) to their corresponding aldehydes. The results are comparable to reported transition-metal catalysts including conventional Pt/C and Ru/C catalysts for certain substrates under solvent-free conditions. The possible activation process of the oxidant and substrates by the surface oxygen groups and defect species are revealed with model catalysts, ex situ electrochemical measurements, and ex situ attenuated total reflectance. The zigzag edges of sp 2 carbon planes are shown to play a key role in these reactions. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Evaluation of reaction mechanisms and the kinetic parameters for the transesterification of castor oil by liquid enzymes

DEFF Research Database (Denmark)

Andrade, Thalles Allan; Errico, Massimiliano; Christensen, Knud Villy

2017-01-01

of the transesterification of castor oil with methanol using the enzyme Eversa® Transform as catalyst were investigated. Reactions were carried out for 8 hours at 35 °C with: an alcohol-to-oil molar ratio equal to 6:1, a 5 wt% of liquid enzyme solution and addition of 5 wt% of water by weight of castor oil. From...... methanolysis rates of glycerides obtained, indicated that transesterification dominates over hydrolysis. The mechanism among the four models proposed that gave the best fit could be simplified, eliminating the kinetic parameters with negligible effects on the reaction rates. This model was able to fit...

Nanoporous magnesium aluminometasilicate tablets for precise, controlled, and continuous dosing of chemical reagents and catalysts

DEFF Research Database (Denmark)

Ruhland, T.; Nielsen, S.D.; Holm, P.

2007-01-01

Mechanically robust tablets of nanoporous magnesium aluminometasilicate with high surface area and porosity can be loaded with a variety of organic and inorganic reagents and catalysts. The scope of this novel dosing methodology is demonstrated through the evaluation of 14 diverse organic reactions...

Effect of coke and catalyst structure on oxidative regeneration of hydroprocessing catalysts

Energy Technology Data Exchange (ETDEWEB)

Furimsky, E. (CANMET, Ottawa, ON (Canada). Energy Research Laboratories)

1991-04-01

Two industrial hydroprocessing catalysts used for upgrading an atmospheric residue and a gas oil, respectively were regenerated in a fixed bed using air and 2 vol.% O{sub 2}+N{sub 2} balance mixture. The regeneration in air resulted in a significant sintering of the catalyst's material. The surface area of catalysts regenerated in 2 vol.% O{sub 2} mixture was similar to that of fresh catalysts, whereas a significant loss of surface area was observed after regeneration in air. The X-ray diffraction pattern of catalysts regenerated in 2 vol.% O{sub 2}+N{sub 2} balance mixture was also similar to that of fresh catalysts. 22 refs., 9 figs., 7 tabs.

Hydroprocessing catalyst development

Energy Technology Data Exchange (ETDEWEB)

Boorman, P.M.; Kydd, R.A.; Sorensen, T.S.; Chong, K.; Lewis, J.

1992-08-01

Co-Mo and Ni-Mo hydroprocessing catalysts were examined for their activity in removal of sulfur from thiophene in model compounds, and in the cracking and hydrocracking of cumene. Three types of support materials were examined: carbon, modified carbon, and carbon covered alumina. The objective of the study was to examine the correlation between catalyst activity in the hydrodenitrogenation of model compounds, and the resistance of the catalyst to nitrogen poisoning during use in the hydroprocessing of gas oils. The use of model compound testing provided information on the individual catalytic reactions promoted by those materials. Infrared spectroscopy was used to study surface species on the catalysts and to explain many of the trends in activity observed, revealing the role of fluoride and phosphorus as a secondary promoter. Testing of the catalysts in hydrotreating of gas oils allowed comparison of model compound results with those from a real feedstock. The gas oil was also spiked with a model nitrogen compound and the results from catalytic hydrotreating of this material were compared with those from unspiked material. A key finding was that the carbon supported catalysts were the most effective in treating high-nitrogen feeds. The very favorable deactivation properties of carbon and carbon-covered alumina supported catalysts make these promising from an industrial point of view where catalyst deactivation is a limiting factor. 171 refs., 25 figs., 43 tabs.

Palm Frond and Spikelet as Environmentally Benign Alternative Solid Acid Catalysts for Biodiesel Production

Directory of Open Access Journals (Sweden)

Yahaya Muhammad Sani

2015-04-01

Full Text Available A carbonization-sulfonation method was utilized in synthesizing sulfonated mesoporous catalysts from palm tree biomass. Brunauer-Emmet-Teller (BET, powder X-ray diffraction (XRD, energy dispersive X-ray (EDX, and field emission scanning emission microscopy (FE-SEM analyses were used to evaluate the structural and textural properties of the catalysts. Further, Fourier transform infrared (FT-IR spectroscopy and titrimetric analyses measured the strong acid value and acidity distribution of the materials. These analyses indicated that the catalysts had large mesopore volume, large surface area, uniform pore size, and high acid density. The catalytic activity exhibited by esterifying used frying oil (UFO containing high (48% free fatty acid (FFA content further indicated these properties. All catalysts exhibited high activity, with sPTS/400 converting more than 98% FFA into fatty acid methyl esters (FAMEs. The catalyst exhibited the highest acid density, 1.2974 mmol/g, determined by NaOH titration. This is outstanding considering the lower reaction parameters of 5 h, 5:1 methanol-to-oil ratio, and a moderate temperature range between 100 and 200 °C. The study further illustrates the prospect of converting wastes into highly efficient, benign, and recyclable solid acid catalysts.

Transfer-free graphene synthesis on sapphire by catalyst metal agglomeration technique and demonstration of top-gate field-effect transistors

International Nuclear Information System (INIS)

Miyoshi, Makoto; Arima, Yukinori; Kubo, Toshiharu; Egawa, Takashi; Mizuno, Masaya; Soga, Tetsuo

2015-01-01

Transfer-free graphene synthesis was performed on sapphire substrates by using the catalyst metal agglomeration technique, and the graphene film quality was compared to that synthesized on sputtered SiO 2 /Si substrates. Raman scattering measurements indicated that the graphene film on sapphire has better structural qualities than that on sputtered SiO 2 /Si substrates. The cross-sectional transmission microscopic study also revealed that the film flatness was drastically improved by using sapphire substrates instead of sputtered SiO 2 /Si substrates. These quality improvements seemed to be due the chemical and thermal stabilities of sapphire. Top-gate field-effect transistors were fabricated using the graphene films on sapphire, and it was confirmed that their drain current can be modulated with applied gate voltages. The maximum field-effect mobilities were estimated to be 720 cm 2 /V s for electrons and 880 cm 2 /V s for holes, respectively

Transfer-free graphene synthesis on sapphire by catalyst metal agglomeration technique and demonstration of top-gate field-effect transistors

Energy Technology Data Exchange (ETDEWEB)

Miyoshi, Makoto, E-mail: miyoshi.makoto@nitech.ac.jp; Arima, Yukinori; Kubo, Toshiharu; Egawa, Takashi [Research Center for Nano Device and Advanced Materials, Nagoya Institute of Technology, Nagoya 466-8555 (Japan); Mizuno, Masaya [Research Center for Nano Device and Advanced Materials, Nagoya Institute of Technology, Nagoya 466-8555 (Japan); Department of Frontier Materials, Nagoya Institute of Technology, Nagoya 466-8555 (Japan); Soga, Tetsuo [Department of Frontier Materials, Nagoya Institute of Technology, Nagoya 466-8555 (Japan)

2015-08-17

Transfer-free graphene synthesis was performed on sapphire substrates by using the catalyst metal agglomeration technique, and the graphene film quality was compared to that synthesized on sputtered SiO{sub 2}/Si substrates. Raman scattering measurements indicated that the graphene film on sapphire has better structural qualities than that on sputtered SiO{sub 2}/Si substrates. The cross-sectional transmission microscopic study also revealed that the film flatness was drastically improved by using sapphire substrates instead of sputtered SiO{sub 2}/Si substrates. These quality improvements seemed to be due the chemical and thermal stabilities of sapphire. Top-gate field-effect transistors were fabricated using the graphene films on sapphire, and it was confirmed that their drain current can be modulated with applied gate voltages. The maximum field-effect mobilities were estimated to be 720 cm{sup 2}/V s for electrons and 880 cm{sup 2}/V s for holes, respectively.

Magnetic properties of iron-based catalysts activated by various CO{sub 2} concentrations

Energy Technology Data Exchange (ETDEWEB)

Lim, Jung Tae; Kim, Chul Sung [Kookmin University, Seoul (Korea, Republic of); Chun, Dong Hyun; Park, Ji Chan [Korea Institute of Energy Research, Daejeon (Korea, Republic of)

2014-12-15

Fresh catalyst samples of 100Fe/5.26Cu/4.76K/18.2SiO{sub 2} in part per weight were synthesized by using a combination of a co-precipitation technique and spray-drying method and were activated in situ by using syngas (H{sub 2}/CO/xCO{sub 2}) with different amounts of CO{sub 2} (x = 0.0, 0.5, 1.0, and 2.0). All activated catalyst samples showed similar XRD patterns, a combination of ferrihydrite, magnetite, χ-carbide, and ε'-carbide, regardless of the CO{sub 2} contents. From the Moessbauer spectra, we also observed a combination of ferrihydrite, magnetite, χ-carbide, and ε'-carbide in all activated catalyst samples. The main compound of the activated catalyst sample activated by using CO{sub 2}-free syngas (H{sub 2}/CO) was magnetic χ-carbide, and the main compound changed from χ-carbide to ferrihydrite with increasing CO{sub 2} concentration, confirmed by both, Moessbauer spectra and XRD pattern.

Report of liquefaction catalyst study meeting (March 1996); Ekika shokubai kentokai hokoku

Energy Technology Data Exchange (ETDEWEB)

NONE

1996-03-01

Studied in the research are four iron-based catalysts, which are natural pyrite, synthetic iron sulfide, synthetic iron hydroxide, and catalyst-attached carbon. Tanito Harum coal is treated in a 0.01t/d-capable continuous operation furnace (once-through) under conditions of 450 degrees C and 170kgf/cm{sup 2} with catalyst addition of 1.0, 3.0wt% (catalyst-attached carbon 0.6, 1.0wt%), and a liquid yield of 41.5-48.6wt%-daf coal is achieved. A higher yield results when more catalyst is added. The same yield as achieved by the addition of 3wt% natural pyrite is obtained by the addition of 1.9wt% synthetic iron sulfide, 1.5wt% of synthetic iron hydroxide, or 0.7wt% catalyst-attached coal. The catalyst cost for treating a ton of coal is 4-9 hundred yen, which is far more expensive than the cost set forth as the target. Catalysts whose production process embodiment is now under study are natural pyrite and synthetic iron sulfide, and studies for others are just preliminary. Provided that the practical application of the liquefaction technology realizes in about 2000, then the petroleum price is predicted to be 23 dollars per barrel. Coal liquefaction products will have to be produced at a cost which will enable competition with the said petroleum price. (NEDO)

High-throughput heterogeneous catalyst research

Science.gov (United States)

Turner, Howard W.; Volpe, Anthony F., Jr.; Weinberg, W. H.

2009-06-01

With the discovery of abundant and low cost crude oil in the early 1900's came the need to create efficient conversion processes to produce low cost fuels and basic chemicals. Enormous investment over the last century has led to the development of a set of highly efficient catalytic processes which define the modern oil refinery and which produce most of the raw materials and fuels used in modern society. Process evolution and development has led to a refining infrastructure that is both dominated and enabled by modern heterogeneous catalyst technologies. Refineries and chemical manufacturers are currently under intense pressure to improve efficiency, adapt to increasingly disadvantaged feedstocks including biomass, lower their environmental footprint, and continue to deliver their products at low cost. This pressure creates a demand for new and more robust catalyst systems and processes that can accommodate them. Traditional methods of catalyst synthesis and testing are slow and inefficient, particularly in heterogeneous systems where the structure of the active sites is typically complex and the reaction mechanism is at best ill-defined. While theoretical modeling and a growing understanding of fundamental surface science help guide the chemist in designing and synthesizing targets, even in the most well understood areas of catalysis, the parameter space that one needs to explore experimentally is vast. The result is that the chemist using traditional methods must navigate a complex and unpredictable diversity space with a limited data set to make discoveries or to optimize known systems. We describe here a mature set of synthesis and screening technologies that together form a workflow that breaks this traditional paradigm and allows for rapid and efficient heterogeneous catalyst discovery and optimization. We exemplify the power of these new technologies by describing their use in the development and commercialization of a novel catalyst for the

Silica-supported (nBuCp)2ZrCl2: Effect of catalyst active center distribution on ethylene-1-hexene copolymerization

KAUST Repository

Atiqullah, Muhammad

2013-08-12

Metallocenes are a modern innovation in polyolefin catalysis research. Therefore, two supported metallocene catalysts-silica/MAO/(nBuCp)2ZrCl2 (Catalyst 1) and silica/nBuSnCl3/MAO/(nBuCp)2ZrCl2 (Catalyst 2), where MAO is methylaluminoxane-were synthesized, and subsequently used to prepare, without separate feeding of MAO, ethylene-1-hexene Copolymer 1 and Copolymer 2, respectively. Fouling-free copolymerization, catalyst kinetic stability and production of free-flowing polymer particles (replicating the catalyst particle size distribution) confirmed the occurrence of heterogeneous catalysis. The catalyst active center distribution was modeled by deconvoluting the measured molecular weight distribution and copolymer composition distribution. Five different active center types were predicted for each catalyst, which was corroborated by successive self-nucleation and annealing experiments, as well as by an extended X-ray absorption fine structure spectroscopy report published in the literature. Hence, metallocenes impregnated particularly on an MAO-pretreated support may be rightly envisioned to comprise an ensemble of isolated single sites that have varying coordination environments. This study shows how the active center distribution and the design of supported MAO anions affect copolymerization activity, polymerization mechanism and the resulting polymer microstructures. Catalyst 2 showed less copolymerization activity than Catalyst 1. Strong chain transfer and positive co-monomer effect-both by 1-hexene-were common. Each copolymer demonstrated vinyl, vinylidene and trans-vinylene end groups, and compositional heterogeneity. All these findings were explained, as appropriate, considering the modeled active center distribution, MAO cage structure repeat units, proposed catalyst surface chemistry, segregation effects and the literature that concerns and supports this study. While doing so, new insights were obtained. Additionally, future research, along the direction

Silica-supported (nBuCp)2ZrCl2: Effect of catalyst active center distribution on ethylene-1-hexene copolymerization

KAUST Repository

Atiqullah, Muhammad; Anantawaraskul, Siripon; Emwas, Abdul-Hamid M.; Al-Harthi, Mamdouh Ahmed; Hussain, Ikram; Ul-Hamid, Anwar; Hossaen, Anwar

2013-01-01

Metallocenes are a modern innovation in polyolefin catalysis research. Therefore, two supported metallocene catalysts-silica/MAO/(nBuCp)2ZrCl2 (Catalyst 1) and silica/nBuSnCl3/MAO/(nBuCp)2ZrCl2 (Catalyst 2), where MAO is methylaluminoxane-were synthesized, and subsequently used to prepare, without separate feeding of MAO, ethylene-1-hexene Copolymer 1 and Copolymer 2, respectively. Fouling-free copolymerization, catalyst kinetic stability and production of free-flowing polymer particles (replicating the catalyst particle size distribution) confirmed the occurrence of heterogeneous catalysis. The catalyst active center distribution was modeled by deconvoluting the measured molecular weight distribution and copolymer composition distribution. Five different active center types were predicted for each catalyst, which was corroborated by successive self-nucleation and annealing experiments, as well as by an extended X-ray absorption fine structure spectroscopy report published in the literature. Hence, metallocenes impregnated particularly on an MAO-pretreated support may be rightly envisioned to comprise an ensemble of isolated single sites that have varying coordination environments. This study shows how the active center distribution and the design of supported MAO anions affect copolymerization activity, polymerization mechanism and the resulting polymer microstructures. Catalyst 2 showed less copolymerization activity than Catalyst 1. Strong chain transfer and positive co-monomer effect-both by 1-hexene-were common. Each copolymer demonstrated vinyl, vinylidene and trans-vinylene end groups, and compositional heterogeneity. All these findings were explained, as appropriate, considering the modeled active center distribution, MAO cage structure repeat units, proposed catalyst surface chemistry, segregation effects and the literature that concerns and supports this study. While doing so, new insights were obtained. Additionally, future research, along the direction

Amberlyst-15: An Efficient and reusable heterogeneous catalyst for the synthesis of β-amino carbonyl compounds

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Pathakota Venkata Ramana

2015-12-01

Full Text Available A simple and efficient method has been developed for the synthesis of β-amino carbonyl compounds from aromatic ketones, aldehydes and amines by Mannich reaction in the presence of amberlyst-15 as a reusable heterogeneous catalyst at room temperature under solvent-free conditions. The noteworthy advantages of the present method are short reaction times, good product yields, simple procedures and use of non-toxic catalyst.

ZnAl2O4@SiO2 nanocomposite catalyst for the acetylation of alcohols, phenols and amines with acetic anhydride under solvent-free conditions

Institute of Scientific and Technical Information of China (English)

Saeed Farhadi; Kosar Jahanara

2014-01-01

A ZnAl2O4@SiO2 nanocomposite was prepared from metal nitrates and tetraethyl orthosilicate by the sol-gel process, and characterized by X-ray diffraction, Fourier transform infrared, transmission electron microscopy, and N2 adsorption-desorption measurements. The nanocomposite was tested as a heterogeneous catalyst for the acetylation of alcohols, phenols, and amines under solvent-free conditions. Under optimized conditions, efficient acetylation of these substrates with acetic anhy-dride over the ZnAl2O4@SiO2 nanocomposite was obtained. Acetylation of anilines and primary aliphatic amines proceeded rapidly at room temperature, while the reaction time was longer for the acetylation of alcohols and phenols, showing that an amine NH2 group can be selectively acetylated in the presence of alcoholic or phenolic OH groups. The catalyst can be reused without obvious loss of catalytic activity. The catalytic activity of the ZnAl2O4@SiO2 nanocomposite was higher than that of pure ZnAl2O4. The method gives high yields, and is clean, cost effective, compatible with sub-strates having other functional groups and it is suitable for practical organic synthesis.

Supported catalyst systems and method of making biodiesel products using such catalysts

Science.gov (United States)

Kim, Manhoe; Yan, Shuli; Salley, Steven O.; Ng, K. Y. Simon

2015-10-20

A heterogeneous catalyst system, a method of preparing the catalyst system and a method of forming a biodiesel product via transesterification reactions using the catalyst system is disclosed. The catalyst system according to one aspect of the present disclosure represents a class of supported mixed metal oxides that include at least calcium oxide and another metal oxide deposited on a lanthanum oxide or cerium oxide support. Preferably, the catalysts include CaO--CeO.sub.2ZLa.sub.2O.sub.3 or CaO--La.sub.2O.sub.3/CeO.sub.2. Optionally, the catalyst may further include additional metal oxides, such as CaO--La.sub.2O.sub.3--GdOxZLa.sub.2O.sub.3.

A micro alkaline direct ethanol fuel cell with platinum-free catalysts

International Nuclear Information System (INIS)

Verjulio, R W; Sabaté, N; Torres-Herrero, N; Esquivel, J P; Santander, J; Alcaide, F; Álvarez, G

2013-01-01

This paper presents the fabrication and characterization of a micro alkaline direct ethanol fuel cell. The device has been conceived as a feasibility demonstrator, using microtechnologies for the fabrication of the current collectors and traditional techniques for the membrane electrode assembly production. The fuel cell works in passive mode, as expected for the simplicity required for micro power systems. Non-noble catalysts have been used in order to implement the main advantage of alkaline systems, showing the feasibility of such a device as a potential very-low-cost power device at mini- and micro scales. (paper)

Continuous-flow Heck synthesis of 4-methoxybiphenyl and methyl 4-methoxycinnamate in supercritical carbon dioxide expanded solvent solutions

Directory of Open Access Journals (Sweden)

Phei Li Lau

2013-12-01

Full Text Available The palladium metal catalysed Heck reaction of 4-iodoanisole with styrene or methyl acrylate has been studied in a continuous plug flow reactor (PFR using supercritical carbon dioxide (scCO2 as the solvent, with THF and methanol as modifiers. The catalyst was 2% palladium on silica and the base was diisopropylethylamine due to its solubility in the reaction solvent. No phosphine co-catalysts were used so the work-up procedure was simplified and the green credentials of the reaction were enhanced. The reactions were studied as a function of temperature, pressure and flow rate and in the case of the reaction with styrene compared against a standard, stirred autoclave reaction. Conversion was determined and, in the case of the reaction with styrene, the isomeric product distribution was monitored by GC. In the case of the reaction with methyl acrylate the reactor was scaled from a 1.0 mm to 3.9 mm internal diameter and the conversion and turnover frequency determined. The results show that the Heck reaction can be effectively performed in scCO2 under continuous flow conditions with a palladium metal, phosphine-free catalyst, but care must be taken when selecting the reaction temperature in order to ensure the appropriate isomer distribution is achieved. Higher reaction temperatures were found to enhance formation of the branched terminal alkene isomer as opposed to the linear trans-isomer.

