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Sample records for catalyst supports

  1. Supported organoiridium catalysts for alkane dehydrogenation

    Energy Technology Data Exchange (ETDEWEB)

    Baker, R. Thomas; Sattelberger, Alfred P.; Li, Hongbo

    2013-09-03

    Solid supported organoiridium catalysts, a process for preparing such solid supported organoiridium catalysts, and the use of such solid supported organoiridium catalysts in dehydrogenation reactions of alkanes is provided. The catalysts can be easily recovered and recycled.

  2. Supported molten-metal catalysts

    Science.gov (United States)

    Datta, Ravindra; Singh, Ajeet; Halasz, Istvan; Serban, Manuela

    2001-01-01

    An entirely new class of catalysts called supported molten-metal catalysts, SMMC, which can replace some of the existing precious metal catalysts used in the production of fuels, commodity chemicals, and fine chemicals, as well as in combating pollution. SMMC are based on supporting ultra-thin films or micro-droplets of the relatively low-melting (<600.degree. C.), inexpensive, and abundant metals and semimetals from groups 1, 12, 13, 14, 15 and 16, of the periodic table, or their alloys and intermetallic compounds, on porous refractory supports, much like supported microcrystallites of the traditional solid metal catalysts. It thus provides orders of magnitude higher surface area than is obtainable in conventional reactors containing molten metals in pool form and also avoids corrosion. These have so far been the chief stumbling blocks in the application of molten metal catalysts.

  3. Alumina supported iridium catalysts - preparation

    International Nuclear Information System (INIS)

    This report describes the method employed in the preparation of alumina supported iridium catalysts, with metal contents between 30 and 40%, that will be used for hydrazine monopropellant decomposition. (author)

  4. Separately supported polymetallic reforming catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Kresge, C. T.; Krishnamurthy, S.; McHale, W. D.

    1985-01-15

    There is provided, in accordance with the present invention, a catalyst composition made up of a mixture of two components, one component comprising a minor proportion of platinum and rhenium on a support and the second component comprising a minor proportion of iridium and rhenium on a separate support. A process for reforming a charge stock, such as naphtha, utilizing such catalyst is also provided.

  5. Synchrotron radiation studies of supported metal catalysts

    International Nuclear Information System (INIS)

    Metallic clusters supported on refractory oxides have been used extensively for several decades in the production of chemicals and petroleum derived transportation fuels. Catalysts containing more than one metal component are of particular interest since the addition of a second metal provides a method of controlling the selectivity of the catalyst. That is, the second metal can alter the rates of competing reactions in a complex reaction sequence and thus alter the final product distribution of the reaction. In this work the reactions of cyclohexane in hydrogen over silica supported ruthenium and osmium catalysts were studied. Bimetallic catalysts represent an important class of materials that are of interest both scientifically and technologically. Despite the importance and long-standing use of supported metal catalysts, detailed information on the structure of the metal clusters has been difficult to obtain. The development of x-ray absorption spectroscopy with the increasing availability of synchrotron radiation, however, has provided a powerful and versatile tool for studying the structure of these complex systems. Using the Extended X-ray Absorption Fine Structure (EXAFS) technique, it is possible to obtain information on the local atomic structure of supported monometallic catalytic metals and their interaction with the support. In the discussion that follows the authors will focus on results that have been obtained on the structure of supported bimetallic cluster catalysts

  6. 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.

  7. Thermodynamic Properties of Supported Catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Gorte, Raymond J.

    2014-03-26

    The goals of this work were to develop Coulometric Titration as a method for characterizing the thermodynamic redox properties of oxides and to apply this technique to the characterization of ceria- and vanadia-based catalysts. The redox properties of ceria and vanadia are a major part of what makes these materials catalytically active but their properties are also dependent on their structure and the presence of other oxides. Quantifying these properties through the measurement of oxidation energetics was the goal of this work.

  8. CROTONALDEHYDE HYDROGENATION ON Rh SUPPORTED CATALYSTS

    OpenAIRE

    Reyes, P.; M. Aguirre; Pecchi, G.; Fierro, J.L.G.

    2000-01-01

    The vapor-phase hydrogenation of crotonaldehyde on Rh supported catalysts has been studied. The effect of some variables of preparation in catalysts prepared by the sol-gel and impregnation methods on the surface and catalytic properties were analyzed. It was found, that the porosity of the support has a small effect on the selectivity to the unsaturated alcohol and the presence of partially reducible supports such as ZrO2 and TiO2, may increase the selectivity to crotyl alcohol via an enhanc...

  9. Overview of Support Effects in Hydrotreating Catalysts

    Institute of Scientific and Technical Information of China (English)

    Michèle Breysse

    2004-01-01

    @@ Industrial hydrotreating (HDT) catalysts are composed of a molybdenum sulfide (or tungsten sulfide) phase promoted by cobalt or nickel and usually supported on alumina. The origin of the almost exclu1sive use of alumina as support has to be ascribed to its outstanding textural and mechanical properties and its relatively low cost[1].

  10. Thermal decomposition of supported lithium nitrate catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Ruiz, Maria Lucia [INTEQUI (CONICET-UNSL), 25 de Mayo 384, V. Mercedes, 5730, San Luis (Argentina); Lick, Ileana Daniela [CINDECA (CONICET-UNLP), Calle 47 No 257, La Plata, 1900, Buenos Aires (Argentina); Ponzi, Marta Isabel [INTEQUI (CONICET-UNSL), 25 de Mayo 384, V. Mercedes, 5730, San Luis (Argentina); Castellon, Enrique Rodriguez; Jimenez-Lopez, Antonio [Departamento de Quimica Inorganica, Cristalografia y Mineralogia. Facultad de Ciencias, Universidad de Malaga, Campus de Teatinos, 29071 Malaga (Spain); Ponzi, Esther Natalia, E-mail: eponzi@quimica.unlp.edu.ar [CINDECA (CONICET-UNLP), Calle 47 No 257, La Plata, 1900, Buenos Aires (Argentina)

    2010-02-20

    New catalysts for soot combustion were prepared by impregnation of different supports (SiO{sub 2}, ZrO{sub 2} and ZrO{sub 2}.nH{sub 2}O) with a LiNO{sub 3} solution and then characterized by means of FTIR, XPS, TGA and UV-vis spectroscopy, whereby the presence of lithium nitrate in the prepared catalysts was identified and quantified. The soot combustion rate using this series of catalysts (LiNO{sub 3}/support) was compared with the activity of a series of impregnated catalysts prepared using LiOH (Li{sub 2}O/supports). Catalysts prepared using LiNO{sub 3} are found to be more active than those prepared using LiOH. The catalytic performance was also studied with a NO/O{sub 2} mixture in the feed, demonstrating that NO increases the combustion rate of soot, probably as a consequence of lithium oxide forming an 'in situ' nitrate ion.

  11. Polypropylene obtained through zeolite supported catalysts

    Directory of Open Access Journals (Sweden)

    Queli C. Bastos

    2004-01-01

    Full Text Available Propylene polymerizations were carried out with f2C(Flu(CpZrCl2 and SiMe2(Ind2ZrCl2 catalysts supported on silica, zeolite sodic mordenite (NaM and acid mordenite (HM. The polymerizations were performed at different temperatures and varying aluminium/zirconium molar ratios ([Al]/[Zr]. The effect of these reaction parameters on the catalyst activity was investigated using a proposed statistical experimental planning. In the case of f2C(Flu(CpZrCl2, SiO2 and NaM were used as support and the catalyst performance evaluated using toluene and pentane as polymerization solvent. The molecular weight, molecular weight distribution, melting point and crystallinity of the polymers were examined. The results indicate very high activities for the syndiospecific heterogeneous system. Also, the polymers obtained had superior Mw and stereoregularity.

  12. Polypropylene obtained through zeolite supported catalysts

    International Nuclear Information System (INIS)

    Propylene polymerizations were carried out with φ2C(Flu)(Cp)ZrCl2 and SiMe2(Ind)2ZrCl2 catalysts supported on silica, zeolite sodic mordenite (NaM) and acid mordenite (HM). The polymerizations were performed at different temperatures and varying aluminium/zirconium molar ratios ([Al]/[Zr]). The effect of these reaction parameters on the catalyst activity was investigated using a proposed statistical experimental planning. In the case of f2C(Flu)(Cp)ZrCl2, SiO2 and NaM were used as support and the catalyst performance evaluated using toluene and pentane as polymerization solvent. The molecular weight, molecular weight distribution, melting point and crystallinity of the polymers were examined. The results indicate very high activities for the syndiospecific heterogeneous system. Also, the polymers obtained had superior Mw and stereo regularity. (author)

  13. Alkane dehydrogenation over supported chromium oxide catalysts

    NARCIS (Netherlands)

    Weckhuysen, B.M.; Schoonheydt, R.A.

    1999-01-01

    The dehydrogenation of alkanes over supported chromium oxide catalysts in the absence of oxygen is of high interest for the industrial production of propene and isobutene. In this review, a critical overview is given of the current knowledge nowadays available about chromium-based dehydrogenation ca

  14. Titanium Dioxide as a Catalyst Support in Heterogeneous Catalysis

    OpenAIRE

    Samira Bagheri; Nurhidayatullaili Muhd Julkapli; Sharifah Bee Abd Hamid

    2014-01-01

    The lack of stability is a challenge for most heterogeneous catalysts. During operations, the agglomeration of particles may block the active sites of the catalyst, which is believed to contribute to its instability. Recently, titanium oxide (TiO2) was introduced as an alternative support material for heterogeneous catalyst due to the effect of its high surface area stabilizing the catalysts in its mesoporous structure. TiO2 supported metal catalysts have attracted interest due to TiO2 nanopa...

  15. Chemisorption on supported-metal catalysts

    Science.gov (United States)

    Davison, S. G.; Bose, S. M.; Sulston, K. W.

    1988-07-01

    A Gree-function formalism is developed to describe the electronic and chemisorption properties of a supported-metal composite substrate. Within the framework of the tight-binding approximation, the metal catalyst is represented by a finite chain of d-orbitals, while the semi-infinite semiconductor support is characterized by a linear chain of alternating s- and p-orbitals. The Anderson-Newns model is used to calculate the chemisorption energy and adatom charge transfer for hydrogen chemisorption on the Ni/ZnO composite system.

  16. Hydrogen recombiner catalyst test supporting data

    Energy Technology Data Exchange (ETDEWEB)

    Britton, M.D.

    1995-01-19

    This is a data package supporting the Hydrogen Recombiner Catalyst Performance and Carbon Monoxide Sorption Capacity Test Report, WHC-SD-WM-TRP-211, Rev 0. This report contains 10 appendices which consist of the following: Mass spectrometer analysis reports: HRC samples 93-001 through 93-157; Gas spectrometry analysis reports: HRC samples 93-141 through 93-658; Mass spectrometer procedure PNL-MA-299 ALO-284; Alternate analytical method for ammonia and water vapor; Sample log sheets; Job Safety analysis; Certificate of mixture analysis for feed gases; Flow controller calibration check; Westinghouse Standards Laboratory report on Bois flow calibrator; and Sorption capacity test data, tables, and graphs.

  17. Hydrogen recombiner catalyst test supporting data

    International Nuclear Information System (INIS)

    This is a data package supporting the Hydrogen Recombiner Catalyst Performance and Carbon Monoxide Sorption Capacity Test Report, WHC-SD-WM-TRP-211, Rev 0. This report contains 10 appendices which consist of the following: Mass spectrometer analysis reports: HRC samples 93-001 through 93-157; Gas spectrometry analysis reports: HRC samples 93-141 through 93-658; Mass spectrometer procedure PNL-MA-299 ALO-284; Alternate analytical method for ammonia and water vapor; Sample log sheets; Job Safety analysis; Certificate of mixture analysis for feed gases; Flow controller calibration check; Westinghouse Standards Laboratory report on Bois flow calibrator; and Sorption capacity test data, tables, and graphs

  18. Design strategies for the molecular level synthesis of supported catalysts.

    Science.gov (United States)

    Wegener, Staci L; Marks, Tobin J; Stair, Peter C

    2012-02-21

    Supported catalysts, metal or oxide catalytic centers constructed on an underlying solid phase, are making an increasingly important contribution to heterogeneous catalysis. For example, in industry, supported catalysts are employed in selective oxidation, selective reduction, and polymerization reactions. Supported structures increase the thermal stability, dispersion, and surface area of the catalyst relative to the neat catalytic material. However, structural and mechanistic characterization of these catalysts presents a formidable challenge because traditional preparations typically afford complex mixtures of structures whose individual components cannot be isolated. As a result, the characterization of supported catalysts requires a combination of advanced spectroscopies for their characterization, unlike homogeneous catalysts, which have relatively uniform structures and can often be characterized using standard methods. Moreover, these advanced spectroscopic techniques only provide ensemble averages and therefore do not isolate the catalytic function of individual components within the mixture. New synthetic approaches are required to more controllably tailor supported catalyst structures. In this Account, we review advances in supported catalyst synthesis and characterization developed in our laboratories at Northwestern University. We first present an overview of traditional synthetic methods with a focus on supported vanadium oxide catalysts. We next describe approaches for the design and synthesis of supported polymerization and hydrogenation catalysts, using anchoring techniques which provide molecular catalyst structures with exceptional activity and high percentages of catalytically significant sites. We then highlight similar approaches for preparing supported metal oxide catalysts using atomic layer deposition and organometallic grafting. Throughout this Account, we describe the use of incisive spectroscopic techniques, including high

  19. Monolayer dispersion thresholds and threshold effect displayed by supported catalysts

    Institute of Scientific and Technical Information of China (English)

    Cun DENG

    2008-01-01

    The principle of spontaneous monolayer dis-persion holds that active components of many supported catalysts will disperse spontaneously onto the surface of the carrier. The monolayer dispersion threshold of the active component on the surface of the carrier can be measured by X-ray diffraction phase-quantitative extra-polation method, etc. By measuring the monolayer disper-sion threshold, beneficial information on the surface structure and dispersion of supported catalysts can be obtained, and the optimal preparative processing condi-tions of the catalysts can be chosen. The proportion of the active component of many supported catalysts can be optimized while its monolayer dispersion threshold is observed. Mutation values of many physicochemical properties of supported catalysts are related to monolayer dispersion thresholds; the threshold effect on catalysts is apparent, and the proposal regarding the threshold effect provides instruction for the research on catalysts.

  20. Ceramic wash-coat for catalyst support

    Science.gov (United States)

    Kulkarni, Anand A.; Subramanian, Ramesh; Sabol, Stephen M.

    2012-08-14

    A wash-coat (16) for use as a support for an active catalyst species (18) and a catalytic combustor component (10) incorporating such wash-coat. The wash-coat is a solid solution of alumina or alumina-based material (Al.sub.2O.sub.3-0-3 wt % La.sub.2O.sub.3) and a further oxide exhibiting a coefficient of thermal expansion that is lower than that exhibited by alumina. The further oxide may be silicon dioxide (2-30 wt % SiO.sub.2), zirconia silicate (2-30 wt % ZrSiO.sub.4), neodymium oxide (0-4 wt %), titania (Al.sub.2O.sub.3-3-40% TiO.sub.2) or alumina-based magnesium aluminate spinel (Al.sub.2O.sub.3-25 wt % MgO) in various embodiments. The active catalyst species may be palladium and a second metal in a concentration of 10-50% of the concentration of the palladium.

  1. An attempt to selectively oxidize methane over supported gold catalysts

    OpenAIRE

    Hereijgers, B.P.C.; Weckhuysen, B. M.

    2011-01-01

    The potential of supported gold catalysts for the selective gas-phase oxidation of methane to methanol with molecular oxygen was investigated. A broad range of supported gold-based catalyst materials was synthesized using reducible and non-reducible support materials. Although the formation of small gold nanoparticles was established for all catalyst materials, only a very low activity for the total oxidation of methane was observed, at temperatures[250 C. Since no traces of partial oxidation...

  2. Functionalized Graphitic Supports for Improved Fuel Cell Catalyst Stability Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Physical Sciences Inc. (PSI) together with the University of Connecticut (UCONN) proposes to demonstrate the improved fuel cell catalyst support durability offered...

  3. An attempt to selectively oxidize methane over supported gold catalysts

    NARCIS (Netherlands)

    Hereijgers, B.P.C.; Weckhuysen, B.M.

    2011-01-01

    The potential of supported gold catalysts for the selective gas-phase oxidation of methane to methanol with molecular oxygen was investigated. A broad range of supported gold-based catalyst materials was synthesized using reducible and non-reducible support materials. Although the formation of small

  4. Method of forming supported doped palladium containing oxidation catalysts

    Science.gov (United States)

    Mohajeri, Nahid

    2014-04-22

    A method of forming a supported oxidation catalyst includes providing a support comprising a metal oxide or a metal salt, and depositing first palladium compound particles and second precious metal group (PMG) metal particles on the support while in a liquid phase including at least one solvent to form mixed metal comprising particles on the support. The PMG metal is not palladium. The mixed metal particles on the support are separated from the liquid phase to provide the supported oxidation catalyst.

  5. 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.

  6. Carbon Nanofibers as Catalyst Support for Noble Metals

    OpenAIRE

    Toebes, M.L.

    2004-01-01

    In the quest for new and well-defined support materials for heterogeneous catalysts we explored the potential of carbon nanofibers (CNF). CNF belongs to the by now extensive family of synthetic graphite-like carbon materials with advantageous and tunable physico-chemical properties. Aim of the work described in this thesis has been the exploration of the potential of CNF as catalyst support material, notably for platinum and ruthenium, and its role in the performance of these catalysts in hyd...

  7. Supported heteropolyacid catalyst, method for the production thereof, and use

    OpenAIRE

    Rojas Muñoz, Sergio; Ojeda Pineda, Manuel; Ladera Gallardo, Rosa M.; García Fierro, José Luis

    2014-01-01

    [EN] The invention relates to various supported heteropolyacid catalysts, to the method for the product thereof, and to the use of same as an acid catalyst in heterogeneous phase processes, concretely in the production of dimethyl ether from methanol. By supporting the heteropolyacid catalysts in inorganic solids by means of the impregnation technique, the area of the heteropolyacids (very low in the pure form thereof) increases dramatically and catalytic processes are therefore favoured in t...

  8. Graphene: A Promising Two-Dimensional Support for Heterogeneous Catalysts

    OpenAIRE

    Fan, Xiaobin

    2015-01-01

    Graphene has many advantages that make it an attractive two-dimensional (2D) support for heterogeneous catalysts. It not only allows the high loading of targeted catalytic species but also facilitates the mass transfer during the reaction processes. These advantages, along with its unique physical and chemical properties, endow graphene great potential as catalyst support in heterogeneous catalysis.

  9. A Catalyst for Collaboration: Supporting Technology in Teaching through Partnerships.

    Science.gov (United States)

    Alway, Mark; Lewis, Tom; Macklin, Scott

    The Web-based Catalyst Initiative was created at the University of Washington (UW) to support innovation in teaching through technology. The approach utilizes participatory design techniques in the development of next generation technologies in order to scale beyond early to second wave adopters. Catalyst is the product of a support strategy that…

  10. Dynamic structural disorder in supported nanoscale catalysts.

    Science.gov (United States)

    Rehr, J J; Vila, F D

    2014-04-01

    We investigate the origin and physical effects of "dynamic structural disorder" (DSD) in supported nano-scale catalysts. DSD refers to the intrinsic fluctuating, inhomogeneous structure of such nano-scale systems. In contrast to bulk materials, nano-scale systems exhibit substantial fluctuations in structure, charge, temperature, and other quantities, as well as large surface effects. The DSD is driven largely by the stochastic librational motion of the center of mass and fluxional bonding at the nanoparticle surface due to thermal coupling with the substrate. Our approach for calculating and understanding DSD is based on a combination of real-time density functional theory/molecular dynamics simulations, transient coupled-oscillator models, and statistical mechanics. This approach treats thermal and dynamic effects over multiple time-scales, and includes bond-stretching and -bending vibrations, and transient tethering to the substrate at longer ps time-scales. Potential effects on the catalytic properties of these clusters are briefly explored. Model calculations of molecule-cluster interactions and molecular dissociation reaction paths are presented in which the reactant molecules are adsorbed on the surface of dynamically sampled clusters. This model suggests that DSD can affect both the prefactors and distribution of energy barriers in reaction rates, and thus can significantly affect catalytic activity at the nano-scale. PMID:24712802

  11. Dynamic structural disorder in supported nanoscale catalysts

    International Nuclear Information System (INIS)

    We investigate the origin and physical effects of “dynamic structural disorder” (DSD) in supported nano-scale catalysts. DSD refers to the intrinsic fluctuating, inhomogeneous structure of such nano-scale systems. In contrast to bulk materials, nano-scale systems exhibit substantial fluctuations in structure, charge, temperature, and other quantities, as well as large surface effects. The DSD is driven largely by the stochastic librational motion of the center of mass and fluxional bonding at the nanoparticle surface due to thermal coupling with the substrate. Our approach for calculating and understanding DSD is based on a combination of real-time density functional theory/molecular dynamics simulations, transient coupled-oscillator models, and statistical mechanics. This approach treats thermal and dynamic effects over multiple time-scales, and includes bond-stretching and -bending vibrations, and transient tethering to the substrate at longer ps time-scales. Potential effects on the catalytic properties of these clusters are briefly explored. Model calculations of molecule-cluster interactions and molecular dissociation reaction paths are presented in which the reactant molecules are adsorbed on the surface of dynamically sampled clusters. This model suggests that DSD can affect both the prefactors and distribution of energy barriers in reaction rates, and thus can significantly affect catalytic activity at the nano-scale

  12. Hydroliquefaction of coal with supported catalysts: 1980 status review

    Energy Technology Data Exchange (ETDEWEB)

    Polinski, Leon M.; Stiegel, Gary J.; Tischer, Richard E.

    1981-06-01

    The objectives of the program have been to determine catalyst deactivation kinetic models and catalyst deactivation modes for supported Co-Mo and Ni-Mo catalysts used primarily in coal liquefaction via the H-COAL process. Emphasis has been on developing methods to increase catalyst usage by determining how to decrease catalyst replacement rates in the process and how to decrease catalyst poisoning. An important conclusion reached via model analysis and verified by experiment is that larger diameter (1/16 in.) catalysts resist poisoning deactivation much more than smaller (1/32 in.) catalysts over extended periods (60 to 110 hours) of time. If this trend can be verified, it gives a powerful tool for reducing catalyst replacement rate in the H-COAL ebullated bed system by factors of 2 or more. A second conclusion is that poisoning of catalysts occurs by several possible mechanisms or modes. Indirect or direct evidence of all these modes can be presented, though the relative importance of each mechanism has not been established. The modes include (a) poisoning by coking - with gradual increase in C/H ratio (more refractory coke) with time, (b) poisoning by metallization (selective/non-selective adsorption of inorganics such as Ti and Fe on the catalyst), (c) sintering - increase in larger pores/decrease in surface area, and (d) parallel poisoning by irreversible nitrogen compound adsorption.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  14. Supported Molten Metal Catalysis. A New Class of Catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Ravindra Datta; Ajeet Singh; Manuela Serban; Istvan Halasz

    2006-06-02

    We describe a new class of heterogeneous catalysts called supported molten metal catalysis (SMMC), in which molten metal catalysts are dispersed as nanodroplets on the surface of porous supports, allowing much larger active surface area than is possible in conventional contacting techniques for catalytic metals that are molten under reaction conditions, thus greatly enhancing their activity and potential utility. Specific examples of different types of reactions are provided to demonstrate the broad applicability of the technique in designing active, selective, and stable new catalysts. It is shown that dispersing the molten metal on a support in the suggested manner can enhance the rate of a reaction by three to four orders of magnitude as a result of the concomitant increase in the active surface area. New reaction examples include {gamma}-Al{sub 2}O{sub 3} supported molten Te (melting point 450 C) and Ga (MP 30 C) catalysts for bifunctional methylcyclohexane dehydrogenation. These catalysts provide activity similar to conventional Pt-based catalysts for this with better resistance to coking. In addition, results are described for a controlled pore glass supported molten In (MP 157 C) catalyst for the selective catalytic reduction of NO with ethanol in the presence of water, demonstrating activities superior to conventional catalysts for this reaction. A discussion is also provided on the characterization of the active surface area and dispersion of these novel supported catalysts. It is clear based on the results described that the development of new active and selective supported molten metal catalysts for practical applications is entirely plausible.

  15. An investigation into coking on catalyst support materials & supported metal catalysts

    OpenAIRE

    O'Brien, Michael A

    1997-01-01

    The deposition of coke on oxidation catalysts leads to deactivation. For oxide supports this phenomena of coking has previously been identified with acidic sites. Measurement of coke formation on silica gel, a-, r|- and y-Al2 0 3 showed that the greatest amount of coke was formed on y-A12 0 3 followed by r(-Al2 0 3 with no detectable coking occurring on either a-Al2 0 3 or silica gel. Titration results showed y-Al2 0 3 to contain the highest concentration of acidic and Bronsted basic sites...

  16. Supported organometallic catalysts for hydrogenation and Olefin Polymerization

    Science.gov (United States)

    Marks, Tobin J.; Ahn, Hongsang

    2001-01-01

    Novel heterogeneous catalysts for the which hydrogenation of olefins and arenes with high conversion rates under ambient conditions and the polymerization of olefins have been developed. The catalysts are synthesized from Ziegler-type precatalysts by supporting them on sulfate-modified zirconia.

  17. Graphene-supported platinum catalysts for fuel cells

    DEFF Research Database (Denmark)

    Seselj, Nedjeljko; Engelbrekt, Christian; Zhang, Jingdong

    2015-01-01

    past 15 years. It is focused on polymer electrolyte membrane fuel cells as an environmentally benign and feasible energy source. Graphene is used as a promising support material for Pt catalysts. It ensures high catalyst loading, good electrocatalysis and stability. Attention has been drawn to...

  18. Synthesis, characterization and hydrotreating performance of supported tungsten phosphide catalysts

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Supported tungsten phosphide catalysts were prepared by temperature-programmed reduction of their precursors (supported phospho-tungstate catalysts) in H2 and characterized by X-ray diffraction (XRD),BET,temperature-programmed desorption of ammonia (NH3-TPD) and X-ray photoelectron spectroscopy (XPS).The reduction-phosphiding processes of the precursors were investigated by thermogravimetry and differential thermal analysis (TG-DTA) and the suitable phosphiding temperatures were defined.The hydrodesulfurization (HDS) and hydrodenitrogenation (HDN) activities of the catalysts were tested by using thiophene,pyridine,dibenzothiophene,carbazole and diesel oil as the feed-stock.The TiO2,γ-Al2O3 supports and the Ni,Co promoters could remarkably increase and stabilize active W species on the catalyst surface.A suitable amount of Ni (3%-5%),Co (5%-7%) and V (1%-3%) could increase dispersivity of the W species and the BET surface area of the WP/γ-Al2O3 catalyst.The WP/γ-Al2O3 catalyst possesses much higher thiophene HDS and carbazole HDN activities and the WP/TiO2 catalyst has much higher dibenzothiophene (DBT) HDS and pyridine HDN activities.The Ni,Co and V can obviously promote the HDS activity and inhibit the HDN activity of the WP/γ-Al2O3 catalyst.The G-Ni5 catalyst possesses a much higher diesel oil HDS activity than the sulphided industrial NiW/γ-Al2O3 catalyst.In general,a support or promoter in the WP/γ-Al2O3 catalyst which can increase the amount and dispersivity of the active W species can promote its HDS and HDN activities.

  19. CO methanation over supported bimetallic Ni-Fe catalysts: From computational studies towards catalyst optimization

    DEFF Research Database (Denmark)

    Kustov, Arkadii; Frey, Anne Mette; Larsen, Kasper Emil;

    2007-01-01

    DFT calculations combined with a computational screening method have previously shown that bimetallic Ni-Fe alloys should be more active than the traditional Ni-based catalyst for CO methanation. That was confirmed experimentally for a number of bimetallic Ni-Fe catalysts supported on MgAl2O4. He...

  20. Graphene supported heterogeneous catalysts for Li-O2 batteries

    Science.gov (United States)

    Alaf, M.; Tocoglu, U.; Kartal, M.; Akbulut, H.

    2016-09-01

    In this study production and characterization of free-standing and flexible (i) graphene, (ii) α-MnO2/graphene, (iii) Pt/graphene (iv) α-MnO2/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, N2 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.

  1. Polymer-Supported Raney Nickel Catalysts for Sustainable Reduction Reactions

    Directory of Open Access Journals (Sweden)

    Haibin Jiang

    2016-06-01

    Full Text Available Green is the future of chemistry. Catalysts with high selectivity are the key to green chemistry. Polymer-supported Raney catalysts have been found to have outstanding performance in the clean preparation of some chemicals. For example, a polyamide 6-supported Raney nickel catalyst provided a 100.0% conversion of n-butyraldehyde without producing any detectable n-butyl ether, the main byproduct in industry, and eliminated the two main byproducts (isopropyl ether and methyl-iso-butylcarbinol in the hydrogenation of acetone to isopropanol. Meanwhile, a model for how the polymer support brought about the elimination of byproducts is proposed and confirmed. In this account the preparation and applications of polymer-supported Raney catalysts along with the corresponding models will be reviewed.

  2. Dissolution of Metal Supported Spent Auto Catalysts in Acids

    OpenAIRE

    Fornalczyk A.; Kraszewski M.; Willner J.; Kaduková J.; Mrážiková A.; Marcinčáková R.; Velgosová O.

    2016-01-01

    Metal supported auto catalysts, have been used in sports and racing cars initially, but nowadays their application systematically increases. In Metal Substrate (supported) Converters (MSC), catalytic functions are performed by the Platinum Group Metals (PGM): Pt, Pd, Rh, similarly to the catalysts on ceramic carriers. The contents of these metals make that spent catalytic converters are valuable source of precious metals. All over the world there are many methods for the metals recovery from ...

  3. Tungsten materials as durable catalyst supports for fuel cell electrodes

    Science.gov (United States)

    Perchthaler, M.; Ossiander, T.; Juhart, V.; Mitzel, J.; Heinzl, C.; Scheu, C.; Hacker, V.

    2013-12-01

    Durable platinum catalyst support materials, e.g. tungsten carbide (WC), tungsten oxide (WOx) and self-synthesized tungsten oxide (WOxs) were evaluated for the use in High-Temperature Proton Exchange Fuel Cells (HT-PEM) based on phosphoric acid doped polybenzimidazole as electrolyte. The support materials and the catalyst loaded support materials were characterized ex-situ by cyclic voltammetry in HClO4, potential cycling, CO-stripping, electron microscopy and X-ray diffraction measurements. The tungsten oxide and tungsten carbide based supported catalysts were compared to High Surface Area Carbon (HSAC), each coated with platinum via the same in-house manufacturing procedures. The in-house manufacturing procedures resulted in catalyst particle sizes on HSAC of 3-4 nm with a uniform distribution. The in-situ Potential Cycling experiments of WOx or WOxs supported catalysts showed much lower degradation rates compared to High Surface Area Carbons. The formation of WOx species on WC was proven by ex- and in-situ cyclic voltammetric studies and thermogravimetric analyses. X-ray diffraction, ex-situ cyclic voltammetry and in-situ cyclic voltammetry showed that WOx is formed from WC as starting material under oxidizing conditions. Finally a 1000 h durability test with WOx as catalyst support material on the anode was done in a HT-PEM fuel cell with reformed methanol on the anode.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1999-06-29

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

  5. Sulfur tolerant zeolite supported platinum catalysts for aromatics hydrogenation

    Energy Technology Data Exchange (ETDEWEB)

    Bergem, Haakon

    1997-12-31

    The increased demand for transportation fuels at the expence of heavier fuel oil has forced the refinery industry to expand their conversion capacity with hydrotreating as one of the key processes. A shift towards more diesel powered vehicles along with tightening fuel regulations demanding cleaner fuels has lead to increasing interest in catalytic processes for the manufacturing of such environmentally acceptable fuels. This provides the motivation for this thesis. Its main objective was to study possible catalysts active for desulfurization, hydrogenation, and ring-opening of aromatics all in the presence of sulfur. A close examination of the physical properties and kinetical behaviour of the chosen catalysts has been performed. A high pressure reactor setup was designed and built for activity measurements. Zeolite supported platinum catalysts were prepared and both the metal and acid functions were characterized utilizing various experimental techniques. Hydrogenation of toluene was used as a model reaction and the effect of sulfur adsorption on the activity and kinetic behaviour of the catalysts was investigated. The catalyst samples showed hydrogenation activities comparable to a commercial Pt/Al2O3 catalyst. There were no clear differences in the effect of the various sulfur compounds studied. Platinum supported on zeolite Y gave considerably more sulfur tolerant catalysts compared to Al2O3 as support. 155 refs., 58 figs., 36 tabs.

  6. Catalytic removal of carbon monoxide over carbon supported palladium catalyst

    International Nuclear Information System (INIS)

    Highlights: ► Carbon supported palladium (Pd/C) catalyst was prepared. ► Catalytic removal of CO over Pd/C catalyst was studied under dynamic conditions. ► Effects of Pd %, CO conc., humidity, GHSV and reaction environment were studied. - Abstract: Carbon supported palladium (Pd/C) catalyst was prepared by impregnation of palladium chloride using incipient wetness technique, which was followed by liquid phase reduction with formaldehyde. Thereafter, Pd/C catalyst was characterized using X-ray diffractometery, scanning electron microscopy, atomic absorption spectroscopy, thermo gravimetry, differential scanning calorimetry and surface characterization techniques. Catalytic removal of carbon monoxide (CO) over Pd/C catalyst was studied under dynamic conditions. Pd/C catalyst was found to be continuously converting CO to CO2 through the catalyzed reaction, i.e., CO + 1/2O2 → CO2. Pd/C catalyst provided excellent protection against CO. Effects of palladium wt%, CO concentration, humidity, space velocity and reaction environment were also studied on the breakthrough behavior of CO.

  7. Sorbitol hydrogenolysis to glycols by supported ruthenium catalysts

    Institute of Scientific and Technical Information of China (English)

    Inmaculada Murillo Leo; Manuel Lopez Granados; Jose Luis Garcia Fierro; Rafael Mariscal

    2014-01-01

    Supported Ru catalysts were prepared by wet impregnation to evaluate the role of different oxide supports (Al2O3, SiO2, TiO2, ZrO2) in sorbitol hydrogenolysis to glycols. X-ray diffraction, transmis-sion electron microscopy, hydrogen chemisorption, X-ray photoelectron spectroscopy, and NH3 temperature-programmed desorption were used to characterize the catalysts, which were active in the hydrogenolysis of sorbitol. The support affected both the physicochemical properties and cata-lytic behavior of the supported Ru particles. The characterization results revealed that the Ru/Al2O3 catalyst has a high surface acidity, partially oxidized Ru species on the surface, and a higher surface Ru/Al atomic ratio, which gave it the highest selectivity and yield to glycols.