Down-conversion phosphors as noble-metal-free co-catalyst in ZnO for efficient visible light photocatalysis

Energy Technology Data Exchange (ETDEWEB)

Chu, Haipeng [Institute of Coordination Bond Metrology and Engineering, College of Materials Science and Engineering, China Jiliang University, Hangzhou 310018 (China); Liu, Xinjuan, E-mail: lxj669635@126.com [Institute of Coordination Bond Metrology and Engineering, College of Materials Science and Engineering, China Jiliang University, Hangzhou 310018 (China); Liu, Jiaqing [Engineering Research Center for Nanophotonics & Advanced Instrument, Ministry of Education, Department of Physics, East China Normal University, Shanghai 200062 (China); Lei, Wenyan [Institute of Coordination Bond Metrology and Engineering, College of Materials Science and Engineering, China Jiliang University, Hangzhou 310018 (China); Li, Jinliang [Engineering Research Center for Nanophotonics & Advanced Instrument, Ministry of Education, Department of Physics, East China Normal University, Shanghai 200062 (China); Wu, Tianyang [Institute of Coordination Bond Metrology and Engineering, College of Materials Science and Engineering, China Jiliang University, Hangzhou 310018 (China); Li, Ping [Shanghai Nanotechnology Promotion Center, Shanghai 200237 (China); Li, Huili; Pan, Likun [Engineering Research Center for Nanophotonics & Advanced Instrument, Ministry of Education, Department of Physics, East China Normal University, Shanghai 200062 (China)

2017-01-01

Graphical abstract: ZnO-Lu{sub 3}(Al,Si){sub 5}(O,N){sub 12}:Ce{sup 3+} hybrid photocatalysts were synthesized via a fast microwave-assisted approach for visible light photocatalytic degradation of organic pollutions with a high degradation rate of 91%. - Highlights: • ZnO-Lu{sub 3}(Al,Si){sub 5}(O,N){sub 12}:Ce{sup 3+} were synthesized via a facile microwave-assisted method. • Lu{sub 3}(Al,Si){sub 5}(O,N){sub 12}:Ce{sup 3+} acts as co-catalyst to facilitates the self-sensitized degradation of MB. • ZnO-Lu{sub 3}(Al,Si){sub 5}(O,N){sub 12}:Ce{sup 3+} exhibited enhanced visible light photocatalytic activity. • A high MB degradation rate of 91% was achieved under visible light irradiation. - Abstract: Exploring novel visible light responsive photocatalysts is one of greatly significant issues from the viewpoint of using solar energy. Here we report the yellow-orange emitting α-Si{sub 3}N{sub 4}-doped Lu{sub 3}Al{sub 5}O{sub 12}:Ce{sup 3+} (Lu{sub 3}Al{sub 5-x}Si{sub x}O{sub 12-x}N{sub x}:Ce{sup 3+}) phosphors as a noble-metal-free co-catalyst for enhanced visible light photocatalytic activity of ZnO. The results show that ZnO-Lu{sub 3}Al{sub 5-x}Si{sub x}O{sub 12-x}N{sub x}:Ce{sup 3+} hybrid photocatalysts using a fast microwave-assisted approach exhibits a 91% methylene blue (MB) degradation under visible light irradiation at 240 min, which evidence the synergistic effect of ZnO and Lu{sub 3}Al{sub 5-x}Si{sub x}O{sub 12-x}N{sub x}:Ce{sup 3+} that suppress the rate of charge recombination and increase the self-sensitized degradation of MB. ZnO-down conversion phosphors can be envisaged as potential candidate in environmental engineering and solar energy applications.

Monolitni katalizatori i reaktori: osnovne značajke, priprava i primjena (Monolith catalysts and reactors: preparation and applications

Directory of Open Access Journals (Sweden)

Tomašić, V.

2004-12-01

Full Text Available Monolithic (honeycomb catalysts are continuous unitary structures containing many narrow, parallel and usually straight channels (or passages. Catalytically active components are dispersed uniformly over the whole porous ceramic monolith structure (so-called incorporated monolithic catalysts or are in a layer of porous material that is deposited on the walls of channels in the monolith's structure (washcoated monolithic catalysts. The material of the main monolithic construction is not limited to ceramics but includes metals, as well. Monolithic catalysts are commonly used in gas phase catalytic processes, such as treatment of automotive exhaust gases, selective catalytic reduction of nitrogen oxides, catalytic removal of volatile organic compounds from industrial processes, etc. Monoliths continue to be the preferred support for environmental applications due to their high geometric surface area, different design options, low pressure drop, high temperature durability, mechanical strength, ease of orientation in a reactor and effectiveness as a support for a catalytic washcoat. As known, monolithic catalysts belong to the class of the structured catalysts and/or reactors (in some cases the distinction between "catalyst" and "reactor" has vanished. Structured catalysts can greatly intensify chemical processes, resulting in smaller, safer, cleaner and more energy efficient technologies. Monolith reactors can be considered as multifunctional reactors, in which chemical conversion is advantageously integrated with another unit operation, such as separation, heat exchange, a secondary reaction, etc. Finally, structured catalysts and/or reactors appear to be one of the most significant and promising developments in the field of heterogeneous catalysis and chemical engineering of the recent years. This paper gives a description of the background and perspectives for application and development of monolithic materials. Different methods and techniques

Aerobic Oxidation of Alcohols over Gold Catalysts: Role of Acid and Base

DEFF Research Database (Denmark)

Klitgaard, Søren Kegnæs; DeLa Riva, Andrew T.; Helveg, Stig

2008-01-01

Gold nanoparticles are deposited on potassium titanate nanowires and used as heterogeneous catalysts in the aerobic oxidation of benzyl alcohol in methanol to methyl benzoate at ambient conditions. The presence of a catalytic amount of base promotes the reaction and the formation of free benzoic...

Porous boron doped diamonds as metal-free catalysts for the oxygen reduction reaction in alkaline solution

Science.gov (United States)

Suo, Ni; Huang, Hao; Wu, Aimin; Cao, Guozhong; Hou, Xiaoduo; Zhang, Guifeng

2018-05-01

Porous boron doped diamonds (BDDs) were obtained on foam nickel substrates with a porosity of 80%, 85%, 90% and 95% respectively by hot filament chemical vapor deposition (HFCVD) technology. Scanning electron microscopy (SEM) reveals that uniform and compact BDDs with a cauliflower-like morphology have covered the overall frame of the foam nickel substrates. Raman spectroscopy shows that the BDDs have a poor crystallinity due to heavily doping boron. X-ray photoelectron spectroscopy (XPS) analysis effectively demonstrates that boron atoms can be successfully incorporated into the crystal lattice of diamonds. Electrochemical measurements indicate that the oxygen reduction potential is unaffected by the specific surface area (SSA), and both the onset potential and the limiting diffusion current density are enhanced with increasing SSA. It is also found that the durability and methanol tolerance of the boron doped diamond catalysts are attenuated as the increasing of SSA. The SSA of the catalyst is directly proportional to the oxygen reduction activity and inversely to the durability and methanol resistance. These results provide a reference to the application of porous boron doped diamonds as potential cathodic catalysts for the oxygen reduction reaction in alkaline solution by adjusting the SSA.

Synthesis of Acrolein from Glycerol Using FePO4 Catalyst in Liquid Phase Dehydration

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Akhmad Zainal Abidin

2016-02-01

Full Text Available Acrolein is currently produced using propylene from crude oil while its price and scarcity are increasing. A renewable material such as glycerol is an attractive alternative for acrolein production. It can be obtained from crude palm oil (CPO and is a byproduct of biodiesel production. Besides being able to compete economically, glycerol is an environmentally friendly material. The purpose of this study is to synthesize acrolein from glycerol using FePO4 catalyst in liquid phase dehydration. The catalyst was prepared by three different methods: hydrothermal (catalyst A, deposition at Fe/P = 1.15 (catalyst B, and deposition at Fe/P = 1.20 (catalyst C. The experimental reaction temperature was varied at 220, 240 and 260 °C under constant atmospheric pressure. The results showed that catalyst C provided the best yield (91%, followed by catalyst A (90% and catalyst B (82%. The increasing reaction temperature showed a tendency to increase the yield of acrolein, while the presence of oxygen reduced the yield of acrolein and allowed the reaction to produce more side products such as glycerol propanal, acetaldehyde, and propionate. Catalyst reuse without any regeneration resulted in a yield profile of acrolein that continued to decline.

Synthesis of Biodiesel in Batch and Packed-Bed Reactors Using Powdered and Granular Sugar Catalyst

Science.gov (United States)

Janaun, J.; Lim, P. M.; Balan, W. S.; Yaser, A. Z.; Chong, K. P.

2017-06-01

Increasing world production of palm oil warrants effective utilization of its waste. In particular, conversion of waste cooking oil into biodiesel has obtained global interest because of renewable energy need and reduction of CO2 emission. In this study, oleic acid used as a model compound for waste cooking oil conversion using esterification reaction catalysed by sugar catalyst (SC) in powdered (P-SC) and granular (G-SC) forms. The catalysts were synthesized via incomplete carbonization of D-glucose followed by functionalization with concentrated sulphuric acid. Catalysts characterizations were done for their physical and chemical properties using modern tools. Batch and packed-bed reactor systems were used to evaluate the reactivity of the catalysts. The results showed that G-SC had slightly higher total acidity and more porous than P-SC. The experimental conditions for batch reaction were temperature of 60°C, molar ratio of 1:20 (Oleic Acid:Methanol) and 2 wt. catalyst with respect to oleic acid. The results showed the maximum oleic acid conversion using G-SC and P-SC were 52 and 48, respectively. Whereas, the continuous reaction with varying feed flow rate as a function of retention time was studied by using 3 g of P-SC in 60 °C and 1:20 molar ratio in a packed-bed reactor. The results showed that a longer retention time which was 6.48 min and feed flow rate 1.38 ml/min, achieved higher average conversion of 9.9 and decreased with further increasing flow rate. G-SC showed a better average conversion of 10.8 at lowest feed flow rate of 1.38 ml/min in continuous reaction experiments. In a broader perspective, large scale continuous biodiesel production is feasible using granular over powdered catalyst mainly due to it lower pressure drop.

Effect of Gas Flowrate on Nucleation Mechanism of MWCNTs for a Compound Catalyst

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S. Shukrullah

2017-01-01

Full Text Available Activation of the catalyst particles during a CVD process can be anticipated from the carbon feeding rate. In this study, Fe2O3/Al2O3 catalyst was synthesized with uniformly dispersed iron over alumina support for onward production of multiwalled carbon nanotubes (MWCNTs in a fluidized bed chemical CVD reactor. The effect of the ethylene flowrate on catalytic activity of the compound catalyst and morphology of the as-grown MWCNTs was also investigated in this study. The dispersed active phases of the catalyst and optimized gas flowrate helped in improving the tube morphology and prevented the aggregation of the as-grown MWCNTs. The flowrates, below 100 sccm, did not provide sufficient reactants to interact with the catalyst for production of defect-free CNT structures. Above 100 sccm, concentration of the carbon precursor did not show notable influence on decomposition rate of the gas molecules. The most promising results on growth and structural properties of MWCNTs were gained at ethylene flowrate of 100 sccm. At this flowrate, the ratio of G and D intensity peaks (IG/ID was deliberated about 1.40, which indicates the growth of graphitic structures of MWCNTs.

Radio-Frequency-Controlled Urea Dosing for NH₃-SCR Catalysts: NH₃ Storage Influence to Catalyst Performance under Transient Conditions.

Science.gov (United States)

Dietrich, Markus; Hagen, Gunter; Reitmeier, Willibald; Burger, Katharina; Hien, Markus; Grass, Philippe; Kubinski, David; Visser, Jaco; Moos, Ralf

2017-11-28

Current developments in exhaust gas aftertreatment led to a huge mistrust in diesel driven passenger cars due to their NO x emissions being too high. The selective catalytic reduction (SCR) with ammonia (NH₃) as reducing agent is the only approach today with the capability to meet upcoming emission limits. Therefore, the radio-frequency-based (RF) catalyst state determination to monitor the NH₃ loading on SCR catalysts has a huge potential in emission reduction. Recent work on this topic proved the basic capability of this technique under realistic conditions on an engine test bench. In these studies, an RF system calibration for the serial type SCR catalyst Cu-SSZ-13 was developed and different approaches for a temperature dependent NH₃ storage were determined. This paper continues this work and uses a fully calibrated RF-SCR system under transient conditions to compare different directly measured and controlled NH₃ storage levels, and NH₃ target curves. It could be clearly demonstrated that the right NH₃ target curve, together with a direct control on the desired level by the RF system, is able to operate the SCR system with the maximum possible NO x conversion efficiency and without NH₃ slip.

Biomimetic Catalysts for Oxidation of Veratryl Alcohol, a Lignin Model Compound

Directory of Open Access Journals (Sweden)

Marcelino Maneiro

2013-03-01

Full Text Available Kraft pulp has to be bleached to eliminate the chromophoric structures, which cause a darkening of the pulp. In Nature, an equivalent role is assumed by ligninolytic enzymes such as lignin peroxidases, manganese peroxidases and laccases. The development of low molecular weight manganese peroxidase mimics may achieve environmentally-safe bleaching catalysts for the industry. Herein we report the synthesis and characterization of six manganese(III complexes 1–6, incorporating dianionic hexadentate Schiff base ligands (H2L1-H2L4 and different anions. Complex 4, Mn2L22(H2O2(DCA2 was crystallographically characterized. Complexes 1–4 behave as more efficient mimics of peroxidase in contrast to 5–6. We have studied the use of these complexes as catalysts for the degradation of the lignin model compound veratryl alcohol. The biomimetic catalysts were used in conjunction with chlorine-free inexpensive co-oxidants as dioxygen or hydrogen peroxide. Yields up to 30% of veratryl alcohol conversion to veratraldehyde have been achieved at room temperature in presence of air flow using 0.5% of catalyst.

Reduction and Analysis of Low Temperature Shift Heterogeneous Catalyst for Water Gas Reaction in Ammonia Production

Directory of Open Access Journals (Sweden)

Zečević, N.

2013-09-01

Full Text Available In order to obtain additional quantities of hydrogen after the reforming reactions of natural gas and protect the ammonia synthesis catalyst, it is crucial to achieve and maintain maximum possible activity, selectivity and stability of the low temperature shift catalyst for conversion of water gas reaction during its lifetime. Whereas the heterogeneous catalyst comes in oxidized form, it is of the utmost importance to conduct the reduction procedure properly. The proper reduction procedure and continuous analysis of its performance would ensure the required activity, selectivity and stability throughout the catalyst’s service time. For the proper reduction procedure ofthe low temperature shift catalyst, in addition to process equipment, also necessary is a reliable and realistic system for temperature measurements, which will be effective for monitoring the exothermal temperature curves through all catalyst bed layers. For efficiency evaluation of low shift temperature catalyst reduction and its optimization, it is necessary to determine at regular time intervals the temperature approach to equilibrium and temperature profiles of individual layers by means of "S" and "die off" temperature exothermal curves. Based on the obtained data, the optimum inlet temperature could be determined, in order to maximally extend the service life of the heterogeneous catalyst as much as possible, and achieve the optimum equilibrium for conversion of the water gas. This paper presents the methodology for in situ reduction of the low temperature shift heterogeneous catalyst and the developed system for monitoring its individual layers to achieve the minimum possible content of carbon monoxide at the exit of the reactor. The developed system for temperature monitoring through heterogeneous catalyst layers provides the proper procedure for reduction and adjustment of optimum process working conditions for the catalyst by the continuous increase of reactor inlet

Selective Hydrodeoxygenation of 5-Hydroxymethylfurfural to 2,5-Dimethylfuran over Heterogeneous Iron Catalysts.

Science.gov (United States)

Li, Jiang; Liu, Jun-Ling; Liu, He-Yang; Xu, Guang-Yue; Zhang, Jun-Jie; Liu, Jia-Xing; Zhou, Guang-Lin; Li, Qin; Xu, Zhi-Hao; Fu, Yao

2017-04-10

This work provided the first example of selective hydrodeoxygenation of 5-hydroxymethylfurfural (HMF) to 2,5-dimethylfuran (DMF) over heterogeneous Fe catalysts. A catalyst prepared by the pyrolysis of an Fe-phenanthroline complex on activated carbon at 800 °C was demonstrated to be the most active heterogeneous Fe catalyst. Under the optimal reaction conditions, complete conversion of HMF was achieved with 86.2 % selectivity to DMF. The reaction pathway was investigated thoroughly, and the hydrogenation of the C=O bond in HMF was demonstrated to be the rate-determining step during the hydrodeoxygenation, which could be accelerated greatly by using alcohol solvents as additional H-donors. The excellent stability of the Fe catalyst, which was probably a result of the well-preserved active species and the pore structure of the Fe catalyst in the presence of H 2 , was demonstrated in batch and continuous flow fixed-bed reactors. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Novel reaction engineering concepts for catalyst immobilisation in hydroformylation

Energy Technology Data Exchange (ETDEWEB)

Cole-Hamilton, D.J.; Desset, S.L.; Muldoon, M.J. [St. Andrews Univ. (United Kingdom). EaStChem, School of Chemistry; Hintermair, U. [St. Andrews Univ. (United Kingdom). EaStChem, School of Chemistry]|[CNRS, Lyon (France). Laboratoire de Chimie Organometallique de Surface; Santini, C.C. [CNRS, Lyon (France). Laboratoire de Chimie Organometallique de Surface

2006-07-01

Various methods for the separation of the aldehyde products from the catalyst and any solvent during or after hydroformylation reactions of long chain alkenes are reviewed. The catalyst can be immobilized on a soluble or insoluble support or in a phase that does not mix with the product phase under the separation conditions. Aqueous, fluorous, and ionic liquid biphasic systems as well as systems involving scCO{sub 2} sometimes in conjunction with one or other of the types of solvents listed above. Hybrid systems in which a liquid phase containing the catalyst is supported on a microporous solid support are also discussed. The advantages and disadvantages of the various systems are considered and new results concerning the addition of [1-octyl-3-methylimidazolium]Br to aqueous biphasic systems and the use of supercritical fluids to transport substrates over supported ionic liquid phases are presented. Both of these new approaches give high reaction rates, which for the supported ionic liquid phase catalysts can be maintained for at least 40 h of continuous flow operation. For the aqueous biphasic systems, leaching is low and phase separation is fast. (orig.)

Defect-rich Ni-Ti layered double hydroxide as a highly efficient support for Au nanoparticles in base-free and solvent-free selective oxidation of benzyl alcohol.

Science.gov (United States)

Liu, Mengran; Fan, Guoli; Yu, Jiaying; Yang, Lan; Li, Feng

2018-04-17

Tuning the surface properties of supported metal catalysts is of vital importance for governing their catalytic performances in nanocatalysis. Here, we report highly dispersed nanometric gold nanoparticles (NPs) supported on Ni-Ti layered double hydroxides (NiTi-LDHs), which were employed in solvent-free and base-free selective oxidation of benzyl alcohol. A series of characterization techniques demonstrated that defect-rich NiTi-LDHs could efficiently stabilize Au NPs and decrease surface electron density of Au NPs. The as-formed Au/NiTi-LDH catalyst with a Ni/Ti molar ratio of 3 : 1 and an Au loading of 0.71 wt% yielded the highest turnover frequency value of ∼4981 h-1 at 120 °C among tested Au/NiTi-LDH catalysts with different Ni/Ti molar ratios, along with a high benzaldehyde selectivity of 98%. High catalytic efficiency of the catalyst was mainly correlated with surface cooperation between unique defects (i.e. defective Ti3+ species and oxygen vacancies) and abundant hydroxyl groups on the brucite-like layers of the NiTi-LDH support, which could lead to the preferential adsorption and activation of an alcohol hydroxyl moiety in benzyl alcohol and oxygen molecule, as well as the formation of more electron-deficient Ni3+ and Au0 species on the catalyst surface. Furthermore, the present Au/NiTi-LDH catalyst tolerated the oxidation of a wide variety of substrate structures into the corresponding aldehydes, acids or ketones. Our primary results illustrate that defect-rich NiTi-LDHs are promising supports which can efficiently modify surface structure and electronic properties of supported metal catalysts and consequently improve their catalytic performances.