  8. Redox properties of doped and supported copper-ceria catalysts.

    Science.gov (United States)

    Beckers, Jurriaan; Rothenberg, Gadi

    2008-12-14

    Copper-doped ceria catalysts feature in a variety of catalytic reactions. One important application is selective hydrogen combustion via oxygen exchange, which forms the basis of cyclic oxidative dehydrogenation. This paper describes the synthesis of monophasic (doped) and biphasic (supported) Cu-ceria catalysts, that are then characterized using a combination of temperature programmed reduction (TPR) and X-ray diffraction (XRD) methods. The catalysts are analyzed both as fresh samples and after redox cycling at 550-800 degrees C. TPR and XRD characterization clarify the role of the active sites on the catalyst surface and the copper-ceria interactions. Depending on the catalyst type, reduction occurs at approximately 110 degrees C, approximately 150 degrees C, or approximately 190 degrees C. The reduction at 110 degrees C is ascribed to highly dispersed copper species doped in the ceria lattice, and that at 190 degrees C to CuO crystallites supported on ceria. Remarkably, both types converge to the 150 degrees C feature after redox cycling. The reduction temperature of the doped catalyst increases after redox cycling, indicating that stable Cu clusters form at the surface. Conversely, the reduction temperature of the "supported" catalyst decreases after redox cycling, and the CuO crystallites disappear. With this knowledge, a copper-doped ceria catalyst is analyzed after application in selective hydrogen combustion (16 consecutive redox cycles at 550 degrees C). No CuO crystallites are observed, and the sample reduces at approximately 110 degrees C. This suggests that copper-doped ceria is the active oxygen exchange phase in selective hydrogen combustion. PMID:19030619

  9. Metal Catalysts Supported on Nanofibrous Polymeric Membranes for Environmental Applications

    Czech Academy of Sciences Publication Activity Database

    Soukup, Karel; Topka, Pavel; Petráš, D.; Šolcová, Olga

    - : -, 2013, s. 111. ISBN N. [International Conference on Catalysis in Membrane Reactors /11./. Porto (PT), 07.07.2013-11.07.2013] R&D Projects: GA ČR GPP106/11/P459; GA ČR(CZ) GAP204/11/1206 Institutional support: RVO:67985858 Keywords : nanofibrous catalyst support * electrospinning * catalytic oxidation Subject RIV: CI - Industrial Chemistry, Chemical Engineering

  10. Interaction of hydrogen with samaria supported rhodium catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Bernal, S.; Botana, F.J.; Calvino, J.J.; Cifredo, G.A.; Rodriguez-Izquierdo, J.M.

    1991-01-01

    Hydrogen chemisorption on several samaria supported rhodium catalysts has been studied. The TPD diagrams were broad and rather complex. Adsorption on both, rhodium and support phases was observed. The occurrence of spill over, as well as of metal decoration phenomena, restricts very much the use of apparent H/Rh data to estimate metallic dispersions.

  11. Interaction of hydrogen with samaria supported rhodium catalysts

    International Nuclear Information System (INIS)

    Hydrogen chemisorption on several samaria supported rhodium catalysts has been studied. The TPD diagrams were broad and rather complex. Adsorption on both, rhodium and support phases was observed. The occurrence of spill over, as well as of metal decoration phenomena, restricts very much the use of apparent H/Rh data to estimate metallic dispersions

  12. The generation of efficient supported (Heterogeneous) olefin metathesis catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Grubbs, Robert H

    2013-04-05

    Over the past decade, a new family of homogeneous metathesis catalysts has been developed that will tolerate most organic functionalities as well as water and air. These homogeneous catalysts are finding numerous applications in the pharmaceutical industry as well as in the production of functional polymers. In addition the catalysts are being used to convert seed oils into products that can substitute for those that are now made from petroleum products. Seed oils are unsaturated, contain double bonds, and are a ready source of linear hydrocarbon fragments that are specifically functionalized. To increase the number of applications in the area of biomaterial conversion to petrol chemicals, the activity and efficiency of the catalysts need to be as high as possible. The higher the efficiency of the catalysts, the lower the cost of the conversion and a larger number of practical applications become available. Active supported catalysts were prepared and tested in the conversion of seed oils and other important starting materials. The outcome of the work was successful and the technology has been transferred to a commercial operation to develop viable applications of the discovered systems. A biorefinery that converts seed oils is under construction in Indonesia. The catalysts developed in this study will be considered for the next generation of operations.

  13. Support effects on hydrotreating activity of NiMo catalysts

    International Nuclear Information System (INIS)

    The effect of the gamma alumina particle size on the catalytic activity of NiMoSx catalysts prepared by precipitation method of aluminum acetate at pH = 10 was studied. The structural characterization of the supports was measured by using XRD, pyridine FTIR-TPD and nitrogen physisorption. NiMo catalysts were characterized during the preparation steps (annealing and sulfidation) using transmission electron microscopy (TEM). Hydrogen TPR studies of the NiMo catalysts were also carried out in order to correlate their hydrogenating properties and their catalytic functionality. Catalytic tests were carried out in a pilot plant at 613, 633 and 653 K temperatures. The results showed that the rate constants of hydrodesulfurization (HDS), hydrodenitrogenation (HDN) and hydrodearomatizing (HDA) at 613-653 K decreased in the following order: A > B > C corresponding to the increase of NiMoS particle size associated to these catalysts

  14. Carbon xerogels as catalyst supports for PEM fuel cell cathode

    International Nuclear Information System (INIS)

    Carbon xerogels with various pore textures were prepared by evaporative drying and pyrolysis of resorcinol-formaldehyde gels, and used as supports for Pt catalysts in PEM fuel cell cathodes. The goal of this study was to determine whether carbon xerogels could replace the carbon aerogels which were previously used as Pt catalyst supports in the same electrochemical system, and to determine how the pore texture influences the cell performances. Pt catalysts were prepared by impregnation of carbon supports with aqueous H2PtCl6 solution followed by reduction in aqueous phase with NaBH4. Fuel cell measurements show that the metal surface actually available for the oxygen reduction reaction and the voltage losses due to diffusion phenomena strongly depend on the carbon pore texture. Finally, some carbon xerogels yield similar performance than carbon aerogels

  15. Influence of support nature on ruthenuim-rhodium catalyst properties

    International Nuclear Information System (INIS)

    Influence of support nature (ThO2, TiO2, γ-Al2O3, activated carbon) on 1% ruthenium-rhodium catalysts properties is studied in the reaction of liquid-phase hydrogenation of model compou with different type of unsaturated bonds at room temperature and atmosphere pressure. It is shown that dependences of hydrogenation rate on the ratio of applied ruthenium and rhodium are extremal. The maximum position is determined by support nature and is practically constant at hydrogenation of different substances. Influence of support nature on the given composition catalyst activity is slightly dpendent on chemical nature of hydrogenated compound and is opposite for ruthenium and rhodium catalysts

  16. Cathode catalyst layer using supported Pt catalyst on ordered mesoporous carbon for direct methanol fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hee-Tak; Yoon, Hae-Kwon; Song, In-Seob [Samsung SDI Co. Ltd., 575 Shin-dong, Yeongtong-gu, Suwon-si, Gyeonggi-do 443-391 (Korea); You, Dae Jong; Joo, Sang Hoon; Pak, Chanho; Chang, Hyuk [Samsung Advanced Institute of Technology, P.O. Box 111, Suwon 440-600 (Korea)

    2008-06-01

    The development of a cathode catalyst layer based on a supported Pt catalyst using an ordered mesoporous carbon (OMC) for direct methanol fuel cell is reported. An OMC with a mesopore structure between hexagonally arranged carbon nanorods is prepared using a template method. Platinum nanoparticles are supported on the OMC (Pt/OMC) with high metal loading of 60 wt.%. Compositional and morphological variations are made by varying the ionomer content and by compressing the catalyst layer to detect a parameter that determines the power performance. Increase in power density with decrease in the volume fraction of ionomer in the agglomerate comprising the Pt/OMC and the ionomer indicates that mass transport through the ionomer phase governs the kinetics of oxygen reduction. Impedance spectroscopic analysis suggests that a significant mass-transport limitation occurs at high ionomer content and in the compressed cathode. The power density of the optimum cathode layer, which employs a Pt/OMC catalyst with a Pt loading of 2 mg cm{sup -2}, is greater than that of a catalyst layer with 6 mg cm{sup -2} Pt-black catalyst at a voltage higher than 0.4 V. This would lead to a significant reduction in the cost of the membrane electrode assembly. (author)

  17. A study of platinum-supported catalysts through hyperfine interactions

    International Nuclear Information System (INIS)

    The effect of indium addition on alumina-supported platinum catalysts was investigated by measurements of hyperfine interactions. Via time differential perturbed angular correlation spectroscopy (TDPAC) on 111Cd, Pt/Al2O3 catalysts were studied in the flow of a heptane/H2 gas stream. The results indicate that some amount of indium sticks to platinum which is then dispersed on the support surface. The amount of In that is free from platinum is mobile under reaction conditions, being capable of diluting platinum particles and draining off coke precursors from the platinum surface. (orig.)

  18. Dissolution of Metal Supported Spent Auto Catalysts in Acids

    Directory of Open Access Journals (Sweden)

    Fornalczyk A.

    2016-03-01

    Full Text Available Metal supported auto catalysts, have been used in sports and racing cars initially, but nowadays their application systematically increases. In Metal Substrate (supported Converters (MSC, catalytic functions are performed by the Platinum Group Metals (PGM: Pt, Pd, Rh, similarly to the catalysts on ceramic carriers. The contents of these metals make that spent catalytic converters are valuable source of precious metals. All over the world there are many methods for the metals recovery from the ceramic carriers, however, the issue of platinum recovery from metal supported catalysts has not been studied sufficiently yet. The paper presents preliminary results of dissolution of spent automotive catalyst on a metal carrier by means of acids: H2SO4, HCl, HNO3, H3PO4. The main assumption of the research was the dissolution of base metals (Fe, Cr, Al from metallic carrier of catalyst, avoiding dissolution of PGMs. Dissolution was the most effective when concentrated hydrochloric acid, and 2M sulfuric acid (VI was used. It was observed that the dust, remaining after leaching, contained platinum in the level of 0.8% and 0.7%, respectively.

  19. Sulfide Catalysts Supported on Porous Aromatic Frameworks for Naphthalene Hydroprocessing

    Directory of Open Access Journals (Sweden)

    Eduard Karakhanov

    2016-08-01

    Full Text Available This paper describes the first example of using porous aromatic frameworks as supports for sulfide catalysts for the hydrogenation of aromatic hydrocarbons. The synthesis of bimetallic Ni-W and Ni-Mo sulfides was performed by in situ decomposition of [(n-Bu4N]2[Ni(MeS42] (Me = W, Mo complexes, supported on mesoporous aromatic framework with a diamond-like structure. It is shown that the highest naphthalene conversions were achieved in the case of additional sulfidation with sulfur. After the reaction, catalysts were characterized by X-ray photoelectron spectroscopy and high-resolution transmission electron microscopy. The activity of synthesized catalysts has been studied using naphthalene as a model substrate. The materials used in this study were substantially active in hydrogenation and slightly in hydrocracking of naphthalene.

  20. Novel zeolite-supported rhodium catalysts for ethanol steam reforming

    Science.gov (United States)

    Campos-Skrobot, Fabiana C.; Rizzo-Domingues, Roberta C. P.; Fernandes-Machado, Nádia R. C.; Cantão, Mauricio P.

    Renewable bioethanol is an interesting hydrogen source for fuel cells through steam reforming, but its C-C bond promotes parallel reactions, mainly coke and by-products formation. In this way, good ethanol reforming catalysts are still needed, which explains current research and development efforts around the world. Most catalysts proposed for ethanol reforming are based on oxide-supported noble metals with surface area below 100 m 2 g -1 and reaction temperatures above 500 °C. Novel Rh and Rh-K catalysts supported on NaY zeolite with surface area above 440 m 2 g -1 are presented in this work. Reaction temperature was fixed at 300 °C and H 2O/EtOH molar ratio and reagent flow were varied. Ethanol conversion varied from 50 to 99%, with average increase of 50% due to K promoter, and hydrogen production yield achieved 68%.

  1. Reactions of synthesis gas on silica supported transition metal catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Niemelae, M. [VTT Chemical Technology, Espoo (Finland). Lab. of Industrial Chemistry

    1997-12-31

    The effect of catalyst precursor and composition on the activation of CO was investigated using CO hydrogenation as a test reaction. The interrelations of preparation, pretreatment, characteristics and activity were clarified. For Co/SiO{sub 2} catalyst, MgO promotion increased the CO adsorption capacity and the hydrogen uptake, although the extent of reduction for cobalt remained the same or decreased. The conversion per active metallic cobalt site consequently increased in conjunction with MgO promotion, while the effect on overall performance per 1 g of catalyst remained moderate. The precursor affected the performance of Co/SiO{sub 2} considerably. CO was more strongly adsorbed on catalysts of carbonyl origin than on those derived from cobalt nitrate, the activity thus being higher. Although the nitrate derived Co/SiO{sub 2} appeared both to retain its activity and to regain its adsorption capacity better than the catalysts of carbonyl origin, the performance of the latter was superior with time on stream. For tetranuclear cluster based Co-Ru and Co-Rh catalysts, rhodium or ruthenium was in contact with the support and cobalt was enriched on top. On Co-Ru/SiO{sub 2} ruthenium enhanced deactivation, and no benefits in activity or oxygenate selectivity were achieved relative to the monometallic catalysts of cluster origin. The Co-Rh/SiO{sub 2} catalysts were also less active than those derived from monometallic clusters, but they exhibited higher selectivities to oxygenated compounds due to the presence of active sites on the perimeter of the cobalt particles located on rhodium. The highest selectivity to oxygenates was achieved by changing the decomposition atmosphere of Rh{sub 4}(CO){sub 12}/SiO{sub 2} from hydrogen to carbon monoxide. The results also showed two types of active sites to be operative in the formation of oxygenates - one for ethanol and another for aldehydes. (orig.) 69 refs.

  2. Carbon Nanofibers as Catalyst Support for Noble Metals

    NARCIS (Netherlands)

    Toebes, M.L.

    2004-01-01

    In the quest for new and well-defined support materials for heterogeneous catalysts we explored the potential of carbon nanofibers (CNF). CNF belongs to the by now extensive family of synthetic graphite-like carbon materials with advantageous and tunable physico-chemical properties. Aim of the work

  3. Highly active gauze-supported skeletal nickel catalysts

    OpenAIRE

    Fow, Kam Loon; Ganapathi, Murugan; Stassen, Ivo; Fransaer, Jan; Binnemans, Koen; De Vos, Dirk E.

    2013-01-01

    Gauze-supported skeletal nickel catalysts were prepared by electrodeposition of Ni–Zn alloys from an acetamide–DMSO2–NiCl2–ZnCl2 quaternary melt, followed by chemical or electrochemical leaching of zinc from the alloys. The activity and selectivity of the structured RANEY® nickel surpass those of commercial RANEY® nickel in the hydrogenation of acetophenone.

  4. Mesoporous molecular sieves as advanced supports for olefin metathesis catalysts

    Czech Academy of Sciences Publication Activity Database

    Balcar, Hynek; Čejka, Jiří

    2013-01-01

    Roč. 257, 21-22 (2013), s. 3107-3124. ISSN 0010-8545 R&D Projects: GA AV ČR IAA400400805; GA ČR GBP106/12/G015 Institutional support: RVO:61388955 Keywords : Olefin metathesis * mesoporous molecular sieves * Heterogeneous catalysts Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 12.098, year: 2013

  5. Exceptionally Stable and Efficient Solid Supported Hoveyda-Type Catalyst

    Czech Academy of Sciences Publication Activity Database

    Skowerski, K.; Pastva, J.; Czarnocki, S. J.; Janošcová, Jana

    2015-01-01

    Roč. 19, č. 7 (2015), s. 872-877. ISSN 1083-6160 Institutional support: RVO:61388955 Keywords : OLEFIN-METATHESIS CATALYSTS * RING-CLOSING METATHESIS * N-HETEROCYCLIC CARBENES Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.528, year: 2014

  6. Palladium catalysts deposited on silica materials: Comparison of catalysts based on mesoporous and amorphous supports in Heck reaction

    Czech Academy of Sciences Publication Activity Database

    Demel, J.; Čejka, Jiří; Štěpnička, P.

    2010-01-01

    Roč. 329, 1-2 (2010), s. 13-20. ISSN 1381-1169 R&D Projects: GA ČR GA104/09/0561 Institutional research plan: CEZ:AV0Z40400503 Keywords : heterogeneous catalysts * immobolized catalysts * supported catalysts Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.872, year: 2010

  7. Characterization and Dehydrogenation Activity of SBA-15 and HMS Supported Chromia Catalysts

    Institute of Scientific and Technical Information of China (English)

    YUE,Hong-Yong(乐洪咏); ZHENG,Bo(郑波); YUE,Ying-Hong(乐英红); ZHANG,Xue-Zheng(张雪峥); HUA,Wei-Ming(华伟明); GAO,Zi(高滋)

    2002-01-01

    SBA-15 and HMS supported chromia catalysts were prepared and characterized. Chromia is highly dispersed on the mesoporous supports when its loading is ≤7 wt%. The supported catalysts display high activity, selectivity and stability for dehydrogenation of ethyibenzene and propane. ESR measurement of the catalysts before and after reaction shows that the active species for dehydrogenation reaction might be Cr3 + species on the catalyst surface, and the activity of the catalyst is probably correlated with the dispersion of Cr3+ species.

  8. Hydrogenolysis of sugar beet fiber by supported metal catalyst

    OpenAIRE

    Guha, Samar K.; Kobayashi, Hirokazu; Hara, Kenji; Kikuchi, Hiroto; Aritsuka, Tsutomu; Fukuoka, Atsushi

    2011-01-01

    Sugar beet fiber is an agricultural by-product in the sugar manufacturing and an available biomass source with a rich hemicellulose component. So far, there has been no report on the catalytic conversion of the beet fiber for the synthesis of chemicals. In this work, the hydrogenolysis of the beet fiber was studied by using supported metal catalysts under pressurized hydrogen conditions. Activated carbon supported Ru was found to show the highest catalytic activity to give arabitol as a major...

  9. Metal Phosphate-Supported Pt Catalysts for CO Oxidation

    Directory of Open Access Journals (Sweden)

    Xiaoshuang Qian

    2014-12-01

    Full Text Available Oxides (such as SiO2, TiO2, ZrO2, Al2O3, Fe2O3, CeO2 have often been used to prepare supported Pt catalysts for CO oxidation and other reactions, whereas metal phosphate-supported Pt catalysts for CO oxidation were rarely reported. Metal phosphates are a family of metal salts with high thermal stability and acid-base properties. Hydroxyapatite (Ca10(PO46(OH2, denoted as Ca-P-O here also has rich hydroxyls. Here we report a series of metal phosphate-supported Pt (Pt/M-P-O, M = Mg, Al, Ca, Fe, Co, Zn, La catalysts for CO oxidation. Pt/Ca-P-O shows the highest activity. Relevant characterization was conducted using N2 adsorption-desorption, inductively coupled plasma (ICP atomic emission spectroscopy, X-ray diffraction (XRD, transmission electron microscopy (TEM, CO2 temperature-programmed desorption (CO2-TPD, X-ray photoelectron spectroscopy (XPS, and H2 temperature-programmed reduction (H2-TPR. This work furnishes a new catalyst system for CO oxidation and other possible reactions.

  10. Graphitised Carbon Nanofibres as Catalyst Support for PEMFC

    DEFF Research Database (Denmark)

    Yli-Rantala, E.; Pasanen, A.; Kauranen, P.;

    2011-01-01

    catalyst and the effects of the different surface treatments were discussed. On the basis of these results, new membrane electrode assemblies (MEAs) were manufactured and tested also for carbon corrosion by in situ FTIR analysis of the cathode exhaust gases. It was observed that the G-CNFs showed 5?times......Graphitised carbon nanofibres (G-CNFs) show superior thermal stability and corrosion resistance in PEM fuel cell environment over traditional carbon black (CB) and carbon nanotube catalyst supports. However, G-CNFs have an inert surface with only very limited amount of surface defects for the...... anchorage of Pt catalyst nanoparticles. Modification of the fibre surface is therefore needed. In this study Pt nanoparticles have been deposited onto as-received and surface-modified G-CNFs. The surface modifications of the fibres comprise acid treatment and nitrogen doping by pyrolysis of a polyaniline...

  11. Ternary nickel catalysts promoted with metal oxide supports

    International Nuclear Information System (INIS)

    Nickel catalysts supported with different metal oxides proved to be suitable for H/D isotopic exchange between hydrogen and water vapour. Chromium oxide proved to be suitable as promoter for nickel catalysts for such reaction. Fe2O3 Coo and Mn O were selected to be the second promoter for nickel catalyst in addition to Cr2O3 producing ternary catalytic systems. Accordingly, Ni/Cr2O3/Fe2O3, Ni/Cr2O3/Coo and Ni/Cr2O3/Mn O ternary catalytic systems were prepared by the co-precipitation technique. These systems were characterized through complex metric titration, .R. absorption spectroscopy, thermal analysis and x-ray analysis. The catalytic activity of the examined systems were carried out a simple test reaction. The kinetic and thermodynamic parameters of the three systems were calculated and discussed. 3 figs, 4 tabs

  12. Co-Assembled Supported Catalysts: Synthesis of Nano-Structured Supported Catalysts with Hierarchic Pores through Combined Flow and Radiation Induced Co-Assembled Nano-Reactors

    Directory of Open Access Journals (Sweden)

    Galip Akay

    2016-05-01

    Full Text Available A novel generic method of silica supported catalyst system generation from a fluid state is presented. The technique is based on the combined flow and radiation (such as microwave, thermal or UV induced co-assembly of the support and catalyst precursors forming nano-reactors, followed by catalyst precursor decomposition. The transformation from the precursor to supported catalyst oxide state can be controlled from a few seconds to several minutes. The resulting nano-structured micro-porous silica supported catalyst system has a surface area approaching 300 m2/g and X-ray Diffraction (XRD-based catalyst size controlled in the range of 1–10 nm in which the catalyst structure appears as lamellar sheets sandwiched between the catalyst support. These catalyst characteristics are dependent primarily on the processing history as well as the catalyst (Fe, Co and Ni studied when the catalyst/support molar ratio is typically 0.1–2. In addition, Ca, Mn and Cu were used as co-catalysts with Fe and Co in the evaluation of the mechanism of catalyst generation. Based on extensive XRD, Scanning Electron Microscopy (SEM and Transmission Electron Microscopy (TEM studies, the micro- and nano-structure of the catalyst system were evaluated. It was found that the catalyst and silica support form extensive 0.6–2 nm thick lamellar sheets of 10–100 nm planar dimensions. In these lamellae, the alternate silica support and catalyst layer appear in the form of a bar-code structure. When these lamellae structures pack, they form the walls of a micro-porous catalyst system which typically has a density of 0.2 g/cm3. A tentative mechanism of catalyst nano-structure formation is provided based on the rheology and fluid mechanics of the catalyst/support precursor fluid as well as co-assembly nano-reactor formation during processing. In order to achieve these structures and characteristics, catalyst support must be in the form of silane coated silica nano

  13. Autothermal Reforming of n-Hexane over Supported Metal Catalysts

    OpenAIRE

    Brandmair, Maria

    2007-01-01

    Autothermal reforming was investigated with hexane as a model compound for alkanes. Therefore, oxide supports (CeO2, ZrO2, Zr0.92Y0.08O2, gamma-Al2O3) were impregnated with metals (Ni, Pt und Rh) and their physico-chemical and catalytic properties were studied. Alumina supported rhodium showed the best and most stable performance. Detailed kinetic studies were performed on rhodium supported monolithic alumina in comparison with a monolithic industrial catalyst in a wide range of reaction temp...

  14. Coarse-pored ceramic supports for pyrolysis catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Potapova, L.L.; Cherches, B.Kh.; Egiazarov, Yu.G.

    1988-03-20

    One promising trend in improvement of pyrolysis of hydrocarbon feedstocks is the use of heterogeneous catalysts in the process. The industrial use of highly effective catalysts would result in substantially increased product yields and in decrease of energy consumption in comparison with the requirements of drastic thermal processes. The aims of the present work were to obtain a mechanically strong coarse-pored ceramic support for pyrolysis catalysts and to study the influence of various factors on formation of its structure. The support material was made from an industrial ceramic mass of the following composition (%): koalin 30, plastic refractory clay 21, quartz 32, pegmatite 17. Various additives were used for formation of a porous structure: noncombustible highly porous (pumice, claydite), partially combustible (shungite), and completely combustible (SKT) activated carbon). The authors results show that 15 mass % of SKT carbon (particle size 0.1-0.2 mm) and 1-2 mass % of sodium trimetaphosphate should be added to the ceramic mass. The crushing strength of the resultant support samples reaches 550-630 kg/cm/sup 2/, with 34-35% porosity. Under the optimal conditions of pyrolysis of a straight-run gasoline fraction the catalyst obtained by deposition of 12 mass % of In/sub 2/O/sub 3/ and 4% K/sub 2/O on the synthesized support gives a yield of 39-41 mass % of ethylene and 61-62 mass % of unsaturated C/sub 2/-C/sub 4/ hydrocarbons, with 88-90 mass % gasification.

  15. Fischer-Tropsch synthesis on alumina supported cobalt catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Bechara, R.; Balloy, D.; Vanhove, D.

    1997-11-01

    Physico-chemical properties of Co/Al{sub 2}O{sub 3}-gamma were investigated by XRD, XPS, thermogravimetry and catalytic measurements. Interactions between the metal and its support were found for catalysts prepared from alumina with the greater specific area. For the Fischer-Tropsch synthesis, the products distribution appeared not to be sensitive to the cobalt particle size, but seems to depend on the degree of cobalt reduction.

  16. Ammoxidation of Substituted Toluenes on Silica-Supported VPO Catalysts

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The ammoxidation of substituted toluenes to their corresponding nitriles over silica-supported vanadium phosphorus oxide (VPO/SiO2) catalysts has been studied. The effects of carrier silica, the addition of phosphorus, the substituents and the loadings have been discussed. Compared with unsupported VPO, the VPO/SiO2 catalysts have higher catalytic activity for ammoxidation of substituted toluenes and much lower reaction temperature. XRD shows that vanadium phosphorus oxides exist as amorphous phase and disperse to a high degree on the silica surface in 10 % loading catalyst. When the loadings are over 10 %, the crystalline α-VOPO4 would emerge, which would decrease the yield and selectivity. Additional phosphorus can form composite oxides with vanadia and play concerted catalytic function, which increase the selectivity of nitriles remarkably. Different substituents or same substituents on diffetent positions have different influences because of the variant electronic stability of intermediates, the hindered accessibility of methyl group or the chemisorption state of the substrate molecule on the electrophilic catalyst surface.

  17. Carbon foams as catalyst supports for phenol photodegradation

    International Nuclear Information System (INIS)

    A carbon foam using coal tar pitch as precursor was prepared and investigated as support for titanium oxide for the photocatalytic degradation of phenol. The performance of the carbon foam/titania composite was compared to those of unsupported titania and other activated carbon composites from the literature. The photodegradation rate of phenol over the catalysts under UV illumination was fitted to the Langmuir-Hinshelwood model; data showed that the apparent rate constant of the carbon foam supported titania was almost three times larger than that of bare titania, and comparable to that of other carbon supported composites. Considering the low porous features of the carbon foam, this suggests that large surface area supports are not essential to achieve high degradation rates and efficiencies. Moreover, when titania is supported on the carbon foam large amounts of catechol are detected in solution after UV irradiation, indicating a better degradation efficiency.

  18. Recovery of metals from monometallic and non-supported catalysts

    International Nuclear Information System (INIS)

    This work presents a study on the dissolution of some commercial monometallic and non-supported deactivated catalysts in HF + H2O2 mixtures (and, eventually, other media) under mild experimental conditions, after a previous oxidation step. The samples were neither crushed nor grinded. The best experimental conditions were dependent on the nature of the support and of the active phase. For example, the Pt/Al2O3 catalyst was dissolved in about 10 minutes, without agitation and heating; however, dissolution of the Pd/Al2O3, Ni/Al2O3, Ni/SiO2, Cu/Al2O3 and V2O5 samples required a temperature of 60 deg C and an agitation of 400 rpm. A careful addition of a NaOH solution allowed a quantitative precipitation of aluminium as criolite (Na3AlF6) or precipitation of Si as Na2SiF6; NaF was obtained as a by-product. As expected, processing of Pd/C, V2O5 and CuO.Cr2O3 samples was relatively simple. Metals recovery from catalysts reached a quantitative level in all samples studied; it is particularly interesting that platinum and palladium could be easily recovered in a single step process, thus separating them from aluminium. (author)

  19. Selective recovery of catalyst layer from supporting matrix of ceramic-honeycomb-type automobile catalyst.

    Science.gov (United States)

    Kim, Wantae; Kim, Boungyoung; Choi, Doyoung; Oki, Tatsuya; Kim, Sangbae

    2010-11-15

    Natural resources of platinum group metals (PGMs) are limited and their demand is increasing because of their extensive uses in industrial applications. The low rate of production of PGMs due to low concentration in the related natural ores and high cost of production have made the recovery of PGMs from previously discarded catalytic converters a viable proposition. The ceramic-honeycomb-type automobile catalytic converter contains appreciable amount of PGMs. These valuable substances, which are embedded in the catalyst layer and covered on the surface of the supporting matrix, were selectively recovered by attrition scrubbing. The attrition scrubbing was effective for the selective recovery of catalyst layer. The process was convinced as the comminution and separation process by physical impact and shearing action between particles in the scrubbing vessel. The catalyst layer was dislodged from the surface of the supporting matrix into fine particles by attrition scrubbing. The recovery of Al(2)O(3) and total PGMs in the fraction less than 300 μm increased with the residence time whereas their contents in the recovered materials slightly decreased. The interparticle scrubbing became favorable when the initial input size increased. However, the solid/liquid ratio in the mixing vessel was slightly affected by the low density of converter particles. PMID:20728274

  20. One-pot synthesis of network supported catalyst using supramolecular gel as template

    Institute of Scientific and Technical Information of China (English)

    Yong Liang; Li Ming Tang; Yu Xia; Kai Chen; Bo Tian Li; Xin Jin

    2010-01-01

    A simple and general strategy is described for preparing network supported catalyst through a one-pot synthetic procedure using supramolecular gel as template. This procedure directly attaches iigand to support during fabricating the support. Using this strategy, supported CuBr/di-(2-picolyl)amine catalyst with U-shaped fibrillar network was prepared and used in atom transfer radical polymerization of methyl methacrylate. XPS and SEM characterization of the catalyst revealed homogeneous distribution of ligand, sufficient reactive sites, adequate mechanical strength and macroporosity. The polymerization results demonstrated high activity and reusability of such catalyst. This strategy might be extended to other supported catalysts used in column reactors.

  1. Biotemplated Palladium Catalysts Can Be Stabilized on Different Support Materials

    KAUST Repository

    Yates, Matthew D.

    2014-07-30

    © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Sustainably biotemplated palladium catalysts generated on different carbon-based support materials are examined for durability under electrochemical (oxidative) and mechanical-stress conditions. Biotemplated catalysts on carbon paper under both stresses retain 95% (at 0.6V) of the initial catalytic activity as opposed to 70% for carbon cloth and 60% for graphite. Graphite electrodes retain 95% of initial catalytic activity under a single stress. Using electrodeposited polyaniline (PANI) and polydimethylsiloxane binder increases the current density after the stress tests by 22%, as opposed to a 30% decrease for Nafion. PANI-coated electrodes retain more activity than carbon-paper electrodes under elevated mechanical (94 versus 70%) or increased oxidative (175 versus 62%) stress. Biotemplated catalytic electrodes may be useful alternatives to synthetically produce catalysts for some electrochemical applications. Sustainable electrode fabrication: The biotemplated synthesis of catalytic porous electrodes is a sustainable process and, according to the results of durability tests under electrochemical and mechanical stress, these electrodes (e.g. the Pd/carbon paper electrode shown in the picture) are durable enough to replace catalytic electrodes based on synthetic materials in certain applications.

  2. Synthesis and Characterization of Cluster-Derived Supported Bimetallic Catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Adams, Richard D; Amiridis, Michael D

    2008-10-10

    New procedures have been developed for synthesizing di- and tri-metallic cluster complexes. The chemical properties of the new complexes have been investigated, particularly toward the activation of molecular hydrogen. These complexes were then converted into bi- and tri-metallic nanoparticles on silica and alumina supports. These nanoparticles were characterized by electron microscopy and were then tested for their ability to produce catalytic hydrogenation of unsaturated hydrocarbons and for the preferential oxidation of CO in the presence of hydrogen. The bi- and tri-metallic nanoparticles exhibited far superior activity and selectivity as hydrogenation catalysts when compared to the individual metallic components. It was found that the addition of tin greatly improved the selectivity of the catalysts for the hydrogenation of polyolefins. The addition of iron improves the catalysts for the selective oxidation of CO by platinum in the presence of hydrogen. The observations should lead to the development of lower cost routes to molecules that can be used to produce polymers and plastics for use by the general public and for procedures to purify hydrogen for use as an alternative energy in the hydrogen economy of the future.

  3. Magnetic Carbon Supported Palladium Nanoparticles: An Efficient and Sustainable Catalyst for Hydrogenation Reactions

    Science.gov (United States)

    Magnetic carbon supported Pd catalyst has been synthesized via in situ generation of nanoferrites and incorporation of carbon from renewable cellulose via calcination; the catalyst can be used for the hydrogenation of alkenes and reduction of aryl nitro compounds.

  4. Studies of Immobilized Homogeneous Metal Catalysts on Silica Supports

    Energy Technology Data Exchange (ETDEWEB)

    Keith James Stanger

    2003-05-31

    The tethered, chiral, chelating diphosphine rhodium complex, which catalyzes the enantioselective hydrogenation of methyl-{alpha}-acetamidocinnamate (MAC), has the illustrated structure as established by {sup 31}P NMR and IR studies. Spectral and catalytic investigations also suggest that the mechanism of action of the tethered complex is the same as that of the untethered complex in solution. The rhodium complexes, [Rh(COD)H]{sub 4}, [Rh(COD){sub 2}]{sup +}BF{sub 4}{sup -}, [Rh(COD)Cl]{sub 2}, and RhCl{sub 3} {center_dot} 3H{sub 2}O, adsorbed on SiO{sub 2} are optimally activated for toluene hydrogenation by pretreatment with H{sub 2} at 200 C. The same complexes on Pd-SiO{sub 2} are equally active without pretreatments. The active species in all cases is rhodium metal. The catalysts were characterized by XPS, TEM, DRIFTS, and mercury poisoning experiments. Rhodium on silica catalyzes the hydrogenation of fluorobenzene to produce predominantly fluorocyclohexane in heptane and 1,2-dichloroethane solvents. In heptane/methanol and heptane/water solvents, hydrodefluorination to benzene and subsequent hydrogenation to cyclohexane occurs exclusively. Benzene inhibits the hydrodefluorination of fluorobenzene. In DCE or heptane solvents, fluorocyclohexane reacts with hydrogen fluoride to form cyclohexene. Reaction conditions can be chosen to selectively yield fluorocyclohexane, cyclohexene, benzene, or cyclohexane. The oxorhenium(V) dithiolate catalyst [-S(CH{sub 2}){sub 3}s-]Re(O)(Me)(PPh{sub 3}) was modified by linking it to a tether that could be attached to a silica support. Spectroscopic investigation and catalytic oxidation reactivity showed the heterogenized catalyst's structure and reactivity to be similar to its homogeneous analog. However, the immobilized catalyst offered additional advantages of recyclability, extended stability, and increased resistance to deactivation.

  5. Sustainable catalyst supports for carbon dioxide gas adsorbent

    Science.gov (United States)

    Mazlee, M. N.

    2016-07-01

    The adsorption of carbon dioxide (CO2) become the prime attention nowadays due to the fact that increasing CO2 emissions has been identified as a contributor to global climate change. Major sources of CO2 emissions are thermoelectric power plants and industrial plants which account for approximately 45% of global CO2 emissions. Therefore, it is an urgent need to develop an efficient CO2 reduction technology such as carbon capture and storage (CCS) that can reduce CO2 emissions particularly from the energy sector. A lot of sustainable catalyst supports have been developed particularly for CO2 gas adsorbent applications.