Catalysts for Efficient Production of Carbon Nanotubes

Science.gov (United States)

Sun, Ted X.; Dong, Yi

2009-01-01

Several metal alloys have shown promise as improved catalysts for catalytic thermal decomposition of hydrocarbon gases to produce carbon nanotubes (CNTs). Heretofore almost every experiment on the production of carbon nanotubes by this method has involved the use of iron, nickel, or cobalt as the catalyst. However, the catalytic-conversion efficiencies of these metals have been observed to be limited. The identification of better catalysts is part of a continuing program to develop means of mass production of high-quality carbon nanotubes at costs lower than those achieved thus far (as much as $100/g for purified multi-wall CNTs or $1,000/g for single-wall CNTs in year 2002). The main effort thus far in this program has been the design and implementation of a process tailored specifically for high-throughput screening of alloys for catalyzing the growth of CNTs. The process includes an integral combination of (1) formulation of libraries of catalysts, (2) synthesis of CNTs from decomposition of ethylene on powders of the alloys in a pyrolytic chemical-vapor-decomposition reactor, and (3) scanning- electron-microscope screening of the CNTs thus synthesized to evaluate the catalytic efficiencies of the alloys. Information gained in this process is put into a database and analyzed to identify promising alloy compositions, which are to be subjected to further evaluation in a subsequent round of testing. Some of these alloys have been found to catalyze the formation of carbon nano tubes from ethylene at temperatures as low as 350 to 400 C. In contrast, the temperatures typically required for prior catalysts range from 550 to 750 C.

High-Activity Dealloyed Catalysts

Energy Technology Data Exchange (ETDEWEB)

Kongkanand, Anusorn [General Motors LLC, Pontiac, MI (United States)

2014-09-30

Reduction of costly Pt usage in proton exchange membrane fuel cell electrodes is one of the major challenges towards development and commercialization of fuel cell vehicles. Although few have met the initial-kinetic activity requirements in a realistic fuel cell device, no catalyst material has ever met the demanding fuel cell durability targets set by DOE. In this project, a team of 4 universities and 2 companies came together to investigate a concept that appeared promising in preliminary non-fuel cell tests then to further develop the catalyst to a mature level ready for vehicle implementation. The team consists of academia with technical leadership in their respective areas, a catalyst supplier, and a fuel cell system integrator.The tightly collaborative project enabled development of a highly active and durable catalyst with performance that significantly exceeds that of previous catalysts and meets the DOE targets for the first time (Figure 1A). The catalyst was then further evaluated in full-active-area stack in a realistic vehicle operating condition (Figure 1B). This is the first public demonstration that one can realize the performance benefit and Pt cost reduction over a conventional pure Pt catalyst in a long-term realistic PEMFC system. Furthermore, systematic analyses of a range of catalysts with different performance after fuel cell testing allowed for correlation between catalyst microstructure and its electrocatalytic activity and durability. This will in turn aid future catalyst development.

GRINDING SOLVENT-FREE PAAL-KNORR PYRROLE SYNTHESIS ...

African Journals Online (AJOL)

Paal-Knorr pyrrole synthesis on smectites as recyclable and green catalysts. Bull. Chem. Soc. .... 1-Propyl-2,5-dimethyl-1H-pyrrole (8a). Oil (reported as oil .... of pyrroles catalyzed by zirconium chloride under solvent-free conditions . Ultrason.

Development of Molecular Catalysts to Bridge the Gap between Heterogeneous and Homogeneous Catalysts

Science.gov (United States)

Ye, Rong

Catalysts, heterogeneous, homogeneous, and enzymatic, are comprised of nanometer-sized inorganic and/or organic components. They share molecular factors including charge, coordination, interatomic distance, bonding, and orientation of catalytically active atoms. By controlling the governing catalytic components and molecular factors, catalytic processes of a multichannel and multiproduct nature could be run in all three catalytic platforms to create unique end-products. Unifying the fields of catalysis is the key to achieving the goal of 100% selectivity in catalysis. Recyclable catalysts, especially those that display selective reactivity, are vital for the development of sustainable chemical processes. Among available catalyst platforms, heterogeneous catalysts are particularly well-disposed toward separation from the reaction mixture via filtration methods, which renders them readily recyclable. Furthermore, heterogeneous catalysts offer numerous handles - some without homogeneous analogues - for performance and selectivity optimization. These handles include nanoparticle size, pore profile of porous supports, surface ligands and interface with oxide supports, and flow rate through a solid catalyst bed. Despite these available handles, however, conventional heterogeneous catalysts are themselves often structurally heterogeneous compared to homogeneous catalysts, which complicates efforts to optimize and expand the scope of their reactivity and selectivity. Ongoing efforts are aimed to address the above challenge by heterogenizing homogeneous catalysts, which can be defined as the modification of homogeneous catalysts to render them in a separable (solid) phase from the starting materials and products. Specifically, we grow the small nanoclusters in dendrimers, a class of uniform polymers with the connectivity of fractal trees and generally radial symmetry. Thanks to their dense multivalency, shape persistence and structural uniformity, dendrimers have proven to

Communicating catalysts

Science.gov (United States)

Weckhuysen, Bert M.

2018-06-01

The beauty and activity of enzymes inspire chemists to tailor new and better non-biological catalysts. Now, a study reveals that the active sites within heterogeneous catalysts actively cooperate in a fashion phenomenologically similar to, but mechanistically distinct, from enzymes.

A Continuous-Exchange Cell-Free Protein Synthesis System Based on Extracts from Cultured Insect Cells

Science.gov (United States)

Stech, Marlitt; Quast, Robert B.; Sachse, Rita; Schulze, Corina; Wüstenhagen, Doreen A.; Kubick, Stefan

2014-01-01

In this study, we present a novel technique for the synthesis of complex prokaryotic and eukaryotic proteins by using a continuous-exchange cell-free (CECF) protein synthesis system based on extracts from cultured insect cells. Our approach consists of two basic elements: First, protein synthesis is performed in insect cell lysates which harbor endogenous microsomal vesicles, enabling a translocation of de novo synthesized target proteins into the lumen of the insect vesicles or, in the case of membrane proteins, their embedding into a natural membrane scaffold. Second, cell-free reactions are performed in a two chamber dialysis device for 48 h. The combination of the eukaryotic cell-free translation system based on insect cell extracts and the CECF translation system results in significantly prolonged reaction life times and increased protein yields compared to conventional batch reactions. In this context, we demonstrate the synthesis of various representative model proteins, among them cytosolic proteins, pharmacological relevant membrane proteins and glycosylated proteins in an endotoxin-free environment. Furthermore, the cell-free system used in this study is well-suited for the synthesis of biologically active tissue-type-plasminogen activator, a complex eukaryotic protein harboring multiple disulfide bonds. PMID:24804975

The effect of axial loads on free vibration of symmetric frame structures using continuous system method

Directory of Open Access Journals (Sweden)

Elham Ghandi

2016-09-01

Full Text Available The free vibration of frame structures has been usually studied in literature without considering the effect of axial loads. In this paper, the continuous system method is employed to investigate this effect on the free flexural and torsional vibration of two and three dimensional symmetric frames. In the continuous system method, in approximate analysis of buildings, commonly, the structure is replaced by an equivalent beam which matches the dominant characteristics of the structure. Accordingly, the natural frequencies of the symmetric frame structures are obtained through solving the governing differential equation of the equivalent beam whose stiffness and mass are supposed to be uniformly distributed along the length. The corresponding axial load applied to the replaced beam is calculated based on the total weight and the number of stories of the building. A numerical example is presented to show the simplicity and efficiency of the proposed solution.

Methods of making textured catalysts

Science.gov (United States)

Werpy, Todd [West Richland, WA; Frye, Jr., John G.; Wang, Yong [Richland, WA; Zacher, Alan H [Kennewick, WA

2010-08-17

A textured catalyst having a hydrothermally-stable support, a metal oxide and a catalyst component is described. Methods of conducting aqueous phase reactions that are catalyzed by a textured catalyst are also described. The invention also provides methods of making textured catalysts and methods of making chemical products using a textured catalyst.

Continuous time quantum random walks in free space

Science.gov (United States)

Eichelkraut, Toni; Vetter, Christian; Perez-Leija, Armando; Christodoulides, Demetrios; Szameit, Alexander

2014-05-01

We show theoretically and experimentally that two-dimensional continuous time coherent random walks are possible in free space, that is, in the absence of any external potential, by properly tailoring the associated initial wave function. These effects are experimentally demonstrated using classical paraxial light. Evidently, the usage of classical beams to explore the dynamics of point-like quantum particles is possible since both phenomena are mathematically equivalent. This in turn makes our approach suitable for the realization of random walks using different quantum particles, including electrons and photons. To study the spatial evolution of a wavefunction theoretically, we consider the one-dimensional paraxial wave equation (i∂z +1/2 ∂x2) Ψ = 0 . Starting with the initially localized wavefunction Ψ (x , 0) = exp [ -x2 / 2σ2 ] J0 (αx) , one can show that the evolution of such Gaussian-apodized Bessel envelopes within a region of validity resembles the probability pattern of a quantum walker traversing a uniform lattice. In order to generate the desired input-field in our experimental setting we shape the amplitude and phase of a collimated light beam originating from a classical HeNe-Laser (633 nm) utilizing a spatial light modulator.

Sustainable solid catalyst alkylation of commercial olefins by regeneration with supercritical isobutane

Energy Technology Data Exchange (ETDEWEB)

Daniel M. Ginosar; David N. Thompson; Kyle C. Burch

2005-12-01

Supercritical isobutane regeneration of a USY zeolite alkylation catalyst was examined in a continuous, automated reaction / regeneration system. Two feeds were studied; a synthetic isobutane / 2-butene blend, and a commercial refinery isoparaffin / olefin blend. The refinery blend was minimally treated, containing a variety of light olefins, and contaminants, including butadiene, oxygenates and sulfur, which are well known to cause severe catalyst deactivation. Synthetic feed experiments showed that high levels of butene conversion was maintained for more than 200 hours time on stream, and that product quality and catalyst maintenance was relatively stable over the course of the experiment using a 3 hour reaction / 3 hour regeneration cycle. Catalyst activity maintenance was lower when the commercial feed was employed. High levels of alkene conversion were maintained for 78 hours and 192 hours using a 3 hour reaction / 3 hour regeneration cycle and a 2 hour reaction / 2 hour regeneration cycle, respectively.

Biodiesel production from acid oils and ethanol using a solid basic resin as catalyst

International Nuclear Information System (INIS)

Marchetti, J.M.; Errazu, A.F.

2010-01-01

In the search of an alternative fuel to substitute diesel fuel, biodiesel appears as one of the most promising sources of energy for diesel engines because of its environmental advantages and also due to the evolution of the petroleum market. Refined oil is the conventional raw material for the production of this biofuel; however, its major disadvantage is the high cost of its production. Therefore, frying oils, waste oils, crude oils and/or acid oils are being tested as alternative raw materials; nevertheless, there will be some problems if a homogeneous basic catalyst (NaOH) is employed due to the high amount of free fatty acid present in the raw oil. In this work, the transesterification reaction of acid oil using solid resin, Dowex monosphere 550 A, was studied as an alternative process. Ethanol was employed to have a natural and sustainable final product. The reaction temperature's effects, the initial amount of free fatty acid, the molar ratio of alcohol/oil and the type of catalyst (homogeneous or heterogeneous) over the main reaction are analyzed and their effects compared. The results obtained show that the solid resin is an alternative catalyst to be used to produce fatty acid ethyl esters (FAEEs) by a transesterification reaction with a final conversion over 90%. On the other hand, the time required to achieve this conversion is bigger than the one required using conventional technology which employs a homogeneous basic catalyst. This reaction time needs to be optimized. (author)

Model studies of methanol synthesis on copper catalysts

Energy Technology Data Exchange (ETDEWEB)

Nakamura, J.; Nakamura, I.; Uchijima, T. [Univ. of Tsukuba, Ibaraki (Japan); Watanabe, T. [Research Inst. of Innovative Technology for Earth, Kyoto (Japan); Fujitani, T. [National Inst. for Resources and Environment, Ibaraki (Japan)

1996-12-31

The synthesis of methanol by the hydrogenation of CO{sub 2} over Zn-deposited and Zn-free copper surfaces has been studied using an XPS apparatus combined with a high-pressure flow reactor (18 atm). It was shown that the Zn deposited on Cu(111) and poly-Cu acted as a promoter for methanol synthesis, while the Zn on Cu(110) and Cu(100) had no such a promotional effect. The turnover frequency (TOF) for Zn/Cu(111) linearly increased with Zn coverage below {Theta}Zn--0.19, and then decreased above {Theta}Zn=0.20. The optimum TOF obtained at {Theta}Zn--0-19 was thirteen-fold larger than TOF for the Zn-free Cu(111) surface. On the other hand, no promotional effect of Zn was observed for the reverse water-gas shift reaction on all the surfaces. The results indicate the formation of special sites for methanol synthesis on Zn/Cu(111). The Zn-deposited Cu(111) can be regarded as a model of Cu/ZnO catalysts because the TOF and the activation energy for methanol formation over the Zn-deposited Cu(111) were in fairly good agreement with those for the Cu/ZnO powder catalysts. The post-reaction surface analysis by XPS showed the formation of formate species (HCOOa). The formate coverage was proportional to the activity for methanol formation below {Theta}Zn=0.20, suggesting that the hydrogenation of the formate species is the rate-determining step of methanol formation. The formate species was stabilized by Zn species on Cu(111) in the absence of ZnO species. STM results on the Zn-deposited Cu(111) suggested the formation of a Cu-Zn surface alloy. The presence of special sites for methanol synthesis was also indicated in the results of powder catalysts.

In-situ hydrodeoxygenation of phenol by supported Ni catalyst-explanation for catalyst performance

DEFF Research Database (Denmark)

Wang, Ze; Zeng, Ying; Lin, Weigang

2017-01-01

In-situ hydrodeoxygenation of phenol with aqueous hydrogen donor over supported Ni catalyst was investigated. The supported Ni catalysts exerted very poor performance, if formic acid was used as the hydrogen donor. Catalyst modification by loading K, Na, Mg or La salt could not make the catalyst...... performance improved. If gaseous hydrogen was used as the hydrogen source the activity of Ni/Al2O3 was pretty high. CO2 was found poisonous to the catalysis, due to the competitive adoption of phenol with CO2. If formic acid was replaced by methanol, the catalyst performance improved remarkably, with major...... products of cyclohexanone and cyclohexanol. The better effect of methanol enlightened the application of the supported Ni catalyst in in-situ hydrodeoxygenation of phenol....

Pyrolysis of polyethylene terephthalate containing real waste plastics using Ni loaded zeolite catalysts

Science.gov (United States)

Al-asadi, M.; Miskolczi, N.

2018-05-01

In this work the pyrolysis of polyethylene terephthalate (PET) containing real waste plastic was investigated using different Ni loaded catalysts: Ni/ZSM-5, Ni/y-zeolite, Ni/β-zeolite and Ni/natural zeolite (clinoptilolite). Raw materials were pyrolyzed in a horizontal tubular reactor between 600 and 900°C using 10% of catalysts. It was found, that both temperature increasing and catalysts presence can increase the gas yields, however owing to gasification reactions, the pyrolysis oil yield decreased with increasing temperature. Ni/y-zeolite catalyst had the most benefit in gas yield increasing at low temperature; however Ni/ZSM-5 showed advanced property in gas yield increasing at high temperature. Gases contained hydrogen, carbon oxides and hydrocarbons, which composition was significantly affected by catalysts. Ni loaded zeolites favoured to the formation of hydrogen and branched hydrocarbons; furthermore the concentrations of both CO and CO2 were also increased as function of elevated temperature. That phenomenon was attributed to the further decomposition of PET, especially to the side chain scission reactions. Owing to the Boudouard reaction, the ratio of CO2/CO can increased with temperature. Pyrolysis oils were the mixtures of n-saturated, n-unsaturated, branched, oxygen free aromatics and oxygenated hydrocarbons. Temperature increasing has a significant effect to the aromatization and isomerization reactions, while the catalysts can efficiently decreased the concentration of oxygen containing compounds.

Self-Catalyzing Chemiluminescence of Luminol-Diazonium Ion and Its Application for Catalyst-Free Hydrogen Peroxide Detection and Rat Arthritis Imaging.

Science.gov (United States)

Zhao, Chunxin; Cui, Hongbo; Duan, Jing; Zhang, Shenghai; Lv, Jiagen

2018-02-06

We report the unique self-catalyzing chemiluminescence (CL) of luminol-diazonium ion (N 2 + -luminol) and its analytical potential. Visual CL emission was initially observed when N 2 + -luminol was subjected to alkaline aqueous H 2 O 2 without the aid of any catalysts. Further experimental investigations found peroxidase-like activity of N 2 + -luminol on the cleavage of H 2 O 2 into OH • radical. Together with other experimental evidence, the CL mechanism is suggested as the activation of N 2 + -luminol and its dediazotization product 3-hydroxyl luminol by OH • radical into corresponding intermediate radicals, and then further oxidation to excited-state 3-N 2 + -phthalic acid and 3-hydroxyphthalic acid, which finally produce 415 nm CL. The self-catalyzing CL of N 2 + -luminol provides us an opportunity to achieve the attractive catalyst-free CL detection of H 2 O 2 . Experiments demonstrated the 10 -8 M level detection sensitivity to H 2 O 2 as well as to glucose or uric acid if presubjected to glucose oxidase or uricase. With the exampled determination of serum glucose and uric acid, N 2 + -luminol shows its analytical potential for other analytes linking the production or consumption of H 2 O 2 . Under physiological condition, N 2 + -luminol exhibits highly selective and sensitive CL toward 1 O 2 among the common reactive oxygen species. This capacity supports the significant application of N 2 + -luminol for detecting 1 O 2 in live animals. By imaging the arthritis in LEW rats, N 2 + -luminol CL is demonstrated as a potential tool for mapping the inflammation-relevant biological events in a live body.

Large scale metal-free synthesis of graphene on sapphire and transfer-free device fabrication.

Science.gov (United States)

Song, Hyun Jae; Son, Minhyeok; Park, Chibeom; Lim, Hyunseob; Levendorf, Mark P; Tsen, Adam W; Park, Jiwoong; Choi, Hee Cheul

2012-05-21

Metal catalyst-free growth of large scale single layer graphene film on a sapphire substrate by a chemical vapor deposition (CVD) process at 950 °C is demonstrated. A top-gated graphene field effect transistor (FET) device is successfully fabricated without any transfer process. The detailed growth process is investigated by the atomic force microscopy (AFM) studies.

Non-PGM cell catalysts

Energy Technology Data Exchange (ETDEWEB)

Colon-Mercado, H. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Elvington, M. [Savannah River Consulting, Aiken, SC (United States); Ganesan, P. [Savannah River Consulting, Aiken, SC (United States)

2017-09-27

A unique approach has been developed to probe the non-PGM catalyst active site for the Oxygen Reduction Reaction (ORR) for PEMFCs. Iron based functionalities have been engineered into a variety of catalysts to evaluate their impact on activity for the ORR. A series of high surface area catalysts were synthesized and the impact of the chemical structure on the electrochemical and electrocatalytic properties was investigated. Elemental and surface analyses of the prepared catalysts reveal the incorporation of iron in a targeted and controlled manner. A high surface area framework catalyst was prepared that shows exceptional activity, comparable to state-of-the-art materials. The results of this research project provided critical seed data for the newly awarded ElectroCat project, which focuses on rationally designed framework catalysts for the oxygen reduction reaction.