  6. Highly Loaded Carbon Black Supported Pt Catalysts for Fuel Cells

    Czech Academy of Sciences Publication Activity Database

    Kaluža, Luděk; Zdražil, Miroslav; Gulková, Daniela; Vít, Zdeněk; Šolcová, Olga; Soukup, Karel; Maixnerová, Lucie

    Prague: Orgit, 2014, s. 35. ISBN 978-80-02-02555-9. [International Congress of Chemical and Process Engineering /21./ - CHISA 2014 and Conference on Process Integration, Modelling and Optimisation for Energy Saving and Pollution Reduction /17./ - PRES 2014. Prague (CZ), 23.08.2014-27.08.2014] R&D Projects: GA MŠk(CZ) 7HX13003 EU Projects: European Commission(XE) 303466 - IMMEDIATE Institutional support: RVO:67985858 Keywords : pt catalysts * fuel cells * carbon black Subject RIV: CI - Industrial Chemistry, Chemical Engineering

  7. SiC nanocrystals as Pt catalyst supports for fuel cell applications

    DEFF Research Database (Denmark)

    Dhiman, Rajnish; Morgen, Per; Skou, E.M.;

    2013-01-01

    A robust catalyst support is pivotal to Proton Exchange Membrane Fuel Cells (PEMFCs) to overcome challenges such as catalyst support corrosion, low catalyst utilization and overall capital cost. SiC is a promising candidate material which could be applied as a catalyst support in PEMFCs. SiC...... nanocrystals of SiC-SPR and SiC-NS by the polyol method. The SiC substrates are subjected to an acid treatment to introduce the surface groups, which help to anchor the Pt nano-catalysts. These SiC based catalysts have been found to have a higher electrochemical activity than commercially available Vulcan...... based catalysts (BASF & HISPEC). These promising results signal a new era of SiC based catalysts for fuel cell applications. © The Royal Society of Chemistry 2013....

  8. MASS TRANSFER IN PORE STRUCTURES OF SUPPORTED CATALYSTS

    Directory of Open Access Journals (Sweden)

    F.R.C. Silva

    1997-09-01

    Full Text Available The effects of gas-solid interaction and mass transfer in fixed-bed systems of supported catalysts were analyzed for g -Al2O3 (support and Cu/g -Al2O3 (catalyst systems. Evaluations of the mass transfer coefficients in the macropores and of the diffusivity in the micropores, as formed by the crystallite agglomerates of the metallic phases, were obtained. Dynamic experiments with gaseous tracers permitted the quantification of the parameters based on models for these two pore structures. With a flow in a range of 18 cm3 s-1 to 39.98 cm3 s-1 at 45oC, 65oC and 100oC, mass transfer coefficients km =4.33x10-4 m s-1 to 7.38x10-4 m s-1 for macropore structures and diffusivities Dm =1.29x10-11 m2 s-1 to 5.35x10-11 m2 s-1 for micropore structures were estimated

  9. The effect of catalyst support on the RWGS reaction

    International Nuclear Information System (INIS)

    'Full text:' Methane steam reforming is generally applied in order to produce synthesis gas mainly consist of hydrogen and carbon monoxide for later utilization in SOFC. This reaction is always carried out with the water gas shift reaction over a catalyst at elevated temperatures resulting in some carbon dioxide production. The CO/CO2 production selectivity strongly depends on the influence of water gas shift reaction. It was observed that the reactivity of this reaction depended on the type of support material. Stabilities, activities, and kinetics of the reverse water gas shift reaction (RWGS) for commercial nickel on CeO2, ZrO2, CeO2-ZrO2, TiO2, MgO, and Al2O3 supports were studied in order to observe the influence of the support on this reaction. According to the experiment, the activities of Ni/CeO2 toward the reverse water gas shift reaction (RWGS) were very high, and reached equilibrium level at approximately 600oC (where the conversion of CO2 was closed to 1). Other oxide supports provided lower activities toward this reaction. It was observed that the activity of Ni/Al2O3 toward this reaction was the lowest. The kinetics of this reaction was also studied. Carbon dioxide presented positive effect on the reverse water gas shift reaction. The reaction orders in carbon dioxide were observed to be positive partial value between 0-1. It slightly decreased with increasing temperature for Ni/ CeO2 and Ni/CeO2-ZrO2, whereas it seemed to be independent of the operating temperature for other materials in the range of conditions studied. Hydrogen also showed positive effect on the reverse water gas shift reaction for all materials. The reaction order in hydrogen for all materials was observed to be the positive value and less than one for the range of conditions studied. The approximate values for all catalysts were between 0.45-0.65, and seemed to be independent of the operating temperature. The estimated values of the apparent activation energy for RWGS reaction

  10. Polystyrene-supported chloroaluminate ionic liquid as a new heterogeneous Lewis acid catalyst for Knoevenagel condensation

    Institute of Scientific and Technical Information of China (English)

    Kaveh Parvanak Boroujeni; Mina Jafarinasab

    2012-01-01

    Non-hygroscopic polystyrene-supported chloroaluminate ionic liquid was prepared from the reaction of Merrifield resin with 1-methylimidazole followed by reaction with aluminum chloride.This Lewis acidic ionic liquid is environmentally friendly heterogeneous catalyst for the Knoevenagel condensation of aromatic and aliphatic aldehydes with ethyl cyanoacetate.The catalyst is stable (as a bench top catalyst) and reusable.

  11. Selective oxidation of propylene to acrolein by silica-supported bismuth molybdate catalysts

    DEFF Research Database (Denmark)

    Duc, Duc Truong; Ha, Hanh Nguyen; Fehrmann, Rasmus;

    2011-01-01

    Silica-supported bismuth molybdate catalysts have been prepared by impregnation, structurally characterized and examined as improved catalysts for the selective oxidation of propylene to acrolein. Catalysts with a wide range of loadings (from 10 to 90 wt%) of beta bismuth molybdate (β-Bi2Mo2O9) w...

  12. SELECTIVE HYDROGENATION OF CINNAMALDEHYDE WITH Pt AND Pt-Fe CATALYSTS: EFFECTS OF THE SUPPORT

    Directory of Open Access Journals (Sweden)

    A.B. da Silva

    1998-06-01

    Full Text Available Low-temperature reduced TiO2-supported Pt and Pt-Fe catalysts are much more active and selective for the liquid–phase hydrogenation of cinnamaldehyde to unsaturated cinnamyl alcohol than the corresponding carbon-supported catalysts. High-temperature reduced catalysts, where the SMSI effect should be present, are almost inactive for this reaction. There is at present no definitive explanation for this effect but an electronic metal-support interaction is most probably involved.

  13. Controlled Radical Polymerization of Methyl Methacrylate Catalyzed by Hybrid Supported Iron Catalyst

    Institute of Scientific and Technical Information of China (English)

    LI Zhong-hui; ZHANG Yong-ming; XUE Min-zhao; ZHOU Lei; LIU Yan-gang

    2005-01-01

    A supported iron catalyst, which was prepared by anchoring FeCl2/FeCl3 on the cross-linking macroporous polyacrylate ion exchange resin, was evaluated via the controlled radical polymerization. When a small amount of CuCl2/Me6TREN was added, the controllability of the polymerization over the iron-mediated catalyst was significantly improved(Mw/Mn=1.23-1.73), affording a polymer with a low residual metal via a simple catalyst separation procedure. After suitable regeneration, the supported iron catalyst could also be recycled. UV-Vis analysis showed that the additional copper catalyst could facilitate the radical deactivation process.

  14. Novel Carbon Nanotubes-supported NiB Amorphors Alloy Catalyst for Benzene Hydrogenation

    Institute of Scientific and Technical Information of China (English)

    Mei Hua YANG; Rong Bin ZHANG; Feng Yi LI

    2004-01-01

    The NiB amorphous alloy catalysts supported on CNTs and alumina were prepared by impregnation and chemical reduction. The gas-phase benzene hydrogenation was used as a probe reaction to evaluate the catalytic activity. The result showed that the NiB amorphous alloy catalyst supported on carbon nanotubes exhibited higher activity than that supported on alumina.

  15. Propene Hydroformylation by Supported Aqueous-phase Rh-NORBOS Catalysts

    DEFF Research Database (Denmark)

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

    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(...

  16. POLYMER-SUPPORTED LEWIS ACID CATALYSTS. VI. POLYSTYRENE-BONDED STANNIC CHLORIDE CATALYST

    Institute of Scientific and Technical Information of China (English)

    RAN Ruicheng; FU Diankui

    1991-01-01

    A polystyrene-bonded stannic chloride catalyst was synthesized by the method of lithium polystyryl combined with stannic chloride. This catalyst is a polymeric organometallic compound containing 0.25 mmol Sn(IV)/g catalyst. The catalyst showed sufficient stability and catalytic activity in organic reaction such as esterification, acetalation and ketal formation, and it could be reused many times without losing its catalytic activity.

  17. Fuel Cell Platinum Catalysts Supported on Mediate Surface Area Carbon Black Supports

    Czech Academy of Sciences Publication Activity Database

    Kaluža, Luděk; Larsen, M.J.; Zdražil, Miroslav; Gulková, Daniela; Odgaard, M.

    2015-01-01

    Roč. 43, č. 2015 (2015), s. 913-918. ISSN 1974-9791. [International Conference on Chemical and Process Engineering - ICheaP12 /12./. Milano, 19.05.2015-22.05.2015] R&D Projects: GA MŠk(CZ) 7HX13003 EU Projects: European Commission(XE) 303466 - IMMEDIATE Institutional support: RVO:67985858 Keywords : carbon black * platinum catalyst * fuel cell Subject RIV: CI - Industrial Chemistry, Chemical Engineering

  18. Organophilic worm-like ruthenium nanoparticles catalysts by the modification of CTAB on montmorillonite supports.

    Science.gov (United States)

    Zhou, Limei; Qi, Xiaolong; Jiang, Xiaohui; Zhou, Yafen; Fu, Haiyan; Chen, Hua

    2013-02-15

    A supported Ru catalyst was prepared by using cetyltrimethylammonium bromide (CTAB) intercalated montmorillonite as the supporting matrix. The as-prepared Ru catalyst was subsequently characterized by XRD, XPS, N(2) sorption, TEM, and dispersibility measurement. The results showed that the Ru nanoparticles were in the modified montmorillonite interlayers, and the morphology of Ru nanoparticle was worm-like. Moreover, this supported Ru catalyst could be well dispersed in organic solvents such as toluene. The catalyst exhibited high activity and selectivity in the hydrogenation of quinoline even without stirring. PMID:23141762

  19. Oxide-supported metal clusters: models for heterogeneous catalysts

    International Nuclear Information System (INIS)

    Understanding the size-dependent electronic, structural and chemical properties of metal clusters on oxide supports is an important aspect of heterogeneous catalysis. Recently model oxide-supported metal catalysts have been prepared by vapour deposition of catalytically relevant metals onto ultra-thin oxide films grown on a refractory metal substrate. Reactivity and spectroscopic/microscopic studies have shown that these ultra-thin oxide films are excellent models for the corresponding bulk oxides, yet are sufficiently electrically conductive for use with various modern surface probes including scanning tunnelling microscopy (STM). Measurements on metal clusters have revealed a metal to nonmetal transition as well as changes in the crystal and electronic structures (including lattice parameters, band width, band splitting and core-level binding energy shifts) as a function of cluster size. Size-dependent catalytic reactivity studies have been carried out for several important reactions, and time-dependent catalytic deactivation has been shown to arise from sintering of metal particles under elevated gas pressures and/or reactor temperatures. In situ STM methodologies have been developed to follow the growth and sintering kinetics on a cluster-by-cluster basis. Although several critical issues have been addressed by several groups worldwide, much more remains to be done. This article highlights some of these accomplishments and summarizes the challenges that lie ahead. (topical review)

  20. Nafion-Teflon bimembrane-supported palladium catalysts for Suzuki coupling reactions

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Nafion-Teflon bimembrane was used as an efficient support for the preparation and application of heterogeneous palladium catalysts. The supported palladium catalysts exhibit high activity and stability in the Suzuki cross-coupling of aryl bromides with arylboronic acids to afford the corresponding biaryls in good to excellent yields, and can be readily recovered and reused several times without significant loss of activity.

  1. Supported Catalysts Useful in Ring-Closing Metathesis, Cross Metathesis, and Ring-Opening Metathesis Polymerization

    Directory of Open Access Journals (Sweden)

    Jakkrit Suriboot

    2016-04-01

    Full Text Available Ruthenium and molybdenum catalysts are widely used in synthesis of both small molecules and macromolecules. While major developments have led to new increasingly active catalysts that have high functional group compatibility and stereoselectivity, catalyst/product separation, catalyst recycling, and/or catalyst residue/product separation remain an issue in some applications of these catalysts. This review highlights some of the history of efforts to address these problems, first discussing the problem in the context of reactions like ring-closing metathesis and cross metathesis catalysis used in the synthesis of low molecular weight compounds. It then discusses in more detail progress in dealing with these issues in ring opening metathesis polymerization chemistry. Such approaches depend on a biphasic solid/liquid or liquid separation and can use either always biphasic or sometimes biphasic systems and approaches to this problem using insoluble inorganic supports, insoluble crosslinked polymeric organic supports, soluble polymeric supports, ionic liquids and fluorous phases are discussed.

  2. Synthesis and characterization of platinum supported on alumina doped with cerium catalyst

    International Nuclear Information System (INIS)

    The synthesis and characterization of gamma-alumina doped with cerium as platinum support for the automobile exhaust catalyst are described. Platinum/alumina/ceria catalyst were prepared by impregnation of hexachloroplatinic acid and sintered at 500 degree Celsius to obtain metal dispersions of 1.0 wt%. Catalyst distribution inside the powder and the effects of the addition of cerium to alumina were analyzed by the scanning electron microscopy (SEM) and x-ray fluorescence spectroscopy (XRF). The results showed that the alumina - supported catalysts contained well dispersion of the noble metal

  3. Hysteresis Phenomena in Sulfur Dioxide Oxidation over Supported Vanadium Catalysts

    DEFF Research Database (Denmark)

    Masters, Stephen G.; Eriksen, Kim Michael; Fehrmann, Rasmus

    1997-01-01

    Catalyst deactivation and hysteresis behavior in industrial SO2-oxidation catalysts have been studied in the temperature region 350-480 C by combined in situ EPR spectroscopy and catalytic activity measurements. The feed gas composition simulated sulfuric acid synthesis gas and wet/dry de...

  4. CARBON NANOTUBES VIA METHANE DECOMPOSITION ON AN ALUMINA SUPPORTED COBALT AEROGEL CATALYST

    Institute of Scientific and Technical Information of China (English)

    Lingyu Piao; Jiuling Chen; Yongdan Li

    2003-01-01

    An alumina-supported cobalt aerogel catalyst prepared from a sol-gel and a supercritical drying method was used in the catalytic decomposition of methane. The physical-chemical properties of the catalyst were characterized and its activity for methane decomposition was investigated. The effects of calcination and reaction temperatures on the activity of the catalyst and the morphology of the carbon nanotubes produced were discussed. A CoAl2O4 spinel structure formed in the calcined catalyst. The quantity of the nanotubes produced in the reaction increases with the amount of cobalt in the reduced catalyst. A higher reaction temperature leads to a higher reaction rate, though faster deactivation of the catalyst occurs with the change. The carbon nanotubes grown on the catalyst have smooth walls and uniform diameter distribution.

  5. Binary supported nickel catalysts for the deuterium exchange reaction between hydrogen and water vapour

    International Nuclear Information System (INIS)

    Nickel catalysts supported by Fe2O3, CuO, MnO and CeO were prepared from the corresponding metal nitrates. Chemical treatment of the catalysts was carried out at room temperature, while thermal treatment was made at 350 0C. The total surface area of the catalysts was measured by nitrogen adsorption at -195 0C using the BET equation. The specific metallic surface area was measured by hydrogen chemisorption at liquid nitrogen temperature. The activity of the catalysts was tested for the isotopic exchange reaction of deuterium between hydrogen and water vapour. The results obtained showed that Ni-Fe2O3, Ni-CuO and Ni-MnO catalysts exhibit catalytic activity for the deuterium exchange between hydrogen and water vapour, while the catalyst supported by CeO has no such activity. (author)

  6. Effects of Cu over Pd based catalysts supported on silica or niobia

    Directory of Open Access Journals (Sweden)

    Roma M.N.S.C.

    2000-01-01

    Full Text Available Palladium and palladium-copper catalysts supported on silica and niobia were characterized by H2 chemisorption and H2-O2 titration. Systems over silica were also analyzed by transmission electron microscopy and EXAFS. The metallic dispersion decreased from 20% to 7% when the content of Pd was increased from 0.5wt.-% to 3wt.-% in monometallic catalysts. The addition of 3 wt.-% Cu to obtain Pd-Cu catalysts caused a remarkable capacity loss of hydrogen chemisorption. TPR analysis suggested an interaction between the two metals and EXAFS characterization of the catalyst supported on silica confirmed the formation of Pd-Cu alloy. Pd/Nb2O5 catalysts showed turnover numbers higher than those obtained with the Pd/SiO2 systems in the cyclohexane dehydrogenation. However, the bimetallic catalysts showed very low turnover numbers.

  7. Effects of carrier and Mn loading on supported manganese oxide catalysts for catalytic combustion of methane

    Institute of Scientific and Technical Information of China (English)

    Jinyan Hu; Wei Chu; Limin Shi

    2008-01-01

    Supported manganese oxide catalysts were prepared by incipient wetness impregnation method for methane cat-alytic combustion, and effects of the support (Al2O3, SiO2 and TiO2) and Mn loading were investigated. These catalysts were characterized with N2 adsorption, X-ray diffraction, X-ray photoelectron spectroscopy and temperature-programmed reduction techniques. Methane conversion varied in a large range depending on supports or Mn loading. Al2O3 supported 15% Mn cata-lyst exhibited better activity toward methane catalytic oxidation. The manganese state and oxygen species played an important role in the catalytic performance.

  8. Mesoporous zeolite SBA-15 supported nickel diimine catalysts for ethylene polymerization

    Institute of Scientific and Technical Information of China (English)

    GUO Chao; ZHANG Dao; JIN Guoxin

    2004-01-01

    The novel mesoporous zeolite SBA-15 is successfully used as the support to immobilize late-transition metal nickel diimine catalyst, both in physical and chemical methods, EA, ICP, FT-IR and XRD are applied to characterizing these supported catalysts. The results of ethylene polymerization reveal that these supported catalysts have high catalytic activity as their homogenous counterpart does, moreover, polyethylene with a fibrous morphology is produced due to the channel effect of support, and both the molecular weight and molecular weight distributions of polymers are increased greatly.

  9. Silica supported Brӧnsted acids as catalyst in organic transformations:A comprehensive review

    Institute of Scientific and Technical Information of China (English)

    Manpreet Kaur; Sahil Sharma; Preet M. S. Bedi

    2015-01-01

    Brӧnsted acid catalysts have been used in a number of organic transformations. To overcome limi‐tations, such as toxicity, volatility, high price and hazardous nature of the conventional methods, the catalysts are adsorbed on silica gel to give the benefits and advantages of ready availability, simple work‐up procedure, long catalytic life, environment‐friendliness, good to excellent yields and recy‐clability. The uses of such catalysts have gained importance worldwide. This article describes some of the important silicated catalysts, namely, heteropolyacids, polyphosphoric acid, perchloric acid, fluoroboric acid, and silicated sulphuric acid. These catalysts have been used in a number of organic reactions to yield compounds that are important in the chemical and pharmaceutical industries. We summarize the beneficial effects of these catalysts and the reports that have been published on them in the past several years. In the present review, the description of the catalysts are introduced followed by a recent research history, and a comparison between the silica supported catalysts and other (polymer) supported catalysts. The article ends up giving the advantages of these catalytic systems over the conventional catalyst.

  10. Altervalent cation-doped MCM-41 supported palladium catalysts and their catalytic properties

    OpenAIRE

    HAIHUI JIANG; LIGANG GAI; YAN TIAN

    2011-01-01

    Metal cation-doped MCM-41 (M-MCM-41, M = Al, Ce, Co, V or Zr) supported Pd catalysts (Pd/M-MCM-41) were prepared by a solution-based reduction method. The catalysts were characterized by X-ray diffraction (XRD) analysis, infrared spectroscopy (IR), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), and further evaluated by selective hydrogenation of para-chloronitrobenzene (p-CNB) in anhydrous ethanol. The metal cation-containing Pd catalysts can efficiently enhanc...

  11. Niobia supported on silica as a catalyst for Biodiesel production from waste oil

    OpenAIRE

    Tesser R.; Vitiello R.; Carotenuto G.; Garcia Sancho C.; Vergara A; Maireles Torres P.J.; Li Changzhu; Di Serio M.

    2015-01-01

    The activity and stability of niobia supported on silica catalyst have been tested in continuous micro-pilot reactors, for biodiesel production starting from acid vegetable oils. A catalyst was prepared by the impregnation of silica pellets with a loading of 12% of Nb and was extensively characterized. The activity of this catalyst in both esterification and transesterification was tested in a continuous micro-pilot laboratory plant in which acid oil was fed (FFA 10% w...

  12. Graphene-Supported Platinum Catalyst-Based Membrane Electrode Assembly for PEM Fuel Cell

    Science.gov (United States)

    Devrim, Yilser; Albostan, Ayhan

    2016-08-01

    The aim of this study is the preparation and characterization of a graphene-supported platinum (Pt) catalyst for proton exchange membrane fuel cell (PEMFC) applications. The graphene-supported Pt catalysts were prepared by chemical reduction of graphene and chloroplatinic acid (H2PtCl6) in ethylene glycol. X-ray powder diffraction, thermogravimetric analysis (TGA) and scanning electron microscopy have been used to analyze structure and surface morphology of the graphene-supported catalyst. The TGA results showed that the Pt loading of the graphene-supported catalyst was 31%. The proof of the Pt particles on the support surfaces was also verified by energy-dispersive x-ray spectroscopy analysis. The commercial carbon-supported catalyst and prepared Pt/graphene catalysts were used as both anode and cathode electrodes for PEMFC at ambient pressure and 70°C. The maximum power density was obtained for the Pt/graphene-based membrane electrode assembly (MEA) with H2/O2 reactant gases as 0.925 W cm2. The maximum current density of the Pt/graphene-based MEA can reach 1.267 and 0.43 A/cm2 at 0.6 V with H2/O2 and H2/air, respectively. The MEA prepared by the Pt/graphene catalyst shows good stability in long-term PEMFC durability tests. The PEMFC cell voltage was maintained at 0.6 V without apparent voltage drop when operated at 0.43 A/cm2 constant current density and 70°C for 400 h. As a result, PEMFC performance was found to be superlative for the graphene-supported Pt catalyst compared with the Pt/C commercial catalyst. The results indicate the graphene-supported Pt catalyst could be utilized as the electrocatalyst for PEMFC applications.

  13. Graphene-Supported Platinum Catalyst-Based Membrane Electrode Assembly for PEM Fuel Cell

    Science.gov (United States)

    Devrim, Yilser; Albostan, Ayhan

    2016-06-01

    The aim of this study is the preparation and characterization of a graphene-supported platinum (Pt) catalyst for proton exchange membrane fuel cell (PEMFC) applications. The graphene-supported Pt catalysts were prepared by chemical reduction of graphene and chloroplatinic acid (H2PtCl6) in ethylene glycol. X-ray powder diffraction, thermogravimetric analysis (TGA) and scanning electron microscopy have been used to analyze structure and surface morphology of the graphene-supported catalyst. The TGA results showed that the Pt loading of the graphene-supported catalyst was 31%. The proof of the Pt particles on the support surfaces was also verified by energy-dispersive x-ray spectroscopy analysis. The commercial carbon-supported catalyst and prepared Pt/graphene catalysts were used as both anode and cathode electrodes for PEMFC at ambient pressure and 70°C. The maximum power density was obtained for the Pt/graphene-based membrane electrode assembly (MEA) with H2/O2 reactant gases as 0.925 W cm2. The maximum current density of the Pt/graphene-based MEA can reach 1.267 and 0.43 A/cm2 at 0.6 V with H2/O2 and H2/air, respectively. The MEA prepared by the Pt/graphene catalyst shows good stability in long-term PEMFC durability tests. The PEMFC cell voltage was maintained at 0.6 V without apparent voltage drop when operated at 0.43 A/cm2 constant current density and 70°C for 400 h. As a result, PEMFC performance was found to be superlative for the graphene-supported Pt catalyst compared with the Pt/C commercial catalyst. The results indicate the graphene-supported Pt catalyst could be utilized as the electrocatalyst for PEMFC applications.

  14. Selective CO oxidation over ceria supported CuO catalysts

    International Nuclear Information System (INIS)

    The effect of preparation method and pretreatment on the characteristic properties and selective CO oxidation activities of 50/50 CuO/CeO2, 25/25/50 CuO/Co3O4/CeO2 and 5/95 CuO/CeO2 catalysts was investigated. Catalysts were characterized by BET surface area measurement, N2 physisorption, SEM micrographs and X-ray diffraction. The selective oxidation reaction in H2 rich stream was carried out between the 110 deg. C and 210 deg. C temperatures. The 5/95 CuO/CeO2 catalysts gave the best CO conversion and selectivity result. The 5/95 CuO/CeO2 catalyst calcined at 700 deg. C protected its activity and selectivity at 200 deg. C during 24 h.

  15. Sulphur poisoning of palladium catalysts used for methane combustion: Effect of the support

    International Nuclear Information System (INIS)

    Four different supported palladium catalysts (using alumina, silica, zirconia and titania as supports), prepared by incipient wetness impregnation, were tested as catalysts for methane oxidation in presence of sulphur dioxide. The catalyst supported on zirconia showed the best performance, whereas the silica-supported one showed the fastest deactivation. Temperature-programmed desorption experiments of the poisoned catalysts suggest that SO2 adsorption capacity of the support plays a key role in the catalyst poisoning. In order to study the effect of promoters, expected to improve the thermal stability and thioresistance of the catalyst, commercial zirconia modified by yttrium and lantane was tested as supports. It was found that the presence of these promoters does not improve the performance of the zirconia-supported catalyst. A deactivation model - considering two different active sites (fresh and poisoning), pseudo-first order dependence on methane concentration and poisoning rate depending on sulphur concentration and fraction of non-poisoned palladium - was used for modelling the deactivation behaviour

  16. Ammoxidation of 2-methyl pyrazine on supported ammonium salt of 12-molybdophosphoric acid catalysts: The influence of nature of support

    Indian Academy of Sciences (India)

    Katabathini Narasimharao; B Hari Babu; N Lingaiah; P S Sai Prasad; Shaeel A Al-Thabaiti

    2014-03-01

    Influence of the nature of support on the formation of catalytically active species was investigated to clarify the key factor for the synthesis of supported ammonium salt of 12-molybdophosphoric acid (AMPA) catalyst which maintains the activity of ammoxidation during 2-methylpyrazine reaction.With this aim, different loadings of niobia-, silica- and alumina-, supported AMPA catalysts were prepared. The AMPA loading was varied in the range of 5-25 wt%. The synthesized solids were characterized by nitrogen adsorption for BET surface area, XRD and 31P MAS NMR techniques. All the AMPA-supported samples are poorly crystalline even after 25 wt% AMPA loading. Investigations using 31P MAS NMR spectroscopy of samples revealed that Keggin ion existed as at least five different species on the supports. The investigated properties were acidity of the support and amount of AMPA loading on the support. Active sites for the ammoxidation of MP on supported AMPA catalysts seem to be the interacted and/or the lacunary species.Maximum catalytic activity could be obtained at lower loadings with AMPA deposited on acidic supports whereas the less acidic supports require higher loading. It was found that in order to efficiently generate the active interactive species, the support must have an acidity which promotes the formation of support-AMPA interactive species. It is possible to enhance the catalytic activity of the supported AMPA catalyst for ammoxidation of 2-methylpyrazine by controlling the acidity of the support and AMPA loading on the support.

  17. Preparation of Supported Metal Catalysts by Atomic and Molecular Layer Deposition for Improved Catalytic Performance

    Science.gov (United States)

    Gould, Troy D.

    Creating catalysts with enhanced selectivity and activity requires precise control over particle shape, composition, and size. Here we report the use of atomic layer deposition (ALD) to synthesize supported Ni, Pt, and Ni-Pt catalysts in the size regime (number of ALD cycles, Ni weight loadings were varied from 4.7 wt% to 16.7 wt% and the average particle sizes ranged from 2.5 to 3.3 nm, which increased the selectivity for C 3H6 hydrogenolysis by an order of magnitude over a much larger Ni/Al2O3 catalyst. Pt particles were deposited by varying the number of ALD cycles and the reaction chemistry (H2 or O 2) to control the particle size from approximately 1 to 2 nm, which allowed lower-coordinated surface atoms to populate the particle surface. These Pt ALD catalysts demonstrated some of the highest oxidative dehydrogenation of propane selectivities (37%) of a Pt catalyst synthesized by a scalable technique. Dry reforming of methane (DRM) is a reaction of interest due to the recent increased recovery of natural gas, but this reaction is hindered from industrial implementation because the Ni catalysts are plagued by deactivation from sintering and coking. This work utilized Ni ALD and NiPt ALD catalysts for the DRM reaction. These catalysts did not form destructive carbon whiskers and had enhanced reaction rates due to increased bimetallic interaction. To further limit sintering, the Ni and NiPt ALD catalysts were coated with a porous alumina matrix by molecular layer deposition (MLD). The catalysts were evaluated for DRM at 973 K, and the MLD-coated Ni catalysts outperformed the uncoated Ni catalysts in either activity (with 5 MLD cycles) or stability (with 10 MLD cycles). In summary, this thesis developed a new Ni nanoparticle ALD chemistry, explored possibilities for changing Pt ALD particle size, brought the two techniques together to create enhanced bimetallic catalysts, and stabilized the catalysts using MLD.

  18. Noble metal supported catalysts for lactose transformations in liquid phase

    OpenAIRE

    Meyer, Nathalie

    2014-01-01

    Carbohydrates are an important source of renewable materials which can be converted into high added-value products. Sugar transformations should ideally be carried out with recyclable catalysts, in water, with the highest possible selectivity in the desired product. The aim of the present work was to explore the microstructural properties of the heterogeneous catalysts needed to carry out selectively lactose oxidation into lactobionic acid and lactose hydrogenation into lactitol. The first pa...

  19. Potassium hydroxide catalyst supported on palm shell activated carbon for transesterification of palm oil

    Energy Technology Data Exchange (ETDEWEB)

    Baroutian, Saeid; Aroua, Mohamed Kheireddine; Raman, Abdul Aziz Abdul; Sulaiman, Nik Meriam Nik [Department of Chemical Engineering, Faculty of Engineering, University of Malaya, 50603 Kuala Lumpur (Malaysia)

    2010-11-15

    In this study, potassium hydroxide catalyst supported on palm shell activated carbon was developed for transesterification of palm oil. The Central Composite Design (CCD) of the Response Surface Methodology (RSM) was employed to investigate the effects of reaction temperature, catalyst loading and methanol to oil molar ratio on the production of biodiesel using activated carbon supported catalyst. The highest yield was obtained at 64.1 C reaction temperature, 30.3 wt.% catalyst loading and 24:1 methanol to oil molar ratio. The physical and chemical properties of the produced biodiesel met the standard specifications. This study proves that activated carbon supported potassium hydroxide is an effective catalyst for transesterification of palm oil. (author)

  20. Ceria-Modified Clay Supported Palladium Catalysts for Complete Oxidation of Volatile Organic Compounds

    Institute of Scientific and Technical Information of China (English)

    Li Jinjun; Hao Zhengping; Hu Chun

    2004-01-01

    Ceria- and alumina-pillared interlayered clays were synthesized in the presence of PEO surfactant by using laponite clay as raw material.And the synthesized pillared clays were used as supports to load palladium catalysts for complete oxidation of benzene.Nitrogen adsorption/desorption experiments reveal that the pillared clays have higher tests show that ceria pillar exhibited promoting effect on the activity of the palladium catalysts, and ceria-pillared clay supported palladium catalyst catalyzed the complete oxidation of benzene at less than 250 ℃.The calcination temperature affects the activity of the catalysts significantly, and it is found that the optimal calcination temperature are 600 and 400 ℃ for ceria- and alumina-pillared clay supported palladium catalysts, respectively.

  1. Magnetic silica supported palladium catalyst: synthesis of allyl aryl ethers in water

    Science.gov (United States)

    A simple and benign procedure for the synthesis of aryl allyl ethers has been developed using phenols, allyl acetates and magnetically recyclable silica supported palladium catalyst in water; performance of reaction in air and easy separation of the catalyst using an external mag...

  2. Reusable and Efficient Polystryrene-supported Acidic Ionic Liquid Catalyst for Mononitration of Aromatic Compounds

    International Nuclear Information System (INIS)

    A series of polystyrene-supported 1-(propyl-3-sulfonate)-3-methyl-imidazolium hydrosulfate acidic ionic liquid (PS-[SO3H-PMIM][HSO4]) catalysts were prepared and tested for mononitration of simple aromatics compounds with nitric acid. It was found that the reactivity of the catalysts increased with increasing [SO3HPMIM][HSO4] content. The para-selectivity was not only related to the [SO3H-PMIM][HSO4] content but also the substituent groups in aromatics. A reaction mechanism of nitration over this new catalyst was proposed. The catalytic activity of this catalyst decreased slightly after fifth runs in the synthesis of nitrotoluene

  3. Physicochemical investigations of carbon nanofiber supported Cu/ZrO2 catalyst

    International Nuclear Information System (INIS)

    Zirconia-promoted copper/carbon nanofiber catalysts (Cu‐ZrO2/CNF) were prepared by the sequential deposition precipitation method. The Herringbone type of carbon nanofiber GNF-100 (Graphite nanofiber) was used as a catalyst support. Carbon nanofiber was oxidized to (CNF-O) with 5% and 65 % concentration of nitric acid (HNO3). The CNF activated with 5% HNO3 produced higher surface area which is 155 m2/g. The catalyst was characterized by X-ray Diffraction (XRD), Fourier Transform Infra-Red (FTIR) and N2 adsorption-desorption. The results showed that increase of HNO3 concentration reduced the surface area and porosity of the catalyst

  4. Physicochemical investigations of carbon nanofiber supported Cu / ZrO2 catalyst

    Science.gov (United States)

    Din, Israf Ud; Shaharun, Maizatul S.; Subbarao, Duvvuri; Naeem, A.

    2014-10-01

    Zirconia-promoted copper/carbon nanofiber catalysts (Cu - ZrO2/ CNF ) were prepared by the sequential deposition precipitation method. The Herringbone type of carbon nanofiber GNF-100 (Graphite nanofiber) was used as a catalyst support. Carbon nanofiber was oxidized to (CNF-O) with 5% and 65 % concentration of nitric acid (HNO3). The CNF activated with 5% HNO3 produced higher surface area which is 155 m2/g. The catalyst was characterized by X-ray Diffraction (XRD), Fourier Transform Infra-Red (FTIR) and N2 adsorption-desorption. The results showed that increase of HNO3 concentration reduced the surface area and porosity of the catalyst.

  5. Stability and catalytic performance of vanadia supported on nanostructured titania catalyst in oxidative dehydrogenation of propane

    International Nuclear Information System (INIS)

    Highlights: • Vanadia supported on titanate nanotube shows enhanced dispersion of vanadia. • Deactivatoin during propane ODH related to the rutile development. • Titanate nanotube transfers to anatase due to calcinations and presence of vanadia. - Abstract: Titanate nanotubes with a high specific surface area were synthesized by the simple hydrothermal method and investigated as support for V2O5 catalyst in oxidative dehydrogenation of propane (ODP). The structures of pristine nanotubes as well as the prepared catalysts were investigated by XRD, Raman, FTIR, HRTEM, SEM, EDS, BET, and XPS techniques. The characterization of the as-synthesized nanotubes showed the synthesis of hydrogen titanate nanotube. The incipient wetness impregnation method was utilized to prepare VTNT-x (x = 5, 10, and 15 wt.% vanadia supported on nanotube) together with VTi5 (5 wt.% vanadia supported on Degussa P25). The anatase phase was developed in VTNT-x catalysts upon calcination along with specific surface area loss. Higher vanadia loading resulted in the lowering of support capacity in maintaining vanadia in dispersed state such that eventually crystalline vanadia appeared. The measured catalyst activity demonstrates that in spite of major support surface area loss in VTNT-5 catalyst, the propylene yield is superior in comparison with VTi5 catalyst. The catalyst activity can be correlated with maximum reduction temperature. Deactivation of VTi5 and VTNT-5 as well as VTNT-15 were studied for 3,000 min time-on-stream. It was found that the activity of VTNT-5 catalyst remain unchanged while a decline in catalytic activity observed in VTi5 and VTNT-15 catalysts. The development of rutile was considered as being a major element in the deactivation of the investigated catalysts which is influenced by the presence of vanadium and reaction atmosphere

  6. Stability and catalytic performance of vanadia supported on nanostructured titania catalyst in oxidative dehydrogenation of propane

    Energy Technology Data Exchange (ETDEWEB)

    Kootenaei, A.H. Shahbazi [Department of Chemical Engineering, College of Engineering, Tarbiat Modares University, P.O. Box 14115-143, Tehran (Iran, Islamic Republic of); Towfighi, J., E-mail: towfighi@modares.ac.ir [Department of Chemical Engineering, College of Engineering, Tarbiat Modares University, P.O. Box 14115-143, Tehran (Iran, Islamic Republic of); Khodadadi, A.; Mortazavi, Y. [Catalysis and Nanostructured Materials Laboratory, Oil and Gas Processing Center of Excellence, Department of Chemical Engineering, College of Engineering, University of Tehran, P.O. Box 11365-4563, Tehran (Iran, Islamic Republic of)

    2014-04-01

    Highlights: • Vanadia supported on titanate nanotube shows enhanced dispersion of vanadia. • Deactivatoin during propane ODH related to the rutile development. • Titanate nanotube transfers to anatase due to calcinations and presence of vanadia. - Abstract: Titanate nanotubes with a high specific surface area were synthesized by the simple hydrothermal method and investigated as support for V{sub 2}O{sub 5} catalyst in oxidative dehydrogenation of propane (ODP). The structures of pristine nanotubes as well as the prepared catalysts were investigated by XRD, Raman, FTIR, HRTEM, SEM, EDS, BET, and XPS techniques. The characterization of the as-synthesized nanotubes showed the synthesis of hydrogen titanate nanotube. The incipient wetness impregnation method was utilized to prepare VTNT-x (x = 5, 10, and 15 wt.% vanadia supported on nanotube) together with VTi5 (5 wt.% vanadia supported on Degussa P25). The anatase phase was developed in VTNT-x catalysts upon calcination along with specific surface area loss. Higher vanadia loading resulted in the lowering of support capacity in maintaining vanadia in dispersed state such that eventually crystalline vanadia appeared. The measured catalyst activity demonstrates that in spite of major support surface area loss in VTNT-5 catalyst, the propylene yield is superior in comparison with VTi5 catalyst. The catalyst activity can be correlated with maximum reduction temperature. Deactivation of VTi5 and VTNT-5 as well as VTNT-15 were studied for 3,000 min time-on-stream. It was found that the activity of VTNT-5 catalyst remain unchanged while a decline in catalytic activity observed in VTi5 and VTNT-15 catalysts. The development of rutile was considered as being a major element in the deactivation of the investigated catalysts which is influenced by the presence of vanadium and reaction atmosphere.

  7. Preparation and heat treatment characterization of alumina-based ceramic catalyst supports

    International Nuclear Information System (INIS)

    Physical and chemical properties of support materials are as equally important as the precursor metals to the overall performance and function of the heterogeneous catalyst system. Studies on support properties could lead to development of procedure for production of catalyst designed for a desired functionality. This paper reports on the studies of changes of physical properties of alumina and mullite, that have been synthesized for catalyst support, after undergoing heat treatment. The crystallization has been studied by XRD technique, and the phase transformation was monitored by TGA and DTA methods. The surface area changes were followed by BET nitrogen adsorption method

  8. Titania-Supported Catalysts for Levulinic Acid Hydrogenation: Influence of Support and its Impact on γ-Valerolactone Yield.

    Science.gov (United States)

    Ruppert, A M; Grams, J; Jędrzejczyk, M; Matras-Michalska, J; Keller, N; Ostojska, K; Sautet, P

    2015-05-11

    A series of titania-supported ruthenium and platinum catalysts was investigated in the levulinic acid hydrogenation towards γ-valerolactone, a key reaction for the catalytic transformation of biomass. It was shown that various morphologies and phases of titania strongly influence the physicochemical and catalytic properties of supported Ru and Pt catalysts in different ways. In the case of the catalyst supported on mixed TiO2 phases, Ru particles are exclusively located on the minority rutile crystallites, whereas such an effect was not observed for platinum. The platinum catalyst activity could be increased when the metal was dispersed on the large surface-area anatase, which was not the case for ruthenium as a result of its agglomeration on this support. The activity of ruthenium on anatase could be increased in two ways: a) when RuO2 formation during catalyst preparation was avoided; b) when pure anatase support material was modified so that it exhibited no microporosity. The obtained results allow a better understanding of the role of the support for Ru and Pt catalysts. PMID:25641864

  9. Synthesis and characterization of supported polysugar-stabilized palladium nanoparticle catalysts for enhanced hydrodechlorination of trichloroethylene

    International Nuclear Information System (INIS)

    Palladium (Pd) nanoparticle catalysts were successfully synthesized within an aqueous phase using sodium carboxymethyl cellulose (CMC) as a capping ligand which offers a green alternative to conventional nanoparticle synthesis techniques. The CMC-stabilized Pd nanoparticles were subsequently dispersed within support materials using the incipient wetness impregnation technique for utilization in heterogeneous catalyst systems. The unsupported and supported (both calcined and uncalcined) Pd nanoparticle catalysts were characterized using transmission electron microscopy, energy dispersive x-ray spectrometry, x-ray diffraction, and Brunauer–Emmett–Teller surface area measurement and their catalytic activity toward the hydrodechlorination of trichloroethylene (TCE) in aqueous media was examined using homogeneous and heterogeneous catalyst systems, respectively. The unsupported Pd nanoparticles showed considerable activity toward the degradation of TCE, as demonstrated by the reaction kinetics. Although the supported Pd nanoparticle catalysts had a lower catalytic activity than the unsupported particles that were homogeneously dispersed in the aqueous solutions, the supported catalysts retained sufficient activity toward the degradation of TCE. In addition, the use of the hydrophilic Al2O3 support material induced a mass transfer resistance to TCE that affected the initial hydrodechlorination rate. This paper demonstrates that supported Pd catalysts can be applied to the heterogeneous catalytic hydrodechlorination of TCE. (paper)

  10. Stability and catalytic performance of vanadia supported on nanostructured titania catalyst in oxidative dehydrogenation of propane

    Science.gov (United States)

    Kootenaei, A. H. Shahbazi; Towfighi, J.; Khodadadi, A.; Mortazavi, Y.

    2014-04-01

    Titanate nanotubes with a high specific surface area were synthesized by the simple hydrothermal method and investigated as support for V2O5 catalyst in oxidative dehydrogenation of propane (ODP). The structures of pristine nanotubes as well as the prepared catalysts were investigated by XRD, Raman, FTIR, HRTEM, SEM, EDS, BET, and XPS techniques. The characterization of the as-synthesized nanotubes showed the synthesis of hydrogen titanate nanotube. The incipient wetness impregnation method was utilized to prepare VTNT-x (x = 5, 10, and 15 wt.% vanadia supported on nanotube) together with VTi5 (5 wt.% vanadia supported on Degussa P25). The anatase phase was developed in VTNT-x catalysts upon calcination along with specific surface area loss. Higher vanadia loading resulted in the lowering of support capacity in maintaining vanadia in dispersed state such that eventually crystalline vanadia appeared. The measured catalyst activity demonstrates that in spite of major support surface area loss in VTNT-5 catalyst, the propylene yield is superior in comparison with VTi5 catalyst. The catalyst activity can be correlated with maximum reduction temperature. Deactivation of VTi5 and VTNT-5 as well as VTNT-15 were studied for 3,000 min time-on-stream. It was found that the activity of VTNT-5 catalyst remain unchanged while a decline in catalytic activity observed in VTi5 and VTNT-15 catalysts. The development of rutile was considered as being a major element in the deactivation of the investigated catalysts which is influenced by the presence of vanadium and reaction atmosphere.

  11. Catalytic wet air oxidation of chlorophenols over supported ruthenium catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Li Ning [Institut de recherches sur la catalyse et l' environnement de Lyon (IRCELYON), UMR 5256, CNRS/Universite Claude Bernard Lyon 1, 2 Avenue Albert Einstein, 69626 Villeurbanne Cedex (France); Descorme, Claude [Institut de recherches sur la catalyse et l' environnement de Lyon (IRCELYON), UMR 5256, CNRS/Universite Claude Bernard Lyon 1, 2 Avenue Albert Einstein, 69626 Villeurbanne Cedex (France)]. E-mail: claude.descorme@catalyse.cnrs.fr; Besson, Michele [Institut de recherches sur la catalyse et l' environnement de Lyon (IRCELYON), UMR 5256, CNRS/Universite Claude Bernard Lyon 1, 2 Avenue Albert Einstein, 69626 Villeurbanne Cedex (France)

    2007-07-31

    A series of noble metal (Pt, Pd, Ru) loaded zirconia catalysts were evaluated in the catalytic wet air oxidation (CWAO) of mono-chlorophenols (2-CP, 3-CP, 4-CP) under relatively mild reaction conditions. Among the investigated noble metals, Ru appeared to be the best to promote the CWAO of CPs as far as incipient-wetness impregnation was used to prepare all the catalysts. The position of the chlorine substitution on the aromatic ring was also shown to have a significant effect on the CP reactivity in the CWAO over 3 wt.% Ru/ZrO{sub 2}. 2-CP was relatively easier to degradate compared to 3-CP and 4-CP. One reason could be the higher adsorption of 2-CP on the catalyst surface. Further investigations suggested that 3 wt.% Ru/ZrO{sub 2} is a very efficient catalyst in the CWAO of 2-CP as far as high 2-CP conversion and TOC abatement could still be reached at even lower temperature (393 K) and lower total pressure (3 MPa). Additionally, the conversion of 2-CP was demonstrated to increase with the initial pH of the 2-CP solution. The dechlorination reaction is promoted at higher pH. In all cases, the adsorption of the reactants and the reaction intermediates was shown to play a major role. All parameters that would control the molecule speciation in solution or the catalyst surface properties would have a key effect.

  12. A New Model Describing the Metal-Support Interaction in Noble Metal Catalysts

    NARCIS (Netherlands)

    Koningsberger, D.C.; Mojet, B.L.; Miller, J.T.; Ramaker, D.E.

    1999-01-01

    The catalytic activity and spectroscopic properties of supported noble metal catalysts are strongly influenced by the acidity/alkalinity of the support but are relatively independent of the metal (Pd or Pt) or the type of support (zeolite LTL or SiO{2}). As the alkalinity of the support increases, t

  13. Low-temperature SCR of NOx with NH3 over carbon-ceramic supported catalysts

    International Nuclear Information System (INIS)

    A new method for preparing vanadium oxide supported on carbon-ceramic cellular monoliths is described. This includes a support oxidation step with HNO3, followed by ionic exchange with a NaOH solution, equilibrium adsorption impregnation of VO2+ and thermal treatment. As a result an active catalyst for low-temperature selective catalytic reduction (SCR) reaction is obtained. The V-catalyst is more resistant to SO2 poisoning than the previously developed Mn-catalyst. Inhibition by water is reversible for both types of catalysts. Testing of the vanadium catalyst after subjecting it to the outlet gas stream of a power plant shows fast deactivation until constant residual activity is reached. Deactivation seems to be caused by arsenic poisoning and the formation of superficial sulphates

  14. Fundamental investigations of supported monometallic and bimetallic catalysts by proton magnetic resonance spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Xi.

    1990-09-21

    Proton magnetic resonance spectroscopy, or nuclear magnetic resonance (NMR) of hydrogen, has been applied to investigate silica-supported Group VIII monometallic and Group VIII-Group IB bimetallic catalysts and alumina- and silica-supported platinum-rhenium bimetallic catalysts. Two adsorbed states of hydrogen, i.e., irreversible and reversible hydrogen, on the surfaces of monometallic Ru, Pt, and Cu particles and bimetallic Ru-Group Ib, Pt-Group Ib, and Pt-Re particles were observed directly via proton NMR. The same amounts of the irreversible hydrogen adsorbed on pure Ru catalysts were measured by both proton NMR and the volumetric technique. The electronic environments on surfaces of monometallic catalysts are sensitive to changes in metal dispersion, state of adsorbed hydrogen, and residual chlorine. Surface compositions for the Ru--Cu and Pt--Cu bimetallic catalysts were determined by NMR of adsorbed hydrogen. 297 refs., 96 figs., 19 tabs.

  15. Gaseous exchange reaction of deuterium between hydrogen and water on hydrophobic catalyst supporting platinum

    International Nuclear Information System (INIS)

    The deuterium exchange reaction between hydrogen and water in the gas phase where the fed hydrogen gas is saturated with water vapor is studied experimentally by use of the proper hydrophobic catalysts supporting platinum. It is found that the activities of those catalysts for this reaction system are very high compared with the other known ones for the systems in which gas and liquid should coexist on catalyst surfaces, and that the apparent catalytic activity becomes larger as the amount of platinum supported on a catalyst particle increases. By analyses of the data the following informations are obtained. The exchange reaction can be expressed by a first order reversible reaction kinetics. The pore diffusion in the catalyst particles has significant effect on the overall reaction mechanisms. (author)

  16. Particle size effects in Fischer-Tropsch synthesis by Co catalyst supported on carbon nanotubes

    Institute of Scientific and Technical Information of China (English)

    Ali Nakhaei Pour; Elham Hosaini; Mohammad Izadyar; Mohammad Reza Housaindokht

    2015-01-01

    The effect of Co particle size on the Fischer-Tropsch synthesis (FTS) activity of carbon nanotube (CNT)-supported Co catalysts was investigated. Microemulsion (using water-to-surfactant molar ratios of 2 to12) and impregnation techniques were used to prepare catalysts with different Co particle sizes. Kinetic studies were performed to understand the effect of Co particle size on catalytic activity. Size-dependent kinetic parameters were developed using a thermodynamic method, to evaluate the structural sensitivity of the CNT-supported Co catalysts. The size-independent FTS reaction rate constant and size-independent adsorption parameter increased with increasing reac-tion temperature. The Polani parameter also depended on catalyst particle size, because of changes in the catalyst surface coverage.

  17. Hydrotalcite-supported Pd-Cu catalyst for nitrate adsorption and reduction from water

    Institute of Scientific and Technical Information of China (English)

    WANG Ying; QU Jiuhui; LIU Huijuan; WU Rongcheng

    2006-01-01

    Hydrotalcite-supported Pd-Cu catalyst for nitrate adsorption and catalytic reduction from water is prepared by co-impregnation method and characterized by surface area (BET), X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM) and X-ray photoelectron spectrum (XPS). The performance of adsorption and hydrogenation of nitrate was evaluated and compared with Al2O3, TiO2, and HZSM-supported Pd-Cu catalysts. The experimental results demonstrated that hydrotalcite-supported Pd-Cu catalyst exhibited a high surface area (185.3 m2/g) and mesopore structure (average pore diameter of 52.2 (A)). The active metal clusters were homogeneously dispersed on the support, and the size of the most was less than 10 nm. Excellent adsorption for nitrate resulted from that nitrate ions were forced to enter the interlayer space when the calcined hydrotalcite regenerated layer structure in nitrate solution. The adsorption isotherm could be well described by the Langmuir model. The comparison between the adsorption and catalytic hydrogenation for nitrate using hydrogen indicated that nitrate reduction on hydrotalcite-supported Pd-Cu catalysts was a consecutive and dynamic adsorption and catalytic hydrogenation process. Compared with the Al2O3, TiO2, and HZSM- supported catalysts, hydrotalcite-supported Pd-Cu catalyst possessed higher catalytic activity and selectivity. The analysis on the dissolving of metals in the solution demonstrated that there was hydrolyzation on the surface of the hydrotalcite-supported Pd-Cu catalyst. However, the concentrations of dissolved metals in the solution were lower than the standard executed in China. The activity of the hydrotalcite-supported Pd-Cu catalyst for nitrate reduction kept steady after repeated use.

  18. Chemical and electrochemical promotion of supported rhodium catalyst

    OpenAIRE

    Baranova, Olena; Comninellis, Christos

    2007-01-01

    The chemical and electrochemical promotion of highly dispersed nanofilm Rh catalysts (dispersion: about 10 %, film thickness: 40 nm) has been investigated for the first time. To this end Rh metal was sputter-deposited, either on a purely ionic conductor (8 % Y2O3-stabilized ZrO2) or on a mixed ionic-electronic conductor (TiO2), the latter being a highly dispersed layer of TiO2 (4 µm) deposited on YSZ. These catalysts are designated as Rh/YSZ and Rh/TiO2/YSZ, respectively. It was established a...

  19. Supported ZnO catalysts for the conversion of alkanes: About the metamorphosis of a heterogeneous catalyst

    Institute of Scientific and Technical Information of China (English)

    S.Arndt; B.Uysal; A.Berthold; T.Otrebma; Y.Aksu; M.Driess; R.Schom(a)cker

    2012-01-01

    ZnO could be a suitable catalyst for the oxidative conversion of CH4,C2H6 and C3H8.However,the main drawback is its thermal instability.Therefore,ZnO supported on ZrO2,TiO2,γ-Al2O3 and SiO2 was investigated for the oxidative dehydrogenation of propane,and ethane,and the oxidative coupling of methane.The stability of the supported ZnO is partially improved,but ZnO reacts with the support material,forming new compounds (Zn-zirconates,-titanates,-aluminates and-silicates),which already occurs below reaction temperature.This might also be the case for many other heterogeneous catalysts.

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

    Science.gov (United States)

    Pierantozzi, Ronald

    1985-01-01

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

  1. Steam Reforming of Ethylene Glycol over MgAl₂O₄ Supported Rh, Ni, and Co Catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Mei, Donghai; Lebarbier, Vanessa M.; Xing, Rong; Albrecht, Karl O.; Dagle, Robert A.

    2015-11-25

    Steam reforming of ethylene glycol (EG) over MgAl₂O₄ supported metal (15 wt.% Ni, 5 wt.% Rh, and 15 wt.% Co) catalysts were investigated using combined experimental and theoretical methods. Compared to highly active Rh and Ni catalysts with 100% conversion, the steam reforming activity of EG over the Co catalyst is comparatively lower with only 42% conversion under the same reaction conditions (500°C, 1 atm, 119,000 h⁻¹, S/C=3.3 mol). However, CH₄ selectivity over the Co catalyst is remarkably lower. For example, by varying the gas hour space velocity (GHSV) such that complete conversion is achieved for all the catalysts, CH₄ selectivity for the Co catalyst is only 8%, which is much lower than the equilibrium CH₄ selectivity of ~ 24% obtained for both the Rh and Ni catalysts. Further studies show that varying H₂O concentration over the Co catalyst has a negligible effect on activity, thus indicating zero-order dependence on H₂O. These experimental results suggest that the supported Co catalyst is a promising EG steam reforming catalyst for high hydrogen production. To gain mechanistic insight for rationalizing the lower CH₃ selectivity observed for the Co catalyst, the initial decomposition reaction steps of ethylene glycol via C-O, O-H, C-H, and C-C bond scissions on the Rh(111), Ni(111) and Co(0001) surfaces were investigated using density functional theory (DFT) calculations. Despite the fact that the bond scission sequence in the EG decomposition on the three metal surfaces varies, which leads to different reaction intermediates, the lower CH₄ selectivity over the Co catalyst, as compared to the Rh and Ni catalysts, is primarily due to the higher barrier for CH₄ formation. The higher S/C ratio enhances the Co catalyst stability, which can be elucidated by the facile water dissociation and an alternative reaction path to remove the CH species as a coking precursor via the HCOH formation. This work was financially supported by the United

  2. Characterization of Al2O3 Supported Nickel Catalysts Derived from RFNon-thermal Plasma Technology

    International Nuclear Information System (INIS)

    Catalysts derived from non-thermal plasma techniques have previously shown unusual and highly advantageous catalytic properties including room temperature reduction, unusual metal particle structure and metal-support interactions, and enhanced selectivity and stability. This study focuses on the characterization of Al2O3 supported Ni catalysts derived from the RF non-thermal plasma technique with in-situ XRD, TPR-MS and STEM and on relating the results to the enhanced activity and stability of benzene hydrogenation. The results suggest that catalysts with plasma treatments before impregnation are relatively easier to be reduced and result in better activities under mild reduction conditions. These plasma treatments stabilize the nickel particle sizes of air(B) and H2(B) catalysts at 600 C by slowing down the sintering process. Plasma treatments after the impregnation of precursors, on the other hand, tend to delay the growth of nickel particles below 600 C, forming smaller Ni particles, but with a sudden increase in particle size near 600 C. It suggests that the structure of Ni nitrate and the metal-support interaction have been altered by the plasma treatments. The reduction patterns of plasma 1 treated catalysts are, therefore, changed. The catalyst with a combination plasma treatment demonstrates that the effect of a combination plasma treatment is larger than either the plasma treatment before or after the impregnation alone. Both plasma treatments before and after the impregnation of metal precursor play important roles in modifying supported metal catalysts.

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

    OpenAIRE

    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), as well as with ammonia adsorption microcalorimetry. Good results are obtained with initial glycerol conversions of over 70% and with 50-70% selectivity to acrolein. We investigate the influence of...

  4. New Construction and Catalyst Support Materials for Water Electrolysis at Elevated Temperatures

    DEFF Research Database (Denmark)

    Nikiforov, Aleksey

    in question are those for bipolar plates, gas diusion layers (GDLs), catalysts and catalyst supports. This work is focused on developing bipolar plate, GDL and catalyst support materials for the anode compartment of PEM electrolyzers, operating at elevated temperatures. The thesis starts with Chapter...... electrolysis. Chapter 4 reports results of testing dierent types of commercially available stainless steels, Ni-based alloys as well as titanium and tantalum as possible metallic bipolar plates and construction materials for HTPEMEC. The corrosion resistance was measured under simulated conditions of high...

  5. Nano carbon supported platinum catalyst interaction behavior with perfluorosulfonic acid ionomer and their interface structures

    DEFF Research Database (Denmark)

    Andersen, Shuang Ma

    2016-01-01

    behavior of Nafion ionomer on platinized carbon nano fibers (CNFs), carbon nano tubes (CNTs) and amorphous carbon (Vulcan). The interaction is affected by the catalyst surface oxygen groups as well as porosity. Comparisons between the carbon supports and platinized equivalents are carried out. It reveals......, the ionomer may have an adsorption preference to the platinum nano particle rather than to the overall catalyst. This was verified by a close examination on the decomposition temperature of the carbon support and the ionomer. The electrochemical stability of the catalyst ionomer composite electrode suggests...

  6. 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.

  7. Vanadia-based SCR Catalysts Supported on Tungstated and Sulfated Zirconia: Influence of Doping with Potassium

    DEFF Research Database (Denmark)

    Due-Hansen, Johannes; Boghosian, Soghomon; Kustov, Arkadii;

    2007-01-01

    A series of vanadium-based SCR catalysts supported on sulfated or tungstated ZrO2 were synthesized and characterized by means of N2-BET, XRD, NH3-TPD and in situ Raman spectroscopy. The effect of potassium doping on the properties of vanadia species is studied in detail. A number of catalyst...... preparation parameters were examined, including the choice of precipitant, variation of carrier surface area, potassium poisoning, crystallinity, and ZrO2-phase composition. The results show that the catalysts structure and SCR activity is affected from the synthesis route by means of support crystallinity...

  8. The role of support and promoter on the oxidation of sulfur dioxide using platinum based catalysts

    DEFF Research Database (Denmark)

    Koutsopoulos, Sotiris; Rasmussen, Søren Birk; Eriksen, Kim Michael;

    2006-01-01

    The catalytic oxidation of SO2 to SO3 was studied over platinum based catalysts in the absence and the presence of dopants. The active metal was supported on silica gel or titania (anatase) by impregnation. The activities of the silica supported catalysts were found to follow the order PtRh/SiO2 ......H of the impregnation solution and of the reduction temperature of the precursor salts resulted in a very active catalyst with average particle size of 1.7 nm. (c) 2006 Elsevier B.V. All rights reserved....

  9. Life Support Catalyst Regeneration Using Ionic Liquids and In Situ Resources

    Science.gov (United States)

    Abney, Morgan B.; Karr, Laurel; Paley, Mark S.; Donovan, David N.

    2016-01-01

    Oxygen recovery from metabolic carbon dioxide is an enabling capability for long-duration manned space flight. Complete recovery of oxygen (100%) involves the production of solid carbon. Catalytic approaches for this purpose, such as Bosch technology, have been limited in trade analyses due in part to the mass penalty for high catalyst resupply caused by carbon fouling of the iron or nickel catalyst. In an effort to mitigate this challenge, several technology approaches have been proposed. These approaches have included methods to prolong the life of the catalysts by increasing the total carbon mass loading per mass catalyst, methods for simplified catalyst introduction and removal to limit the resupply container mass, methods of using in situ resources, and methods to regenerate catalyst material. Research and development into these methods is ongoing, but only use of in situ resources and/or complete regeneration of catalyst material has the potential to entirely eliminate the need for resupply. The use of ionic liquids provides an opportunity to combine these methods in a technology approach designed to eliminate the need for resupply of oxygen recovery catalyst. Here we describe the results of an initial feasibility study using ionic liquids and in situ resources for life support catalyst regeneration, we discuss the key challenges with the approach, and we propose future efforts to advance the technology.

  10. Dehydration of Glycerin to Acrolein Over Heteropolyacid Nano-Catalysts Supported on Silica-Alumina.

    Science.gov (United States)

    Kang, Tae Hun; Choi, Jung Ho; Choi, Jun Seon; Song, In Kyu

    2015-10-01

    A series of H3PW12O40 nano-catalysts supported on silica-alumina (XH3PW12O40/SA (X = 10, 15, 20, 25, and 30)) with different H3PW12O40 content (X, wt%) were prepared, and they were applied to the dehydration of glycerin to acrolein. The effect of H3PW12O40 content on the physicochemical properties and catalytic activities of XH3PW12O40/SA nano-catalysts was investigated. Surface area and pore volume of XH3PW12O40/SA catalysts decreased with increasing H3PW12O40 content. Formation of H3PW12O40 aggregates was observed in the catalysts with high H3PW12O40 loading. Brønsted acidity of the catalysts showed a volcano-shaped trend with respect to H3PW12O40 content. It was revealed that yield for acrolein increased with increasing Brønsted acidity of XH3PW12O40/SA catalysts. Brønsted acidity of XH3PW12O40/SA catalysts served as a crucial factor determining the catalytic performance in the dehydration of glycerin. Among the catalysts tested, 25H3PW12O40/SA catalyst with the largest Brønsted acidity showed the best catalytic performance. PMID:26726511

  11. Carbon-supported iron and iron-molybdenum sulfide catalysts

    International Nuclear Information System (INIS)

    The main objective was to describe the relations between the characteristics (composition and dispersion) of the actual sulfide phase and the catalytic activity. Attention was also paid to the influence of preparational aspects on these characteristics. The catalysts were characterized using in-situ Moessbauer spectroscopy down to 2.0 K. 254 refs.; 47 figs.; 22 tabs

  12. Mesoporous molecular sieves as supports for metathesis catalysts

    Czech Academy of Sciences Publication Activity Database

    Balcar, Hynek; Čejka, Jiří

    Dordrecht : Springer, 2007, s. 151-166. ISBN 978-1-4020-6090-8 R&D Projects: GA AV ČR IAA4040411; GA ČR GA203/05/2194 Institutional research plan: CEZ:AV0Z40400503 Keywords : mesoporous molecular sieves * heterogeneous catalysts * olefin metathesis * metathesis polymerization Subject RIV: CF - Physical ; Theoretical Chemistry

  13. Ethanol oxidation on carbon supported platinum-rhodium bimetallic catalysts

    International Nuclear Information System (INIS)

    Platinum is the most investigated catalyst for the electrochemical oxidation of small organic molecules. This metal presents high overpotentials for the oxidation of organic compounds and the poisoning of active sites by strongly adsorbed intermediates, mainly CO, which decrease the efficiency of a direct alcohol fuel cell (DAFC). Ethanol is an ideal fuel for these DAFC systems due to its high energy density, but one of the problems with the electro-oxidation of this fuel is the low yield for the total oxidation to CO2. The purpose of the work reported here was to study the influence of the composition of Pt-Rh/C catalysts on the CO2 yields. In addition, using the differential electrochemical mass spectrometry (DEMS) technique, it is shown that Pt-Rh/C catalysts enhance the total ethanol oxidation with respect to pure Pt/C by driving the reaction via the CO2 route. The faradaic current efficiency for the oxidation of ethanol to CO2 increased from 0.08 on pure Pt/C to 0.5 on the Pt47Rh53/C catalyst at 0.7 V vs. RHE. It was concluded that electronic effects play a key role in the mechanism of ethanol oxidation on Pt-Rh/C electrodes

  14. Ni catalysts with different promoters supported on zeolite for dry reforming of methane

    KAUST Repository

    Alotaibi, Raja

    2015-07-08

    Dry reforming of methane (DRM) is considered a high endothermic reaction with operating temperatures between 700 and 1000 °C to achieve high equilibrium conversion of CH4 and CO2 to the syngas (H2 and CO). The conventional catalysts used for DRM are Ni-based catalysts. However, many of these catalysts suffer from the short longevity due to carbon deposition. This study aims to evaluate the effect of La and Ca as promoters for Ni-based catalysts supported on two different zeolite supports, ZL (A) (BET surface area = 925 m2/g, SiO2/Al2O3 mol ratio = 5.1), and ZL (B) (BET surface area = 730 m2/g, SiO2/Al2O3 mol ratio = 12), for DRM. The physicochemical properties of the prepared catalysts were characterized with XRD, BET, TEM and TGA. These catalysts were tested for DRM in a microtubular reactor at reaction conditions of 700 °C. The catalyst activity results show that the catalysts Ni/ZL (B) and Ca-Ni/ZL (B) give the highest methane conversion (60 %) with less time on stream stability compared with promoted Ni on ZL (A). In contrast, La-containing catalysts, La-Ni/ZL (B), show more time on stream stability with minimum carbon content for the spent catalyst indicating the enhancement of the promoters to the Ni/ZL (A) and (B), but with less catalytic activity performance in terms of methane and carbon dioxide conversions due to rapid catalyst deactivation.

  15. LDRD final report on new homogeneous and supported oligomerization catalysts (LDRD 42461).

    Energy Technology Data Exchange (ETDEWEB)

    Hascall, Anthony G.; Kemp, Richard Alan

    2004-11-01

    The overall purpose of this LDRD is multifold. First, we are interested in preparing new homogeneous catalysts that can be used in the oligomerization of ethylene and in understanding commercially important systems better. Second, we are interested in attempting to support these new homogeneous catalysts in the pores of nano- or mesoporous materials in order to force new and unusual distributions of a-olefins to be formed during the oligomerization. Thus the overall purpose is to try to prepare new catalytic species and to possibly control the active site architecture in order to yield certain desired products during a catalytic reaction, much like nature does with enzymes. In order to rationally synthesize catalysts it is imperative to comprehend the function of the various components of the catalyst. In heterogeneous systems, it is of utmost importance to know how a support interacts with the active site of the catalyst. In fact, in the catalysis world this lack of fundamental understanding of the relationship between active site and support is the single largest reason catalysis is considered an 'empirical' or 'black box' science rather than a well-understood one. In this work we will be preparing novel ethylene oligomerization catalysts, which are normally P-O chelated homogeneous complexes, with new ligands that replace P with a stable carbene. We will also examine a commercially catalyst system and investigate the active site in it via X-ray crystallography. We will also attempt to support these materials inside the pores of nano- and mesoporous materials. Essentially, we will be tailoring the size and scale of the catalyst active site and its surrounding environment to match the size of the molecular product(s) we wish to make. The overall purpose of the study will be to prepare new homogeneous catalysts, and if successful in supporting them to examine the effects that steric constraints and pore structures can have on growing oligomer

  16. Dehydrogenation of light alkanes over rhenium catalysts on conventional and mesoporous MFI supports

    DEFF Research Database (Denmark)

    Rovik, Anne Krogh; Hagen, Anke; Schmidt, I.;

    2006-01-01

    Recently, Re/HZSM-5 (Si/Al = 15) was shown to be an efficient catalyst for ethane dehydrogenation and aromatization at 823 K and atmospheric pressure. In this reaction, the major initial products were benzene, toluene and xylene (BTX), but increasing amounts of ethene were produced with time on...... stream due to deactivation of the catalyst. We show that by use of rhenium impregnated MFI supports with very few or no acidic sites (Si/Al > 500), highly selective ethane dehydrogenation catalysts are obtained with ethene selectivities of 98%. By use of mesoporous MFI supports (Si/Al > 500) the lifetime...... of the catalyst appears to be slightly improved compared to conventional MFI crystals. The beneficial effect of a mesoporous MFI support is convincingly demonstrated in propane dehydrogenation, where both conversion and selectivities on the mesoporous MFI (Si/Al > 500) impregnated with Re are...

  17. Environmental friendly lubricants through selective hydrogenation of rapeseed oil over supported copper catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Ravasio, Nicoletta; Zaccheria, Federica; Fusi, Achille; Poli, Nicola; Psaro, Rinaldo [Centro CNR CSSCMTBSO e Dip. Chimica Inorganica Metallorganica e Analitica, Universita degli Studi di Milano, Via Venezian 21, 20133 Milan (Italy); Gargano, Michele [Dipartimento di Chimica, Universita di Bari, Via Orabona 4, 70126 Bari (Italy); Recchia, Sandro [Dipartimento Scienze CCFFMM, Universita dell' Insubria, Via Lucini 3, 22100 Como (Italy)

    2002-07-10

    Different supported copper catalysts are compared in the selective hydrogenation of vegetable oils and their methylesters. The influence of parameters such as the catalysts preparation method, the support used and the activation treatment are critically evaluated in terms of catalytic activity and selectivity. All ex situ reduced catalysts prepared by the chemisorption-hydrolysis (CH) method show better performances than the ones prepared by incipient wetness technique. These data are directly matched up to the different morphology of the supported copper particles obtained with these two methods. By using a 8% Cu/SiO{sub 2} catalyst the trienic component C18:3 can be eliminated and the dienic one lowered from 22 to 3-5% without increasing the stearic C18:0 content and limiting the cis/trans-isomerisation process. These oils, with a C18:1 content up to 88% show remarkable oxidation stability and keep fluid down to -15C.