A catalytic reactor for the organocatalyzed enantioselective continuous flow alkylation of aldehydes.

Science.gov (United States)

Porta, Riccardo; Benaglia, Maurizio; Puglisi, Alessandra; Mandoli, Alessandro; Gualandi, Andrea; Cozzi, Pier Giorgio

2014-12-01

The use of immobilized metal-free catalysts offers the unique possibility to develop sustainable processes in flow mode. The challenging intermolecular organocatalyzed enantioselective alkylation of aldehydes was performed for the first time under continuous flow conditions. By using a packed-bed reactor filled with readily available supported enantiopure imidazolidinone, different aldehydes were treated with three distinct cationic electrophiles. In the organocatalyzed α-alkylation of aldehydes with 1,3-benzodithiolylium tetrafluoroborate, excellent enantioselectivities, in some cases even better than those obtained in the flask process (up to 95% ee at 25 °C), and high productivity (more than 3800 h(-1) ) were obtained, which thus shows that a catalytic reactor may continuously produce enantiomerically enriched compounds. Treatment of the alkylated products with Raney-nickel furnished enantiomerically enriched α-methyl derivatives, key intermediates for active pharmaceutical ingredients and natural products. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Heterogeneous electrochemical CO2 reduction using nonmetallic carbon-based catalysts: current status and future challenges

Science.gov (United States)

Ma, Tao; Fan, Qun; Tao, Hengcong; Han, Zishan; Jia, Mingwen; Gao, Yunnan; Ma, Wangjing; Sun, Zhenyu

2017-11-01

Electrochemical CO2 reduction (ECR) offers an important pathway for renewable energy storage and fuels production. It still remains a challenge in designing highly selective, energy-efficient, robust, and cost-effective electrocatalysts to facilitate this kinetically slow process. Metal-free carbon-based materials have features of low cost, good electrical conductivity, renewability, diverse structure, and tunability in surface chemistry. In particular, surface functionalization of carbon materials, for example by doping with heteroatoms, enables access to unique active site architectures for CO2 adsorption and activation, leading to interesting catalytic performances in ECR. We aim to provide a comprehensive review of this category of metal-free catalysts for ECR, providing discussions and/or comparisons among different nonmetallic catalysts, and also possible origin of catalytic activity. Fundamentals and some future challenges are also described.

New Titanium-Based Catalysts for the Synthesis of Poly(ethylene terephthalate)

International Nuclear Information System (INIS)

Yang, Youngkeun; Yoon, Seungwoong; Hwang, Yongtaek; Song, Bogeun

2012-01-01

Poly(ethylene terephthalate) (PET) is a polymer with relatively low cost and high performance, which is widely used in various applications such as bottles, textile fibers, films and engineering plastics for automobiles and electric industries. Commercial catalysts used for synthesis of PET are in general antimony (Sb) compounds. Antimony(III) oxide, antimony(III) acetate and antimony(III) glycolate are used as a catalyst in 95% of PET manufacturing industries worldwide. The few organoantimony compounds that have been identified in environmental and biological samples are all in the form of methylated Sb-species. The Sb trace element is extremely toxic to mammals, and interferes with embryonic and fetal development, also, carcinogenic to humans. In addition to being found in drinking water, food packaging and soft-drink bottles. According to the World Health Organization (WHO), Sb species concentration lower than 20 ppb are acceptable for drinking water. According to a recent study, in 14 brands of bottled water from Canada, Sb concentrations increased on average 19% during 6 months storage at room temperature, but 48 brands of water from 11 European countries increased on average 90% under identical conditions. Therefore, a very important challenge for polyester catalysis is to come-up with a new Sb-free catalysts with low environmental impact. Intensive efforts have been made to find other stable and more environmental friendly non-antimony catalysts, such as those based on titanium. Titanium-based catalysts have been known for many years and actually are used for polybutylene terephthalate (PBT) and polypropylene terephthalate (PPT) production, however, polycondensation (PC) of PET manufacture is not well studied in literature. To date, only few esterification processes have been applied for the synthesis of PET by titanium catalysts. Herein, we report an efficient synthesis characterization and polymerization of PET for a series of new nontoxic organotitanium

The MOVPE growth mechanism of catalyst-free self-organized GaN columns in H2 and N2 carrier gases

Science.gov (United States)

Wang, Xue; Jahn, Uwe; Ledig, Johannes; Wehmann, Hergo-H.; Mandl, Martin; Straßburg, Martin; Waag, Andreas

2013-12-01

Columnar structures of III-V semiconductors recently attract considerable attention because of their potential applications in novel optoelectronic and electronic devices. In the present study, the mechanisms for the growth of catalyst-free self-organized GaN columns on sapphire substrate by metal organic vapor phase epitaxy have been thoroughly investigated. The growth behaviours are strongly affected by the choice of carrier gas. If pure nitrogen is used, Ga droplets are able to accumulate on the top of columns during growth, and they are converted into a high quality GaN layer during the cool down phase due to nitridation. Hydrogen as the carrier gas can improve the optical quality of the overall GaN columns substantially, and in addition increase the vertical growth rate. In this case, no indication of Ga droplets could be detected. Furthermore, silane doping during the growth promotes the vertical growth in both cases either pure nitrogen or pure hydrogen as the carrier gas.

Hydrodeoxygenation of phenols as lignin models under acid-free conditions with carbon-supported platinum catalysts.

Science.gov (United States)

Ohta, Hidetoshi; Kobayashi, Hirokazu; Hara, Kenji; Fukuoka, Atsushi

2011-11-28

Carbon-supported Pt catalysts are highly active and reusable for the aqueous-phase hydrodeoxygenation of phenols as lignin models without adding any acids. It is suggested that Pt/carbon facilitates the hydrogenation of phenols and the hydrogenolysis of the resulting cyclohexanols.

Alloy catalyst material

DEFF Research Database (Denmark)

2014-01-01

The present invention relates to a novel alloy catalyst material for use in the synthesis of hydrogen peroxide from oxygen and hydrogen, or from oxygen and water. The present invention also relates to a cathode and an electrochemical cell comprising the novel catalyst material, and the process use...... of the novel catalyst material for synthesising hydrogen peroxide from oxygen and hydrogen, or from oxygen and water....

Process engineering and optimization of glycerol separation in a packed-bed reactor for enzymatic biodiesel production.

Science.gov (United States)

Hama, Shinji; Tamalampudi, Sriappareddy; Yoshida, Ayumi; Tamadani, Naoki; Kuratani, Nobuyuki; Noda, Hideo; Fukuda, Hideki; Kondo, Akihiko

2011-11-01

A process model for efficient glycerol separation during methanolysis in an enzymatic packed-bed reactor (PBR) was developed. A theoretical glycerol removal efficiency from the reaction mixture containing over 30% methyl esters was achieved at a high flow rate of 540 ml/h. To facilitate a stable operation of the PBR system, a batch reaction prior to continuous methanolysis was conducted using oils with different acid values and immobilized lipases pretreated with methyl esters. The reaction system successfully attained the methyl ester content of over 30% along with reduced viscosity and water content. Furthermore, to obtain a high methyl ester content above 96% continuously, long-term lipase stability was confirmed by operating a bench-scale PBR system for 550 h, in which the intermediates containing methyl esters and residual glycerides were fed into the enzyme-packed columns connected in series. Therefore, the developed process model is considered useful for industrial biodiesel production. Copyright © 2011 Elsevier Ltd. All rights reserved.

Utilization of eggshell waste as low-cost solid base catalyst for biodiesel production from used cooking oil

Science.gov (United States)

Asri, N. P.; Podjojono, B.; Fujiani, R.; Nuraini

2017-05-01

A solid CaO-based catalyst of waste eggshell was developed for biodiesel production from used cooking oil. The waste eggshell powder was calcined in air at 90° C for 4 h to convert calcium species in the eggshells into active CaO catalysts. The characterization of CaO catalyst was done by XRD and BET analysis. The CaO catalyst was then introduced for transesterification of used cooking oil (UCO) for testing of its catalytic activity. The experiment was conducted in batch type reactor that consists of three-neck glass equipped by reflux condenser and magnetic stirrer. Before tranesterification process, the UCO was treated by coconut coir powder in order to reduce the free fatty acid content. The result showed that the catalyst was potentially use for transesterification of used cooking oil into biodiesel with relatively high yield of 75.92% was achieved at reaction temperature, reaction time, molar ratio UCO to methanol and catalyst amount of 65° C, 7 h, 1:15 and 6%, respectively.

Vibration measurements of automobile catalyst

Science.gov (United States)

Aatola, Seppo

1994-09-01

Vibration of catalyst cell, which is inside the casing of the catalyst, is difficult to measure with usual measuring instrumentation. When catalyst is in use, there is hot exhaust gas flow though the catalyst cell and temperature of the cell is approximately +900 degree(s)C. Therefore non-contact Laser- Doppler-Vibrometer was used to measure vibration velocity of the catalyst cell. The laser beam was directed towards the cell through pipe which was put through and welded to the casing of the catalyst. The outer end of the pipe was screw down with a tempered class to prevent exhaust gas flow from the pipe. The inner end of the pipe was open and few millimeters away from the measuring point. Catalyst was attached to the engine with two ways, rigidly close to the engine and flexible under the engine. The engine was running in test bench under controlled conditions. Vibration measurements were carried out during constant running speeds of the engine. Vibration signals were captured and analyzed with FFT-analyzer. Vibration of catalyst cell was strongest at running speed of 5000 rpm, from 10 to 20 g (1 g equals 9.81 ms-2), when catalyst was attached rigidly close to the engine. At running speed of 3000 rpm, vibration of catalyst cell was from 2 to 3 g in most cases, when catalyst was attached either rigidly or flexible to the engine. It is estimated that in real life, i.e. when catalyst is attached to car with same engine, vibration of catalyst cell at running speed of 5000 rpm is somewhere between 1 and 10 g. At running speed of 3000 rpm, which may be more often used when driving car (car speed approximately 100 kmh-1), vibration of catalyst cell is probably few g's.

Comb-Resolved Dual-Comb Spectroscopy Stabilized by Free-Running Continuous-Wave Lasers

Science.gov (United States)

Kuse, Naoya; Ozawa, Akira; Kobayashi, Yohei

2012-11-01

We demonstrate dual-comb spectroscopy with relatively phase-locked two frequency combs, instead of frequency combs firmly fixed to the absolute frequency references. By stabilizing two beat frequencies between two mode-locked lasers at different wavelengths observed via free-running continuous-wave (CW) lasers, two combs are tightly phase locked to each other. The frequency noise of the CW lasers barely affects the performance of dual-comb spectroscopy because of the extremely fast common-mode noise rejection. Transform-limited comb-resolved dual-comb spectroscopy with a 6 Hz radio frequency linewidth is demonstrated by the use of Yb-fiber oscillators.

Development of a polymer catalyst for HANARO detritiation

International Nuclear Information System (INIS)

Chung, H.; Kang, H.S.; Paek, S.W.; Yoo, J.H.; Shon, S.H.; Kim, K.R.; Lee, S.H.; Ahn, D.H.; Lee, H.S.

1998-01-01

The use of heavy water as a reflector in HANARO results in the continuous exposure of deuterium oxide to neutron flux. Substantial quantities of tritium are generated by neutron activation of deuterium in the reflector. Airborne emissions and staff internal radiation doses could be caused by tritiated heavy water escaping from the system. A detritiation facility is thought to be effective in reducing the overall radiological impact. The detritiation process may consist of a catalytic exchange in the front-end and a cryogenic deuterium distillation section. In this paper, the catalyst manufacturing and its performance evaluation technology was presented. The waterproof polymer catalyst has a specific surface area larger than 400m 2 /g. It showed a high reaction rate in the hydrogen isotope exchange reaction. (author)

Effect of Ni-Co Ternary Molten Salt Catalysts on Coal Catalytic Pyrolysis Process

Science.gov (United States)

Cui, Xin; Qi, Cong; Li, Liang; Li, Yimin; Li, Song

2017-08-01

In order to facilitate efficient and clean utilization of coal, a series of Ni-Co ternary molten salt crystals are explored and the catalytic pyrolysis mechanism of Datong coal is investigated. The reaction mechanisms of coal are achieved by thermal gravimetric analyzer (TGA), and a reactive kinetic model is constructed. The microcosmic structure and macerals are observed by scanning electron microscope (SEM). The catalytic effects of ternary molten salt crystals at different stages of pyrolysis are analyzed. The experimental results show that Ni-Co ternary molten salt catalysts have the capability to bring down activation energy required by pyrolytic reactions at its initial phase. Also, the catalysts exert a preferable catalytic action on macromolecular structure decomposition and free radical polycondensation reactions. Furthermore, the high-temperature condensation polymerization is driven to decompose further with a faster reaction rate by the additions of Ni-Co ternary molten salt crystal catalysts. According to pyrolysis kinetic research, the addition of catalysts can effectively decrease the activation energy needed in each phase of pyrolysis reaction.

Catalyst for microelectromechanical systems microreactors

Science.gov (United States)

Morse, Jeffrey D [Martinez, CA; Sopchak, David A [Livermore, CA; Upadhye, Ravindra S [Pleasanton, CA; Reynolds, John G [San Ramon, CA; Satcher, Joseph H [Patterson, CA; Gash, Alex E [Brentwood, CA

2010-06-29

A microreactor comprising a silicon wafer, a multiplicity of microchannels in the silicon wafer, and a catalyst coating the microchannels. In one embodiment the catalyst coating the microchannels comprises a nanostructured material. In another embodiment the catalyst coating the microchannels comprises an aerogel. In another embodiment the catalyst coating the microchannels comprises a solgel. In another embodiment the catalyst coating the microchannels comprises carbon nanotubes.

Potassium Hydroxide Impregnated Alumina (KOH-Alumina) as a Recyclable Catalyst for the Solvent-Free Multicomponent Synthesis of Highly Functionalized Substituted Pyridazines and/or Substituted Pyridazin-3(2H)-ones under Microwave Irradiation.

Science.gov (United States)

Mecadon, Hormi; Myrboh, Bekington

2011-01-01

The work described herein employs potassium hydroxide impregnated alumina (KOH-alumina) as a mild, efficient, and recyclable catalyst for a one-pot solvent-free and environmentally safer synthesis of 3,4,6-triarylpyridazines and some substituted pyridazines from active methylene carbonyl species, 1,2-dicarbonyls, and hydrazine hydrate by microwave (MW) irradiation. The method offers highly convergent, inexpensive, and functionality-tolerable procedure for rapid access to important pyridazine compounds in good yields.

A novel hybrid catalyst for the esterification of high FFA in Jatropha oil for biodiesel production

International Nuclear Information System (INIS)

Mushtaq, M.; Tan, I.M.; Sagir, M.; Suleman Tahir, M.; Pervaiz, M.

2016-01-01

The synthesis and application of a hybrid catalyst for the esterification of free fatty acids (FFA) in Jatropha oil is reported. Three catalysts, namely silica sulfuric acid, silica supported boron trifluoride and a combination of the two in the weight ratio of 1:1, the hybrid catalyst, were investigated. Jatropha oil samples with a wide range of FFA values i.e. 6.64 to 45.64% were prepared and utilized for the experimental work. This study revealed that silica sulfuric acid and silica supported boron trifluoride were not very effective when used independently. However, a strong synergistic effect was noted in the catalytic activity of the hybrid catalyst which reduced the FFA value from 45.64 to 0.903% with a conversion efficiency of 98%. Reusability of the catalyst was also tested and the results were promising in up to three cycles of use when used with lower amounts of FFA (6.64%) in the oil. Under the influence of the catalyst, the reaction was found to follow first order kinetics. Activation energy was calculated to be 45.42 KJ·mol−1 for 2 wt.% of hybrid catalyst. The products were analyzed by FT-IR and NMR spectroscopic techniques and the results are reported. [es

Meso- and macroporous sulfonated starch solid acid catalyst for esterification of palm fatty acid

Directory of Open Access Journals (Sweden)

Ibrahim M. Lokman

2016-03-01

Full Text Available In the present work, a heterogeneous solid acid catalyst was successfully developed from starch. The catalyst was prepared by a significant two-step process; the initial step was incomplete carbonization of starch (ICS at 400 °C for 12 h and consequently followed by sulfonation process using concentrated H2SO4 to produce sulfonated-incomplete carbonized starch (ICS-SO3H. The characterization of the ICS-SO3H catalyst was done for chemical and physical properties such as X-ray diffraction (XRD, ammonia-temperature programmed desorption (NH3-TPD, surface area analysis, thermal gravimetric analysis (TGA, elemental analysis and morphology analysis by scanning electron microscope (SEM. BET results showed the structure of ICS-SO3H consists of meso- and macro-porous properties, which allowed high density of the SO3H group attached on its carbon networks. The catalytic activity of ICS-SO3H catalyst was determined by analyzing the catalyst performance to esterify palm fatty acid distillate (PFAD and sequentially produced methyl ester. The maximum free fatty acid (FFA conversion and FAME yield were as high as 94.6% and 90.4%, respectively, at 75 °C using 10:1 methanol-to-PFAD molar ratio and 2 wt.% of catalyst within 3 h. The catalyst has sufficient potential to recycle up to 6 reactions without reactivation step and any remarkable loss of catalytic activity. It revealed that the heterogeneous ICS-SO3H catalyst exhibits high stability, reusability and catalytic activity.

Non-Catalytic and MgSO4 - Catalyst based Degradation of Glycerol in Subcritical and Supercritical Water Media

Directory of Open Access Journals (Sweden)

Mahfud Mahfud

2011-02-01

Full Text Available This research aims to study the glycerol degradation reaction in subcritical and supercritical water media. The degradation of glycerol into other products was performed both with sulphate salt catalysts and without catalyst. The reactant was made from glycerol and water with the mass ratio of 1:10. The experiments were carried out using a batch reactor at a constant pressure of 250 kgf/cm2, with the temperature range of 200-400oC, reaction time of 30 minutes, and catalyst mol ratio in glycerol of 1:10 and 1:8. The products of the non-catalytic glycerol degradation were acetaldehyde, methanol, and ethanol. The use of sulphate salt as catalyst has high selectivity to acetaldehyde and still allows the formation alcohol product in small quantities. The mechanism of ionic reaction and free radical reaction can occur at lower temperature in hydrothermal area or subcritical water. Conversion of glycerol on catalytic reaction showed a higher yield when compared with the reaction performed without catalyst

Role of ultrasonic irradiation on transesterification of palm oil using calcium oxide as a solid base catalyst

International Nuclear Information System (INIS)

Poosumas, Jutipong; Ngaosuwan, Kanokwan; Quitain, Armando T.; Assabumrungrat, Suttichai

2016-01-01

Highlights: • Transesterification of palm oil using a circulated continuous flow ultrasonic reactor. • Heterogeneous system using CaO as catalyst. • Effects of ultrasonic frequency and power, and catalyst reusability were considered. • A single high frequency and high intensity irradiation is favorable for heterogeneous system. - Abstract: Biodiesel production from transesterification of palm oil using a circulated continuous flow ultrasonic reactor was investigated. Transesterification was carried out at 60 °C, 1 atm and a methanol-to-oil molar ratio of 9:1. The highest reaction rate was achieved at the catalyst loading of 2 wt%, and biodiesel yield constantly increased until transesterification equilibrium (about 80%) was reached. A higher ultrasonic frequency (50 kHz) promoted the heterogeneously catalyzed transesterification of refined palm oil, because the three-phase system (packed solid catalyst, methanol and oil) required more spatial distribution by ultrasonic irradiation. Moreover, the highest ultrasonic power also provided highest transesterification rate and biodiesel yield due to cavitation activity enhancement. Reusability of calcium oxide catalysts was also investigated, and results showed that this can be reused to provide high biodiesel yield for at least three operations with slight decrease in the rate of reaction due to counter balance effect of organic compounds deposition on the catalyst surface. The results from this study can be a basis for scaling up of the process to industrial scale.