  18. Synthesis of Gold Catalysts Supported on Mesoporous Silica Materials: Recent Developments

    Directory of Open Access Journals (Sweden)

    Khaled Belkacemi

    2011-12-01

    Full Text Available Mesoporous silica materials (MSM with ordered and controllable porous structure, high surface area, pore volume and thermal stability are very suitable catalyst supports, because they provide high dispersion of metal nanoparticles and facilitate the access of the substrates to the active sites. Since the conventional wet-impregnation and deposition-precipitation methods are not appropriate for the incorporation of gold nanoparticles (AuNPs into MSM, considerable efforts have been made to develop suitable methods to synthesize Au/MSM catalysts, because the incorporation of AuNPs into the channel system can prevent their agglomeration and leaching. In this review, we summarize the main methods to synthesize active gold catalysts supported on MSM. Examples and details of the preparative methods, as well as selected applications are provided. We expect this article to be interesting to researchers due to the wide variety of chemical reactions that can be catalyzed by gold supported catalysts.

  19. High-performance PdRu bimetallic catalyst supported on mesoporous silica nanoparticles for phenol hydrogenation

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Chao [The Key Laboratory of Fuel Cell Technology of Guangdong Province and The Key Laboratory for New Energy of Guangdong Universities, School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou (China); Yang, Xu [Key Laboratory of Renewable Energy, Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences, Guangzhou (China); Yang, Hui; Huang, Peiyan; Song, Huiyu [The Key Laboratory of Fuel Cell Technology of Guangdong Province and The Key Laboratory for New Energy of Guangdong Universities, School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou (China); Liao, Shijun, E-mail: chsjliao@scut.edu.cn [The Key Laboratory of Fuel Cell Technology of Guangdong Province and The Key Laboratory for New Energy of Guangdong Universities, School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou (China)

    2014-10-01

    Graphical abstract: The addition of Ru could significantly improve the performance of the mesoporous silica nanoparticles supported PdRu/MSN catalyst, which showed over 5 times higher mass activity than the mono-Pd/MSN towards the liquid-phase hydrogenation of phenol. The improved dispersion and the electronic interaction contributed to the enhanced catalytic activity for the catalyst towards phenol hydrogenation. - Highlights: • PdRu bimetal catalyst supported on mesoporous silica nanoparticles was prepared. • The average sizeof PdRu alloy is smaller than that of mono-Pd. • The addition of Ru to Pd modulates the electronic properties between Pd and Ru. • PdRu/MSN catalyst shows superior activity on phenol hydrogenation than Pd/MSN. • PdRu/MSN catalyst shows good selectivity for cyclohexanol to some extent. - Abstract: A high-performance PdRu bimetallic catalyst supported on mesoporous silica nanoparticles (MSN), PdRu/MSN, was prepared by a facile impregnation–hydrogen reduction method. It was found that PdRu/MSN showed 5 times higher activity than that of Pd/MSN towards the liquid-phase hydrogenation of phenol. The catalysts were characterized comprehensively by multiple techniques, X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and hydrogen temperature program reduction (TPR). It was revealed that adding Ru could effectively improve the Pd dispersion and promote the electronic interaction between the Pd and Ru, both of which contribute to enhancing the catalytic activity.

  20. High-performance PdRu bimetallic catalyst supported on mesoporous silica nanoparticles for phenol hydrogenation

    International Nuclear Information System (INIS)

    Graphical abstract: The addition of Ru could significantly improve the performance of the mesoporous silica nanoparticles supported PdRu/MSN catalyst, which showed over 5 times higher mass activity than the mono-Pd/MSN towards the liquid-phase hydrogenation of phenol. The improved dispersion and the electronic interaction contributed to the enhanced catalytic activity for the catalyst towards phenol hydrogenation. - Highlights: • PdRu bimetal catalyst supported on mesoporous silica nanoparticles was prepared. • The average sizeof PdRu alloy is smaller than that of mono-Pd. • The addition of Ru to Pd modulates the electronic properties between Pd and Ru. • PdRu/MSN catalyst shows superior activity on phenol hydrogenation than Pd/MSN. • PdRu/MSN catalyst shows good selectivity for cyclohexanol to some extent. - Abstract: A high-performance PdRu bimetallic catalyst supported on mesoporous silica nanoparticles (MSN), PdRu/MSN, was prepared by a facile impregnation–hydrogen reduction method. It was found that PdRu/MSN showed 5 times higher activity than that of Pd/MSN towards the liquid-phase hydrogenation of phenol. The catalysts were characterized comprehensively by multiple techniques, X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and hydrogen temperature program reduction (TPR). It was revealed that adding Ru could effectively improve the Pd dispersion and promote the electronic interaction between the Pd and Ru, both of which contribute to enhancing the catalytic activity

  1. Nanoparticle-supported and magnetically recoverable palladium (Pd) catalyst: a selective and sustainable oxidation protocol with high turnover number

    Science.gov (United States)

    A magnetic nanoparticle-supported ruthenium hydroxide catalyst was readily prepared from inexpensive starting materials and shown to catalyze hydration of nitriles with excellent yield in benign aqueous medium. Catalyst recovery using an external magnetic field, superior activity...

  2. Polyethylene Glycol as Support and Phase Transfer Catalyst in Aqueous Palladium-catalyzed Liquid-phase Synthesis

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Excellent yields and purity were obtained in the aqueous medium Suzuki, Sonogashira, Stille and Heck reactions using palladium (Ⅱ) as catalyst in liquid phase synthesis. Polyethylene glycol (PEG) acted as soluble polymeric support and phase transfer catalyst as well.

  3. MCM-41-supported cobalt-molybdenum catalysts for deep hydrodesulfurization of diesel and jet fuel feedstocks

    Science.gov (United States)

    Turaga, Uday Tsrpr

    Regulatory issues require new catalysts for the deep hydrodesulfurization (HDS) of refractory polyaromatic sulfur compounds such as 4,6-dimethyldibenzothiophene (4,6-DMDBT) present in diesel and jet fuel. Molybdenum sulfide (MoS2 ) supported on mesoporous molecular sieve MCM-41 and promoted by cobalt was hypothesized to have superior activity for deep HDS because of MCM-41's (1) high surface area and uniform mesopores and (2) superior acidity as compared to conventional supports such as gamma-alumina (gamma-Al 2O3). This study examines the role of MCM-41 as a support for new cobalt (Co)-molybdenum (Mo) HDS catalysts. At CoO-MoO3 loadings typical of commercially available HDS catalysts, MCM-41-supported catalysts were only slightly better. At higher loadings---27.0% (by weight) MoO3 and 5.8% CoO---MCM-41-supported catalysts were twice more active than the commercial catalyst. This difference in activities is related to the degree of MoS2 stacking. Remarkable increase in the conversion of 4,6-DMDBT was observed over MCM-41-supported catalysts with decreasing SiO2/Al2O 3 ratio. More significantly, the SiO2/Al2O 3 ratio of MCM-41 has a profound effect on product distribution and catalyst selectivity. Irrespective of CoO-MoO3 loading, catalysts using MCM-41 with a SiO2/Al2O3 ratio of 50 convert more of 4,6-DMDBT through the highly desirable hydrogenolysis pathway. The acidity of these catalysts was measured and correlated to their selectivities for hydrogenolysis and hydrocracking. Co-Mo/MCM-41 continued to demonstrate activities twice that of the commercial catalyst for the HDS of 4,6-DMDBT in petroleum-derived feedstocks such as light cycle oil. However, for a blend of coal- and petroleum-derived feedstocks, nitrogen from the coal-derived liquid inhibited both catalysts for the HDS of 4,6-DMDBT. Basic nitrogen, e.g., quinoline, significantly retards the HDS of 4,6-DMDBT over both catalysts. Non-basic carbazole, on the other hand, inhibited the MCM-41-supported

  4. Hydrogenation of Levulinic Acid over Nickel Catalysts Supported on Aluminum Oxide to Prepare γ-Valerolactone

    Directory of Open Access Journals (Sweden)

    Jie Fu

    2015-12-01

    Full Text Available Four types of nickel catalysts supported on aluminum oxide (Ni/Al2O3 with different nickel loadings were synthesized using the co-precipitation method and were used for the hydrogenation of levulinic acid (LA to prepare γ-valerolactone (GVL. The synthesized Ni/Al2O3 catalysts exhibited excellent catalytic activity in dioxane, and the activity of the catalysts was excellent even after being used four times in dioxane. The catalytic activity in dioxane as a solvent was found to be superior to the activity in water. Nitrogen physisorption, X-ray diffraction, and transmission electron microscopy were employed to characterize the fresh and used catalysts. The effects of the nickel loading, temperature, hydrogen pressure, and substrate/catalyst ratio on the catalytic activity were investigated.

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

    Energy Technology Data Exchange (ETDEWEB)

    Davis, Mark E.

    2009-03-13

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

  6. Possibilities of platinum recovery from metal supported spent auto catalysts

    OpenAIRE

    A. Fornalczyk; Cebulski, J.; M. Saternus; Willner, J

    2014-01-01

    The used auto catalytic converter is a valuable source of platinum group metals, so it is important to have it recycled in order to recover precious metals. World literature describes a number of pyro- or hydrometallurgical methods used for recovery of platinum from used automobile catalytic converters. However, all the methods, available in the literature, are used to recover platinum from ceramic carrier. Among automotive catalysts withdrawn from use, these with metallic carrier constitute ...

  7. High CO methanation activity on zirconia-supported molybdenum sulfide catalyst

    Institute of Scientific and Technical Information of China (English)

    Zhenhua Li; Ye Tian; Jia He; Baowei Wang; Xinbin Ma

    2014-01-01

    In this study, different methods were used to prepare MoO3/ZrO2 catalysts for sulfur resistant methanation reaction. It was found that MoO3/ZrO2 catalyst prepared by one-step co-precipitation method achieved high methanation performance. CO conversion could reach up to 90%on 25 wt%MoO3/ZrO2 catalyst, much higher than that on the conventional 25 wt%MoO3/Al2O3 catalyst. The Mo-based catalysts were characterized by XRF, XRD, Raman, BET, TEM and H2-TPR etc. It was found that MoO3 particles were highly dispersed on ZrO2 support for 25 wt%MoO3/ZrO2 catalyst prepared at 65-85◦C because of its relatively larger pore size, which contributed to a high CO conversion. Meanwhile, when MoO3 loading exceeded the monolayer coverage, the formed crystalline MoO3 and ZrMo2 O8 might block the micropores of the catalyst and make the methanation activity declined. These results are useful for preparing highly efficient catalyst for CO methanation process.

  8. thesis of high-purity carbon nanotubes over alumina and silica supported bimetallic catalysts

    Directory of Open Access Journals (Sweden)

    Sanja Ratković

    2009-10-01

    Full Text Available Carbon nanotubes (CNTs were synthesized by a catalytic chemical vapor deposition method (CCVD of ethylene over alumina and silica supported bimetallic catalysts based on Fe, Co and Ni. The catalysts were prepared by a precipitation method, calcined at 600 °C and in situ reduced in hydrogen flow at 700 °C. The CNTs growth was carried out by a flow the mixture of C2H4 and nitrogen over the catalyst powder in a horizontal oven. The structure and morphology of as-synthesized CNTs were characterized using SEM. The as-synthesized nanotubes were purified by acid and basic treatments in order to remove impurities such as amorphous carbon, graphite nanoparticles and metal catalysts. XRD and DTA/TG analyses showed that the amounts of by-products in the purified CNTs samples were reduced significantly. According to the observed results, ethylene is an active carbon source for growing high-density CNTs with high yield but more on alumina-supported catalysts than on their silica- supported counterparts. The last might be explained by SMSI formed in the case of alumina-supported catalysts, resulting in higher active phase dispersion.

  9. Study of Supported Nickel Catalysts Prepared by Aqueous Hydrazine Method. Hydrogenating Properties and Hydrogen Storage: Support Effect. Silver Additive Effect

    International Nuclear Information System (INIS)

    We have studied Ni or NiAg nano-particles obtained by the reduction of nickel salts (acetate or nitrate) by hydrazine and deposited by simple or EDTA-double impregnation on various supports (γ-Al2O3, amorphous or crystallized SiO2, Nb2O5, CeO2 and carbon). Prepared catalysts were characterized by different methods (XRD, XPS, low temperature adsorption and desorption of N2, FTIR and FTIR-Pyridine, TEM, STEM, EDS, H2-TPR, H2-adsorption, H2-TPD, isopropanol decomposition) and tested in the gas phase hydrogenation of benzene or as carbon materials in the hydrogen storage at room temperature and high pressure. The catalysts prepared exhibited better dispersion and activity than classical catalysts. TOF's of NiAg/SiO2 or Ni/carbon catalysts were similar to Pt catalysts in benzene hydrogenation. Differences in support acidity or preparation method and presence of Ag as metal additive play a crucial role in the chemical reduction of Ni by hydrazine and in the final properties of the materials. Ni/carbon catalysts could store significant amounts of hydrogen at room temperature and high pressure (0.53%/30 bars), probably through the hydrogen spillover effect. (author)

  10. Effect of support on the activity of MoVCeZr catalyst for propane ammoxidation reaction

    International Nuclear Information System (INIS)

    Mixed metal oxide catalysts based on Mo-V have been known as the most active and selective in the ammoxidation of propane to ACN. A series of MoVCeZr (5 % wt/ wt) supported with MOR, TiO2 and MgO have been prepared by incipient wetness impregnation method for propane ammoxidation reaction to ACN. The catalyst was calcined in a two step calcination process in static air between 350 - 600 degree Celsius for 10 hour. The surface area and pore size of these catalysts were measured using physical adsorption of nitrogen following Brunauer, Emmet and Teller (BET) equation. The textural and morphological of these catalysts were determined using Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD). The activities of all catalysts were tested using a fixed-bed reactor with online gas chromatography (GC) at 420 degree Celsius and atmospheric pressure in the presence of 0.5 ml catalyst with composition consisting of 5.8:7:17.4 (propane: ammonia: air) and helium as carrier to give a total flow of 120 ml. Result shows that MoVCeZr support gives a better conversion due to the surface area and pore size characteristic of the catalyst. (author)

  11. Enhanced Activity of Supported Ni Catalysts Promoted by Pt for Rapid Reduction of Aromatic Nitro Compounds

    Directory of Open Access Journals (Sweden)

    Huishan Shang

    2016-06-01

    Full Text Available To improve the activities of non-noble metal catalysts is highly desirable and valuable to the reduced use of noble metal resources. In this work, the supported nickel (Ni and nickel-platinum (NiPt nanocatalysts were derived from a layered double hydroxide/carbon composite precursor. The catalysts were characterized and the role of Pt was analysed using X-ray diffraction (XRD, high-resolution transmission electron microscopy (HRTEM, energy dispersive X-ray spectroscopy (EDS mapping, and X-ray photoelectron spectroscopy (XPS techniques. The Ni2+ was reduced to metallic Ni0 via a self-reduction way utilizing the carbon as a reducing agent. The average sizes of the Ni particles in the NiPt catalysts were smaller than that in the supported Ni catalyst. The electronic structure of Ni was affected by the incorporation of Pt. The optimal NiPt catalysts exhibited remarkably improved activity toward the reduction of nitrophenol, which has an apparent rate constant (Ka of 18.82 × 10−3 s−1, 6.2 times larger than that of Ni catalyst and also larger than most of the reported values of noble-metal and bimetallic catalysts. The enhanced activity could be ascribed to the modification to the electronic structure of Ni by Pt and the effect of exposed crystal planes.

  12. Influence of support material on Ni catalysts for propane dry reforming to synthesis gas

    OpenAIRE

    2008-01-01

    Ni/SiO2 and Ni/Mg(Al)O catalysts with difference metal loadings have been prepared. The activity, selectivity and stability of supported Ni catalysts for propane dry reforming to syngas reaction were investigated by catalytic testing at 600 ºC, C3H8:CO2:H2:N2 (in vol.%) = 10:30:10:50. Ni particle size was investigated by Transmission electron microscopy (TEM). Turn-over frequencies for Ni/SiO2 catalysts were calculated as a guideline to the relationship between catalytic activity and Ni parti...

  13. Catalytic Hydrodeoxygenation of Bio-oils with Supported MoP-Catalysts

    OpenAIRE

    Asphaug, Sindre

    2013-01-01

    The goal of this thesis was to test the MoP catalysts which were made during autumn 2012, in a HDO reaction of phenol to benzene at a HDO rig. The catalysts were supported by Al2O3, SiO2, TiO2 and ZrO2, and they were prepared by impregnation, followed by calcination, reduction and passivation. New samples of the 2 catalysts which showed the highest activity, MoP/Al2O3 and MoP/TiO2, were prepared. They were characterized with N2-adsorption, chemisorption, TPR and XRD, and they were further tes...

  14. Role of vanadium in Keggin heteropoly molybdate supported on titania catalysts for oxidation reactions

    Indian Academy of Sciences (India)

    A Srivani; K T Venkateswara Rao; P S Sai Prasad; N Lingaiah

    2014-03-01

    Vanadium-incorporated molybdophosporic acid catalysts supported on titania were prepared and characterized by FT-IR, X-ray diffraction and laser Raman spectroscopy. Characterization data reveals the incorporation of vanadium into the primary structure of Keggin ion of MPA. Catalysts activities were evaluated for oxidation of 1,2-benzenedimethanol using H2O2 and O2 as oxidants. Vanadium-containing catalysts showed high activity compared to their parent heteropoly acids. Oxidation ability depended on the number of V atoms present in Keggin heteropoly molybdate. Effect of reaction parameters on the oxidation ability was also evaluated.

  15. Hydrogenation of Levulinic Acid over Nickel Catalysts Supported on Aluminum Oxide to Prepare γ-Valerolactone

    OpenAIRE

    Jie Fu; Dong Sheng; Xiuyang Lu

    2015-01-01

    Four types of nickel catalysts supported on aluminum oxide (Ni/Al2O3) with different nickel loadings were synthesized using the co-precipitation method and were used for the hydrogenation of levulinic acid (LA) to prepare γ-valerolactone (GVL). The synthesized Ni/Al2O3 catalysts exhibited excellent catalytic activity in dioxane, and the activity of the catalysts was excellent even after being used four times in dioxane. The catalytic activity in dioxane as a solvent was found to be superior t...

  16. Highly selective oxidative dehydrogenation of ethane with supported molten chloride catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Gaertner, C.A.; Veen, A.C. van; Lercher, J.A. [Technische Univ. Muenchen (Germany). Catalysis Research Center

    2011-07-01

    Ethene production is one of the most important transformations in chemical industry, given that C{sub 2}H{sub 4} serves as building block for many mass-market products. Besides conventional thermal processes like steam cracking of ethane, ethane can be produced selectively by catalytic processes. One of the classes of catalysts that have been reported in literature as active and highly selective for the oxidative dehydrogenation of ethane is that of supported molten chloride catalysts, containing an alkali chloride overlayer on a solid support. This work deals with fundamental aspects of the catalytic action in latter class of catalysts. Results from kinetic reaction studies are related to observations in detailed characterization and lead to a comprehensive mechanistic understanding. Of fundamental importance towards mechanistic insights is the oxygen storage capacity of the catalysts that has been determined by transient step experiments. (orig.)

  17. Selective liquid phase oxidation of glycerol to glyceric acid over novel supported Pt catalysts

    Directory of Open Access Journals (Sweden)

    Sproge Elina

    2013-01-01

    Full Text Available Several supported platinum catalysts were prepared by extractive-pyrolytic method for the selective glyceric acid production from glycerol. Al2O3, Y2O3, Lu2O3, ZrO2-Y2O3 TiO2, SG, Fe2O3, γ-AlO(OH and C were used as catalyst supports, glycerol oxidation was carried out in the alkaline solutions and oxygen was used as oxidant. The optimal catalyst preparation parameters and glycerol oxidation conditions to obtain glyceric acid were determined. The best result (selectivity to glyceric acid 57% with glycerol conversion 92% was achieved in the presence of 4.8%Pt/Al2O3 catalyst.

  18. Comparative Investigation of Benzene Steam Reforming over Spinel Supported Rh and Ir Catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Mei, Donghai; Lebarbier, Vanessa MC; Rousseau, Roger J.; Glezakou, Vassiliki Alexandra; Albrecht, Karl O.; Kovarik, Libor; Flake, Matthew D.; Dagle, Robert A.

    2013-06-01

    In a combined experimental and first-principles density functional theory (DFT) study, benzene steam reforming (BSR) over MgAl2O4 supported Rh and Ir catalysts was investigated. Experimentally, it has been found that both highly dispersed Rh and Ir clusters (1-2 nm) on the MgAl2O4 spinel support are stable during the BSR in the temperature range of 700-850˚C. Compared to the Ir/MgAl2O4 catalyst, the Rh/MgAl2O4 catalyst is more active with higher benzene turnover frequency and conversion. At typical steam conditions with the steam-to-carbon ratio > 12, the benzene conversion is only a weak function of the H2O concentration in the feed. This suggests that the initial benzene decomposition step rather than the benzene adsorption is most likely the rate-determined step in BSR over supported Rh and Ir catalysts. In order to understand the differences between the two catalysts, we followed with a comparative DFT study of initial benzene decomposition pathways over two representative model systems for each supported metal (Rh and Ir) catalysts. A periodic terrace (111) surface and an amorphous 50-atom metal cluster with a diameter of 1.0 nm were used to represent the two supported model catalysts under low and high dispersion conditions. Our DFT results show that the decreasing catalyst particle size enhances the benzene decomposition on supported Rh catalysts by lowering both C-C and C-H bond scission. The activation barriers of the C-C and the C-H bond scission decrease from 1.60 and 1.61 eV on the Rh(111) surface to 1.34 and 1.26 eV on the Rh50 cluster. For supported Ir catalysts, the decreasing particle size only affects the C-C scission. The activation barrier of the C-C scission of benzene decreases from 1.60 eV on the Ir(111) surface to 1.35 eV on the Ir50 cluster while the barriers of the C-H scission are practically the same. The experimentally measured higher BSR activity on the supported highly dispersed Rh catalyst can be rationalized by the thermodynamic

  19. Study on the Reaction Mechanism for Carbon Dioxide Reforming of Methane over supported Nickel Catalyst

    Institute of Scientific and Technical Information of China (English)

    Ling QIAN; Zi Feng YAN

    2003-01-01

    The adsorption and dissociation of methane and carbon dioxide for reforming on nickelcatalyst were extensively investigated by TPSR and TPD experiments. It showed that thedecomposition of methane results in the formation of at least three kinds of surface carbon specieson supported nickel catalyst, while CO2 adsorbed on the catalyst weakly and only existed in onekind of adsorption state. Then the mechanism of interaction between the species dissociatedfrom CH4 and CO2 during reforming was proposed.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-11-15

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

  1. Iron oxide/cassava starch-supported Ziegler-Natta catalysts for in situ ethylene polymerization.

    Science.gov (United States)

    Chancharoenrith, Sittikorn; Kamonsatikul, Choavarit; Namkajorn, Montree; Kiatisevi, Supavadee; Somsook, Ekasith

    2015-03-01

    Iron oxide nanoparticles were used as supporters for in situ polymerization to produce polymer nanocomposites with well-dispersed fillers in polymer matrix. Iron oxide could be sustained as colloidal solutions by cassava starch to produce a good dispersion of iron oxide in the matrix. New supports based on iron oxide/cassava starch or cassava starch for Ziegler-Natta catalysts were utilized as heterogeneous supporters for partially hydrolyzed triethylaluminum. Then, TiCl4 was immobilized on the supports as catalysts for polymerization of ethylene. High-density polyethylene (HDPE) composites were obtained by the synthesized catalysts. A good dispersion of iron oxide/cassava starch particles was observed in the synthesized polymer matrix promoting to good mechanical properties of HDPE. PMID:25498641

  2. Not only V(V) - What really is the nature of supported vanadate catalysts?

    OpenAIRE

    Klose, F.; Wolff, T; Lorenz, H.; Seidel-Morgenstern, A.; Suchorski, Y.; Piorkowska, M.; H. Weiss

    2007-01-01

    Supported vanadia catalysts are important catalysts for oxidation reactions. Depending on the kind of support and on the doping degree, vanadia is either spread over the sup-ports surface forming thin layers of vanadates or it agglomerates at higher loadings yielding V2O5 crystallites. Commonly, vanadates are proposed to consist of VO4 units, in which mono- and polyvanadates are distinguished (e.g. [1-3]). In this concept, in the oxidized state all V atoms are assumed to be in the oxidation s...

  3. High quality syngas production from microwave pyrolysis of rice husk with char-supported metallic catalysts.

    Science.gov (United States)

    Zhang, Shuping; Dong, Qing; Zhang, Li; Xiong, Yuanquan

    2015-09-01

    This study aimed to obtain the maximum possible gas yield and the high quality syngas production from microwave pyrolysis of rice husk with rice husk char and rice husk char-supported metallic (Ni, Fe and Cu) catalysts. The rice husk char-supported metallic catalysts had developed pore structure and catalytic activity for gas productions and tar conversion. The temperature-rising characteristic, product yields, properties of gas products and tar conversion mechanisms were investigated. It was found that three rice husk char-supported metallic catalysts improved the microwave absorption capability and increased heating rate and final temperature. Rice husk char-supported Ni catalyst presented most effective effects on gas production, e.g. the gas yield is 53.9%, and the volume concentration of desired syngas is 69.96%. Rice husk char-supported Ni and Fe catalysts played pivotal roles in tar conversion that less heavy compounds can be detected along with the reduction of organic compound number. PMID:25974618

  4. Metathesis of cardanol over Ru catalysts supported on mesoporousmolecular sieve SBA-15

    Czech Academy of Sciences Publication Activity Database

    Shinde, Tushar; Varga, Vojtěch; Polášek, Miroslav; Horáček, Michal; Žilková, Naděžda; Balcar, Hynek

    2014-01-01

    Roč. 478, MAY 2014 (2014), s. 138-145. ISSN 0926-860X R&D Projects: GA ČR(CZ) GAP106/12/0189 Institutional support: RVO:61388955 Keywords : cardanol * metathesis * supported catalysts Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.942, year: 2014

  5. Behavior of nickel catalysts in supercritical water gasification of glucose: Influence of support

    International Nuclear Information System (INIS)

    The catalytic performance of Ni-based supercritical water gasification (SCWG) catalysts may be influenced strongly by the nature of support. In this paper, Ni catalysts with the different supports (CeO2/Al2O3, La2O3/Al2O3, MgO/Al2O3, ZrO2/Al2O3) were prepared by two-step impregnation method. The fresh and used catalysts were characterized by X-ray diffraction patterns (XRD), scanning electron microscopy with an Energy Dispersive X-ray (SEM-EDX), Brunauer–Emmett–Teller (BET) specific surface area measurements, X-ray photoelectron spectroscopy (XPS) and Thermo-gravimetric analyses (TGA). The catalyst performance testing was conducted by SCWG of glucose at 673 K and 23.5 MPa with an autoclave reactor, to evaluate the influence of support on the hydrogen production. The results showed that H2 yield for different supports decreased in order: CeO2/Al2O3 > La2O3/Al2O3 > MgO/Al2O3 > Al2O3 > ZrO2/Al2O3, and H2 selectivity decreased in order: CeO2/Al2O3 > La2O3/Al2O3 > ZrO2/Al2O3 > Al2O3 > MgO/Al2O3. Ni catalysts were deactivated in SCWG reaction because of sintering and coke deposition. Compared with other supports, CeO2 can be used as the promoter of carbon removal from catalyst surfaces. - Highlights: • Ni catalysts with different supports were prepared by two-step impregnation method. • The fresh and used catalysts were characterized by XRD, BET, SEM, XPS and TGA. • The influences of support on hydrogen production were evaluate by SCWG of glucose. • The order of hydrogen yield and selectivity for different supports was obtained. • CeO2 can be used as the promoter of carbon removal from catalyst surfaces

  6. Nanocrystalline MgO supported nickel-based bimetallic catalysts for carbon dioxide reforming of methane

    Energy Technology Data Exchange (ETDEWEB)

    Meshkani, Fereshteh [Catalyst and Advanced Materials Research Laboratory, Chemical Engineering Department, Faculty of Engineering, University of Kashan, Kashan (Iran); Rezaei, Mehran [Catalyst and Advanced Materials Research Laboratory, Chemical Engineering Department, Faculty of Engineering, University of Kashan, Kashan (Iran); Institute of Nanoscience and Nanotechnology, University of Kashan, Kashan (Iran)

    2010-10-15

    Nanocrystalline magnesium oxide with high surface area and plate-like shape was employed as catalyst support for preparation of nickel-based bimetallic catalysts in methane reforming with carbon dioxide. The prepared samples were characterized by X-ray diffraction (XRD), N{sub 2} adsorption (BET), Temperature programmed oxidation and desorption (TPO-TPD), Thermal gravimetric and differential thermal gravimetric (TGA-DTG), H{sub 2} chemisorption and Transmission and electron microscopies (TEM and SEM) analyses. CO{sub 2}-TPD data showed the high CO{sub 2} adsorption capacity of catalysts which improves the resistance of catalysts against the carbon formation. The H{sub 2} chemisorption results also indicated that the addition of Pt to nickel catalyst improved the nickel dispersion. The obtained results revealed that the prepared catalysts showed a high activity and stability during the reaction with a low amount of deposited carbon. Addition of Pt to nickel catalyst improved both the activity and resistivity against carbon formation. (author)

  7. Oxidation-resistant catalyst supports for proton exchange membrane fuel cells

    Science.gov (United States)

    Chhina, Harmeet

    In automotive applications, when proton exchange membrane fuel cells (PEMFCs) are subjected to frequent startup-shutdown cycles, a significant drop in performance is observed. One reason for this drop in performance is oxidation of the carbon in the catalyst layer when cathode potential excursions as high as 1.5V are observed. In this work, non-carbon based catalyst support materials were studied. The materials investigated include: tungsten carbide (WC), tungsten oxide (WOx), and niobium (Nb) or tungsten (W) doped titania. Platinum was dispersed on commercial samples of WC and WO x. Stability tests were performed by stepping the materials between 0.6 to 1.8V. Higher stability of both WC and WOx was observed compared to carbon based commercial catalyst (HiSpec 4000). The performance of Pt supported on WC or WOx was found to be lower than that of Pt/C due to poor dispersion of Pt on these low surface area commercial powders. High surface area Nb and W doped titania materials synthesized using sol-gel techniques were subjected to several heat treatments and atmospheres, and their resulting physical properties characterized. The materials' phase changes and their impact on electrical conductivity were evaluated. W doped titania was found to be resistive, and for Nb doped titania, the rutile phase was found to be more conductive than the anatase phase. Conventionally, 10-50 wt% Pt is supported on carbon, but as the non-carbon catalyst support materials have different densities, similar mass ratios of catalyst to support will not result in directly comparable performances. It is recommended that the ratio of Pt surface area to the support surface area should be similar when comparing Pt supported on carbon to Pt supported on a non-carbon support. A normalization approach was investigated in this work, and the ORR performance of 40wt.%Pt/C was found to be similar to that of 10wt.%Pt/Nb-TiO2. Fuel cell performance tests showed significantly higher stability of Pt on Nb

  8. Enhanced Activity and Selectivity of Carbon Nanofiber Supported Pd Catalysts for Nitrite Reduction

    KAUST Repository

    Shuai, Danmeng

    2012-03-06

    Pd-based catalyst treatment represents an emerging technology that shows promise to remove nitrate and nitrite from drinking water. In this work we use vapor-grown carbon nanofiber (CNF) supports in order to explore the effects of Pd nanoparticle size and interior versus exterior loading on nitrite reduction activity and selectivity (i.e., dinitrogen over ammonia production). Results show that nitrite reduction activity increases by 3.1-fold and selectivity decreases by 8.0-fold, with decreasing Pd nanoparticle size from 1.4 to 9.6 nm. Both activity and selectivity are not significantly influenced by Pd interior versus exterior CNF loading. Consequently, turnover frequencies (TOFs) among all CNF catalysts are similar, suggesting nitrite reduction is not sensitive to Pd location on CNFs nor Pd structure. CNF-based catalysts compare favorably to conventional Pd catalysts (i.e., Pd on activated carbon or alumina) with respect to nitrite reduction activity and selectivity, and they maintain activity over multiple reduction cycles. Hence, our results suggest new insights that an optimum Pd nanoparticle size on CNFs balances faster kinetics with lower ammonia production, that catalysts can be tailored at the nanoscale to improve catalytic performance for nitrite, and that CNFs hold promise as highly effective catalyst supports in drinking water treatment. © 2012 American Chemical Society.

  9. Characterization of a surface modified carbon cryogel and a carbon supported Pt catalyst

    Directory of Open Access Journals (Sweden)

    BILJANA M. BABIĆ

    2007-08-01

    Full Text Available A carbon cryogel, synthesized by carbonization of a resorcinol/formaldehyde cryogel and oxidized in nitric acid, was used as catalyst support for Pt nano-particles. The Pt/C catalyst was prepared by a modified polyol synthesis method in an ethylene glycol (EG solution. Characterization by nitrogen adsorption showed that the carbon cryogel support and the Pt/C catalyst were mesoporous materials with high specific surface areas (SBET > 400 m2 g-1 and large mesoporous volumes. X-Ray diffraction of the catalyst demonstrated the successful reduction of the Pt precursor to metallic form. TEM Images of the Pt/C catalyst and Pt particle size distribution showed that the mean Pt particle size was about 3.3 nm. Cyclic voltammetry (CV experiments at various scan rates (from 2 to 200 mV s-1 were performed in 0.5 mol dm-3 HClO4 solution. The large capacitance of the oxidized carbon cryogel electrode, which arises from a combination of the double-layer capacitance and pseudocapacitance, associated with the participation of surface redox-type reactions was demonstrated. For the oxidized carbon cryogel, the total specific capacitance determined by 1/C vs. ν0.5 extrapolation method was found to be 386 F g-1. The hydrogen oxidation reaction at the investigated Pt/C catalyst proceeded as an electrochemically reversible, two-electron direct discharge reaction.

  10. Catalyst nanoscale assembly from the vapor phase on corrosion resistant supports

    International Nuclear Information System (INIS)

    The synthesis process, reactive spray deposition technology (RSDT), utilized a jet-flame to produce Pt nanoparticles. The RSDT process bypasses traditional wet chemical routes by simultaneously nucleating the catalyst on a support and sequential deposition of catalyst layer via the gas phase. Pt nanoparticles were attached, in the process gas during the time-of-flight, to the surface of several supports. The supports show promising corrosion resistance under the cathode conditions of a proton exchange membrane fuel cell (PEMFC). The supported Pt catalysts were then studied in regards to structure, stability and electrochemical behavior toward the oxygen reduction reaction (ORR) in perchloric acid. Transmission electron microscopy studies showed that the average Pt particle diameter is ∼2.5 nm. The average diameter and distribution of the Pt particles are independent of the support type and a high degree of catalyst dispersion has been achieved on all supports. The greatest surface area and electrochemical mass activity were obtained using Vulcan XC-72R, while a graphitized carbon support produced the highest specific activity. Based on X-ray photoelectric spectroscopy (XPS) measurements, approximately 30% of the surface of the Pt particles is comprised of Pt2+. This oxide coverage does not extend into the bulk and is below the detection limits of X-ray diffraction (XRD). The electrochemical reduction of oxygen exhibits a typical Tafel slope of −65 to 71 mV/dec

  11. Fe phase complexes and their thermal stability in iron phosphate catalysts supported on silica

    International Nuclear Information System (INIS)

    Comparative XRD and Mössbauer spectroscopy studies have been conducted on the effect of temperature on the phase transformations of an iron phosphate catalyst synthesized using the ammonia gel method (CAT1) and a commercial grade FePO 4 catalyst supported on silica using wet impregnation method (CAT2). The XRD patterns of both catalysts showed the presence of iron phosphate and the tridymite phase of aluminum phosphate. Mössbauer spectra of the catalysts show that the phases present in CAT1 are thermally stable up to 500 ∘C, but CAT2 shows significant changes with the tridymite phase of iron phosphate increasing from 6 % to 29 % of the spectral area at a temperature of 500 ∘C

  12. Preparation of Mesoporous Silica-Supported Palladium Catalysts for Biofuel Upgrade

    Directory of Open Access Journals (Sweden)

    Ling Fei

    2012-01-01

    Full Text Available We report the preparation of two hydrocracking catalysts Pd/CoMoO4/silica and Pd/CNTs/CoMoO4/silica (CNTs, carbon nanotubes. The structure, morphologies, composition, and thermal stability of catalysts were studied by X-ray diffraction (XRD, scanning electron microscopy (SEM, Raman spectroscopy, transmission electron microscopy (TEM, energy-dispersive X-ray (EDX, and thermogravimetric analysis (TGA. The catalyst activity was measured in a Parr reactor with camelina fatty acid methyl esters (FAMEs as the feed. The analysis shows that the palladium nanoparticles have been incorporated onto mesoporous silica in Pd/CoMoO4/silica or on the CNTs surface in Pd/CNTs/CoMoO4/silica catalysts. The different combinations of metals and supports have selective control cracking on heavy hydrocarbons.

  13. Fe phase complexes and their thermal stability in iron phosphate catalysts supported on silica

    Energy Technology Data Exchange (ETDEWEB)

    Dasireddy, Venkata D. B. C., E-mail: dasireddy@gmail.com; Bharuth-Ram, K.; Harilal, A.; Singh, S.; Friedrich, H. B. [University of KwaZulu-Natal, School of Chemistry and Physics (South Africa)

    2015-04-15

    Comparative XRD and Mössbauer spectroscopy studies have been conducted on the effect of temperature on the phase transformations of an iron phosphate catalyst synthesized using the ammonia gel method (CAT1) and a commercial grade FePO {sub 4} catalyst supported on silica using wet impregnation method (CAT2). The XRD patterns of both catalysts showed the presence of iron phosphate and the tridymite phase of aluminum phosphate. Mössbauer spectra of the catalysts show that the phases present in CAT1 are thermally stable up to 500 {sup ∘}C, but CAT2 shows significant changes with the tridymite phase of iron phosphate increasing from 6 % to 29 % of the spectral area at a temperature of 500 {sup ∘}C.

  14. Vapor-phase Nitration of Benzene to Nitrobenzene over Supported Sulfuric Acid Catalyst

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Vapor-phase nitration of benzene over solid acid catalyst is expected to be a clean process with no sulfuric acid waste.We investigated this process over solid acidic catalysts utilizing diluted nitric acid (60-70%) as nitrating agent,and found that supported sulfuric acid catalyst exhibited a very high catalytic activity.Under the conditions of reaction temperature 160-170℃,space velocity (SV) 1200 h-1,the yield and the space-time yield (STY) of nitrobenzene (NB) based on HNO3 were more than 98% and 0.75 kg@kgcat-1@h-1 over 10% H2SO4/SiO2 (by weight) catalyst respectively.

  15. Chitosan as a Natural Polymer for Heterogeneous Catalysts Support: A Short Review on Its Applications

    Directory of Open Access Journals (Sweden)

    Mengshan Lee

    2015-11-01

    Full Text Available Chitosan, a bio-based polymer which has similar characteristics to those of cellulose, exhibits cationic behavior in acidic solutions and strong affinity for metals ions. Thus, it has received increased attention for the preparation of heterogeneous catalysts. Recent studies demonstrated that chitosan-based catalysts had high sorption capacities, chelating activities, stability and versatility, which could be potentially applied as green reactants in various scientific and engineering applications. This study intends to review the recent development of chitosan-based catalysts, particularly in the aspects of the main mechanisms for preparing the materials and their applications in environmental green chemistry. Studies on the preparation of catalyst nanoparticles/nanospheres supported on chitosan were also reviewed.

  16. Electro-Deposition Pt Catalysts Supported on Carbon-Nanotubes for Methanol Oxidation

    Institute of Scientific and Technical Information of China (English)

    Hailin Song; Peixia Yang; Xiaoyu Wen; Maozhong An; Jinqiu Zhang

    2015-01-01

    In order to study the properties of supporting Pt catalysts for methanol oxidation, carbon⁃nanotubes are used by electrochemical deposition method. Different deposition turns, different cyclic voltammetry scanning speeds and processing time with ascorbic acid are investigated in this paper. The micrographs of Pt/CNTs catalysts are characterized by scanning electron microscopy, the electro⁃catalytic properties of Pt/CNTs catalysts for methanol oxidation are investigated by cycle voltammetry and chronoamperometry. The results show that the size of platinum will be greater with the faster scanning speed. After dissolution in ascorbic acid, Pt nano⁃particles disperse uniformly. The obtained Pt/CNTs catalysts show a high electro⁃catalytic activity and stability.

  17. Self-Supporting Metal-Organic Layers as Single-Site Solid Catalysts.

    Science.gov (United States)

    Cao, Lingyun; Lin, Zekai; Peng, Fei; Wang, Weiwei; Huang, Ruiyun; Wang, Cheng; Yan, Jiawei; Liang, Jie; Zhang, Zhiming; Zhang, Teng; Long, Lasheng; Sun, Junliang; Lin, Wenbin

    2016-04-11

    Metal-organic layers (MOLs) represent an emerging class of tunable and functionalizable two-dimensional materials. In this work, the scalable solvothermal synthesis of self-supporting MOLs composed of [Hf6 O4 (OH)4 (HCO2 )6 ] secondary building units (SBUs) and benzene-1,3,5-tribenzoate (BTB) bridging ligands is reported. The MOL structures were directly imaged by TEM and AFM, and doped with 4'-(4-benzoate)-(2,2',2''-terpyridine)-5,5''-dicarboxylate (TPY) before being coordinated with iron centers to afford highly active and reusable single-site solid catalysts for the hydrosilylation of terminal olefins. MOL-based heterogeneous catalysts are free from the diffusional constraints placed on all known porous solid catalysts, including metal-organic frameworks. This work uncovers an entirely new strategy for designing single-site solid catalysts and opens the door to a new class of two-dimensional coordination materials with molecular functionalities. PMID:26954885

  18. Preparation of Meso porous Silica-Supported Palladium Catalysts for Bio fuel Upgrade

    International Nuclear Information System (INIS)

    We report the preparation of two hydrocracking catalysts Pd/CoMoO4/silica and Pd/CNTs/CoMoO4/silica (CNTs, carbon nano tubes). The structure, morphologies, composition, and thermal stability of catalysts were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectroscopy, transmission electron microscopy (TEM), energy-dispersive X-ray (EDX), and thermogravimetric analysis (TGA). The catalyst activity was measured in a Parr reactor with camelina fatty acid methyl esters (FAMEs) as the feed. The analysis shows that the palladium nanoparticles have been incorporated onto meso porous silica in Pd/CoMoO4/silica or on the CNTs surface in Pd/CNTs/CoMoO4/silica catalysts. The different combinations of metals and supports have selective control cracking on heavy hydrocarbons.

  19. Physicochemical investigations of carbon nanofiber supported Cu/ZrO{sub 2} catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Din, Israf Ud, E-mail: drisraf@yahoo.com, E-mail: maizats@petronas.com.my; Shaharun, Maizatul S., E-mail: drisraf@yahoo.com, E-mail: maizats@petronas.com.my [Department of Fundamental and Applied Sciences, Universiti Teknologi PETRONAS (Malaysia); Subbarao, Duvvuri, E-mail: duvvuri-subbarao@petronas.com.my [Department of Chemical Engineering, Universiti Teknologi PETRONAS (Malaysia); Naeem, A., E-mail: naeeem64@yahoo.com [National Centre of Excellence in Physical Chemistry, University of Peshawar (Pakistan)

    2014-10-24

    Zirconia-promoted copper/carbon nanofiber catalysts (Cu‐ZrO{sub 2}/CNF) were prepared by the sequential deposition precipitation method. The Herringbone type of carbon nanofiber GNF-100 (Graphite nanofiber) was used as a catalyst support. Carbon nanofiber was oxidized to (CNF-O) with 5% and 65 % concentration of nitric acid (HNO{sub 3}). The CNF activated with 5% HNO{sub 3} produced higher surface area which is 155 m{sup 2}/g. The catalyst was characterized by X-ray Diffraction (XRD), Fourier Transform Infra-Red (FTIR) and N{sub 2} adsorption-desorption. The results showed that increase of HNO{sub 3} concentration reduced the surface area and porosity of the catalyst.

  20. Direct decomposition of methane over SBA-15 supported Ni, Co and Fe based bimetallic catalysts

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • Synthesis and characterization of Ni, Co and Fe based bimetallic catalysts supported over SBA-15. • Thermocatalytic decomposition of methane over the SBA-15 supported bimetallic catalysts. • Enhanced catalytic efficiency of the bimetallic catalysts for the production of COx free hydrogen and nanocarbon. • Production of value added open tip hollow multi-walled carbon nanotubes. • Crystalline characterization of carbon nanotubes by XRD, Raman and thermogravimetric analysis. - Abstract: Thermocatalytic decomposition of methane is an alternative route for the production of COx-free hydrogen and carbon nanomaterials. In this work, a set of novel Ni, Co and Fe based bimetallic catalysts supported over mesoporous SBA-15 was synthesized by a facile wet impregnation route, characterized for their structural, textural and reduction properties and were successfully used for the methane decomposition. The fine dispersion of metal oxide particles on the surface of SBA-15, without affecting its mesoporous texture was clearly shown in the low angle X-ray diffraction patterns and the transmission electron microscopy (TEM) images. The nitrogen sorption analysis showed the reduced specific surface area and pore volume of SBA-15, after metal loading due to the partial filling of hexagonal mesopores by metal species. The results of methane decomposition experiments indicated that all of the bimetallic catalysts were highly active and stable for the reaction at 700 °C even after 300 min of time on stream (TOS). However, a maximum hydrogen yield of ∼56% was observed for the NiCo/SBA-15 catalyst within 30 min of TOS. A high catalytic stability was shown by the CoFe/SBA-15 catalyst with 51% of hydrogen yield during the course of reaction. The catalytic stability of the bimetallic catalysts was attributed to the formation of bimetallic alloys. Moreover, the deposited carbons were found to be in the form of a new set of hollow multi

  1. Direct decomposition of methane over SBA-15 supported Ni, Co and Fe based bimetallic catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Pudukudy, Manoj, E-mail: manojpudukudy@gmail.com [Fuel Cell Institute, Universiti Kebangsaan Malaysia, UKM, Bangi 43600, Selangor (Malaysia); Department of Chemical and Process Engineering, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia, UKM, Bangi 43600, Selangor (Malaysia); Yaakob, Zahira, E-mail: zahirayaakob65@gmail.com [Department of Chemical and Process Engineering, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia, UKM, Bangi 43600, Selangor (Malaysia); Akmal, Zubair Shamsul [Department of Chemical and Process Engineering, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia, UKM, Bangi 43600, Selangor (Malaysia)

    2015-03-01

    Graphical abstract: - Highlights: • Synthesis and characterization of Ni, Co and Fe based bimetallic catalysts supported over SBA-15. • Thermocatalytic decomposition of methane over the SBA-15 supported bimetallic catalysts. • Enhanced catalytic efficiency of the bimetallic catalysts for the production of CO{sub x} free hydrogen and nanocarbon. • Production of value added open tip hollow multi-walled carbon nanotubes. • Crystalline characterization of carbon nanotubes by XRD, Raman and thermogravimetric analysis. - Abstract: Thermocatalytic decomposition of methane is an alternative route for the production of CO{sub x}-free hydrogen and carbon nanomaterials. In this work, a set of novel Ni, Co and Fe based bimetallic catalysts supported over mesoporous SBA-15 was synthesized by a facile wet impregnation route, characterized for their structural, textural and reduction properties and were successfully used for the methane decomposition. The fine dispersion of metal oxide particles on the surface of SBA-15, without affecting its mesoporous texture was clearly shown in the low angle X-ray diffraction patterns and the transmission electron microscopy (TEM) images. The nitrogen sorption analysis showed the reduced specific surface area and pore volume of SBA-15, after metal loading due to the partial filling of hexagonal mesopores by metal species. The results of methane decomposition experiments indicated that all of the bimetallic catalysts were highly active and stable for the reaction at 700 °C even after 300 min of time on stream (TOS). However, a maximum hydrogen yield of ∼56% was observed for the NiCo/SBA-15 catalyst within 30 min of TOS. A high catalytic stability was shown by the CoFe/SBA-15 catalyst with 51% of hydrogen yield during the course of reaction. The catalytic stability of the bimetallic catalysts was attributed to the formation of bimetallic alloys. Moreover, the deposited carbons were found to be in the form of a new set of hollow

  2. Nanostructural and Chemical Characterization of Supported Metal Oxide Catalysts by Aberration Corrected Analytical Electron Microscopy

    Science.gov (United States)

    Zhou, Wu

    In this thesis, aberration corrected STEM imaging and chemical analysis techniques have been extensively applied in the structural and chemical characterization of supported tungsten oxide catalysts in an attempt to reveal the structure-activity relationships at play in these catalyst systems. The supported WO3/ZrO2 solid acid catalyst system is a major focal point of this thesis, and detailed aberration-corrected STEM-HAADF imaging studies were performed on a systematic set of catalysts showing different level of catalytic performance. The nature of the catalytically most active WOx species was identified by correlating structural information, obtained from STEM-HAADF and in-situ optical spectroscopy studies, with catalytic testing results. Specifically, ˜1nm distorted Zr-WOx mixed oxide clusters were identified to be the most active species for both the methanol dehydration and n-pentane isomerization reactions in the WO3/ZrO2 catalyst system. The use of amorphous zirconia as a precursor support material makes it much easier to extract and incorporate Zr cations into the surface WOx clusters during calcination. The calcination temperature was also identified to also play an important role in the formation of these most active Zr-WOx clusters. When the calcination temperature is comparable to or higher than the 896K Huttig temperature of ZrO2 (at which surface ZrO x species have sufficient mobility to agglomerate and sinter), the chance for successful surface WOx and ZrOx intermixing is significantly increased. Based on this perceived structure-activity relationship, several new catalyst synthesis strategies were developed in an attempt to optimize the catalytic performance of WOx-based catalysts. We have demonstrated in Chapter 3 that co-impregnation of WOx and ZrOx precursors onto an inactive model WO3/ZrO2 catalyst, followed by a calcination treatment above the 896K Huttig temperature of ZrO 2, promotes the surface diffusion of ZrO2 and intermixing of Zr

  3. Studies on Co-based catalysts supported on modified carbon substrates for PEMFC cathodes

    Energy Technology Data Exchange (ETDEWEB)

    Subramanian, Nalini P.; Kumaraguru, Swaminatha P.; Colon-Mercado, Hector; Popov, Branko N. [Department of Chemical Engineering, University of South Carolina, Columbia, SC 29208 (United States); Kim, Hansung [Department of Chemical Engineering Yonsei University, Seoul (Korea, Republic of); Black, Timothy; Chen, Donna A. [Department of Chemistry and Biochemistry, University of South Carolina, Columbia, SC 29208 (United States)

    2006-06-19

    Cobalt based non-precious metal catalysts were prepared by supporting cobalt-ethylene diamine complex on carbon followed by a heat treatment at elevated temperatures (800{sup o}C). Surface oxygen groups on carbon were introduced with HNO{sub 3} oxidation. Co catalysts supported on oxidized carbon showed improved activity and selectivity towards four-electron reduction of molecular oxygen. Quinone groups introduced by nitric acid treatment, in addition to increasing the dispersion of the chelate complexes, play a role in forming the active site for oxygen reduction. (author)

  4. Density Functional Theory for Green Chemical Catalyst Supported on S-Terminated GaN(0001)

    Science.gov (United States)

    Yokoyama, Mami; Tsukamoto, Shiro; Ishii, Akira

    2011-12-01

    A novel function of nitried-based semiconductor is successfully developed for organic synthesis, in which palladium supported on the surface of S-terminated GaN(0001) serves as a unique green chemical catalyst. In this study we determined the structure of Pd-catalyst supported on S-terminated GaN(0001) surface by means of the density functional theory (DFT) within a Local Density Approximation (LDA). The important role of S on the case of GaN substrate is to make the number of the valence electron to be close to 0, it happened same way for GaAs substrate.

  5. Hydrogenation of cinnamaldehyde using catalysts prepared from supported palladium phosphine complexes

    Energy Technology Data Exchange (ETDEWEB)

    Cairns, G.R.; Cross, R.J.; Stirling, D. [Univ. of Glasgow (United Kingdom)

    1997-02-01

    The liquid phase hydrogenation of cinnamaldehyde has been studied using catalysts prepared from the binuclear palladium complexes [Pd{sub 2}X{sub 4}(PR{sub 3}){sub 2}] (X = Cl, Br, or I; R = Me, Et, and Pr{sup i} or Bu for X =Br only) on silica, and the results have been compared with the performance of a standard Pd/SiO{sub 2} catalyst prepared from Pd(NO{sub 3}){sub 2} and with that of the unsupported molecular complexes. When X = Br, cinnamaldehyde is rapidly hydrogenated selectively to hydrocinnamaldehyde and no further reaction occurs. When X = I, the reactions are extremely slow but are again limited to hydrocinnamaidehyde formation. The catalysts prepared from the chloride-containing precursors behave differently, and some phenyl propanol is formed along with hydrocinnamaldehyde. However, the reaction mechanisms are different from that which operates with the silica-supported palladium catalyst. The rates of the reactions are dependent on the nature of the phosphine substituent, but the selectivities are dependent primarily on the halide. Hydrogenation reactions on all of the catalysts prepared from the binuclear complexes proceed only after an induction period during which partial reduction and/or surface reconstruction of the supported complexes occur. This contrasts with the performance of the standard Pd/SiO{sub 2} catalysts for cinnamaldehyde hydrogenation, which proceeds without any induction period. The reactions of all of these catalysts are thought to take place on a hydrocarbonaceous overlayer which is formed rapidly from unsaturated aldehydes and alcohols. Hydrogenations of cinnamaldehyde using the unsupported complexes in solution proceed at much lower rates, but reveal the same selectivities observed with their silica-supported counterparts. 46 refs., 4 figs., 1 tab.

  6. Efficient oxidative degradation of 2-chlorophenol and 4-chlorophenol over supported CuO-based catalysts

    Institute of Scientific and Technical Information of China (English)

    Jingjing Li; Yang Hu; Wenhui Lü; Lei Shi; Qi Sun; Yonggang Zhou; Jianfeng Xu; Jian Wang; Bizhong Shen

    2011-01-01

    A series of metal oxide catalysts for catalytic oxidative degradation of 2-chlorophenol (2-CP) and 4-chlorophenol (4-CP) were prepared,and the supported CuO catalysts were studied particularly.The supported CuO catalysts were characterized by XRD and NH3-TPD techniques,in which CuO/γ-Al2O3 exhibited high degradation activity.The addition of Na2O or K2O into CuO/γ-Al2O3 improved the oxidative degradation of CPs remarkably,in which Na2O was more efficient than K2O.Over CuO/γ-Al2O3-Na2O,CPs were completely converted and the liberation of the inorganic chloride from 2-CP or 4-CP reached 97% or 100% respectively at 30 ℃ for 2 h.The supported CuO catalysts with good dispersion of CuO particles and less acid sites were favorable for the efficient oxidative degradation of CPs.In addition,the initial pH of the reaction solution was found to be an important factor which influenced the catalytic oxidative degradation of CPs and the initial pH of 11.2 and 9.8 was preferred for the oxidative degradation of 2-CP and 4-CP respectively over CuO/γ-Al2O3 catalyst.

  7. Monodisperse metal nanoparticle catalysts on silica mesoporous supports: synthesis, characterizations, and catalytic reactions

    Energy Technology Data Exchange (ETDEWEB)

    Somorjai, G.A.

    2009-09-14

    The design of high performance catalyst achieving near 100% product selectivity at maximum activity is one of the most important goals in the modern catalytic science research. To this end, the preparation of model catalysts whose catalytic performances can be predicted in a systematic and rational manner is of significant importance, which thereby allows understanding of the molecular ingredients affecting the catalytic performances. We have designed novel 3-dimensional (3D) high surface area model catalysts by the integration of colloidal metal nanoparticles and mesoporous silica supports. Monodisperse colloidal metal NPs with controllable size and shape were synthesized using dendrimers, polymers, or surfactants as the surface stabilizers. The size of Pt, and Rh nanoparticles can be varied from sub 1 nm to 15 nm, while the shape of Pt can be controlled to cube, cuboctahedron, and octahedron. The 3D model catalysts were generated by the incorporation of metal nanoparticles into the pores of mesoporous silica supports via two methods: capillary inclusion (CI) and nanoparticle encapsulation (NE). The former method relies on the sonication-induced inclusion of metal nanoparticles into the pores of mesoporous silica, whereas the latter is performed by the encapsulation of metal nanoparticles during the hydrothermal synthesis of mesoporous silica. The 3D model catalysts were comprehensively characterized by a variety of physical and chemical methods. These catalysts were found to show structure sensitivity in hydrocarbon conversion reactions. The Pt NPs supported on mesoporous SBA-15 silica (Pt/SBA-15) displayed significant particle size sensitivity in ethane hydrogenolysis over the size range of 1-7 nm. The Pt/SBA-15 catalysts also exhibited particle size dependent product selectivity in cyclohexene hydrogenation, crotonaldehyde hydrogenation, and pyrrole hydrogenation. The Rh loaded SBA-15 silica catalyst showed structure sensitivity in CO oxidation reaction. In

  8. Effects of K and Pt promoters on the performance of cobalt catalyst supported on CNTs

    Energy Technology Data Exchange (ETDEWEB)

    Zabidi, Noor Asmawati Mohd, E-mail: noorasmawati-mzabidi@petronas.com.my [Department of Fundamental and Applied Sciences, Universiti Teknologi PETRONAS, Bandar Seri Iskandar, 31750 Tronoh, Perak (Malaysia); Ali, Sardar, E-mail: alikhan-635@yahoo.com [Centralized Analytical Laboratory, Universiti Teknologi PETRONAS, Bandar Seri Iskandar, 31750 Tronoh, Perak (Malaysia); Subbarao, Duvvuri, E-mail: duvvuri-subbarao@petronas.com.my [Department of Chemical Engineering, Universiti Teknologi PETRONAS, Bandar Seri Iskandar, 31750 Tronoh, Perak (Malaysia)

    2014-10-24

    This paper presents a comparative study on the effects of incorporation of potassium (K) and platinum (Pt) as promoters on the physicochemical properties of cobalt catalyst. The catalyst was prepared by a wet impregnation method on a CNTs support. Samples were characterized using transmission electron microscopy (TEM), H{sub 2}-temperature-programmed reduction (TPR) and X-ray photoelectron spectroscopy (XPS) techniques. Fischer-Tropsch Synthesis (FTS) was carried out in a fixed-bed microreactor at 543 K and 1 atm, with H{sub 2}/CO = 2v/v and space velocity, SV of 12 L/g.h for 5 hours. The K-promoted and Pt-promoted Co catalysts have different physicochemical properties and catalytic performances compared to that of the un-promoted Co catalyst. XPS analysis revealed that K and Pt promoters induced electronic modifications as exhibited by the shifts in the Co binding energies. Incorporation of 0.06 wt% K and 0.06 wt% Pt in Co/CNTs catalyst resulted in an increase in the CO conversion and C{sub 5+} selectivity and a decrease in methane selectivity. Potassium was found to be a better promoter for Co/CNTs catalyst compared to platinum.

  9. Supported noble metal catalysts in the catalytic wet air oxidation of industrial wastewaters and sewage sludges.

    Science.gov (United States)

    Besson, M; Descorme, C; Bernardi, M; Gallezot, P; di Gregorio, F; Grosjean, N; Minh, D Pham; Pintar, A

    2010-12-01

    This paper reviews some catalytic wet air oxidation (CWAO) investigations of industrial wastewaters over platinum and ruthenium catalysts supported on TiO2 and ZrO2 formulated to be active and resistant to leaching, with particular focus on the stability of the catalyst. Catalyst recycling experiments were performed in batch reactors and long-term stability tests were conducted in trickle-bed reactors. The catalyst did not leach upon treatment of Kraft bleaching plant and olive oil mill effluents, and could be either recycled or used for long periods of time in continuous reactors. Conversely, these catalysts were rapidly leached when used to treat effluents from the production of polymeric membranes containing N,N-dimethylformamide. The intermediate formation of amines, such as dimethylamine and methylamine with a high complexing capacity for the metal, was shown to be responsible for the metal leaching. These heterogeneous catalysts also deactivated upon CWAO of sewage sludges due to the adsorption of the solid organic matter. Pre-sonication of the sludge to disintegrate the flocs and improve solubility was inefficient. PMID:21214003

  10. Effects of K and Pt promoters on the performance of cobalt catalyst supported on CNTs

    International Nuclear Information System (INIS)

    This paper presents a comparative study on the effects of incorporation of potassium (K) and platinum (Pt) as promoters on the physicochemical properties of cobalt catalyst. The catalyst was prepared by a wet impregnation method on a CNTs support. Samples were characterized using transmission electron microscopy (TEM), H2-temperature-programmed reduction (TPR) and X-ray photoelectron spectroscopy (XPS) techniques. Fischer-Tropsch Synthesis (FTS) was carried out in a fixed-bed microreactor at 543 K and 1 atm, with H2/CO = 2v/v and space velocity, SV of 12 L/g.h for 5 hours. The K-promoted and Pt-promoted Co catalysts have different physicochemical properties and catalytic performances compared to that of the un-promoted Co catalyst. XPS analysis revealed that K and Pt promoters induced electronic modifications as exhibited by the shifts in the Co binding energies. Incorporation of 0.06 wt% K and 0.06 wt% Pt in Co/CNTs catalyst resulted in an increase in the CO conversion and C5+ selectivity and a decrease in methane selectivity. Potassium was found to be a better promoter for Co/CNTs catalyst compared to platinum

  11. Supported heteronuclear noble metal cluster catalysts and method for preparing same

    International Nuclear Information System (INIS)

    New heteronuclear noble metal cluster complexes have been discovered and synthesized for the first time. These complexes are (pyridine)2Pt(Ir2(CO)15), (pyridine)2 Pt(Ir2(CO)7), (Pyridine)3Pt(Ru3(CO)12), ((C6H5)3P)2Pt(Ir(CO)3(P6H5)3)2, ((C6H5)3P)2Rh(CO)(IR(CO)4), and (pyridine)2Pt(Rh(CO)2(P(C6H5)3)3)2. These new heteronuclear noble metal cluster complexes are useful as supported mixed noble metal catalyst precursors. These new cluster complexes, of known stoichiometry, are deposited on anhydrous refractory inorganic oxide or carbon supports and then reduced resulting in the formation of a supported heteronuclear noble metal catalyst having the same metals stoichiometry as the starting cluster complexes. In this way, precise control can be exercised over the ratio and distribution of multiple metal components in a mixed noble metal catalyst. The usage of preformed heteronuclear noble metal cluster complexes as supported mixed metal catalyst precursors maximizes surface alloy formation and also yields unique mixed-metal cluster structures on the support surface

  12. The model thin film alumina catalyst support suitable for catalysis-oriented surface science studies

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • New model catalyst on “AlOx-thin film/FeCrAl” support is presented. • Metal substrate minimizes sample charging, allows fast and uniform heating. • Surface is rough to model the catalyst support's morphology. • Planar alumina is stable in air/gases/solutions and similar to γ-Al2O3. • New model support is suitable for in situ XPS, STM, TPD, TPR, etc. - Abstract: The preparation of thin continuous alumina film at the surface of metal substrate in UHV (ultra high vacuum) conditions is described. The peculiarities of the obtained films studied by XPS (X-ray photoelectron spectroscopy) and STM (scanning tunneling microscopy) are discussed. The long-term durability of the oxide film was tested and proved both under ambient conditions and in acidic aqueous solutions. The stability of the planar alumina samples toward oxidation by oxygen was checked in the wide ranges of gas pressure and sample temperature. The suggested procedure ensures the controlled and reproducible preparation of thin alumina films – model support appropriate for wet chemistry catalyst preparation, suitable for STM and for other Surface Science techniques studies of alumina supported metal catalysts

  13. The model thin film alumina catalyst support suitable for catalysis-oriented surface science studies

    Energy Technology Data Exchange (ETDEWEB)

    Nartova, Anna V., E-mail: avnartova@gmail.com [Boreskov Institute of Catalysis SB RAS, Lavrentieva Ave., 5, Novosibirsk, 630090 (Russian Federation); Novosibirsk State University, Pirogova St., 2, Novosibirsk, 630090 (Russian Federation); Bukhtiyarov, Andrey V., E-mail: avb@catalysis.ru [Boreskov Institute of Catalysis SB RAS, Lavrentieva Ave., 5, Novosibirsk, 630090 (Russian Federation); Kvon, Ren I., E-mail: kvon@catalysis.ru [Boreskov Institute of Catalysis SB RAS, Lavrentieva Ave., 5, Novosibirsk, 630090 (Russian Federation); Bukhtiyarov, Valerii I., E-mail: vib@catalysis.ru [Boreskov Institute of Catalysis SB RAS, Lavrentieva Ave., 5, Novosibirsk, 630090 (Russian Federation); Novosibirsk State University, Pirogova St., 2, Novosibirsk, 630090 (Russian Federation)

    2015-09-15

    Graphical abstract: - Highlights: • New model catalyst on “AlOx-thin film/FeCrAl” support is presented. • Metal substrate minimizes sample charging, allows fast and uniform heating. • Surface is rough to model the catalyst support's morphology. • Planar alumina is stable in air/gases/solutions and similar to γ-Al{sub 2}O{sub 3}. • New model support is suitable for in situ XPS, STM, TPD, TPR, etc. - Abstract: The preparation of thin continuous alumina film at the surface of metal substrate in UHV (ultra high vacuum) conditions is described. The peculiarities of the obtained films studied by XPS (X-ray photoelectron spectroscopy) and STM (scanning tunneling microscopy) are discussed. The long-term durability of the oxide film was tested and proved both under ambient conditions and in acidic aqueous solutions. The stability of the planar alumina samples toward oxidation by oxygen was checked in the wide ranges of gas pressure and sample temperature. The suggested procedure ensures the controlled and reproducible preparation of thin alumina films – model support appropriate for wet chemistry catalyst preparation, suitable for STM and for other Surface Science techniques studies of alumina supported metal catalysts.

  14. Perlite as a potential support for nickel catalyst in the process of sunflower oil hydrogenation

    Science.gov (United States)

    Radonjić, V.; Krstić, J.; Lončarević, D.; Jovanović, D.; Vukelić, N.; Stanković, M.; Nikolova, D.; Gabrovska, M.

    2015-12-01

    Investigation was conducted in order to elucidate the possibility of using perlite as support for preparation of nickel based precursor catalyst, potentially applicable in vegetable oil hydrogenation process. On three differently prepared expanded perlite, nickel catalyst precursors with identical Ni/SiO2 = 1.1 and Ni/Mg = 10/1 ratios were synthesized by precipitation-deposition method. Different techniques, SEM micrography, He-pycnometry, calcimetry, Hg-porosimetry, N2-physisorption, H2-chemisorption and temperature programmed reduction, were used for characterization of obtained samples. Determining the precursor texture, morphology and reducibility shows a successfully deposited nickel phase on perlite support with promising properties for vegetable oil hydrogenation. Chosen precursor was reduced and passivated in paraffin oil and the obtained catalyst showed significant catalytic activity in the test of sunflower oil hydrogenation.

  15. Ni supported on activated carbon as catalyst for flue gas desulfurization

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    A series of Ni supported on activated carbon are prepared by excessive impregnation and the desulfurization activity is investigated. It has been shown that the activated carbon-supported Ni is an efficient solid catalyst for flue gas desulfurization. The activated carbon treated by HNO3 exhibits high desulfurization activity, and different amounts of loaded-Ni on activated carbon significantly influence the desulfurization activity. The catalysts are studied by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The results of XRD and XPS indicate that the activated carbon treated by HNO3 can increase oxygen-containing functional groups. Ni on activated carbon after calcination at 800 °C shows major Ni phase and minor NiO phase, and with increasing Ni content on activated carbon, Ni phase increases and affects the desulfurization activity of the catalyst, which proves that Ni is the main active phase.

  16. Selective Oxidation of Isobutane to Methacrylic Acid over Supported V-Mo-P Based Composite Oxide Catalysts

    Institute of Scientific and Technical Information of China (English)

    Feifei Sun; Yunfeng Geng; Shunhe Zhong

    2002-01-01

    Heteropolyacid, the most popular catalyst for the direct oxidation of isobutane, exhibits high catalytic activity, poor thermal stability and a short lifetime. Therefore, the catalyst requires further research to improve its performance. Catalysts composed of mixed oxides (V2O5, P2O5, or MoO3) supported on silica were prepared by the sol-gel method to catalyze the reaction. Results of XRD, IR, and BET corroborated that the mixed oxides were dispersed homogeneously on the surface of support. The activity of lattice oxygen in the catalysts was studied by TPR, and the chemisorption property of isobutane on the surface of the catalysts was investigated by the TPD method. H2-TPR of the catalysts revealed that the lattice oxygen of the vanadium-based catalysts is more active than that of the molybdenum-based catalysts. The rcdox property of V or Mo species is slightly affected by other compositions of the series catalysts. The TPD curves illustrate that there are two kinds of adsorptive species of isobutane on the surface of the V and Mo based catalysts. The adsorbing species on the VMoP/SiO2 catalyst are identical to the main adsorbing species on VP/SiO2 and MoP/SiO2. The catalyst VMoP/SiO2 is more active than others in the selective oxidation of isobutane.

  17. Highly active and stable platinum catalyst supported on porous carbon nanofibers for improved performance of PEMFC

    International Nuclear Information System (INIS)

    Porous carbon nanofibers (PCNFs) were used as the support to prepare platinum (Pt) catalyst (Pt/PCNFs) for proton exchange membrane fuel cell (PEMFC) applications. As a comparison, Pt supported on carbon black (Vulcan XC-72) (Pt/Vulcan) was also synthesized by the same ethylene glycol reduction method. Platinum was more uniformly deposited on PCNFs than that on the Vulcan XC-72. The electrocatalytic activity and stability of the resultant catalysts along with the commercial one (JM20) were investigated using cyclic voltammetry (CV) and linear sweep voltammetry (LSV) with a rotating disk electrode (RDE). The Pt/PCNFs exhibited much-enhanced electrocatalytic activity and stability compared with the Pt/Vulcan and JM20. The mass activity (at 0.80 V) of Pt/PCNFs is 2.6 times higher and 20% higher than that of Pt/Vulcan and JM20, respectively; the Pt/PCNFs retained about 50% of ECSA whereas JM20 and Pt/Vulcan kept only 25% and 5% of ECSA, respectively, even after 1000 cycles. Furthermore, the single cell performance of Pt/PCNFs was superior to that of Pt/Vulcan and even better than JM20 during high current densities. The cross-section of the membrane electrode assembly (MEA) showed that the Pt/PCNFs construct a loose three-dimensionally connected catalyst layer that is totally different from the tightly stacking catalyst layer composed of carbon black support. Thus, the mass transfer resistance is reduced and water drainage becomes easy when Pt/PCNFs were used as cathode catalyst. These results indicate PCNFs a promising candidate as catalyst supports for the enhancement of PEMFC performance

  18. A Review on Metal-support Interaction in Automotive Catalysts

    Institute of Scientific and Technical Information of China (English)

    ZHENG Tingting; HE Junjun; WANG Song; LU Jun; ZHAO Yunkun

    2012-01-01

    TWC-equipped exhausts are widely used in gasoline-fueled vehicles to meet stringent emission regulations.The main components in TWCs are precious metals such as palladium (Pd),platinum (Pt),and rhodium (Rh) as the active component,and inorganic oxides such as γ-alumina (Al2O3),ceria (CeO2),zirconia (ZrO2) and ceria-zirconia (CeO2-ZrO2) are used as the support.Interaction of precious metals and support plays an important role in the thermal stability and catalytic performance of TWCs.The support can improve the dispersion of precious metals and suppress the sintering of precious metals at high temperature.In the same,precious metals can also enhance the redox performance and oxygen storage capacity of support.This paper reviews the reaction phenomenon and mechanism of precious metals (Pt,Pd,Rh) and supports such as Al2O3,CeO2-based composite oxides.