UV-induced polymerization of size-controlled platinum/poly[styrene-divinylbenzene-tri(propylene glycol) diacrylate] hydrophobic catalyst beads in microfluidics

Energy Technology Data Exchange (ETDEWEB)

Wi, Jun; Li, Xiang; Song, Tong; Song, Zi Fan; Chang, Zhen Qi [School of Nuclear Science and Technology, University of Science and Technology of China, Hefei (China); Meng, Da Qiao [Si Chuan Institute of Materials and Technology, Jiang You (China)

2015-10-15

The catalytic exchange of hydrogen isotopes between hydrogen and water has been known to be a very useful process for the separation of tritium from tritiated water. For the process, a highly active hydrophobic catalyst is needed. This study provides an effective fabrication method of size-controlled platinum/poly[styrene-divinylbenzene-tri(propylene glycol) diacrylate] [Pt/poly(SDB-TPGDA)] hydrophobic catalyst beads with a narrow size distribution. Platinum nanoparticles were prepared by γ-ray-induced reduction in the aqueous phase first, and then uniformly dispersed in SDB-TPGDA comonomer after the hydrophobization of platinum nanoparticles with alkylamine stabilizers. The porous Pt/poly(SDB-TPGDA) hydrophobic catalyst beads were synthesized by the UV-initiated polymerization of the mixture droplets prepared in a capillary-based microfluidic system. The size of as-prepared catalyst beads can be controlled in the range of 200-1,000 μm by adjusting the flow rate of dispersed and continuous phases, as well as the viscosity of the continuous phase. Sorbitan monooleate and cyclohexanol were used as coporogens to control the porosities of the catalyst beads.

UV-induced polymerization of size-controlled platinum/poly[styrene-divinylbenzene-tri(propylene glycol) diacrylate] hydrophobic catalyst beads in microfluidics

International Nuclear Information System (INIS)

Wi, Jun; Li, Xiang; Song, Tong; Song, Zi Fan; Chang, Zhen Qi; Meng, Da Qiao

2015-01-01

The catalytic exchange of hydrogen isotopes between hydrogen and water has been known to be a very useful process for the separation of tritium from tritiated water. For the process, a highly active hydrophobic catalyst is needed. This study provides an effective fabrication method of size-controlled platinum/poly[styrene-divinylbenzene-tri(propylene glycol) diacrylate] [Pt/poly(SDB-TPGDA)] hydrophobic catalyst beads with a narrow size distribution. Platinum nanoparticles were prepared by γ-ray-induced reduction in the aqueous phase first, and then uniformly dispersed in SDB-TPGDA comonomer after the hydrophobization of platinum nanoparticles with alkylamine stabilizers. The porous Pt/poly(SDB-TPGDA) hydrophobic catalyst beads were synthesized by the UV-initiated polymerization of the mixture droplets prepared in a capillary-based microfluidic system. The size of as-prepared catalyst beads can be controlled in the range of 200-1,000 μm by adjusting the flow rate of dispersed and continuous phases, as well as the viscosity of the continuous phase. Sorbitan monooleate and cyclohexanol were used as coporogens to control the porosities of the catalyst beads

Synthesis and essay of an Ionomer like catalyst of olefins epoxidation

International Nuclear Information System (INIS)

Boyaca Mendivelso, Alejandro; Tempesti, Ezio

1995-01-01

The purpose of the present work is the preparation of an ionomer with base in Molybdenum and to evaluate its activity like catalyst of olefins epoxidation like alternative of synthesis of catalysts of the Hawk process. A polymer is synthesized with available functional groups to stabilize the metal starting from sodium molybdate; the characterization is made by atomic absorption, spectroscopy to GO, and X.P.S. The characterization indicates that indeed it is possible to stabilize the Mo in the main polymeric. The evaluation in reaction in liquid phase allows similar conversions to those of a homogeneous catalyst. The selective epoxidation of olefins for alkyl hydroperoxides, it has acquired great importance inside the industrial processes obtaining of propylene oxide due to the recent use of the terbutilic alcohol (co-produced together with the epoxide), as preservative in gasoline free of lead. In the environment of these processes, and in particular in the Hawk process possibilities of technological innovation, in the concerning to the heterogenization of conventional catalysts, at the moment used in homogeneous phase. The present work collaborate to some tentative that look for to generate alternative of preparation of catalysts for the process Hawk, synthesizing and testing the activity of an ionomer like epoxidation catalyst, which tries to reproduce the chemical structure of the complexes organ-metallic pear to suppress the separation stages and necessary recovery facilitating its recurrent reutilization with eventual economic repercussions in the industrial process. It is described the procedure of synthesis of the ionomer, the characterization and the evaluation of the activity in reaction under diverse conditions. Of the made characterization it comes off that the heterogenization of catalysts for olefins epoxidation, according to the Hawk process, is possible by means of the preparation of polymers modified appropriately. Likewise the evaluation in

Isobutane alkylation over solid catalysts

Energy Technology Data Exchange (ETDEWEB)

Kozorezov, Y.I.; Lisin, V.I.

1979-05-01

Commercial alumina modified with 6Vertical Bar3< by wt boron trifluoride was active in isobutane alkylation with ethylene in a flow reactor at 5:1 isobutane-ethylene and 5-20 min reaction time. The reaction rate was first-order in ethylene and increased with increasing temperature (20/sup 0/-80/sup 0/C) and ethylene pressure (0.2-3 atm). The calculated activation energy was 8.4 kj. Kinetic data and the activity of tert.-butyl chloride, but not ethyl chloride as alkylating agents in place of ethylene suggested a carbonium-ion chain mechanism involving both surface and gas-phase reactions. The ethylene-based yield of the alkylate decreased from 132 to 41Vertical Bar3< by wt after nine hours on stream, and its bromine number increased from 0.2 to 1 g Br/sub 2//100 ml. This inhibition was attributed to adsorption on the active acidic sites of the reaction products, particularly C/sub 10//sup +/ olefins. Catalyst stabilization could probably be achieved by selecting an appropriate solvent that would continuously desorb the inhibiting products from the catalyst surface.

Regeneration of Hydrotreating and FCC Catalysts

Energy Technology Data Exchange (ETDEWEB)

CM Wai; JG Frye; JL Fulton; LE Bowman; LJ Silva; MA Gerber

1999-09-30

Hydrotreating, hydrocracking, and fluid catalytic cracking (FCC) catalysts are important components of petroleum refining processes. Hydrotreating and hydrocracking catalysts are used to improve the yield of high-quality light oil fractions from heavier crude oil and petroleum feedstocks containing high levels of impurities. FCC catalysts improve the yield of higher octane gasoline from crude oil. Residuum hydrotreating and cracking catalysts are susceptible to irreversible deactivation caused by adsorption of sulfur and by metals impurities, such as vanadium and nickel. The gradual buildup of these impurities in a hydrotreating catalyst eventually plugs the pores and deactivates it. Nickel and vanadium adversely affect the behavior of cracking catalysts, reducing product yield and quality. Replacing deactivated catalysts represents a significant cost in petroleum refining. Equally important are the costs and potential liabilities associated with treating and disposing spent catalysts. For example, recent US Environmental Protection Agency rulings have listed spent hydrotreating and hydrorefining catalysts as hazardous wastes. FCC catalysts, though more easily disposed of as road-base or as filler in asphalt and cement, are still an economic concern mainly because of the large volumes of spent catalysts generated. New processes are being considered to increase the useful life of catalysts or for meeting more stringent disposal requirements for spent catalysts containing metals. This report discusses a collaborative effort between Pacific Northwest National Laboratory (PNNL) and Phillips Petroleum, Inc., to identify promising chemical processes for removing metals adhered to spent hydrodesulfurization (HDS, a type of hydrotreating catalyst) and FCC catalysts. This study, conducted by PNNL, was funded by the US Department of Energy's Bartlesville Project Office. Fresh and spent catalysts were provided by Phillips Petroleum. The FCC catalyst was a rare

Benign by design: catalyst-free in-water, on-water green chemical methodologies in organic synthesis

Science.gov (United States)

The development of organic synthesis under sustainable conditions is a primary goal of practicing green chemists who want to prevent pollution and design safer pathways. Although, it is challenging to avoid the use of catalysts, or solvents in all the organic reactions but progre...

Catalysts in petroleum refining and petrochemical industries 1995

Energy Technology Data Exchange (ETDEWEB)

Absi-Halabi, M.; Beshara, J.; Qabazard, H.; Stanislaus, A. [eds.] [Petroleum, Petrochemicals and Materials Division, Kuwait Institute of Scientific Research, Kuwait (Kuwait)

1996-07-01

Catalysis plays an increasingly critical role in modern petroleum refining and basic petrochemical industries. The market demands for and specifications of petroleum and petrochemical products are continuously changing. They have impacted the industry significantly over the past twenty years. Numerous new refining processes have been developed and significant improvements were made on existing technologies. Catalysts have been instrumental in enabling the industry to meet the continuous challenges posed by the market. As we enter the 21st century, new challenges for catalysis science and technology are anticipated in almost every field. Particularly, better utilization of petroleum resources and demands for cleaner transportation fuels are major items on the agenda. It is against this background that the 2nd International Conference on Catalysts in Petroleum Refining and Petrochemical Industries was organized. The papers from the conference were carefully selected from around 100 submissions. They were a mix of reviews providing an overview of selected areas, original fundamental research results, and industrial experiences. The papers in the proceedings were grouped in the following sections for quick reference: Plenary Papers; Hydroprocessing of Petroleum Residues and Distillates; Fluid Catalytic Cracking; Oxidation Catalysis; Aromatization and Polymerization Catalysis; Catalyst Characterization and Performance. The plenary papers were mostly reviews covering important topics related to the objectives of the conference. The remaining sections cover various topics of major impact on modern petroleum refining and petrochemical industries. A large number of papers dealt with hydroprocessing of petroleum distillates and residues which reflects the concern over meeting future sulfur-level specifications for diesel and fuel oils

Surface heterogeneity and ionization of Cs promoter in carbon-based ruthenium catalyst for ammonia synthesis

International Nuclear Information System (INIS)

Kotarba, Andrzej; Dmytrzyk, Jaromir; Rarog-Pilecka, Wioletta; Kowalczyk, Zbigniew

2003-01-01

Second-generation ammonia synthesis cesium-doped ruthenium catalyst supported on turbostratic carbon was investigated by the species resolved thermal alkali desorption method (SR-TAD). Energetic barriers for cesium ions (2.86 eV), ground state (1.96 eV) and electronically excited atoms (5.76 eV) desorbing from the Cs-Ru/C catalyst were determined. In the case of ruthenium-free Cs/C system, cesium desorbs as ground state atoms only, with an energy barrier of 2.87 eV. The work functions determined by the thermionic emission of electrons from Cs/C and Cs-Ru/C were of the same value (2.9 eV). It was concluded that ruthenium induces heterogeneous distribution of cesium on the catalyst surface. The promoter stability is reduced on low work function areas and its surface ionization on high work function areas opens the ionic desorption channel. The Cs desorption from the catalyst is discussed in terms of the literature data for the cesium/graphite system

Characterization and parametrical study of Rh-TPPTS supported ionic liquid phase (SILP) catalysts for ethylene hydroformylation

DEFF Research Database (Denmark)

Hanh, Nguyen Thi Ha; Duc, Duc Truong; Thang, Vu Dao

2012-01-01

The supported ionic liquid phase (SILP) catalysis technology was applied to continuous, gas-phase hydroformylation of ethylene. Rh-TPPTS SILP catalysts with relatively low ionic liquid loading were shown to be stable and highly activity for ethylene hydroformylation. However, the catalytic activity......, BET surface area and pore morphology of the catalysts depended on the content of ionic liquid. Hence, catalysts with high ionic liquid loading content showed deactivation at high reaction temperatures, possibly caused by redistribution of ionic liquid out of the pores under these conditions. (C) 2012...

Catalysts for synthetic liquid fuels

Energy Technology Data Exchange (ETDEWEB)

Bruce, L.A.; Turney, T.W.

1987-12-01

Fischer-Tropsch catalysts have been designed, characterized and tested for the selective production of hydrocarbons suitable as synthetic liquid transport fuels from synthesis gas (i.e., by the reduction of carbon monoxide with hydrogen). It was found that hydrocarbons in the middle distillate range, or suitable for conversion to that range, could be produced over several of the new catalyst systems. The various catalysts examined included: (1) synthetic cobalt clays, mainly cobalt chlorites; (2) cobalt hydrotalcites; (3) ruthenium metal supported on rare earth oxides of high surface area; and (4) a novel promoted cobalt catalyst. Active and selective catalysts have been obtained, in each category. With the exception of the clays, reproducibility of catalyst performance has been good. Catalysts in groups 2 and 4 have exhibited very high activity, with long lifetimes and easy regeneration.

Structural and luminescence properties of GaN nanowires grown using cobalt phthalocyanine as catalyst

Science.gov (United States)

Yadav, Shivesh; Rodríguez-Fernández, Carlos; de Lima, Mauricio M.; Cantarero, Andres; Dhar, Subhabrata

2015-12-01

Catalyst free methods have usually been employed to avoid any catalyst induced contamination for the synthesis of GaN nanowires with better transport and optical properties. Here, we have used a catalytic route to grow GaN nanowires, which show good optical quality. Structural and luminescence properties of GaN nanowires grown by vapor-liquid-solid technique using cobalt phthalocyanine as catalyst are systematically investigated as a function of various growth parameters such as the growth temperature and III/V ratio. The study reveals that most of the nanowires, which are several tens of microns long, grow along [ 10 1 ¯ 0 ] direction. Interestingly, the average wire diameter has been found to decrease with the increase in III/V ratio. It has also been observed that in these samples, defect related broad luminescence features, which are often present in GaN, are completely suppressed. At all temperatures, photoluminescence spectrum is found to be dominated only by a band edge feature, which comprises of free and bound excitonic transitions. Our study furthermore reveals that the bound excitonic feature is associated with excitons trapped in certain deep level defects, which result from the deficiency of nitrogen during growth. This transition has a strong coupling with the localized vibrational modes of the defects.

Synthesis H-Zeolite catalyst by impregnation KI/KIO3 and performance test catalyst for biodiesel production

Science.gov (United States)

Widayat, W.; Rizky Wicaksono, Adit; Hakim Firdaus, Lukman; Okvitarini, Ndaru

2016-02-01

The objective of this research is to produce H-catalyst catalyst that was impregnated with KI/KIO3. The catalyst was analyzed about surface area, X-Ray Diffraction (XRD) and performance test of catalyst for biodiesel production. An H-Zeolite catalyst was synthesized from natural zeolite with chemical treatment processing, impregnation KI/KIO3 and physical treatment. The results shows that the surface area of the catalyst by 27.236 m2/g at a concentration of 5% KI. XRD analysis shows peak 2-θ at 23.627o indicating that KI was impregnated on H-zeolite catalyst. The catalyst was tested in production of biodiesel using palm oil with conventional methods for 3 hour at temperature of 70-80 oC. The result for conversion Fatty Acid Methyl Ester (FAME) reached maximum value on 87.91% under production process using catalyst 5% KIO3-H zeolite.

Regeneration of LOHC dehydrogenation catalysts: In-situ IR spectroscopy on single crystals, model catalysts, and real catalysts from UHV to near ambient pressure

International Nuclear Information System (INIS)

Amende, Max; Kaftan, Andre; Bachmann, Philipp; Brehmer, Richard; Preuster, Patrick; Koch, Marcus

2016-01-01

Graphical abstract: - Highlights: • We examine the regeneration of Pt-based catalysts poisoned by LOHC degradation. • A microscopic mechanism of the removal of degradation products from Pt is proposed. • Results of our UHV studies on model catalysts are transferred to real catalysis. • Oxidative regeneration of Pt/alumina is possible under mild conditions (600 K). • The degree and temperature regime of regeneration depends on the catalyst morphology. - Abstract: The Liquid Organic Hydrogen Carrier (LOHC) concept offers an efficient route to store hydrogen using organic compounds that are reversibly hydrogenated and dehydrogenated. One important challenge towards application of the LOHC technology at a larger scale is to minimize degradation of Pt-based dehydrogenation catalysts during long-term operation. Herein, we investigate the regeneration of Pt/alumina catalysts poisoned by LOHC degradation. We combine ultrahigh vacuum (UHV) studies on Pt(111), investigations on well-defined Pt/Al_2O_3 model catalysts, and near-ambient pressure (NAP) measurements on real core–shell Pt/Al_2O_3 catalyst pellets. The catalysts were purposely poisoned by reaction with the LOHC perhydro-dibenzyltoluene (H18-MSH) and with dicyclohexylmethane (DCHM) as a simpler model compound. We focus on oxidative regeneration under conditions that may be applied in real dehydrogenation reactors. The degree of poisoning and regeneration under oxidative reaction conditions was quantified using CO as a probe molecule and measured by infrared reflection-absorption spectroscopy (IRAS) and diffuse reflectance Fourier transform IR spectroscopy (DRIFTS) for planar model systems and real catalysts, respectively. We find that regeneration strongly depends on the composition of the catalyst surface. While the clean surface of a poisoned Pt(111) single crystal is fully restored upon thermal treatment in oxygen up to 700 K, contaminated Pt/Al_2O_3 model catalyst and core–shell pellet were only

Regeneration of LOHC dehydrogenation catalysts: In-situ IR spectroscopy on single crystals, model catalysts, and real catalysts from UHV to near ambient pressure

Energy Technology Data Exchange (ETDEWEB)

Amende, Max, E-mail: max.amende@fau.de [Lehrstuhl für Physikalische Chemie II, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstr. 3, 91058 Erlangen (Germany); Kaftan, Andre, E-mail: andre.kaftan@fau.de [Lehrstuhl für Physikalische Chemie II, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstr. 3, 91058 Erlangen (Germany); Bachmann, Philipp, E-mail: philipp.bachmann@fau.de [Lehrstuhl für Physikalische Chemie II, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstr. 3, 91058 Erlangen (Germany); Brehmer, Richard, E-mail: richard.brehmer@fau.de [Lehrstuhl für Chemische Reaktionstechnik, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstr. 3, 91058 Erlangen (Germany); Preuster, Patrick, E-mail: patrick.preuster@fau.de [Lehrstuhl für Chemische Reaktionstechnik, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstr. 3, 91058 Erlangen (Germany); Koch, Marcus, E-mail: marcus.koch@crt.cbi.uni-erlangen.de [Lehrstuhl für Chemische Reaktionstechnik, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstr. 3, 91058 Erlangen (Germany); and others

2016-01-01

Graphical abstract: - Highlights: • We examine the regeneration of Pt-based catalysts poisoned by LOHC degradation. • A microscopic mechanism of the removal of degradation products from Pt is proposed. • Results of our UHV studies on model catalysts are transferred to real catalysis. • Oxidative regeneration of Pt/alumina is possible under mild conditions (600 K). • The degree and temperature regime of regeneration depends on the catalyst morphology. - Abstract: The Liquid Organic Hydrogen Carrier (LOHC) concept offers an efficient route to store hydrogen using organic compounds that are reversibly hydrogenated and dehydrogenated. One important challenge towards application of the LOHC technology at a larger scale is to minimize degradation of Pt-based dehydrogenation catalysts during long-term operation. Herein, we investigate the regeneration of Pt/alumina catalysts poisoned by LOHC degradation. We combine ultrahigh vacuum (UHV) studies on Pt(111), investigations on well-defined Pt/Al{sub 2}O{sub 3} model catalysts, and near-ambient pressure (NAP) measurements on real core–shell Pt/Al{sub 2}O{sub 3} catalyst pellets. The catalysts were purposely poisoned by reaction with the LOHC perhydro-dibenzyltoluene (H18-MSH) and with dicyclohexylmethane (DCHM) as a simpler model compound. We focus on oxidative regeneration under conditions that may be applied in real dehydrogenation reactors. The degree of poisoning and regeneration under oxidative reaction conditions was quantified using CO as a probe molecule and measured by infrared reflection-absorption spectroscopy (IRAS) and diffuse reflectance Fourier transform IR spectroscopy (DRIFTS) for planar model systems and real catalysts, respectively. We find that regeneration strongly depends on the composition of the catalyst surface. While the clean surface of a poisoned Pt(111) single crystal is fully restored upon thermal treatment in oxygen up to 700 K, contaminated Pt/Al{sub 2}O{sub 3} model catalyst and

Nanocarbon/oxide composite catalysts for bifunctional oxygen reduction and evolution in reversible alkaline fuel cells: A mini review

Science.gov (United States)

Chen, Mengjie; Wang, Lei; Yang, Haipeng; Zhao, Shuai; Xu, Hui; Wu, Gang

2018-01-01

A reversible fuel cell (RFC), which integrates a fuel cell with an electrolyzer, is similar to a rechargeable battery. This technology lies on high-performance bifunctional catalysts for the oxygen reduction reaction (ORR) in the fuel cell mode and the oxygen evolution reaction (OER) in the electrolyzer mode. Current catalysts are platinum group metals (PGM) such as Pt and Ir, which are expensive and scarce. Therefore, it is highly desirable to develop PGM-free catalysts for large-scale application of RFCs. In this mini review, we discussed the most promising nanocarbon/oxide composite catalysts for ORR/OER bifunctional catalysis in alkaline media, which is mainly based on our recent progress. Starting with the effectiveness of selected oxides and nanocarbons in terms of their activity and stability, we outlined synthetic methods and the resulting structures and morphologies of catalysts to provide a correlation between synthesis, structure, and property. A special emphasis is put on understanding of the possible synergistic effect between oxide and nanocarbon for enhanced performance. Finally, a few nanocomposite catalysts are discussed as typical examples to elucidate the rules of designing highly active and durable bifunctional catalysts for RFC applications.