  19. Study of different nanostructured carbon supports for fuel cell catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Mirabile Gattia, Daniele; Antisari, Marco Vittori; Giorgi, Leonardo; Marazzi, Renzo; Montone, Amelia [Department of Physical Methods and Materials, ENEA, Research Centre of Casaccia, Via Anguillarese 301, 00123 Rome (Italy); Piscopiello, Emanuela [Department of Physical Methods and Materials, ENEA, Research Centre of Brindisi, Via Appia Km 702, 72100 Brindisi (Italy); Bellitto, Serafina; Licoccia, Silvia; Traversa, Enrico [Dipartimento di Scienze e Tecnologie Chimiche, Universita di Roma ' ' Tor Vergata' ' , Via della Ricerca Scientifica, 00133 Rome (Italy)

    2009-10-20

    Pt clusters were deposited by an impregnation process on three carbon supports: multi-wall carbon nanotubes (MWNT), single-wall carbon nanohorns (SWNH), and Vulcan XC-72 carbon black to investigate the effect of the carbon support structure on the possibility of reducing Pt loading on electrodes for direct methanol (DMFC) fuel cells without impairing performance. MWNT and SWNH were in-house synthesised by a DC and an AC arc discharge process between pure graphite electrodes, respectively. UV-vis spectrophotometry, scanning and transmission electron microscopy, X-ray diffraction, and cyclic voltammetry measurements were used to characterize the Pt particles deposited on the three carbon supports. A differential yield for Pt deposition, not strictly related to the surface area of the carbon support, was observed. SWNH showed the highest surface chemical activity toward Pt deposition. Pt deposited in different forms depending on the carbon support. Electrochemical characterizations showed that the Pt nanostructures deposited on MWNT are particularly efficient in the methanol oxidation reaction. (author)

  20. Sintering-Resistant Single-Site Nickel Catalyst Supported by Metal-Organic Framework.

    Science.gov (United States)

    Li, Zhanyong; Schweitzer, Neil M; League, Aaron B; Bernales, Varinia; Peters, Aaron W; Getsoian, Andrew Bean; Wang, Timothy C; Miller, Jeffrey T; Vjunov, Aleksei; Fulton, John L; Lercher, Johannes A; Cramer, Christopher J; Gagliardi, Laura; Hupp, Joseph T; Farha, Omar K

    2016-02-17

    Developing supported single-site catalysts is an important goal in heterogeneous catalysis since the well-defined active sites afford opportunities for detailed mechanistic studies, thereby facilitating the design of improved catalysts. We present herein a method for installing Ni ions uniformly and precisely on the node of a Zr-based metal-organic framework (MOF), NU-1000, in high density and large quantity (denoted as Ni-AIM) using atomic layer deposition (ALD) in a MOF (AIM). Ni-AIM is demonstrated to be an efficient gas-phase hydrogenation catalyst upon activation. The structure of the active sites in Ni-AIM is proposed, revealing its single-site nature. More importantly, due to the organic linker used to construct the MOF support, the Ni ions stay isolated throughout the hydrogenation catalysis, in accord with its long-term stability. A quantum chemical characterization of the catalyst and the catalytic process complements the experimental results. With validation of computational modeling protocols, we further targeted ethylene oligomerization catalysis by Ni-AIM guided by theoretical prediction. Given the generality of the AIM methodology, this emerging class of materials should prove ripe for the discovery of new catalysts for the transformation of volatile substrates. PMID:26836273

  1. Hydrogen production from biomass gasification using biochar as a catalyst/support.

    Science.gov (United States)

    Yao, Dingding; Hu, Qiang; Wang, Daqian; Yang, Haiping; Wu, Chunfei; Wang, Xianhua; Chen, Hanping

    2016-09-01

    Biochar is a promising catalyst/support for biomass gasification. Hydrogen production from biomass steam gasification with biochar or Ni-based biochar has been investigated using a two stage fixed bed reactor. Commercial activated carbon was also studied as a comparison. Catalyst was prepared with an impregnation method and characterized by X-ray diffraction, specific surface and porosity analysis, X-ray fluorescence and scanning electron micrograph. The effects of gasification temperature, steam to biomass ratio, Ni loading and bio-char properties on catalyst activity in terms of hydrogen production were explored. The Ni/AC catalyst showed the best performance at gasification temperature of 800°C, S/B=4, Ni loading of 15wt.%. Texture and composition characterization of the catalysts suggested the interaction between volatiles and biochar promoted the reforming of pyrolysis volatiles. Cotton-char supported Ni exhibited the highest activity of H2 production (64.02vol.%, 92.08mgg(-1) biomass) from biomass gasification, while rice-char showed the lowest H2 production. PMID:27240230

  2. Sintering-resistant Single-Site Nickel Catalyst Supported by Metal-Organic Framework

    Energy Technology Data Exchange (ETDEWEB)

    Li, Zhanyong; Schweitzer, Neil; League, Aaron; Bernales Candia, Sandra Varinia; Peters, Aaron; Getsoian, Andrew G.; Wang, Timothy; Miller, Jeffrey T.; Vjunov, Aleksei; Fulton, John L.; Lercher, Johannes A.; Cramer, Christopher J.; Gagliardi, Laura; Hupp, Joseph; Farha, Omar

    2016-02-17

    Developing supported single-site catalysts is an important goal in heterogeneous catalysis, since the well-defined active sites afford opportunities for detailed mechanistic studies, thereby facilitating the design of improved catalysts. We present herein a method for installing Ni ions uniformly and precisely on the node of a Zr-based MOF, NU-1000, in high density and large quantity (denoted as Ni-AIM) using atomic layer deposition (ALD) in a metal–organic framework (MOF) (AIM). Ni-AIM is demonstrated to be an efficient gas-phase hydrogenation catalyst upon activation. The structure of the active sites in Ni-AIM is proposed, revealing its single-site nature. More importantly, due to the organic linker used to construct the MOF support, the Ni ions stay isolated throughout the hydrogenation catalysis, in accord with its long-term stability. A quantum chemical characterization of the catalyst and the catalytic process complements the experimental results. With validation of computational modeling protocols, we further targeted ethylene oligomerization catalysis by Ni-AIM guided by theoretical prediction. Given the generality of the AIM methodology, this emerging class of materials should prove ripe for the discovery of new catalysts for the transformation of volatile substrates.

  3. Characterization of Pt catalysts supported in mixed oxides

    International Nuclear Information System (INIS)

    The catalytic supports TiO2, ZrO2 and TiO2-ZrO2 were prepared by the sol-gel technique. The incorporation of Pt to the supports was by the classical impregnation method. The catalytic materials were characterized (Pt/TiO2, Pt/ZrO2 and Pt/TiO2-ZrO2) by diverse techniques to determine: the texture (BET), evolution of the catalytic materials synthesised after drying and calcination (Infrared spectroscopy) and by Thermogravimetric analysis. (Author)

  4. A combined in situ XAS-XRPD-Raman study of Fischer-Tropsch synthesis over a carbon supported Co catalyst

    DEFF Research Database (Denmark)

    Tsakoumis, Nikolaos E.; Dehghan, Roya; Johnsen, Rune;

    2013-01-01

    A cobalt based Fischer-Tropsch synthesis (FTS) catalyst, supported on a carbon nanofibers/carbon felt composite (Co/CNF/CF) was studied in situ at realistic conditions. The catalyst was monitored by Xray absorption spectroscopy (XAS), high-resolution X-ray powder diffraction (HR-XRPD) and Raman...... spectroscopy, while changes in the gas phase were observed by mass spectrometry (MS). Transmission electron microscopy (TEM) was also applied to characterise the catalyst. The catalyst has a bimodal particle size distribution and exhibits a high deactivation rate. During the in situ study the catalyst appears...

  5. Magnetically Recoverable Supported Ruthenium Catalyst for Hydrogenation of Alkynes and Transfer Hydrogenation of Carbonyl Compounds

    Science.gov (United States)

    A ruthenium (Ru) catalyst supported on magnetic nanoparticles (NiFe2O4) has been successfully synthesized and used for hydrogenation of alkynes at room temperature as well as transfer hydrogenation of a number of carbonyl compounds under microwave irradiation conditions. The cata...

  6. Carboxylic Group Embedded Carbon Balls as a New Supported Catalyst for Hydrogen Economic Reactions.

    Science.gov (United States)

    Bordoloi, Ankur

    2016-03-01

    Carboxylic group functionalized carbon balls have been successfully synthesized by using a facile synthesis method and well characterized with different characterization techniques such as XPS, MAS NMR, SEM, ICP and N2 physi-sorption analysis. The synthesized material has been effectively utilized as novel support to immobilized ruthenium catalyst for hydrogen economic reactions. PMID:27455763

  7. X-Ray Absorption Characterization of Supported Palladium Catalysts : A Comparison with Hydrogen Chemisorption

    OpenAIRE

    Zhang, G.; Habib, M; Vittoratos, S.

    1997-01-01

    X-ray absorption spectroscopy was used to characterize the supported palladium hydrocracking catalysts. Results with regard to the percentage of metal exposed are compared with those from hydrogen chemisorption measurements. Results from XAS indicate that hydrogen chemisorption has underestimated the metal dispersion. Possible explanations for this discrepancy are discussed.

  8. Aerobic oxidation of aldehydes under ambient conditions using supported gold nanoparticle catalysts

    DEFF Research Database (Denmark)

    Marsden, Charlotte Clare; Taarning, Esben; Hansen, David;

    2008-01-01

    A new, green protocol for producing simple esters by selectively oxidizing an aldehyde dissolved in a primary alcohol has been established, utilising air as the oxidant and supported gold nanoparticles as catalyst. The oxidative esterifications proceed with excellent selectivities at ambient...

  9. TiO2 Nanotubes Supported NiW Hydrodesulphurization Catalysts: Characterization and Activity

    Czech Academy of Sciences Publication Activity Database

    Palcheva, R.; Dimitrov, L.; Tyuliev, G.; Spojakina, A.; Jirátová, Květa

    2013-01-01

    Roč. 265, JAN 15 (2013), s. 309-313. ISSN 0169-4332 Institutional support: RVO:67985858 Keywords : nano-structured TiO2 * NiW catalysts * XPS Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 2.538, year: 2013

  10. Calcium Oxide Supported on Monoclinic Zirconia as a Highly Active Solid Base Catalyst

    NARCIS (Netherlands)

    Frey, A.M.; Haasterecht, van T.; Jong, de K.P.; Bitter, J.H.

    2013-01-01

    Calcium oxide supported on ZrO2 is a highly active catalyst for base-catalyzed reactions such as aldol-type reactions and transesterification reactions. The role of key parameters during preparation, that is, impregnation versus precipitation, heat treatment, and metal oxide loading on the basicity

  11. Oxygen reduction on carbon supported platinum catalysts in high temperature polymer electrolytes

    DEFF Research Database (Denmark)

    Qingfeng, Li; Bergqvist, R. S.; Hjuler, H. A.;

    1999-01-01

    Oxygen reduction on carbon supported platinum catalysts has been investigated in H3PO4, H3PO4-doped Nafion and PBI polymer electrolytes in a temperature range from 80 to 190°C. Compared with pure H3PO4, using the H3PO4 doped Nafion and PBI polymer electrolytes can significantly improve the oxygen...

  12. Selective oxidation of methyl alpha-d-glucoside on carbon supported platinum catalysts. Doctoral thesis

    Energy Technology Data Exchange (ETDEWEB)

    Schuurman, Y.

    1992-01-27

    The selective oxidation of methyl alpha-D-glucoside to sodium 1-O-methyl alpha-D-glucuronate by molecular oxygen on supported platinum was studied in a three-phase agitated tank reactor. Emphasis was put on the intrinsic kinetics and on the catalyst deactivation during oxidation. The obtained results were applied to the design of an industrial production unit.

  13. Phosphite Ligand Modified Supported Rhodium Catalyst for Hydroformylation of Internal Olefins to Linear Aldehydes

    Institute of Scientific and Technical Information of China (English)

    LI Xian-ming; DING Yun-jie; JIAO Gui-ping; LI Jing-wei; YAN Li; ZHU He-jun

    2009-01-01

    A phosphite ligand modified heterogeneous catalyst was developed for the hydroformylation of internal olefins to linear aldehydes, which showed a high activity and high regioselectivity and could be separated easily by filtration after reaction in an autoclave. Three nanoporous silica sieves were used to investigate the influence of pore structure and shape selective performance of support on the regioselectivity to the linear products.

  14. Core–shell nanostructure supported Pt catalyst with improved electrocatalytic stability in oxygen reduction reaction

    International Nuclear Information System (INIS)

    Core–shell nanostructure electrode (TiO2@C) for oxygen reduction reaction is prepared with TiO2 nanoparticles at 900 °C in a methane atmosphere. The TiO2@C supported Pt catalyst (Pt/TiO2@C) contains Pt nanoparticles on TiO2@C nanostructure electrodes consisting of TiO2 as a core and carbon as a shell. In the accelerated stability test, the Pt/TiO2@C exhibits a superior ORR stability to conventional carbon supported Pt catalyst. It is likely that the enhanced catalytic properties of the nanostructure supported Pt catalyst may be due to graphite-like carbon and an improved electronic conductivity of the core–shell nanostructure. Highlights: ► We synthesize core–shell nanostructure support (TiO2@C) for oxygen reduction reaction. ► The Pt/TiO2@C shows an excellent ORR activity in comparison with Pt/C. ► The Pt catalyst on TiO2@C exhibits a superior ORR stability to Pt/C.

  15. Catalysts Supported on Carbon Materials for the Selective Hydrogenation of Citral

    Directory of Open Access Journals (Sweden)

    Agustín F. Pérez-Cadenas

    2013-10-01

    Full Text Available The heterogeneously catalyzed selective-hydrogenation of citral is one of the more feasible ways for obtaining its appreciated unsaturated-alcohols, nerol and geraniol, which are present in over 250 essential oils. Thus, citral has very recently come to be produced petro-chemically in very large quantities, and so partial hydrogenation of citral has become a very economical route for the production of these compounds. However, the selective hydrogenation of citral is not easy, because citral is an α,β-unsaturated aldehyde which possesses three double bonds that can be hydrogenated: an isolated C=C bond and the conjugated C=O and C=C bonds. For this reason, in catalyst selection there are several important issues which affect the product selectivity, for example, the active metal and metal particle size which are factors related to the catalyst preparation method, catalyst precursor, or support surface area, as well as other factors such as porosity, the addition of a second catalytic metal, and, of course, the type of catalyst support. About this last one, carbon materials are very interesting supports for this type of hydrogenation reaction due to their unique chemical and textural properties. This review collects and analyzes the results obtained in the selective hydrogenation of citral catalyzed by carbon material supported metals.

  16. Synergy between metals in bimetallic zeolite supported catalyst for NO-promoted N2O decomposition

    NARCIS (Netherlands)

    Pieterse, J.A.Z.; Mul, G.; Melian-Cabrera, I.; van den Brink, R.W.

    2005-01-01

    The detrimental effect of NO on N2O decomposition over zeolite supported noble metal catalysts can be (partly) eliminated by combining noble metal with iron or cobalt. In the presence of NO, the total conversion of N2O over these bimetallic-zeolites exceeds the sum of conversions over the monometall

  17. 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; Engelbrekt, Christian; Riisager, Anders

    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...

  18. Stability of cobalt supported on ZrO{sub 2} catalysts for methane combustion

    Energy Technology Data Exchange (ETDEWEB)

    Milt, V.G.; Lombardo, E.A.; Ulla, M.A. [Instituto de Investigaciones en Catalisis y Petroquimica, INCAPE FIQ, UNL-CONICET, Santiago del Estero 2829, 3000 Santa Fe (Argentina)

    2002-04-08

    Cobalt supported catalysts were prepared by two different techniques: atomic layer epitaxy (ALE) and wet impregnation. Either ZrO{sub 2} or La/ZrO{sub 2} (La-doped ZrO{sub 2}) were used as supports. The solids were characterized by XRD, TPR and XPS before and after hydrothermal and catalytic stability tests (TOS: 150h, 970K). The most active catalysts were those in which cobalt was incorporated using the epitaxial growth technique. Moreover, the initial activity of cobalt supported on ZrO{sub 2} by ALE was significantly higher than that on La/ZrO{sub 2}. But, after maintaining the former catalysts for 150h at 970K on stream (stability test), their initial high activities significantly decreased. On the other hand, when Co was supported on La-doped ZrO{sub 2} the resulting catalysts became much more stable. Combining the catalytic results with the characterization information a simple model is proposed that rationalizes the behavior of these solids.

  19. Strategies for designing supported gold-palladium bimetallic catalysts for the direct synthesis of hydrogen peroxide.

    Science.gov (United States)

    Edwards, Jennifer K; Freakley, Simon J; Carley, Albert F; Kiely, Christopher J; Hutchings, Graham J

    2014-03-18

    Hydrogen peroxide is a widely used chemical but is not very efficient to make in smaller than industrial scale. It is an important commodity chemical used for bleaching, disinfection, and chemical manufacture. At present, manufacturers use an indirect process in which anthraquinones are sequentially hydrogenated and oxidized in a manner that hydrogen and oxygen are never mixed. However, this process is only economic at a very large scale producing a concentrated product. For many years, the identification of a direct process has been a research goal because it could operate at the point of need, producing hydrogen peroxide at the required concentration for its applications. Research on this topic has been ongoing for about 100 years. Until the last 10 years, catalyst design was solely directed at using supported palladium nanoparticles. These catalysts require the use of bromide and acid to arrest peroxide decomposition, since palladium is a very active catalyst for hydrogen peroxide hydrogenation. Recently, chemists have shown that supported gold nanoparticles are active when gold is alloyed with palladium because this leads to a significant synergistic enhancement in activity and importantly selectivity. Crucially, bimetallic gold-based catalysts do not require the addition of bromide and acids, but with carbon dioxide as a diluent its solubility in the reaction media acts as an in situ acid promoter, which represents a greener approach for peroxide synthesis. The gold catalysts can operate under intrinsically safe conditions using dilute hydrogen and oxygen, yet these catalysts are so active that they can generate peroxide at commercially significant rates. The major problem associated with the direct synthesis of hydrogen peroxide concerns the selectivity of hydrogen usage, since in the indirect process this factor has been finely tuned over decades of operation. In this Account, we discuss how the gold-palladium bimetallic catalysts have active sites for the

  20. TiO2-Supported Iron-Molybdenum Hydrodesulfurization Catalysts

    Czech Academy of Sciences Publication Activity Database

    Spojakina, A.A.; Kraleva, E.; Jirátová, Květa; Petrov, L.

    2005-01-01

    Roč. 288, 1-2 (2005), s. 10-17. ISSN 0926-860X Institutional research plan: CEZ:AV0Z40720504 Keywords : heteroplycompounds * titania support * hydrodesulfurization Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 2.728, year: 2005

  1. Recent Applications of Polymer Supported Organometallic Catalysts in Organic Synthesis

    Directory of Open Access Journals (Sweden)

    Nina Kann

    2010-09-01

    Full Text Available Recent developments concerning the application of polymer supported organometallic reagents in solid phase synthesis are reviewed, with a special focus on methodology for carbon-carbon formation. Examples of reactions that are covered include the classical Suzuki, Sonogashira and Heck coupings, but also aryl amination, epoxide opening, rearrangements, metathesis and cyclopropanation. Applications in the field of asymmetric synthesis are also discussed.

  2. Highly Loaded Carbon Black Supported Pt Catalysts for Fuel Cells

    Czech Academy of Sciences Publication Activity Database

    Kaluža, Luděk; Larsen, M.J.; Zdražil, Miroslav; Gulková, Daniela; Vít, Zdeněk; Šolcová, Olga; Soukup, Karel; Koštejn, Martin; Bonde, J.L.; Maixnerová, Lucie; Odgaard, M.

    2015-01-01

    Roč. 256, NOV 1 (2015), s. 375-383. ISSN 0920-5861 R&D Projects: GA MŠk(CZ) 7HX13003 EU Projects: European Commission(XE) 303466 - IMMEDIATE Institutional support: RVO:67985858 Keywords : carbon black * fuell cell * electrocatalyst Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 3.893, year: 2014

  3. HDS, HDN and HDA activities of nickel-molybdenum catalysts supported on alumina

    Energy Technology Data Exchange (ETDEWEB)

    Dominguez-Crespo, M.A. [Instituto Mexicano del Petroleo, Programa de Tratamiento de Crudo Maya. Avenida Eje Central Lazaro Cardenas No.152, Col. San Bartolo Atepehuacan, 07730, Mexico D. F. (Mexico); Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada (CICATA-Altamira, IPN) Km 14.5 Carretera Tampico-puerto Industrial 89600, Altamira, Tamaulipas (Mexico); Torres-Huerta, A.M.; Ramirez-Meneses, E. [Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada (CICATA-Altamira, IPN) Km 14.5 Carretera Tampico-puerto Industrial 89600, Altamira, Tamaulipas (Mexico); Diaz-Garcia, L. [Instituto Mexicano del Petroleo, Programa de Tratamiento de Crudo Maya. Avenida Eje Central Lazaro Cardenas No.152, Col. San Bartolo Atepehuacan, 07730, Mexico D. F. (Mexico); Arce-Estrada, E.M. [Instituto Politecnico Nacional, Departamento de Metalurgia y Materiales. A.P. 75-876, 07300 Mexico, D. F. (Mexico)

    2008-08-15

    In this work, NiMo-Al{sub 2}O{sub 3} catalysts were prepared by using different alumina precursors. The supports were impregnated by means of the spray at incipient wetness technique in both basic and acid media. Both the supports and fresh catalysts were characterized by the adsorption-desorption isotherms, Temperature-Programmed Reduction (TPR), Thermal Pyridine Adsorption-Desorption (TPD) and X-Ray Diffraction analyses (XRD). After sulfidation, the NiMoS metallic particles were characterized by Transmission Electron Microscopy (TEM). The initial analyses were performed in a trickle-bed reactor by using a real feedstock (Mexican heavy gas oil) and performing hydrotreating reactions (HDS, HDN and HDA) at three different temperatures: 613, 633 and 653 K; and 54 kg cm{sup -} {sup 2}. The catalytic activities are discussed in relation to the physicochemical properties of the NiMo catalysts, alumina phase and pH of the impregnating solution. The catalytic results show an increase in the conversion profiles with temperature. The sulfur conversion was increased from 89 to 99.25%, 91-99%, 90.8-97%, 83-95% and 78-96% when the crystal size of the support varied from 3 to 20 nm, respectively. The nitrogen and aromatic conversions were also increased in the range of 23-45 wt.%. It was found that the {gamma} phase reached a higher catalytic performance than the {eta} phase. The NiMo catalysts synthesized in a basic medium showed a better catalytic performance than that obtained with those prepared in acid solutions. The significance of the kinetic data to compare the catalysts is discussed. The maximum value of the catalytic activity was reached with the catalysts with the smallest particle sizes. (author)

  4. Ultrastable single-atom gold catalysts with strong covalent metal-support interaction (CMSI)

    Institute of Scientific and Technical Information of China (English)

    Botao Qiao[1; Jin-Xia Liang[3,4; Aiqin Wang[2; Cong-Qiao Xu[3; Jun Li[3; Tao Zhang[2; Jingyue (Jimmy) Liu[1

    2015-01-01

    Supported noble metal nanoparticles (including nanoclusters) are widely used in many industrial catalytic processes. While the finely dispersed nanostructures are highly active, they are usually thermodynamically unstable and tend to aggregate or sinter at elevated temperatures. This scenario is particularly true for supported nanogold catalysts because the gold nanostructures are easily sintered at high temperatures, under reaction conditions, or even during storage at ambient temperature. Here, we demonstrate that isolated Au single atoms dispersed on iron oxide nanocrystallites (Aul/FeOx) are much more sintering- resistant than Au nanostructures, and exhibit extremely high reaction stability for CO oxidation in a wide temperature range. Theoretical studies revealed that the positively charged and surface-anchored Aul atoms with high valent states formed significant covalent metal-support interactions (CMSIs), thus providing the ultra-stability and remarkable catalytic performance. This work may provide insights and a new avenue for fabricating supported Au catalysts with ultra-high stability.

  5. Preparation of Hydrodesulfurization Magnesia Supported Cobalt-Molybdenum Catalysts

    Czech Academy of Sciences Publication Activity Database

    Kaluža, Luděk; Gulková, Daniela; Vít, Zdeněk; Zdražil, Miroslav

    Prague: J. Heyrovský Institute of Physical Chemistry of ASCR, v.v.i, 2014 - (Žilková, N.; Horáček, M.), Po43 ISBN 978-80-87351-34-5. [Symposium on Catalysis /46./. Prague (CZ), 03.11.2014-05.11.2014] R&D Projects: GA ČR GAP106/11/0902 Institutional support: RVO:67985858 Keywords : hydrodesulfurization * Magnesia * Cobalt-Molybdenum Subject RIV: CF - Physical ; Theoretical Chemistry

  6. Oxygen Assisted Dehydrogenation of Ethane over Alumina Supported Pt-Sn Catalysts

    OpenAIRE

    Radstake, Paul B.

    2012-01-01

    The oxygen-assisted dehydrogenation of ethane (ODE) over supported Pt-Sn catalysts seems to be a promising alternative for the conventional steam cracking of ethane for the production of ethylene. However, despite the fact that much research has been performed on this catalytic system during the last years, little is known about the precise role of the Pt-Sn catalyst on the overall product distribution.The focus of this research work lay therefore on gaining a better understanding of the role...

  7. Synthesis of Carbon Nano tubes Using Anadara Granosa Shells as Catalyst Support

    International Nuclear Information System (INIS)

    The synthesis of carbon nano tubes (CNTs) by chemical vapor deposition (CVD) method using natural calcite prepared from Anadara granosa shells (CS), as metal catalyst support was studied. Hexane and iron were used as carbon precursor and catalyst, respectively. The as synthesised CNTs was characterized using XRD, TEM and FESEM. From the XRD patterns the CNTs peak can be seen more incisive after purification process and from the FESEM micrographs the CNTs can be seen as a bunch of rope-like structures. (author)

  8. Healthy cities as catalysts for caring and supportive environments.

    Science.gov (United States)

    Green, Geoff; Jackisch, Josephine; Zamaro, Gianna

    2015-06-01

    'Caring and Supportive Environments' are fundamental to a social model of health and were a core theme of Phase V (2009-13) of the WHO European Healthy Cities Network. Deploying the methodology of realist evaluation, this article synthesizes qualitative evidence from 112 highly structured case studies from 68 Network cities and 71 responses to a General Evaluation Questionnaire, which asked cities to analyze city attributes and trends. A schematic model was developed to describe the interaction between action targeted toward children, migrants, older people and action on social and health services, health literacy and active citizenship-the six subtopics clustered within the theme Caring and Supportive Environments. Four hypotheses were tested: (i) there are prerequisites and processes of local governance that increase city capacity for creating supportive environments; (ii) investing in health and social services, active citizenship and health literacy enhance the social inclusion of vulnerable population groups; (iii) there are synergies between social investment and healthy urban planning; and (iv) these investments promote greater equity in health. The evaluation revealed many innovative practices. Providers of health and social services have developed partnerships with agencies influencing wider determinants of health. Health literacy campaigns address the wider context of people's lives. In a period of economic austerity, cities have utilized the social assets of their citizens. Realist evaluation can help illuminate the pathways from case study interventions to health outcomes, and the prerequisites and processes required to initiate and sustain such investments. PMID:26069322

  9. An Efficient and Recyclable Nanoparticle-Supported Cobalt Catalyst for Quinoxaline Synthesis

    Directory of Open Access Journals (Sweden)

    Fatemeh Rajabi

    2015-11-01

    Full Text Available The syntheses of quinoxalines derived from 1,2-diamine and 1,2-dicarbonyl compounds under mild reaction conditions was carried out using a nanoparticle-supported cobalt catalyst. The supported nanocatalyst exhibited excellent activity and stability and it could be reused for at least ten times without any loss of activity. No cobalt contamination could be detected in the products by AAS measurements, pointing to the excellent activity and stability of the Co nanomaterial.

  10. Supported Co-Mn-Al Mixed Oxides as Catalysts for N2O Decomposition.

    Czech Academy of Sciences Publication Activity Database

    Pacultová, K.; Karásková, C.; Strakošová, J.; Jirátová, Květa; Obalová, L.

    2015-01-01

    Roč. 18, č. 20 (2015), s. 1114-1122. ISSN 1631-0748. [AWPAC2014 - International Symposium on Air & Water Pollution Abatement Catalysis. Krakow, 01.09.2014-05.09.2014] R&D Projects: GA ČR GA14-13750S Institutional support: RVO:67985858 Keywords : supported catalysts * heterogeneous catalysis * spinel phase * nitrogen oxides Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 1.713, year: 2014

  11. Fundamental Studies of the Reforming of Oxygenated Compounds over Supported Metal Catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Dumesic, James

    2016-01-04

    The main objective of our research has been to elucidate fundamental concepts associated with controlling the activity, selectivity, and stability of bifunctional, metal-based heterogeneous catalysts for tandem reactions, such as liquid-phase conversion of oxygenated hydrocarbons derived from biomass. We have shown that bimetallic catalysts that combine a highly-reducible metal (e.g., platinum) with an oxygen-containing metal promoter (e.g., molybdenum) are promising materials for conversion of oxygenated hydrocarbons because of their high activity for selective cleavage for carbon-oxygen bonds. We have developed methods to stabilize metal nanoparticles against leaching and sintering under liquid-phase reaction conditions by using atomic layer deposition (ALD) to apply oxide overcoat layers. We have used controlled surface reactions to produce bimetallic catalysts with controlled particle size and controlled composition, with an important application being the selective conversion of biomass-derived molecules. The synthesis of catalysts by traditional methods may produce a wide distribution of metal particle sizes and compositions; and thus, results from spectroscopic and reactions kinetics measurements have contributions from a distribution of active sites, making it difficult to assess how the size and composition of the metal particles affect the nature of the surface, the active sites, and the catalytic behavior. Thus, we have developed methods to synthesize bimetallic nanoparticles with controlled particle size and controlled composition to achieve an effective link between characterization and reactivity, and between theory and experiment. We have also used ALD to modify supported metal catalysts by addition of promoters with atomic-level precision, to produce new bifunctional sites for selective catalytic transformations. We have used a variety of techniques to characterize the metal nanoparticles in our catalysts, including scanning transmission electron

  12. Support effect on carbon nanotube growth by methane chemical vapor deposition on cobalt catalysts

    International Nuclear Information System (INIS)

    The influence of the support on carbon nanotube production by methane chemical vapor deposition (CVD) on cobalt catalysts was investigated. N2 physisorption, X-ray diffractometry (XRD), temperature programmed reduction (TPR) and H2 and CO chemisorption techniques were used to characterize the structure of cobalt catalysts supported on different metal oxides (Al2O3, SiO2, Nb2O5 and TiO2). Raman spectroscopy, temperature programmed oxidation (TPO) and scanning electron microscopy (SEM) were used for the characterization and quantification of produced carbon species. On carbon nanotube growth, the catalyst produced three main carbon species: amorphous carbon, single walled carbon nanotubes (SWNT) and multi walled carbon nanotubes (MWNT). The characterization techniques showed that the catalyst selectivity to each kind of nanotube depended on the cobalt particle size distribution, which was influenced by the textural properties of the support. Co/TiO2 showed the highest selectivity towards single wall nanotube formation. This high selectivity results from the narrow size distribution of cobalt particles on TiO2. (author)

  13. Inhibition effects in the partial oxidation of cyclohexane on polymer supported Co(II catalysts

    Directory of Open Access Journals (Sweden)

    MAJA ODOVIC

    2005-02-01

    Full Text Available Polymer supported catalysts with different contents of metal ions where synthesized by wet impregnation of the degassed support from ethanolic solutions of cobalt(II nitrate. Amacroreticular copolymer of poly-4-vinylpyridine with divinylbenzene was used as the support. The prepared catalysts were tested in the partial oxidation of cyclohexane to cyclohexanol and cyclohexanone. Activity tests were performed in a stainless steel, laboratory scale, stirred autoclave, in the semi batch regime under isothermal and non-isothermal conditions. Isothermal experiments where performed at 170 °C for 120 min. In the non-isothermal conditions. isothermal experiments where performed at 170 °C for 120 min. In the non-isothermal experiments, a constant heating rate of 0.3 degree/min was used in the range between 110 °C and 170 °C. Non-linear, least-squares analysis with the simplex optimization method and numerical simulation of the reaction model in each iterative step was used for the kinetic characterization of the process in a non-stationary, semi-batch regime. Apparent rate constants were obtained as an invariant measure of the catalytic system. Anon-linear effect of the content of metal ions on the reaction rate and on the ratio of the yield of the products was observed, which is attributed to a complex interactions between the reaction medium and the heterogeneous catalyst, including a catalyst-inhibition effect.

  14. In situ synthesis of nano clay filled polyethylene using polymer support metallocenes catalyst system

    International Nuclear Information System (INIS)

    In situ ethylene polymerizations were performed using bis(cyclopentadiene)titanium dichloride supported on poly ethersulfone as catalyst. The bis(cyclopentadiene)titanium dichloride supported on poly ethersulfone catalyst activity estimated by ethylene polymerization was 360 kg PE/mol Ti/h. During polymerization the fillers used were montmorillonite nano clays having surface modifications with 35-45 wt % dimethyl dialkyl(14-18)amine (FA) and 25-30 wt % trimethyl stearyl ammonium (FB). These fillers were pretreated with methylaluminoxine (MAO; co catalyst) for better dispersion onto the polymer matrix. The formation of polyethylene within the whole matrix was confirmed by FTIR studies. It was found that the nature of nano filler did not have any remarkable effect on the melting characteristics of the polymer. TGA study indicates that nano clay FB filled polyethylene has higher thermal stability than nano clay FA filled polyethylene. The melting temperature of the obtained polyethylenes was 142 degree C, which corresponds to that synthesized by the polyether sulfone supported catalyst. (author)

  15. Gold-supported cerium-doped NiOx catalysts for water oxidation

    Science.gov (United States)

    Ng, Jia Wei Desmond; García-Melchor, Max; Bajdich, Michal; Chakthranont, Pongkarn; Kirk, Charlotte; Vojvodic, Aleksandra; Jaramillo, Thomas F.

    2016-05-01

    The development of high-performance catalysts for the oxygen-evolution reaction (OER) is paramount for cost-effective conversion of renewable electricity to fuels and chemicals. Here we report the significant enhancement of the OER activity of electrodeposited NiOx films resulting from the combined effects of using cerium as a dopant and gold as a metal support. This NiCeOx–Au catalyst delivers high OER activity in alkaline media, and is among the most active OER electrocatalysts yet reported. On the basis of experimental observations and theoretical modelling, we ascribe the activity to a combination of electronic, geometric and support effects, where highly active under-coordinated sites at the oxide support interface are modified by the local chemical binding environment and by doping the host Ni oxide with Ce. The NiCeOx–Au catalyst is further demonstrated in a device context by pairing it with a nickel–molybdenum hydrogen evolution catalyst in a water electrolyser, which delivers 50 mA consistently at 1.5 V over 24 h of continuous operation.