A Facile Synthesis of Hollow Palladium/Copper Alloy Nanocubes Supported on N-Doped Graphene for Ethanol Electrooxidation Catalyst

Directory of Open Access Journals (Sweden)

Zhengyu Bai

2015-04-01

Full Text Available In this paper, a catalyst of hollow PdCu alloy nanocubes supported on nitrogen-doped graphene support (H-PdCu/ppy-NG is successfully synthesized using a simple one-pot template-free method. Two other catalyst materials such as solid PdCu alloy particles supported on this same nitrogen-doped graphene support (PdCu/ppy-NG and hollow PdCu alloy nanocubes supported on the reduced graphene oxide support (H-PdCu/RGO are also prepared using the similar synthesis conditions for comparison. It is found that, among these three catalyst materials, H-PdCu/ppy-NG gives the highest electrochemical active area and both the most uniformity and dispersibility of H-PdCu particles. Electrochemical tests show that the H-PdCu/ppy-NG catalyst can give the best electrocatalytic activity and stability towards the ethanol electrooxidation when compared to other two catalysts. Therefore, H-PdCu/ppy-NG should be a promising catalyst candidate for anodic ethanol oxidation in direct ethanol fuel cells.

First application of supported ionic liquid phase (SILP) catalysis for continuous methanol carbonylation

DEFF Research Database (Denmark)

Riisager, Anders; Jørgensen, Betina; Wasserscheid, Peter

2006-01-01

A solid, silica-supported ionic liquid phase (SILP) rhodium iodide Monsanto-type catalyst system, [BMIM][Rh(CO)(2)I-2]-[BMIM]I -SiO2, exhibits excellent activity and selectivity towards acetyl products in fixed-bed, continuous gas-phase methanol carbonylation.......A solid, silica-supported ionic liquid phase (SILP) rhodium iodide Monsanto-type catalyst system, [BMIM][Rh(CO)(2)I-2]-[BMIM]I -SiO2, exhibits excellent activity and selectivity towards acetyl products in fixed-bed, continuous gas-phase methanol carbonylation....

Copper oxide as efficient catalyst for oxidative dehydrogenation of alcohols with air

DEFF Research Database (Denmark)

Poreddy, Raju; Engelbrekt, Christian; Riisager, Anders

2015-01-01

The oxidative dehydrogenation of alcohols to carbonyl compounds was studied using CuO nanoparticle catalysts prepared by solution synthesis in buffered media. CuO nanoparticles synthesized in N-cyclohexyl- 3-aminopropanesulfonic acid buffer showed high catalytic activity for the oxidation...... of benzylic, alicyclic and unsaturated alcohols to their corresponding carbonyl compounds with excellent selectivities. The observed trend in activity for conversion of substituted alcohols suggested a β-H elimination step to be involved, thus enabling a possible reaction mechanism for oxidative...... dehydrogenation of benzyl alcohols to be proposed. The use of CuO as an inexpensive and efficient heterogeneous catalyst under aerobic conditions provides a new noble metal-free and green reaction protocol for carbonyl compound synthesis....

Naphthenic acid removal from HVGO by alkaline earth metal catalysts

Energy Technology Data Exchange (ETDEWEB)

Ding, L.; Rahimi, P.; Hawkins, R.; Bhatt, S.; Shi, Y. [National Centre for Upgrading Technology, Devon, AB (Canada); Natural Resources Canada, Devon, AB (Canada). CanmetENERGY

2009-07-01

This poster highlighted a study that investigated naphthenic acid removal from bitumen-derived heavy vacuum gas oil (HVGO) by thermal cracking and catalytic decarboxylation over alkaline earth-metal oxides and ZnO catalysts in a batch reactor and a continuous fixed-bed reactor. X-ray diffraction (XRD), thermogravimetric-differential thermal analysis (TG-DTA) temperature-programmed desorption (TPD) of carbon dioxide (CO{sub 2}-TPD), and scanning electron microscopy were used to characterize the fresh and spent catalysts. With MgO and ZnO, naphthenic acid removal proceeded via catalytic decarboxylation. No crystalline phase changes were observed after reaction. With CaO, multiple pathways such as catalytic decarboxylation, neutralization, and thermal cracking were responsible for naphthenic acid conversion. The spent catalysts contained Ca(OH){sub 2} and CaCO{sub 3}. With BaO, naphthenic acid conversion occurred through neutralization. All BaO was converted to Ba(OH){sub 2} during the reaction. tabs., figs.

Continuous Process for Biodiesel Production in Packed Bed Reactor from Waste Frying Oil Using Potassium Hydroxide Supported on Jatropha curcas Fruit Shell as Solid Catalyst

Directory of Open Access Journals (Sweden)

Achanai Buasri

2012-08-01

Full Text Available The transesterification of waste frying oil (WFO with methanol in the presence of potassium hydroxide catalyst supported on Jatropha curcas fruit shell activated carbon (KOH/JS was studied. The catalyst systems were characterized by X-ray diffraction (XRD, scanning electron microscopy (SEM and the Brunauer–Emmett–Teller (BET method. The effects of reaction variables such as residence time, reaction temperature, methanol/oil molar ratio and catalyst bed height in packed bed reactor (PBR on the yield of biodiesel were investigated. SEM images showed that KOH was well distributed on the catalyst support. The optimum conditions for achieving the conversion yield of 86.7% consisted of a residence time of 2 h, reaction temperature of 60 °C, methanol/oil molar ratio of 16 and catalyst bed height of 250 mm. KOH/JS could be used repeatedly five times without any activation treatment, and no significant activity loss was observed. The results confirmed that KOH/JS catalyst had a great potential to be used for industrial application in the transesterification of WFO. The fuel properties of biodiesel were also determined.

Influence of plasma treatment of carbon blacks on electrochemical activity of Pt/carbon blacks catalysts for DMFCs

Science.gov (United States)

Kim, Seok; Cho, Mi-Hwa; Lee, Jae-Rock; Park, Soo-Jin

In this work, in order to improve the dispersion of platinum catalysts deposited on carbon materials, the effects of surface plasma treatment of carbon blacks (CBs) were investigated. The surface characteristics of the CBs were determined by fourier transformed-infrared (FT-IR), X-ray photoelectron spectroscopy (XPS), and Boehm's titration method. The electrochemical properties of the plasma-treated CBs-supported Pt (Pt/CBs) catalysts were analyzed by linear sweep voltammetry (LSV) experiments. From the results of FT-IR and acid-base values, N 2-plasma treatment of the CBs at 300 W intensity led to a formation of a free radical on the CBs. The peak intensity increased with increase of the treatment time, due to the formation of new basic functional groups (such as C-N, C dbnd N, -NH 3 +, -NH, and dbnd NH) by the free radical on the CBs. Accordingly, the basic values were enhanced by the basic functional groups. However, after a specific reaction time, N 2-plasma treatment could hardly influence on change of the surface functional groups of CBs, due to the disappearance of free radical. Consequently, it was found that optimal treatment time was 30 s for the best electro activity of Pt/CBs catalysts and the N 2-plasma treated Pt/CBs possessed the better electrochemical properties than the pristine Pt/CBs.

Spent catalyst waste management. A review. Part 1. Developments in hydroprocessing catalyst waste reduction and use

Energy Technology Data Exchange (ETDEWEB)

Marafi, M.; Stanislaus, A. [Petroleum Refining Department, Petroleum Research and Studies Center, Kuwait Institute for Scientific Research, P.O. Box 24885, 13109-Safat (Kuwait)

2008-04-15

Solid catalysts containing metals, metal oxides or sulfides, which play a key role in the refining of petroleum to clean fuels and many other valuable products, become solid wastes after use. In many refineries, the spent catalysts discarded from hydroprocessing units form a major part of these solid wastes. Disposal of spent hydroprocessing catalysts requires compliance with stringent environmental regulations because of their hazardous nature and toxic chemicals content. Various options such as minimizing spent catalyst waste generation by regeneration and reuse, metals recovery, utilization to produce useful materials and treatment for safe disposal, could be considered to deal with the spent catalyst environmental problem. In this paper, information available in the literature on spent hydroprocessing catalyst waste reduction at source by using improved more active and more stable catalysts, regeneration, rejuvenation and reuse of deactivated catalysts in many cycles, and reusing in other processes are reviewed in detail with focus on recent developments. Available methods for recycling of spent hydroprocessing catalysts by using them as raw materials for the preparation of active new catalysts and many other valuable products are also reviewed. (author)

A new magnetically recoverable catalyst promoting the synthesis of 1,4-dihydropyridine and polyhydroquinoline derivatives via the Hantzsch condensation under solvent-free conditions

Energy Technology Data Exchange (ETDEWEB)

Taheri, Narges; Heidarizadeh, Fariba; Kiasat, Alireza

2017-04-15

In the current study, 1,4-dihydropyridine and polyhydroquinoline derivatives were efficiently synthesized under solvent-less conditions with a magnetic catalyst containing novel acidic ionic liquid functionalized silica modified Fe{sub 3}O{sub 4} nanoparticles through a four component combination of β-ketoester, aldehydes and ammonium acetate (1, 2, 2). Several approaches have been reported for synthesizing these derivatives, while each of these approaches have some weaknesses including long time of reaction, excess of volatile organic solvent, low efficiency, costly reagents, complex operation, high temperatures, production of a number of side products, and difficult catalyst recovery. The simple operation, short time of reaction (5–30 min) and the high efficiency (80–94%) are the special advantages of this technique. The immobilized catalyst exhibited an appropriate thermal stability and excellent recyclability. Different methods such as FT-IR, SEM, EDX, TGA-DTA, and VSM were used to confirm and characterize the catalyst. - Highlights: • A new acidic ionic liquid were first synthesized and applied in both symmetric and asymmetric hantzsch reactions for preparing 1, 4-dihydropyridine and polyhydroquinoline derivatives with high efficiencies under solvent-less conditions. • The immobilized catalyst exhibited an appropriate thermal stability and excellent recyclability. • The nanomagnetic catalyst could be recovered from solution with an external magnet at once, allowing undemanding recovery and reuse. • The catalyst was reused for five times with no considerable decrease in catalytic activity.

Synthesis and refining of sunflower biodiesel in a cascade of continuous centrifugal contactor separators

NARCIS (Netherlands)

Bin Abu Ghazali, Yusuf; van Ulden, Wouter; van de Bovenkamp, Hendrik; Teddy, T; Picchioni, Francesco; Manurung, Robert; Heeres, Hero J.

The synthesis of fatty acid methyl esters (FAME) from sunflower oil and methanol was studied in a continuous centrifugal contactor separator (CCCS) using sodium methoxide as the catalyst. The effect of relevant process variables like oil and methanol flow rate, rotational speed and catalyst

The synthesis of carbon nanocomposites as fuel cell catalyst support and the characterization of fuel cell catalysts by spatially resolved scanning mass spectrometry

Energy Technology Data Exchange (ETDEWEB)

Li, Nan

2007-07-01

Ammonia decomposition over Ni/SiO{sub 2} and Ni/MgO was investigated by temperature-programmed desorption (TPD) and temperature-programmed surface reaction (TPSR) in order to produce CO{sub x} free hydrogen fuel for fuel cell application. A highly efficient route for the synthesis of carbon nanocomposites based on electrochemical deposition and iron catalyzed chemical vapor deposition (CVD) was developed in order to obtain a promising substrate for fuel cell catalysts. The duration of electrochemical deposition, temperature and time for the carbon nanotubes (CNTs) growth had been optimized to achieve higher surface area after the growth. Hierarchically structured CNTs composites had been synthesized and electrochemical studies provided evidence for the strong interaction among the substrate and grown CNTs, which are essential for the application in fuel cells. A straightforward strategy was developed to synthesize well dispersed gold nanoparticles with a diameter of 4 to 6 nm on the sidewall of multi-walled carbon nanotubes (MWNTs). A gas flow set-up was developed for the evaluation of fuel cell catalysts by performing scanning mass spectrometry with integrated constant-distance positioning. Methanol oxidation was identified as a suitable test reaction. The diameter of scanning probe was reduced in order to achieve higher spatial resolution. Spatially resolved scanning mass spectrometry was successfully applied to visualize the catalytic activity over Pt-based catalysts and monitor the local activity of a catalysts coated membrane (CCM). The gas-solid phase reaction results were proved to be accurate, reliable and independent of the sample topography. This analytical method opens the way for fast quality control of the catalyst coating with respect to even coating and absence of damages, and for a better understanding of the CCM degradation in polymer membrane electrolyte fuel cells (PEMFCs). (orig.)

Automotive Catalyst State Diagnosis Using Microwaves

Directory of Open Access Journals (Sweden)

Moos Ralf

2015-01-01

Full Text Available The state of catalysts plays a key role in automotive exhaust gas aftertreatment. The soot or ash loading of Diesel particulate filters, the oxygen loading degree in three-way catalysts, the amount of stored ammonia in SCR catalysts, or the NOx loading degree in NOx storage catalysts are important parameters that are today determined indirectly and in a model-based manner with gas sensors installed upstream and/or downstream of the catalysts. This contribution gives an overview on a novel approach to determine the catalyst state directly by a microwave-based technique. The method exploits the fact that the catalyst housing acts as a microwave cavity resonator. As “sensing” elements, one or two simple antennas are mounted inside the catalyst canning. The electrical properties of the catalyst device (ceramic honeycomb plus coating and storage material can be measured. Preferably, the resonance characteristics, e.g., the resonance frequencies, of selected cavity modes are observed. The information on the catalyst interior obtained in such a contactless manner is very well correlated with the catalyst state as will be demonstrated for different exhaust gas aftertreatment systems.

Catalyst in Basic Oleochemicals

Directory of Open Access Journals (Sweden)

Eva Suyenty

2007-10-01

Full Text Available Currently Indonesia is the world largest palm oil producer with production volume reaching 16 million tones per annum. The high crude oil and ethylene prices in the last 3 – 4 years contribute to the healthy demand growth for basic oleochemicals: fatty acids and fatty alcohols. Oleochemicals are starting to replace crude oil derived products in various applications. As widely practiced in petrochemical industry, catalyst plays a very important role in the production of basic oleochemicals. Catalytic reactions are abound in the production of oleochemicals: Nickel based catalysts are used in the hydrogenation of unsaturated fatty acids; sodium methylate catalyst in the transesterification of triglycerides; sulfonic based polystyrene resin catalyst in esterification of fatty acids; and copper chromite/copper zinc catalyst in the high pressure hydrogenation of methyl esters or fatty acids to produce fatty alcohols. To maintain long catalyst life, it is crucial to ensure the absence of catalyst poisons and inhibitors in the feed. The preparation methods of nickel and copper chromite catalysts are as follows: precipitation, filtration, drying, and calcinations. Sodium methylate is derived from direct reaction of sodium metal and methanol under inert gas. The sulfonic based polystyrene resin is derived from sulfonation of polystyrene crosslinked with di-vinyl-benzene. © 2007 BCREC UNDIP. All rights reserved.[Presented at Symposium and Congress of MKICS 2007, 18-19 April 2007, Semarang, Indonesia][How to Cite: E. Suyenty, H. Sentosa, M. Agustine, S. Anwar, A. Lie, E. Sutanto. (2007. Catalyst in Basic Oleochemicals. Bulletin of Chemical Reaction Engineering and Catalysis, 2 (2-3: 22-31.  doi:10.9767/bcrec.2.2-3.6.22-31][How to Link/DOI: http://dx.doi.org/10.9767/bcrec.2.2-3.6.22-31 || or local: http://ejournal.undip.ac.id/index.php/bcrec/article/view/6

Hydroprocessing catalysts utilization and regeneration schemes

Energy Technology Data Exchange (ETDEWEB)

Furimsky, E.

The catalyst reactor inventory represents an important part of the cost of hydroprocessing operation. The selection of a suitable catalyst and reactor is influenced by feedstock properties. Processes ensuring an uninterrupted operation during catalyst addition and withdrawal are preferred for processing high asphaltene and metal content feedstocks. The spent catalyst can be regenerated and returned to the operation if the extent of its deactivation is not high. The regeneration may be performed either in-situ or off-site. The former is suitable for fixed bed reactors whereas the catalyst from ebullated bed reactors must be regenerated off-site. The regeneration of spent catalysts heavily loaded with metals such as V, Ni and Fe may not be economic. Such catalysts may be suitable for metal reclamation. An environmentally safe method for catalyst disposal must be found if neither regeneration nor metal reclamation from spent catalysts can be performed.

Alternative alkali resistant deNOx catalysts

DEFF Research Database (Denmark)

Putluru, Siva Sankar Reddy; Kristensen, Steffen Buus; Due-Hansen, Johannes

2012-01-01

by onepot sol–gel method. All catalysts were characterized by BET, XRPD and NH3-TPD. Initial SCR activities of 8 out of 9 catalysts showed higher NO conversion at least at one temperature in the temperature range 300–500 ◦C compared to the conventional V2O5-WO3/TiO2 catalyst. After potassium poisoning (100......Alternative alkali resistant deNOx catalysts were prepared using three different supports ZrO2, TiO2 and Mordenite zeolite. The majority of the catalysts were prepared by incipient wetness impregnation of a commercial support, with vanadium, copper or iron precursor, one catalyst was prepared......–130 µmol of K/g of catalyst) the relative drop in SCR activity and acidity was lower for all the alternative catalysts compared to the industrial V2O5-WO3/TiO2 catalyst. Furthermore, Cu/MOR and Nano-V2O5/Sul-TiO2 catalysts showed 8–16 times higher SCR activities than the conventional even after high...

Platinum/ceria/alumina catalysts on microstructures for carbon monoxide conversion

Energy Technology Data Exchange (ETDEWEB)

Germani, G.; Schuurman, Y.; Mirodatos, C. [Institut de Recherches sur la Catalyse, CNRS, 2 Avenue Albert Einstein, 69626 Villeurbanne (France); Alphonse, P.; Courty, M. [CIRIMAT, UMR-CNRS 5085, Universite Paul Sabatier, 118 route de Narbonne, 31062 Toulouse Cedex 04 (France)

2005-12-15

Platinum/ceria/alumina catalysts have been prepared by a sol-gel method and coated in the microchannels of stainless steel platelets. These catalysts are very active for the water-gas shift reaction between 300 and 400{sup o}C. Moreover, they are non-pyrophoric and thus well suited for the purification of hydrogen for PEM fuel cells. The obtained coatings show good adherence and catalytic activity. The influence of the amount of platinum and ceria as well as the effect of a binder on the catalytic performance has been investigated. The samples have been characterized before reaction by XRD, SEM and by N{sub 2} adsorption measurements. The kinetics, free from internal diffusion limitations, over these thin films have been described by a power law rate equation. An activation energy of 86kJ/mol has been found and at 260{sup o}C the TOF corresponds to 0.6+/-0.1s{sup -1} for all investigated samples. The superior activity of the platelets compared to the powder samples is attributed to the diffusion limitations inside the powder pellets. Thus catalysts deposited on microstructured platelets lead to a better platinum utilization.

Efficacy of Catalysts in the Batch Esterification of the Fatty Acids of ...

African Journals Online (AJOL)

The methyl, ethyl, propyl and butyl esters of the fatty acids of Thevetia peruviana seed oil were successfully prepared by the batch-esterification procedures. Various acid catalyst and various molar ratios of fatty acid to alcohol were investigated. H3PO4 was found to be ineffective to catalyze the esterification of the free fatty ...

Fluidized bed catalytic pyrolysis of eucalyptus over hzsm-5: effect of acid density and gallium modification on catalyst deactivation

Science.gov (United States)

Catalytic fast pyrolysis of eucalyptus wood was performed on a continuous laboratory scale fluidized bed fast pyrolysis system. Catalytic activity was monitored from use of fresh catalyst up to a cumulative biomass to catalyst ratio (B/C) of 4/1 over extruded pellets of three different ZSM-5 catalys...

Synergistic Interaction within Bifunctional Ruthenium Nanoparticle/SILP Catalysts for the Selective Hydrodeoxygenation of Phenols.

Science.gov (United States)

Luska, Kylie L; Migowski, Pedro; El Sayed, Sami; Leitner, Walter

2015-12-21

Ruthenium nanoparticles immobilized on acid-functionalized supported ionic liquid phases (Ru NPs@SILPs) act as efficient bifunctional catalysts in the hydrodeoxygenation of phenolic substrates under batch and continuous flow conditions. A synergistic interaction between the metal sites and acid groups within the bifunctional catalyst leads to enhanced catalytic activities for the overall transformation as compared to the individual steps catalyzed by the separate catalytic functionalities. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Transfer free graphene growth on SiO2 substrate at 250 °C

Science.gov (United States)

Vishwakarma, Riteshkumar; Rosmi, Mohamad Saufi; Takahashi, Kazunari; Wakamatsu, Yuji; Yaakob, Yazid; Araby, Mona Ibrahim; Kalita, Golap; Kitazawa, Masashi; Tanemura, Masaki

2017-03-01

Low-temperature growth, as well as the transfer free growth on substrates, is the major concern of graphene research for its practical applications. Here we propose a simple method to achieve the transfer free graphene growth on SiO2 covered Si (SiO2/Si) substrate at 250 °C based on a solid-liquid-solid reaction. The key to this approach is the catalyst metal, which is not popular for graphene growth by chemical vapor deposition. A catalyst metal film of 500 nm thick was deposited onto an amorphous C (50 nm thick) coated SiO2/Si substrate. The sample was then annealed at 250 °C under vacuum condition. Raman spectra measured after the removal of the catalyst by chemical etching showed intense G and 2D peaks together with a small D and intense SiO2 related peaks, confirming the transfer free growth of multilayer graphene on SiO2/Si. The domain size of the graphene confirmed by optical microscope and atomic force microscope was about 5 μm in an average. Thus, this approach will open up a new route for transfer free graphene growth at low temperatures.

In-situ characterization of heterogeneous catalysts

CERN Document Server

Rodriguez, Jose A; Chupas, Peter J

2013-01-01

Helps researchers develop new catalysts for sustainable fuel and chemical production Reviewing the latest developments in the field, this book explores the in-situ characterization of heterogeneous catalysts, enabling readers to take full advantage of the sophisticated techniques used to study heterogeneous catalysts and reaction mechanisms. In using these techniques, readers can learn to improve the selectivity and the performance of catalysts and how to prepare catalysts as efficiently as possible, with minimum waste. In-situ Characterization of Heterogeneous Catalysts feat

Reuse of Hydrotreating Spent Catalyst

International Nuclear Information System (INIS)

Habib, A.M.; Menoufy, M.F.; Amhed, S.H.

2004-01-01

All hydro treating catalysts used in petroleum refining processes gradually lose activity through coking, poisoning by metal, sulfur or halides or lose surface area from sintering at high process temperatures. Waste hydrotreating catalyst, which have been used in re-refining of waste lube oil at Alexandria Petroleum Company (after 5 years lifetime) compared with the same fresh catalyst were used in the present work. Studies are conducted on partial extraction of the active metals of spent catalyst (Mo and Ni) using three leaching solvents,4% oxidized oxalic acid, 10% aqueous sodium hydroxide and 10% citric acid. The leaching experiments are conducting on the de coked extrude [un crushed] spent catalyst samples. These steps are carried out in order to rejuvenate the spent catalyst to be reused in other reactions. The results indicated that 4% oxidized oxalic acid leaching solution gave total metal removal 45.6 for de coked catalyst samples while NaOH gave 35% and citric acid gave 31.9 % The oxidized leaching agent was the most efficient leaching solvent to facilitate the metal removal, and the rejuvenated catalyst was characterized by the unchanged crystalline phase The rejuvenated catalyst was applied for hydrodesulfurization (HDS) of vacuum gas oil as a feedstock, under different hydrogen pressure 20-80 bar in order to compare its HDS activity

Bio diesel synthesis from pongamia pinnata oil over modified CeO2 catalysts

International Nuclear Information System (INIS)

Venkatesh; Sathgatta Z, M. S.; Manjunatha, S.; Thammannigowda V, V.

2014-01-01

This study investigates the use of CeO 2 , ZrO 2 , Mg O and CeO 2 -ZrO 2 , CeO 2 -Mg O, CeO 2 -ZrO 2 -Mg O mixed oxides as solid base catalysts for the transesterification of Pongamia pinnata oil with methanol to produce bio diesel. SO 4 2- /CeO 2 and SO 4 2- /CeO 2 -ZrO 2 were also prepared and used as solid acid catalysts for esterification of Pongamia pinnata oil (P-oil) to reduce the % of free fatty acid (FFA) in P-oil. The oxide catalysts were prepared by an incipient wetness impregnation method and characterized by techniques such as NH 3 -Tpd for surface acidity, CO 2 -Tpd for surface basicity and powder X-ray diffraction for crystallinity. The effect of nature of the catalyst, methanol to P-oil molar ratio and reaction time in esterification as well as in transesterification was investigated. The catalytic materials were reactive d and reused for five reaction cycles and the results showed that the ceria based catalysts have reasonably good reusability both in esterification and transesterification reaction. The test results also revealed that the CeO 2 -ZrO 2 modified with Mg O could have potential for use in the large scale bio diesel production. (Author)

ALKALI RESISTANT CATALYST

DEFF Research Database (Denmark)

2008-01-01

The present invention concerns the selective removal of nitrogen oxides (NOx) from gasses. In particular, the invention concerns a process, a catalyst and the use of a catalyst for the selective removal of nitrogen oxides in the presence of ammonia from gases containing a significant amount...... of alkali metal and/or alkali-earth compounds which process comprises using a catalyst combined of (i) a formed porous superacidic support, said superacidic support having an Hammett acidity stronger than Ho=-12, and (ii) a metal oxide catalytic component deposited on said superacidic support selected from...

Continuous and pulse sonication effects on transesterification of used vegetable oil

International Nuclear Information System (INIS)

Martinez-Guerra, Edith; Gude, Veera Gnaneswar

2015-01-01

Highlights: • We studied continuous and pulse sonication effects on transesterification reaction. • Pulse sonication appears to have superior effects on transesterification reaction. • Effects of various process parameters on FAMEs yield were discussed in detail. • Effects of ultrasonic intensity and power density were compared for both conditions. • Continuous sonication may be beneficial for short time and plug-flow conditions. - Abstract: This study reports on the effects of direct application of continuous and pulse sonication on transesterification reaction of used vegetable oil. Specific to this research, thermal effects of ultrasonics in transesterification reaction without external conventional heating along with the effects of different ultrasonic intensities and power densities were reported. Two process parametric evaluation studies were conducted to compare the effects of continuous and pulse sonication. These included methanol to oil ratio, catalyst concentration and reaction time effects on the transesterification reaction. For continuous sonication, a catalyst amount of 0.5% (wt/wt), methanol to oil ratio of 9:1 was sufficient to complete the transesterification reaction in 1–2 min at a power output of 150 W with a biodiesel yield of 93.5%. For pulse sonication, a maximum biodiesel yield of 98% was achieved at 2.5 min of reaction time, 9:1 methanol to oil ratio, and 1.25% catalyst. Generally, higher biodiesel yields were observed for pulse sonication compared to continuous sonication under any given process condition. Power density and ultrasonic intensity tests revealed that biodiesel yields were more sensitive to continuous sonication due to intense mixing. A plug-flow or contact-type reactor design may improve overall ultrasonic utilization in the transesterification reaction under continuous sonication

Palladium nanoparticles immobilized on multifunctional ‎hyperbranched polyglycerol-grafted magnetic nanoparticles as a ‎sustainable and efficient catalyst for C-C coupling reactions

Directory of Open Access Journals (Sweden)

Mina Amini

2016-07-01

Full Text Available This study offers an exclusive class of magnetic nanoparticles supported hyperbranched polyglycerol (MNP/HPG that was functionalized with citric acid (MNP/HPG-CA as a host immobilization of palladium nanoparticles. The MNP/HPG-CA/Pd catalyst was fully characterized using some different techniques such as thermogravimetric analysis (TGA, x-ray diffraction (XRD, transmission electron microscopy (TEM, scanning electron microscopy (SEM, energy-dispersive x-ray spectroscopy (EDX, inductively coupled plasma (ICP and x-ray photoelectron spectroscopy (XPS. The new catalytic system showed high activity for the Suzuki–Miyaura cross-coupling and Heck reaction under mild and green conditions. Besides, the MNP/HPG-CA/Pd was found to be a convenient catalyst for copper-free Sonogashira coupling reaction in water as a green solvent at room temperature. Moreover, the catalyst could be recovered easily and reused several times without significant loss of reactivity. Ease of preparation, oxygen insensitive, phosphine-free, air- and moisture-stable, and high reusability of this immobilized palladium catalyst are the noteworthy advantages of this catalytic system.

Biodiesel synthesis from Jatropha curcas L. oil and ethanol in a continuous centrifugal contactor separator

NARCIS (Netherlands)

Abduh, Muhammad Yusuf; van Ulden, Wouter; Kalpoe, Vijay; van de Bovenkamp, Hendrik H.; Manurung, Robert; Heeres, Hero J.

The synthesis of fatty acid ethyl esters (FAEE) from Jatropha curcas L. oil was studied in a batch reactor and a continuous centrifugal contactor separator (CCCS) using sodium ethoxide as the catalyst. The effect of relevant process variables like rotational speed, temperature, catalyst

Development of continuous bench scale unit for direct liquefaction

Energy Technology Data Exchange (ETDEWEB)

Yoon, Wang Lai [Korea Inst. of Energy and Resources, Daeduk (Korea, Republic of)

1996-12-31

Batch coal liquefaction experiments using tubing bombs and continuous experiments by cell liquefaction test facility were carried out. The main purpose was to maximize the coal liquefaction yields by improving the activity of coal dissolution catalysts which are oil soluble transition metal naphthenate and to supplement the incomplete research results. In the meantime, the study on the reaction characteristics of coal liquefaction and coal liquid upgrading catalyst upon sulfiding conditions and phosphorous addition have been conducted (author). 102 refs., 35 figs.

Development of continuous bench scale unit for direct liquefaction

Energy Technology Data Exchange (ETDEWEB)

Yoon, Wang Lai [Korea Inst. of Energy and Resources, Daeduk (Korea, Republic of)

1995-12-31

Batch coal liquefaction experiments using tubing bombs and continuous experiments by cell liquefaction test facility were carried out. The main purpose was to maximize the coal liquefaction yields by improving the activity of coal dissolution catalysts which are oil soluble transition metal naphthenate and to supplement the incomplete research results. In the meantime, the study on the reaction characteristics of coal liquefaction and coal liquid upgrading catalyst upon sulfiding conditions and phosphorous addition have been conducted (author). 102 refs., 35 figs.

ZnO nanoparticle catalysts for use in biodiesel production and method of making

Energy Technology Data Exchange (ETDEWEB)

Yan, Shuli; Salley, Steven O; Ng, K. Y. Simon

2014-11-25

A method of forming a biodiesel product and a heterogeneous catalyst system used to form said product that has a high tolerance for the presence of water and free fatty acids (FFA) in the oil feedstock is disclosed. This catalyst system may simultaneously catalyze both the esterification of FAA and the transesterification of triglycerides present in the oil feedstock. The catalyst system is comprised of a mixture of zinc oxide and a second metal oxide. The zinc oxide includes a mixture of amorphous zinc oxide and zinc oxide nanocrystals, the zinc nanocrystals having a mean grain size between about 20 and 80 nanometers with at least one of the nanocrystals including a mesopore having a diameter of about 5 to 15 nanometers. Preferably, the second metal oxide is a lanthanum oxide, the lanthanum oxide being selected as one from the group of La.sub.2CO.sub.5, LaOOH, and combinations or mixtures thereof.

Insights into the Diels-Alder Reaction between 3-Vinylindoles and Methyleneindolinone without and with the Assistance of Hydrogen-Bonding Catalyst Bisthiourea: Mechanism, Origin of Stereoselectivity, and Role of Catalyst.

Science.gov (United States)

Yan, Chao-Xian; Yang, Fan; Yang, Xing; Zhou, Da-Gang; Zhou, Pan-Pan

2017-03-17

The Diels-Alder reaction between 3-vinylindoles and methyleneindolinone can proceed both under catalyst-free conditions and with bisthiourea as the catalyst. The reaction with bisthiourea is much faster and results in higher stereoselectivity of the product. The reaction mechanism, origin of stereoselectivity, and role of the catalyst were elaborated based on quantum mechanical calculations and theoretical methods of reactivity indices, NCI, QTAIM, and distortion/interaction models. In the uncatalyzed reaction, the two C-C bonds that are formed undergo conversion from noncovalent to covalent bonding via a concerted asynchronous mechanism. The weak intermolecular interactions formed in the transition state play important roles. The difference between the interaction and distortion energies is responsible for the stereoselectivity. In the catalyzed reaction, bisthiourea induces both the diene and dienophile to approach it via weak intermolecular interactions, which greatly lowers the energy barrier of the reaction and leads to the product with excellent stereoselectivity. The possible pathways of this reaction were explored, which suggested that the formation of the two C-C bonds goes through either a stepwise or concerted asynchronous mechanism. These results detail the reaction mechanism and shed light on both the significant role of the bisthiourea catalyst and the origin of stereoselectivity for this type of Diels-Alder reaction and related ones.

Esterification of Fatty Acids with Short-Chain Alcohols over Commercial Acid Clays in a Semi-Continuous Reactor

Directory of Open Access Journals (Sweden)

Mohamed H. Frikha

2009-11-01

Full Text Available Production of fatty acid esters from stearic, oleic, and palmitic acids and short-chain alcohols (methanol, ethanol, propanol, and butanol for the production of biodiesel was investigated in this work. A series of montmorillonite-based clays catalysts (KSF, KSF/0, KP10, and K10 were used as acidic catalysts. The influence of the specific surface area and the acidity of the catalysts on the esterification rate were investigated. The best catalytic activities were obtained with KSF/0 catalyst. The esterification reaction has been carried out efficiently in a semi-continuous reactor at 150°C temperature higher than the boiling points of water and alcohol. The reactor used enabled the continuous removal of water and esterification with hydrated alcohol (ethanol 95% without affecting the original activity of the clay.

Paraffin Alkylation Using Zeolite Catalysts in a slurry reactor: Chemical Engineering Principles to Extend Catalyst Lifetime

NARCIS (Netherlands)

Jong, K.P. de; Mesters, C.M.A.M.; Peferoen, D.G.R.; Brugge, P.T.M. van; Groot, C. de

1996-01-01

The alkylation of isobutane with 2-butene is carried out using a zeolitic catalyst in a well stirred slurry reactor. Whereas application of fixed bed technology using a solid acid alkylation catalyst has in the led to catalysts lifetimes in the range of minutes, in this work we report catalyst

Hydroxide catalysts for lignin depolymerization

Science.gov (United States)

Beckham, Gregg T; Biddy, Mary J.; Kruger, Jacob S.; Chmely, Stephen C.; Sturgeon, Matthew

2017-10-17

Solid base catalysts and their use for the base-catalyzed depolymerization (BCD) of lignin to compounds such as aromatics are presented herein. Exemplary catalysts include layered double hydroxides (LDHs) as recyclable, heterogeneous catalysts for BCD of lignin.

Hydroxide catalysts for lignin depolymerization

Energy Technology Data Exchange (ETDEWEB)

Beckham, Gregg T.; Biddy, Mary J.; Chmely, Stephen C.; Sturgeon, Matthew

2017-04-25

Solid base catalysts and their use for the base-catalyzed depolymerization (BCD) of lignin to compounds such as aromatics are presented herein. Exemplary catalysts include layered double hydroxides (LDHs) as recyclable, heterogeneous catalysts for BCD of lignin.

Oxidation catalysts for cleaning of CO and TOC in flue gases - step 1; Oxidationskatalysatorer foer rening av ofoerbraenda roekgaser - etapp 1

Energy Technology Data Exchange (ETDEWEB)

Berg, Magnus [TPS Termiska Processer AB, Nykoeping (Sweden); Harnevie, H. [SwedPower AB (Sweden)

2001-01-01

should take place via a combination of work in both laboratory and full scale. During laboratory experiments, the sensitivity of the catalysts for variations in H{sub 2}O, HCl, SO{sub 2} and O{sub 2} should be examined. Full-scale attempts should include approximately 6 months continuous follow-up in two separate plants. Preferably a plant fired with a fuel containing both chlorine and sulphur and also preferably a plant that fires a fuel relatively free from both these components.

Self-assembled growth and structural analysis of inclined GaN nanorods on nanoimprinted m-sapphire using catalyst-free metal-organic chemical vapor deposition

Energy Technology Data Exchange (ETDEWEB)

Lee, Kyuseung; Chae, Sooryong; Jang, Jongjin; Min, Daehong; Kim, Jaehwan; Nam, Okhyun, E-mail: ohnam@kpu.ac.kr [Convergence Center for Advanced Nano Semiconductor (CANS), Department of Nano-Optical Engineering, Korea Polytechnic University, Siheung, 15073 (Korea, Republic of)

2016-04-15

In this study, self-assembled inclined (1-10-3)-oriented GaN nanorods (NRs) were grown on nanoimprinted (10-10) m-sapphire substrates using catalyst-free metal-organic chemical vapor deposition. According to X-ray phi-scans, the inclined GaN NRs were tilted at an angle of ∼57.5° to the [10-10]{sub sapp} direction. Specifically, the GaN NRs grew in a single inclined direction to the [11-20]{sub sapp}. Uni-directionally inclined NRs were formed through the one-sided (10-11)-faceted growth of the interfacial a-GaN plane layer. It was confirmed that a thin layer of a-GaN was formed on r-facet nanogrooves of the m-sapphire substrate by nitridation. The interfacial a-GaN nucleation affected both the inclined angle and the growth direction of the inclined GaN NRs. Using X-ray diffraction and selective area electron diffraction, the epitaxial relationship between the inclined (1-10-3) GaN NRs and interfacial a-GaN layer on m-sapphire substrates was systematically investigated. Moreover, the inclined GaN NRs were observed to be mostly free of stacking fault-related defects using high-resolution transmission electron microscopy.

Overcoming the Instability of Nanoparticle-Based Catalyst Films in Alkaline Electrolyzers by using Self-Assembling and Self-Healing Films.

Science.gov (United States)

Barwe, Stefan; Masa, Justus; Andronescu, Corina; Mei, Bastian; Schuhmann, Wolfgang; Ventosa, Edgar

2017-07-10

Engineering stable electrodes using highly active catalyst nanopowders for electrochemical water splitting remains a challenge. We report an innovative and general approach for attaining highly stable catalyst films with self-healing capability based on the in situ self-assembly of catalyst particles during electrolysis. The catalyst particles are added to the electrolyte forming a suspension that is pumped through the electrolyzer. Particles with negatively charged surfaces stick onto the anode, while particles with positively charged surfaces stick to the cathode. The self-assembled catalyst films have self-healing properties as long as sufficient catalyst particles are present in the electrolyte. The proof-of-concept was demonstrated in a non-zero gap alkaline electrolyzer using NiFe-LDH and Ni x B catalyst nanopowders for anode and cathode, respectively. Steady cell voltages were maintained for at least three weeks during continuous electrolysis at 50-100 mA cm -2 . © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Hydrous titanium oxide-supported catalysts

International Nuclear Information System (INIS)

Dosch, R.G.; Stohl, F.V.; Richardson, J.T.

1990-01-01

Catalysts were prepared on hydrous titanium oxide (HTO) supports by ion exchange of an active metal for Na + ions incorporated in the HTO support during preparation by reaction with the parent Ti alkoxide. Strong active metal-HTO interactions as a result of the ion exchange reaction can require significantly different conditions for activation as compared to catalysts prepared by more widely used incipient wetness methods. The latter catalysts typically involve conversion or while the HTO catalysts require the alteration of electrostatic bonds between the metal and support with subsequent alteration of the support itself. In this paper, the authors discuss the activation, via sulfidation or reduction, of catalysts consisting of Co, Mo, or Ni-Mo dispersed on HTO supports by ion exchange. Correlations between the activation process and the hydrogenation, hydrodeoxygenation, and hydrodesulfurization activities of the catalysts are presented

Hydrodeoxygenation of water-insoluble bio-oil to alkanes using a highly dispersed Pd-Mo catalyst.

Science.gov (United States)

Duan, Haohong; Dong, Juncai; Gu, Xianrui; Peng, Yung-Kang; Chen, Wenxing; Issariyakul, Titipong; Myers, William K; Li, Meng-Jung; Yi, Ni; Kilpatrick, Alexander F R; Wang, Yu; Zheng, Xusheng; Ji, Shufang; Wang, Qian; Feng, Junting; Chen, Dongliang; Li, Yadong; Buffet, Jean-Charles; Liu, Haichao; Tsang, Shik Chi Edman; O'Hare, Dermot

2017-09-19

Bio-oil, produced by the destructive distillation of cheap and renewable lignocellulosic biomass, contains high energy density oligomers in the water-insoluble fraction that can be utilized for diesel and valuable fine chemicals productions. Here, we show an efficient hydrodeoxygenation catalyst that combines highly dispersed palladium and ultrafine molybdenum phosphate nanoparticles on silica. Using phenol as a model substrate this catalyst is 100% effective and 97.5% selective for hydrodeoxygenation to cyclohexane under mild conditions in a batch reaction; this catalyst also demonstrates regeneration ability in long-term continuous flow tests. Detailed investigations into the nature of the catalyst show that it combines hydrogenation activity of Pd and high density of both Brønsted and Lewis acid sites; we believe these are key features for efficient catalytic hydrodeoxygenation behavior. Using a wood and bark-derived feedstock, this catalyst performs hydrodeoxygenation of lignin, cellulose, and hemicellulose-derived oligomers into liquid alkanes with high efficiency and yield.Bio-oil is a potential major source of renewable fuels and chemicals. Here, the authors report a palladium-molybdenum mixed catalyst for the selective hydrodeoxygenation of water-insoluble bio-oil to mixtures of alkanes with high carbon yield.

Methanol conversion to hydrocarbons using modified clinoptilolite catalysts. Investigation of catalyst lifetime and reactivation

Energy Technology Data Exchange (ETDEWEB)

Hutchings, G J; Themistocleous, T; Copperthwaite, R G

1988-10-17

A study of the deactivation and reactivation of modified clinoptilolite catalysts for methanol conversion to hydrocarbons is reported. Clinoptilolite catalysts, modified by either ammonium ion exchange or hydrochloric acid treatment, exhibit a short useful catalyst lifetime for this reaction (ca. 2-3 h) due to a high rate of coke deposition (3-5.10/sup -3/ g carbon/g catalyst/h). A comparative study of reactivation using oxygen, nitrous oxide and ozone/oxygen as oxidants indicated that nitrous oxide reactivation gives improved catalytic performance when compared to the activity and lifetime of the fresh catalyst. Both oxygen and ozone/oxygen were found to be ineffective for the reactivation of clinoptilolite. Initial studies of in situ on-line reactivation are also described. 3 figs., 15 refs., 4 tabs.

Magnetic catalyst bodies

NARCIS (Netherlands)

Teunissen, Wendy; Bol, A.A.; Geus, John W.

1999-01-01

After a discussion about the importance of the size of the catalyst bodies with reactions in the liquid-phase with a suspended catalyst, the possibilities of magnetic separation are dealt with. Deficiencies of the usual ferromagnetic particles are the reactivity and the clustering of the

Single Atomic Iron Catalysts for Oxygen Reduction in Acidic Media: Particle Size Control and Thermal Activation

Energy Technology Data Exchange (ETDEWEB)

Zhang, Hanguang [Department; Hwang, Sooyeon [Center; Wang, Maoyu [School; Feng, Zhenxing [School; Karakalos, Stavros [Department; Luo, Langli [Pacific Northwest National Laboratory, Richland, Washington 99352, United States; Qiao, Zhi [Department; Xie, Xiaohong [Pacific Northwest National Laboratory, Richland, Washington 99352, United States; Wang, Chongmin [Pacific Northwest National Laboratory, Richland, Washington 99352, United States; Su, Dong [Center; Shao, Yuyan [Pacific Northwest National Laboratory, Richland, Washington 99352, United States; Wu, Gang [Department

2017-09-26

To significantly reduce the cost of proton exchange membrane (PEM) fuel cells, current Pt must be replaced by platinum-metal-group (PGM)-free catalysts for the oxygen reduction reaction (ORR) in acid. We report here a new class of high-performance atomic iron dispersed carbon catalysts through controlled chemical doping of iron ions into zinc-zeolitic imidazolate framework (ZIF), a type of metal-organic framework (MOF). The novel synthetic chemistry enables accurate size control of Fe-doped ZIF catalyst particles with a wide range from 20 to 1000 nm without changing chemical properties, which provides a great opportunity to increase the density of active sites that is determined by the particle size. We elucidated the active site formation mechanism by correlating the chemical and structural changes with thermal activation process for the conversion from Fe-N4 complex containing hydrocarbon networks in ZIF to highly active FeNx sites embedded into carbon. A temperature of 800oC was identified as the critical point to start forming pyridinic nitrogen doping at the edge of the graphitized carbon planes. Further increasing heating temperature to 1100oC leads to increase of graphitic nitrogen, generating possible synergistic effect with FeNx sites to promote ORR activity. The best performing catalyst, which has well-defined particle size around 50 nm and abundance of atomic FeNx sites embedded into carbon structures, achieve a new performance milestone for the ORR in acid including a half-wave potential of 0.85 V vs RHE and only 20 mV loss after 10,000 cycles in O2 saturated H2SO4 electrolyte. The new class PGM-free catalyst with approaching activity to Pt holds great promise for future PEM fuel cells.

Molybdenum carbide nanoparticles as catalysts for oil sands upgrading: Dynamics and free-energy profiles

International Nuclear Information System (INIS)

Liu, Xingchen; Salahub, Dennis R.

2015-01-01

There is no doubt that a huge gap exists in understanding heterogeneous catalysis between a cluster model of a few atoms and a bulk model of periodic slabs. Nanoparticles, which are crucial in heterogeneous catalysis in industry, lie in the middle of the gap. We present here our work on the computational modelling of molybdenum carbide nanoparticles (MCNPs) as the catalysts for the upgrading of oil sands in the in-situ environment, using benzene hydrogenation as a model reaction. With a cluster model, efforts were first made to understand the mechanism of the reaction with a density functional theory (DFT) study on the adsorption of benzene and its hydrogenation product – cyclohexane, as well as the cyclic hydrogenation reaction intermediates on the Mo 2 C(0001) surface. From the thermodynamic data, along with literature information, it was found that the benzene hydrogenation reaction on molybdenum carbide happens most likely through a Langmuir-Hinshelwood mechanism with the gradual lifting up of the benzene molecule. The electron localization function (ELF) was then used to help understand the nature of the interactions between the MCNPs, identifying strong multi-center interactions between the adsorbates and the MCNPs. To enable the treatment of larger nanoparticles, a fast semi-empirical density functional tight-binding (DFTB) method was parameterized. With this method, the potential energy profiles of benzene hydrogenation reactions on different sizes of MCNPs are calculated. The study was then extended to consider a MCNP embedded in solvent (benzene), using a quantum mechanical (DFTB) / molecular mechanical approach. Calculations on the free energies profiles with the umbrella sampling method show that the entropy of the MCNPs and the solvent are essential in understanding the catalytic activity of the transition metal related nanoparticles for solid/liquid heterogeneous catalysis

Molybdenum carbide nanoparticles as catalysts for oil sands upgrading: Dynamics and free-energy profiles

Energy Technology Data Exchange (ETDEWEB)

Liu, Xingchen; Salahub, Dennis R. [Department of Chemistry, Institute for Quantum Science and Technology, and Centre for Molecular Simulation, University of Calgary, 2500 University Drive NW, Calgary, Alberta, Canada T2N 1N4 (Canada)

2015-12-31

There is no doubt that a huge gap exists in understanding heterogeneous catalysis between a cluster model of a few atoms and a bulk model of periodic slabs. Nanoparticles, which are crucial in heterogeneous catalysis in industry, lie in the middle of the gap. We present here our work on the computational modelling of molybdenum carbide nanoparticles (MCNPs) as the catalysts for the upgrading of oil sands in the in-situ environment, using benzene hydrogenation as a model reaction. With a cluster model, efforts were first made to understand the mechanism of the reaction with a density functional theory (DFT) study on the adsorption of benzene and its hydrogenation product – cyclohexane, as well as the cyclic hydrogenation reaction intermediates on the Mo{sub 2}C(0001) surface. From the thermodynamic data, along with literature information, it was found that the benzene hydrogenation reaction on molybdenum carbide happens most likely through a Langmuir-Hinshelwood mechanism with the gradual lifting up of the benzene molecule. The electron localization function (ELF) was then used to help understand the nature of the interactions between the MCNPs, identifying strong multi-center interactions between the adsorbates and the MCNPs. To enable the treatment of larger nanoparticles, a fast semi-empirical density functional tight-binding (DFTB) method was parameterized. With this method, the potential energy profiles of benzene hydrogenation reactions on different sizes of MCNPs are calculated. The study was then extended to consider a MCNP embedded in solvent (benzene), using a quantum mechanical (DFTB) / molecular mechanical approach. Calculations on the free energies profiles with the umbrella sampling method show that the entropy of the MCNPs and the solvent are essential in understanding the catalytic activity of the transition metal related nanoparticles for solid/liquid heterogeneous catalysis.

Tandem base-free synthesis of -hydroxy sulphides under ...

Indian Academy of Sciences (India)

The important features of this methodology are base-free, odourless, high yield, reasonably rapid reaction rate, simple workup, high regioselectivity, costeffective and no requirement of transition metal catalysts. It is noteworthy that ring-opening reaction of 1,2-diphenyldiselane with 2-(phenoxymethyl)oxirane are also ...

Single-atom catalysts for CO2 electroreduction with significant activity and selectivity improvements.

Science.gov (United States)

Back, Seoin; Lim, Juhyung; Kim, Na-Young; Kim, Yong-Hyun; Jung, Yousung

2017-02-01

A single-atom catalyst (SAC) has an electronic structure that is very different from its bulk counterparts, and has shown an unexpectedly high specific activity with a significant reduction in noble metal usage for CO oxidation, fuel cell and hydrogen evolution applications, although physical origins of such performance enhancements are still poorly understood. Herein, by means of density functional theory (DFT) calculations, we for the first time investigate the great potential of single atom catalysts for CO 2 electroreduction applications. In particular, we study a single transition metal atom anchored on defective graphene with single or double vacancies, denoted M@sv-Gr or M@dv-Gr, where M = Ag, Au, Co, Cu, Fe, Ir, Ni, Os, Pd, Pt, Rh or Ru, as a CO 2 reduction catalyst. Many SACs are indeed shown to be highly selective for the CO 2 reduction reaction over a competitive H 2 evolution reaction due to favorable adsorption of carboxyl (*COOH) or formate (*OCHO) over hydrogen (*H) on the catalysts. On the basis of free energy profiles, we identified several promising candidate materials for different products; Ni@dv-Gr (limiting potential U L = -0.41 V) and Pt@dv-Gr (-0.27 V) for CH 3 OH production, and Os@dv-Gr (-0.52 V) and Ru@dv-Gr (-0.52 V) for CH 4 production. In particular, the Pt@dv-Gr catalyst shows remarkable reduction in the limiting potential for CH 3 OH production compared to any existing catalysts, synthesized or predicted. To understand the origin of the activity enhancement of SACs, we find that the lack of an atomic ensemble for adsorbate binding and the unique electronic structure of the single atom catalysts as well as orbital interaction play an important role, contributing to binding energies of SACs that deviate considerably from the conventional scaling relation of bulk transition metals.

A Catalyst-Free Amination of Functional Organolithium Reagents by Flow Chemistry.

Science.gov (United States)

Kim, Heejin; Yonekura, Yuya; Yoshida, Jun-Ichi

2018-04-03

Reported is the electrophilic amination of functional organolithium intermediates with well-designed aminating reagents under mild reaction conditions using flow microreactors. The aminating reagents were optimized to achieve efficient C-N bond formation without using any catalyst. The electrophilic amination reactions of functionalized aryllithiums were successfully conducted under mild reaction conditions, within 1 minute, by using flow microreactors. The aminating reagent was also prepared by the flow method. Based on stopped-flow NMR analysis, the reaction time for the preparation of the aminating reagent was quickly optimized without the necessity of work-up. Integrated one-flow synthesis consisting of the generation of an aryllithium, the preparation of an aminating reagent, and their combined reaction was successfully achieved to give the desired amine within 5 minutes of total reaction time. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Ir-Ru/Al2O3 catalysts used in satellite propulsion

Directory of Open Access Journals (Sweden)

T.G. Soares Neto

2003-09-01

Full Text Available Ir/Al2O3, Ir-Ru/Al2O3 and Ru/Al2O3, catalysts with total metal contents of 30% were prepared using the methods of incipient wetness and incipient coimpregnation wetness and were tested in a 2N microthruster. Their performances were then compared with that of the Shell 405 commercial catalyst (30% Ir/Al2O3. Tests were performed in continuous and pulsed regimes, where there are steep temperature and pressure gradients, from ambient values up to 650 ºC and 14 bar. Performance stability, thrust produced, temperature and stagnation pressure in the chamber and losses of mass were analyzed and compared to the corresponding parameters in Shell 405 tests. It was observed that the performance of all the above-mentioned catalysts was comparable to that of the commercial one, except for in loss of mass, where the values was higher, which was attributed to the lower mechanical resistance of the support.

Development of GREET Catalyst Module

Energy Technology Data Exchange (ETDEWEB)

Wang, Zhichao [Argonne National Lab. (ANL), Argonne, IL (United States). Energy Systems Division; Dunn, Jennifer B. [Argonne National Lab. (ANL), Argonne, IL (United States). Energy Systems Division; Cronauer, Donald C. [Argonne National Lab. (ANL), Argonne, IL (United States). Energy Systems Division

2014-09-01

Catalysts are critical inputs for many pathways that convert biomass into biofuels. Energy consumption and greenhouse gas (GHG) emissions during the production of catalysts and chemical inputs influence the life-cycle energy consumption, and GHG emissions of biofuels and need to be considered in biofuel life-cycle analysis (LCA). In this report, we develop energy and material flows for the production of three different catalysts (tar reforming, alcohol synthesis, Zeolite Socony Mobil-5 [ZSM-5]) and two chemicals (olivine, dimethyl ether of polyethylene glycol [DEPG]). These compounds and catalysts are now included in the Greenhouse Gases, Regulated Emissions and Energy Use in Transportation (GREET™) catalyst module. They were selected because they are consumed in existing U.S. Department of Energy (DOE) analyses of biofuel processes. For example, a thermochemical ethanol production pathway (indirect gasification and mixed alcohol synthesis) developed by the National Renewable Energy Laboratory (NREL) uses olivine, DEPG, and tar reforming and alcohol synthesis catalysts (Dutta et al., 2011). ZSM-5 can be used in biofuel production pathways such as catalytic upgrading of sugars into hydrocarbons (Biddy and Jones, 2013). Other uses for these compounds and catalysts are certainly possible. In this report, we document the data sources and methodology we used to develop material and energy flows for the catalysts and compounds in the GREET catalyst module. In Section 2 we focus on compounds used in the model Dutta et al. (2011) developed. In Section 3, we report material and energy flows associated with ZSM-5 production. Finally, in Section 4, we report results.

Highly active Ni/Y-doped ZrO{sub 2} catalysts for CO{sub 2} methanation

Energy Technology Data Exchange (ETDEWEB)

Takano, H., E-mail: takano_hi@hitachizosen.co.jp [Hitachi Zosen Corporation, Kashiwa, 277-8515 (Japan); Graduate School of Chemical Sciences and Engineering, Hokkaido University, Sapporo, 060-8628 (Japan); Kirihata, Y.; Izumiya, K.; Kumagai, N. [Hitachi Zosen Corporation, Kashiwa, 277-8515 (Japan); Habazaki, H., E-mail: habazaki@eng.hokudai.ac.jp [Graduate School of Chemical Sciences and Engineering, Hokkaido University, Sapporo, 060-8628 (Japan); Division of Applied Chemistry & Frontier Chemistry Center, Faculty of Engineering, Hokkaido University, Sapporo, 060-8628 (Japan); Hashimoto, K. [Tohoku Institute of Technology, Sendai, 277-8515 (Japan)

2016-12-01

Highlights: • The Ni/Y-doped ZrO{sub 2} catalysts show highly catalytic activity for CO{sub 2} methanation. • Bidentate carbonate is a major adsorption spice on the Ni/Y-doped ZrO{sub 2} catalysts. • The oxide support of t-ZrO{sub 2} and/or c-ZrO{sub 2} with oxygen vacancies plays a key role. - Abstract: The catalytic methanation of CO{sub 2} was carried out on Ni catalysts supported on Y-doped ZrO{sub 2} with various Y{sup 3+} concentrations and Ni/(Zr + Y) molar ratio = 1. The catalysts were characterized by X-ray diffraction, scanning transmission electron microscopy, specific surface area, temperature-programmed desorption of CO{sub 2}, and temperature-programmed reaction. In addition, operando diffuse-reflectance infrared Fourier-transform spectroscopy (DRIFT) was used to identify the adsorbed reaction intermediate. Catalysts supported on Y-doped ZrO{sub 2} show higher catalytic activity than the catalyst on Y-free ZrO{sub 2} with a monoclinic ZrO{sub 2} phase. The catalytic activity is also dependent upon the Y{sup 3+} concentration, and the highest activity was obtained for the catalyst with a Y/(Zr + Y) molar ratio of 0.333, which consists mainly of fcc Ni and cubic ZrO{sub 2} phase. Y{sup 3+} doping into ZrO{sub 2} introduces oxygen vacancies, which play an important role in enhancing the catalytic activity. The operando DRIFT study reveals that a CO adsorption intermediate is absent, and bidentate carbonate is an important intermediate for CH{sub 4} formation.

Fischer-Tropsch Synthesis over Iron Manganese Catalysts: Effect of Preparation and Operating Conditions on Catalyst Performance

Directory of Open Access Journals (Sweden)

Ali A. Mirzaei

2009-01-01

molar basis which is the most active catalyst for the conversion of synthesis gas to light olefins. The effects of different promoters and supports with loading of optimum support on the catalytic performance of catalysts are also studied. It was found that the catalyst containing 50%Fe/50%Mn/5 wt.%Al2O3 is an optimum-modified catalyst. The catalytic performance of optimal catalyst has been studied in operation conditions such as a range of reaction temperatures, H2/CO molar feed ratios and a range of total pressures. Characterization of both precursors and calcined catalysts is carried out by powder X-ray diffraction (XRD, scanning electron microscopy (SEM, BET specific surface area and thermal analysis methods such as TGA and DSC.

Polymeric carbon nitride nanomesh as an efficient and durable metal-free catalyst for oxidative desulfurization.

Science.gov (United States)

Shen, Lijuan; Lei, Ganchang; Fang, Yuanxing; Cao, Yanning; Wang, Xinchen; Jiang, Lilong

2018-03-06

We report the first use of polymeric carbon nitride (CN) for the catalytic selective oxidation of H 2 S. The as-prepared CN with unique ultrathin "nanomeshes" structure exhibits excellent H 2 S conversion and high S selectivity. In particular, the CN nanomesh also displays better durability in the desulfurization reaction than traditional catalysts, such as carbon- and iron-based materials.