  16. Gold Functionalized Supported Ionic Liquids Catalyst for CO Oxidation

    Directory of Open Access Journals (Sweden)

    Svetlana Ivanova

    2011-11-01

    Full Text Available The present study tries to give an insight to the combination of the homogeneous and heterogeneous catalytic properties in a new class of materials. Well dispersed gold nanoparticles on an ionic liquid layer supported on a mineral carrier have been prepared. This work is concentrated on the characterizations and understanding of the interactions between all the components of the catalytic system. The application of the materials in the reaction of oxidation of carbon monoxide shows rather unexpected results—a good catalytic activity completely independent of the temperature.

  17. Highly Loaded Carbon Black Supported Platinum Catalysts for Fuel Batteries

    Czech Academy of Sciences Publication Activity Database

    Kaluža, Luděk; Zdražil, Miroslav; Gulková, Daniela

    Prague: J. Heyrovský Institute of Physical Chemistry of ASCR, v.v.i, 2014 - (Žilková, N.; Horáček, M.), Po10 ISBN 978-80-87351-34-5. [Symposium on Catalysis /46./. Prague (CZ), 03.11.2014-05.11.2014] R&D Projects: GA MŠk(CZ) 7HX13003 EU Projects: European Commission(XE) 303466 - IMMEDIATE Institutional support: RVO:67985858 Keywords : Carbon Black * Platinum * fuel cell Subject RIV: CF - Physical ; Theoretical Chemistry

  18. Thermally Activated Palm Kernel Based Carbon as a Support for Edible Oil Hydrogenation Catalyst

    Directory of Open Access Journals (Sweden)

    Abdulmajid Alshaibani

    2013-01-01

    Full Text Available Activated carbon has distinctive properties as a support for hydrogenation catalysts. Thermally activated carbon has been prepared from palm kernel shell at 1073 K and placed under nitrogen flow for 2 h. It was impregnated by palladium using toluene solution of Pd (acac2. The Pd/C was reduced using a water solution of potassium borohydride (KBH4. The Pd-B/C was characterized by the Brunauer-Emmett-Teller surface area analysis (BET, scanning electron microscopy (SEM, transmission electron microscopy (TEM and inductively-coupled plasma mass spectrometry (ICP-MS. Pd-B/C was applied for sunflower oil hydrogenation at a temperature of 373 K, hydrogen pressure of 413.5 kPa and agitation of 1400 rpm for 1 h. Pd-B/C noticeably exhibited a higher overall catalyst activity in comparison to some recently published palladium catalysts.

  19. Alkaline ionic liquids applied in supported ionic liquid catalyst for selective hydrogenation of citral to citronellal

    Directory of Open Access Journals (Sweden)

    Eero eSalminen

    2014-02-01

    Full Text Available The challenge in preparation of ionic liquids containing a strong alkaline anion is to identify a suitable cation which can tolerate the harsh conditions induced by the anion. In this study, a commercial quaternary ammonium compound (quat benzalkonium [ADBA] (alkyldimethylbenzylammonium was used as a cation in the synthesis of different alkaline ionic liquids. In fact, the precursor, benzalkonium chloride, is a mixture of alkyldimethylbenzylammonium chlorides of various alkyl chain lengths and is commonly used in the formulation of various antiseptic products. The prepared ionic liquids were utilized as Supported Ionic Liquid Catalysts (SILCAs. Typically, a SILCA contains metal nanoparticles, enzymes or metal complexes in an ionic liquid layer which is immobilized on a solid carrier material such as an active carbon cloth (ACC. The catalysts were applied in the selective hydrogenation of citral to citronellal which is an important perfumery chemical. Interestingly, 70 % molar yield towards citronellal was achieved over a catalyst containing the alkaline ionic liquid benzalkonium methoxide.

  20. Alkaline ionic liquids applied in supported ionic liquid catalyst for selective hydrogenation of citral to citronellal

    Science.gov (United States)

    Salminen, Eero; Virtanen, Pasi; Mikkola, Jyri-Pekka

    2014-02-01

    The challenge in preparation of ionic liquids containing a strong alkaline anion is to identify a suitable cation which can tolerate the harsh conditions induced by the anion. In this study, a commercial quaternary ammonium compound (quat) benzalkonium [ADBA] (alkyldimethylbenzylammonium) was used as a cation in the synthesis of different alkaline ionic liquids. In fact, the precursor, benzalkonium chloride, is a mixture of alkyldimethylbenzylammonium chlorides of various alkyl chain lengths and is commonly used in the formulation of various antiseptic products. The prepared ionic liquids were utilized as Supported Ionic Liquid Catalysts (SILCAs). Typically, a SILCA contains metal nanoparticles, enzymes or metal complexes in an ionic liquid layer which is immobilized on a solid carrier material such as an active carbon cloth (ACC). The catalysts were applied in the selective hydrogenation of citral to citronellal which is an important perfumery chemical. Interestingly, 70 % molar yield towards citronellal was achieved over a catalyst containing the alkaline ionic liquid benzalkonium methoxide.

  1. Effect of Activated Carbon as a Support on Metal Dispersion and Activity of Ruthenium Catalyst for Ammonia Synthesis

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Ten kinds of activated carbon from different raw materials were used as supports to prepare ruthenium catalysts. N2 physisorption and CO chemisorption were carried out to investigate the pore size distribution and the ruthenium dispersion of the catalysts. It was found that the Ru dispersion of the catalyst was closely related to not only the texture of carbon support but also the purity of activated carbon. The activities of a series of the carbon-supported barium-promoted Ru catalysts for ammonia synthesis were measured at 425 ℃, 10.0 MPa and 10 000 h-1. The result shows that the same raw material activated carbon, with a high purity, high surface area, large pore volume and reasonable pore size distribution might disperse ruthenium and promoter sufficiently, which activated carbon as support, could be used to manufacture ruthenium catalyst with a high activity for ammonia synthesis. The different raw material activated carbon as the support would greatly influence the catalytic properties of the ruthenium catalyst for ammonia synthesis. For example, with coconut shell carbon(AC1) as the support, the ammonia concentration in the effluent was 13.17% over 4%Ru-BaO/AC1 catalyst, while with the desulfurized coal carbon(AC10) as the support, that in the effluent was only 1.37% over 4%Ru-BaO/AC10 catalyst.

  2. Carbon-Supported bimetallic Pd-Fe catalysts for vapor-phase hydrodeoxygenation of guaiacol

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Junming; Karim, Ayman M.; Zhang, He; Kovarik, Libor; Li, Xiaohong S.; Hensley, Alyssa; McEwen, Jean-Sabin; Wang, Yong

    2013-10-01

    Abstract Carbon supported metal catalysts (Cu/C, Fe/C, Pd/C, Pt/C, PdFe/C and Ru/C) have been prepared, characterized and tested for vapor-phase hydrodeoxygenation (HDO) of guaiacol (GUA) at atmospheric pressure. Phenol was the major intermediate on all catalysts. Over the noble metal catalysts saturation of the aromatic ring was the major pathway observed at low temperature (250 °C), forming predominantly cyclohexanone and cyclohexanol. Substantial ring opening reaction was observed on Pt/C and Ru/C at higher reaction temperatures (e.g., 350 °C). Base metal catalysts, especially Fe/C, were found to exhibit high HDO activity without ring-saturation or ring-opening with the main products being benzene, phenol along with small amounts of cresol, toluene and trimethylbenzene (TMB). A substantial enhancement in HDO activity was observed on the PdFe/C catalysts. Compared with Fe/C, the yield to oxygen-free aromatic products (i.e., benzene/toluene/TMB) on PdFe/C increased by a factor of four at 350 °C, and by approximately a factor of two (83.2% versus 43.3%) at 450 °C. The enhanced activity of PdFe/C is attributed to the formation of PdFe alloy as evidenced by STEM, EDS and TPR.

  3. The Stereoselective Epoxidation by a New Type of Soluble Polymer-Supported Catalysts

    Institute of Scientific and Technical Information of China (English)

    Wang Yongmei; Wang Xin; Liu Juyan

    2004-01-01

    As the phase transfer catalyst (PTC) is one of most important catalysts in organic synthesis. Here, we represent initial results of a research program aimed at the rational design of a variety of new two centers, soluble polyethylene glycol (PEG) supported catalysts based on the cinchona alkaloid system and their application in asymmetric expoxidation process.Table 1 and Table 2 summarized the results of epoxidation of substituted chalcone As shown in Table 1 and Table 2, chalcone derivatives as reactive olefins afforded the corresponding epoxided with modest to good enantiomeric excesses. In contrast, a definite trend to higher ee value is displayed by solvent effect. It was found that enantioselectivity becomes higher with the polarity increases(Table 1, Table 2). Changing catalyst 1 to catalyst 2, ee value was increased (entry 6 in Table 1) as well. Compared with Me, NO2 groups, substitution on the aromatic ring of the enone carbonyl function by OMe group increased the enantioselectivity(entry 3 in Table 1 and entry 3' in Table 2).

  4. Direct synthesis of dimethyl carbonate over rare earth oxide supported catalyst

    Institute of Scientific and Technical Information of China (English)

    JIANG Qi; CHENG Jiye; GAO Zhiqin

    2007-01-01

    Solid base catalysts for the direct synthesis of dimethyl carbonate (DMC)from carbon dioxide,methanol,and propylene oxide were prepared by loading KCl and K2CO3 on the surface of La2O3,Y2O31,CeO2 and Nd2O3.The catalysts were characterized by thermogravimetric analysis (TGA) and X-ray diffraction(XRD) techniques.The catalytic activities were efficiently influenced by the preparation conditions.The optimal loading amount of K2CO3 is 17.6%(mass)for KCl-K2CO3/Y2O3 and 22.2%for other catalysts.Supports affected the activity of catalyst.KCl-K2CO3/Nd2O3 exhibited the highest activity.The activity of KCl-K2CO3/Y2O3 increased wilh the increase of Calcination temperature in the range of 800℃-900℃.The formation of KYO2 Y3O4Cl or YOx species probably promoted the catalysts.

  5. Low Temperature Activation of Supported Metathesis Catalysts by Organosilicon Reducing Agents.

    Science.gov (United States)

    Mougel, Victor; Chan, Ka-Wing; Siddiqi, Georges; Kawakita, Kento; Nagae, Haruki; Tsurugi, Hayato; Mashima, Kazushi; Safonova, Olga; Copéret, Christophe

    2016-08-24

    Alkene metathesis is a widely and increasingly used reaction in academia and industry because of its efficiency in terms of atom economy and its wide applicability. This reaction is notably responsible for the production of several million tons of propene annually. Such industrial processes rely on inexpensive silica-supported tungsten oxide catalysts, which operate at high temperatures (>350 °C), in contrast with the mild room temperature reaction conditions typically used with the corresponding molecular alkene metathesis homogeneous catalysts. This large difference in the temperature requirements is generally thought to arise from the difficulty in generating active sites (carbenes or metallacyclobutanes) in the classical metal oxide catalysts and prevents broader applicability, notably with functionalized substrates. We report here a low temperature activation process of well-defined metal oxo surface species using organosilicon reductants, which generate a large amount of active species at only 70 °C (0.6 active sites/W). This high activity at low temperature broadens the scope of these catalysts to functionalized substrates. This activation process can also be applied to classical industrial catalysts. We provide evidence for the formation of a metallacyclopentane intermediate and propose how the active species are formed. PMID:27610418

  6. Mesoporous Silica Supported Au Nanoparticles with Controlled Size as Efficient Heterogeneous Catalyst for Aerobic Oxidation of Alcohols

    Directory of Open Access Journals (Sweden)

    Xuefeng Chu

    2015-01-01

    Full Text Available A series of Au catalysts with different sizes were synthesized and employed on amine group functionalized ordered mesoporous silica solid supports as catalyst for the aerobic oxidation of various alcohols. The mesoporous silica of MCM-41 supported Au nanoparticles (Au-1 exhibited the smallest particle size at ~1.8 nm with superior catalytic activities owing to the confinement effect of the mesoporous channels. Au-1 catalyst is also very stable and reusable under aerobic condition. Therefore, this presented work would obviously provide us a platform for synthesizing more size-controlled metal catalysts to improve the catalytic performances.

  7. NiO-PTA supported on ZIF-8 as a highly effective catalyst for hydrocracking of Jatropha oil

    Science.gov (United States)

    Liu, Jing; He, Jing; Wang, Luying; Li, Rong; Chen, Pan; Rao, Xin; Deng, Lihong; Rong, Long; Lei, Jiandu

    2016-03-01

    Nickel oxide (NiO) and phosphotungstic acid (PTA) supported on a ZIF-8 (NiO-PTA/ZIF-8) catalyst was first synthesized and it showed high activity and good selectivity for the hydrocracking of Jatropha oil. The catalyst was characterized by SEM, SEM-EDS, TEM, N2 adsorption, FT-IR, XRD and XPS. Compared with the NiO-PTA/Al2O3 catalyst, the selectivity of C15-C18 hydrocarbon increased over 36%, and catalytic efficiency increased 10 times over the NiO-PTA/ZIF-8 catalyst. The prepared NiO-PTA/ZIF-8 catalyst was stable for a reaction time of 104 h and the kinetic behavior was also analyzed. This catalyst was found to bypass the presulfurization process, showing promise as an alternative to sulfided catalysts for green diesel production.

  8. Pt and Pd supported on glass fibers as effective combustion catalysts

    OpenAIRE

    Kiwi-Minsker, L.; Yuranov, I.; Slavinskaia, E.; Zaikovskii, V.; Renken, A.

    2000-01-01

    Pd and Pt supported on glass fiber materials with developed porosity and high sp. surface areas were studied in total propane oxidn. The reaction was carried out in recycling reactor and the kinetic parameters were detd. under different reaction conditions in the temp. range 200-500 DegC. Pt catalysts were seen to be more active than Pd for the same metal loading on identical support. Catalytic activity was seen to depend on support compn. The highest activity was obsd. on Pt supported on gla...

  9. Effect of a carrier's nature on the activation of supported iron catalysts

    Science.gov (United States)

    Kazak, V. O.; Chernavskii, P. A.; Pankina, G. V.; Khodakov, A. Y.; Ordomsky, V. V.

    2015-11-01

    The effect a carrier's nature has on the activation of supported iron catalysts in a stream of pure carbon monoxide CO is investigated. It is shown that iron is mainly present in the form of magnetite Fe3O4 in case of carbon supports and in the form of hematite Fe2O3 for silica gel supports. It is shown that all activated samples are chiefly made up of the Hägg carbide χ-Fe5C2, but its concentration is higher for the carbon supports.

  10. Characterization and Catalytic Activity of Montmorillonite K10-Supported Cobalt Catalysts

    International Nuclear Information System (INIS)

    Montmorillonite K10-supported cobalt catalysts were prepared by wet impregnation method. The samples were analyzed by XRD, TPR, FTTR and BET characterization techniques. [Three phases of cobalt species were identified namely, cobalt oxide (Co3O4), cobalt silicate (Co2S1O4) and cobalt aluminate (CoAl2O4). These species were most probably existing within the inter lamellar spaces of the meso porous montmorillonite K10 support]. The two bands observed at 1385 and 760 cm1 were characteristic of metal species rather than the support, being mostly of Co - O bond vibration. The hysteresis loop, pore size distribution, pore volume and BET surface area were greatly affected by cobalt loading. The catalyst containing 18 wt% cobalt was the most selective sample for ethylene production from ethanol dehydration.

  11. Characterization of supported TiO2-based catalysts green-prepared and employed for photodegradation of malodorous DMDS

    International Nuclear Information System (INIS)

    Graphical abstract: Display Omitted Highlights: ► We prepare rutile-TiO2 based catalysts using a simple and eco-efficient method. ► TiO2 based catalysts coated on supporting materials have large BET surface areas. ► Supported TiO2 based catalysts efficiently degrade malodorous DMDS. -- Abstract: Titanium dioxide (TiO2)-based catalysts coated onto two supporting materials (Pyrex glass beads and porous polypropylene fibers) in laboratory have been prepared and characterized. A modified preparation process at low temperature involving the addition of distilled water, aqueous ammonia, and ferrous sulfate, respectively, was used to enhance the spontaneous precipitation of three TiO2-based catalysts. The Brunauer–Emmett–Teller surface area of three catalysts was ranged from 160.1 to 202.7 m2/g. The surface morphology of three catalysts was identified by a scanning electron microscopy equipped with an X-ray energy dispersive spectrometer. The photocatalytic degradation of dimethyldisulfide was investigated using the supported TiO2-based catalysts. The original dimethyldisulfide almost was degraded within 2 h. A similar photocatalytic activity on degrading dimethyldisulfide was demonstrated in comparison with commercial catalysts. Simplicity, low cost, low energy consumption, and solvent-free are the advantages of this proposed method which can be used to photodecompose environmental organic pollutants effectively without heat treatment.

  12. Characterization of supported TiO{sub 2}-based catalysts green-prepared and employed for photodegradation of malodorous DMDS

    Energy Technology Data Exchange (ETDEWEB)

    Chuang, Li-Chin [Department of Hair Styling and Design, Hungkuang University, 1018 Sec. 6 Taiwan Boulevard, Shalu, Taichung 43302, Taiwan (China); Luo, Chin-Hsiang, E-mail: andyluo@hk.edu.tw [Department of Safety, Health and Environmental Engineering, Hungkuang University, 1018 Sec. 6 Taiwan Boulevard, Shalu, Taichung 43302, Taiwan (China)

    2013-02-15

    Graphical abstract: Display Omitted Highlights: ► We prepare rutile-TiO{sub 2} based catalysts using a simple and eco-efficient method. ► TiO{sub 2} based catalysts coated on supporting materials have large BET surface areas. ► Supported TiO{sub 2} based catalysts efficiently degrade malodorous DMDS. -- Abstract: Titanium dioxide (TiO{sub 2})-based catalysts coated onto two supporting materials (Pyrex glass beads and porous polypropylene fibers) in laboratory have been prepared and characterized. A modified preparation process at low temperature involving the addition of distilled water, aqueous ammonia, and ferrous sulfate, respectively, was used to enhance the spontaneous precipitation of three TiO{sub 2}-based catalysts. The Brunauer–Emmett–Teller surface area of three catalysts was ranged from 160.1 to 202.7 m{sup 2}/g. The surface morphology of three catalysts was identified by a scanning electron microscopy equipped with an X-ray energy dispersive spectrometer. The photocatalytic degradation of dimethyldisulfide was investigated using the supported TiO{sub 2}-based catalysts. The original dimethyldisulfide almost was degraded within 2 h. A similar photocatalytic activity on degrading dimethyldisulfide was demonstrated in comparison with commercial catalysts. Simplicity, low cost, low energy consumption, and solvent-free are the advantages of this proposed method which can be used to photodecompose environmental organic pollutants effectively without heat treatment.

  13. MCM-41 Bound Ruthenium Complex as Heterogeneous Catalyst for Hydrogenation Ⅰ: Effect of Support, Ligand and Solvent on the Catalyst Performance

    Institute of Scientific and Technical Information of China (English)

    YU, Ying-Min; FEI, Jin-Hua; ZHANG, Yi-Ping; ZHENG, Xiao-Ming

    2006-01-01

    The functionalized MCM-41 mesoporous bound ruthenium complex was synthesized and characterized using elemental analysis, atomic absorption spectrophotometer, BET, XRD and FTIR. Hydrogenation of carbon dioxide to formic acid was investigated over these catalysts under supercritical CO2 condition. The effect of reactant gas partial pressure, supports, solvents and ligands on the synthesis of formic acid was studied. These factors could influence the catalyst activity, stability and reuse performance greatly and no byproduct was detected. These promising catalysts also offered the industrial advantages such as easy separation.

  14. Study of Alginate-Supported Ionic Liquid and Pd Catalysts

    Directory of Open Access Journals (Sweden)

    Eric Guibal

    2012-01-01

    Full Text Available New catalytic materials, based on palladium immobilized in ionic liquid supported on alginate, were elaborated. Alginate was associated with gelatin for the immobilization of ionic liquids (ILs and the binding of palladium. These catalytic materials were designed in the form of highly porous monoliths (HPMs, in order to be used in a column reactor. The catalytic materials were tested for the hydrogenation of 4-nitroaniline (4-NA in the presence of formic acid as hydrogen donor. The different parameters for the elaboration of the catalytic materials were studied and their impact analyzed in terms of microstructures, palladium sorption properties and catalytic performances. The characteristics of the biopolymer (proportion of β-D-mannuronic acid (M and α-L-guluronic acid (G in the biopolymer defined by the M/G ratio, the concentration of the porogen agent, and the type of coagulating agent significantly influenced catalytic performances. The freezing temperature had a significant impact on structural properties, but hardly affected the catalytic rate. Cellulose fibers were incorporated as mechanical strengthener into the catalytic materials, and allowed to enhance mechanical properties and catalytic efficiency but required increasing the amount of hydrogen donor for catalysis.

  15. Use of heterogeneous CaO and SnO2 catalysts supported on rice husk ash to produce biodiesel

    International Nuclear Information System (INIS)

    Silica obtained from rice husk after acid leaching and calcination was compared to commercial silica as a catalyst support. CaO and SnO2 catalysts were prepared by impregnation and tested in the transesterification of soybean oil and the esterification of oleic acid. CaO catalysts showed basic character and were the most active for transesterification, whereas SnO2 catalysts were acid and the most effective for esterification. In both cases the performances of the catalysts prepared with rice husk ash and commercial silica were similar. These results demonstrate that rice husk is a cost-effective and environmentally-friendly source of silica that can be used as a catalyst support. (author)

  16. Vapor Phase Hydrogenation of Nitrobenzene to Aniline Over Carbon Supported Ruthenium Catalysts.

    Science.gov (United States)

    Srikanth, Chakravartula S; Kumar, Vanama Pavan; Viswanadham, Balaga; Srikanth, Amirineni; Chary, Komandur V R

    2015-07-01

    A series of Ru/Carbon catalysts (0.5-6.0 wt%) were prepared by impregnation method. The catalysts were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), temperature programmed reduction (TPR), X-ray photoelectron spectroscopy (XPS), CO-chemisorption, surface area and pore-size distribution measurements. The catalytic activities were evaluated for the vapor phase hydrogenation of nitrobenzene. The dispersion measured by CO-uptake values suggests that a decrease of dispersion is observed with increasing Ru loading on carbon support. These findings are well supported by the crystallite size measured from XRD measurements. XPS study reveals the formation of Ru0 after reduction at 573 K for 3 h. The catalysts exhibit high conversion/selectivity at 4.5 wt% Ru loading during hydrogenation reaction. The particle size measured from CO-chemisorption and TEM analysis are related to the TOF during the hydrogenation reaction. Ru/C catalysts are found to show higher conversion/selectivities during hydrogenation of nitrobenzene to aniline. PMID:26373150

  17. Transition metal-modified polyoxometalates supported on carbon as catalyst in 2-(methylthio)-benzothiazole sulfoxidation

    Indian Academy of Sciences (India)

    Romina A Frenzel; Gustavo P Romanelli; Mirta N Blanco; Luis R Piz

    2015-01-01

    Polyoxometalates with lacunary Keggin structure modified with transition metal ions [PW11O39M(H2O)]5−, where M = Ni2+, Co2+, Cu2+ or Zn2+, were synthesized and supported on activated carbon to obtain the PW11MC catalysts. Using FT-IR and DTA-TGA it was concluded that the [PW11O39M(H2O)]5− species are interacting with the functional groups of the support, and that thermal treatment leads to the loss of the coordinatively bonded water molecules without any noticeable anion degradation. The activity and selectivity of the catalysts in the sulfoxidation reaction of 2-(methylthio)-benzothiazole, an emerging environmental pollutant, were evaluated. The reaction was carried out in acetonitrile as solvent using H2O2 35% p/v as a clean oxidant. The conversion values decreased in the following order: PW11NiC > PW11CuC > PW11CoC > PW11ZnC, with selectivity to sulfoxide higher than 69%. The catalyst could be reused without appreciable loss of the catalytic activity at least three times. The materials were found to be efficient and recyclable catalysts for 2-(methylthio)-benzothiazole sulfoxidation in order to obtain a more biodegradable product than the corresponding substrate.

  18. Hydrogen production by aqueous-phase reforming of glycerol on supported noble metal catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Boonyanuwat, A.; Jentys, A.; Lercher, J.A. [Technische Univ. Muenchen, Garching (Germany). Dept. Chemie

    2006-07-01

    Hydrogen produced from renewable feedstocks such as crude glycerol, which is the main by-product formed during bio-diesel production, will develop into an attractive alternative energy source in the near future. A low temperature process is being developed using noble metal catalysts supported on gamma alumina. The overall catalytic activity of the catalysts Pt/Al{sub 2}O{sub 3}, Pd/Al{sub 2}O{sub 3}, Ni/Al{sub 2}O{sub 3}, Ru/Al{sub 2}O{sub 3} and Rh/Al{sub 2}O{sub 3} was studied. The activation energy decreased in the order: Pt>Pd>Ni>>Ru>Rh. The H{sub 2} selectivity of Pt was the highest and decreased for Pd > Ni > Ru > Rh. The H{sub 2} selectivity of Pt and Pd supported on gamma alumina was above 90%. The Pt/Al{sub 2}O{sub 3} catalyst showed a long term stability above 2 weeks using 1%wt glycerol in the feed, which indicates that these catalysts might have a high potential to be used for the aqueous phase reforming process of glycerol. (orig.)

  19. Carbon-Supported Silver Catalysts for CO Selective Oxidation in Excess Hydrogen

    Institute of Scientific and Technical Information of China (English)

    Limin Chen; Ding Ma; Barbara Pietruszka; Xinhe Bao

    2006-01-01

    Carbon materials were used as supports for Ag catalysts that are prepared using the conventional wet impregnation method, and their catalytic properties for CO selective oxidation in excess hydrogen at temperatures below 483 K were tested. A variety of techniques, e.g. N2 adsorption, XPS, TPD, UV-Vis DRS, TEM and SEM, were used to determine the influence of physical and chemical properties of the carbon on the properties of Ag catalyst. It was found that defects on the carbon surface served as nucleation sites for silver ions, while functional groups on carbon surface induced their reduction to the metallic form. The formation of silver particles on carbon was governed by homogeneous and/or heterogeneous nucleation during the impregnation and subsequent activation processes. The best catalytic performance was obtained with a Ag/carbon black catalyst with a uniform size distribution of silver nanoparticles (about 12 nm), moderate BET surface area (with a mesoporous structure), and a limited amount of carbon-oxygen groups. The research indicates that carbon materials are potentially good supports for silver catalysts for preferential oxidation of CO in excess hydrogen.

  20. Copper nanoparticles supported on silica coated maghemite as versatile, magnetically recoverable and reusable catalyst for alkyne coupling and cycloadditon reactions

    OpenAIRE

    Nador, Fabiana; Volpe, María A.; Alonso Valdés, Francisco; Feldhoff, Armin; Kirschning, Andreas; Radivoy, Gabriel

    2012-01-01

    A versatile and magnetically recoverable catalyst consisting of copper nanoparticles on silica coated maghemite nanoparticles (MagSilica®) is presented. The catalyst has been prepared under mild conditions by fast reduction of anhydrous CuCl2 with lithium sand and a catalytic amount of DTBB (4,4’-di-tert-butylbiphenyl) as electron carrier, in the presence of the magnetic support. The catalyst has been fully characterized and its performance in different coupling and cycloaddition reactions of...

  1. Direct fabrication of Pt-supported porous carbon catalyst for fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, D.Y.; Wang, G.; Konstantinov, K. [Wollongong Univ., NSW (Australia). Inst. for Superconducting and Electronic Materials; Ma, Z.F.; Liub, H.K. [Shanghai Jiaotong Univ., Shanghai (China). Dept. of Chemical Engineering

    2006-07-01

    Platinum (Pt) based electrocatalysts are generally used in proton exchange membrane fuel cells (PEMFC) and in direct alcohol fuel cells (DAFC) operating at relatively low temperature. Wet impregnation techniques and chemical reduction of the metal precursors are the conventional preparation methods for these electrocatalysts. These conventional synthesis methods are based on impregnation-reduction, microemulsions, sonochemistry, and microwave irradiation. However, Pt-supported carbon catalysts cannot be prepared by such methods due to the very long time needed for the synthesis of carbon. In addition, post-fabrication steps must be taken, such as surface modification of carbon and metal supporting. For these reasons, this study presented a new fabrication method for producing Pt-carbon catalysts directly by a Pt-embedded template. The new method provides a time saving route for the preparation of a Pt catalyst supported on a mesoporous carbon. In this study, Pt-supported porous carbon was prepared using the carbon xerogel method. In particular, a platinum salt was dissolved in an aqueous solution of carbon xerogel precursor and reduced under 5 per cent hydrogen/argon gas along with carbonization. Images from a scanning electron microscope revealed that the nanoscale particle structure of the Pt-embedded carbon electrocatalyst had homogeneously distributed bright particles, likely attributed to Pt. 10 refs.

  2. Gold-Iron Oxide Catalyst for CO Oxidation: Effect of Support Structure

    Directory of Open Access Journals (Sweden)

    Hui-Zhen Cui

    2016-03-01

    Full Text Available Gold-iron oxide (Au/FeOx is one of the highly active catalysts for CO oxidation, and is also a typical system for the study of the chemistry of gold catalysis. In this work, two different types of iron oxide supports, i.e., hydroxylated (Fe_OH and dehydrated iron oxide (Fe_O, have been used for the deposition of gold via a deposition-precipitation (DP method. The structure of iron oxide has been tuned by either selecting precipitated pH of 6.7–11.2 for Fe_OH or changing calcination temperature of from 200 to 600 °C for Fe_O. Then, 1 wt. % Au catalysts on these iron oxide supports were measured for low-temperature CO oxidation reaction. Both fresh and used samples have been characterized by multiple techniques including transmission electron microscopy (TEM and high-resolution TEM (HRTEM, X-ray diffraction (XRD, X-ray photoelectron spectroscopy (XPS, X-ray absorption near edge structure (XANES and temperature-programmed reduction by hydrogen (H2-TPR. It has been demonstrated that the surface properties of the iron oxide support, as well as the metal-support interaction, plays crucial roles on the performance of Au/FeOx catalysts in CO oxidation.

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

    International Nuclear Information System (INIS)

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

  4. Infrared study of isotopic exchange during methanation over supported rhodium catalysts: an inverse spillover effect

    International Nuclear Information System (INIS)

    Infrared spectroscopy has been employed to study the reduction of carbon dioxide on supported catalyst films. The investigation included isotopic labeling using D2 as the reduction gas. Isotopic exchange was observed for both CO2/D2 and CH4/D2 mixtures. The mechanism of this isotopic exchange involves migration of hydrogen from the support to the Rh sites, an ''inverse spillover effect''. A key intermediate in the dissociation of CO2 on the supported Rh films was a carbonyl hydride species. 21 refs., 2 figs

  5. Pd-nanoparticle-supported, PDDA-functionalized graphene as a promising catalyst for alcohol oxidation.

    Science.gov (United States)

    Bin, Duan; Ren, Fangfang; Wang, Ying; Zhai, Chunyang; Wang, Caiqin; Guo, Jun; Yang, Ping; Du, Yukou

    2015-03-01

    Poly(diallyldimethylammonium chloride) (PDDA) has been employed as a modifying material for the development of new functional materials; then, the functionalized graphene was employed as a support for Pd nanoparticles through a facile method. The structures and morphologies of the as-synthesized Pd/PDDA-graphene composites were extensively characterized by Raman spectroscopy, XRD, XPS, and TEM. Morphological observation showed that Pd NPs with average diameters of 4.4 nm were evenly deposited over the functionalized graphene sheets. Moreover, the electrochemical experiments indicated that the Pd/PDDA-graphene catalyst showed improved electrocatalytic activity toward alcohol-oxidation reactions compared to the Pd/graphene and commercial Pd/C systems, as well as previously reported Pd-based catalysts. This study demonstrates the great potential of PDDA-functionalized graphene as a support for the development of metal-graphene nanocomposites for important applications in fuel cells. PMID:25601138

  6. Gold/Iron Carbonyl Clusters for Tailored Au/FeOx Supported Catalysts

    Directory of Open Access Journals (Sweden)

    Stefania Albonetti

    2011-12-01

    Full Text Available A novel preparation method was developed for the preparation of gold/iron oxide supported catalysts using the bimetallic carbonyl cluster salts [NEt4]4[Au4Fe4(CO16] and [NEt4][AuFe4(CO16] as precursors of highly dispersed nanoparticles over different supports. A series of catalysts with different metal loadings were prepared and tested in the complete oxidation of dichlorobenzene, toluene, methanol and in the preferential oxidation of CO in the presence of H2 (PROX as model reactions. The characterization by BET, XRD, TEM, H2-TPR, ICP-AES and XPS point out the way the nature of the precursors and the thermal treatment conditions affected the dispersion of the active phase and their catalytic activity in the studied reactions.

  7. Density functional theory for green chemical catalyst supported on S-terminated GaN(0001)

    Energy Technology Data Exchange (ETDEWEB)

    Yokoyama, Mami; Ishii, Akira [Tottori University, Koyama-minami 4-101, 680-8552 (Japan); Tsukamoto, Shiro [Anan National College of Technology, 265 Aoki Minobayashi, Anan (Japan)

    2011-02-15

    A novel function of nitrid-based semiconductor is successfully developed for organic synthesis, in which palladium supported on the surface of S-terminated GaN(0001) serves as a unique green chemical catalyst. In this study we determined the structure of Pd-catalyst supported on S-terminated GaN(0001) surface by means of the density functional theory (DFT) within a Local Density Approximation (LDA). The important role of S on the case of GaN substrate is to make the number of the valence electron to be close to 0, in contrast to the case of GaAs (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  8. Performance of heterogeneous ZrO2 supported metaloxide catalysts for brown grease esterification and sulfur removal.

    Science.gov (United States)

    Kim, Manhoe; DiMaggio, Craig; Yan, Shuli; Wang, Huali; Salley, Steven O; Ng, K Y Simon

    2011-02-01

    In order to achieve a viable biodiesel industry, new catalyst technology is needed which can process a variety of less expensive waste oils, such as yellow grease and brown grease. However, for these catalysts to be effective for biodiesel production using these feedstocks, they must be able to tolerate higher concentrations of free fatty acids (FFA), water, and sulfur. We have developed a class of zirconia supported metaloxide catalysts that achieve high FAME yields through esterification of FFAs while simultaneously performing desulfurization and de-metallization functions. In fact, methanolysis, with the zirconia supported catalysts, was more effective for desulfurization than an acid washing process. In addition, using zirconia supported catalysts to convert waste grease, high in sulfur content, resulted in a FAME product that could meet the in-use ASTM diesel fuel sulfur specification (<500 ppm). Possible mechanisms of desulfurization and de-metallization by methanolysis were proposed to explain this activity. PMID:21078551

  9. Liquid phase nitration of benzene over supported ammonium salt of 12-molybdophosphoric acid catalysts prepared by sol-gel method

    International Nuclear Information System (INIS)

    A mild and clean liquid nitration of benzene with 65% nitric acid as nitrating agent over silica supported ammonium salt of 12-molybdophosphoric acid catalysts has been investigated. These catalysts with different loadings were prepared by sol-gel method and characterized by X-ray diffraction (XRD) and FTIR spectra. The acidity of these catalysts was measured by the potentiometric titration method. The XRD and IR analysis revealed that supported catalysts possess the Keggin structure which is similar to 12-molybdophosphoric acid. And it can be found that the supported catalysts had high nitration reaction catalytic activity and selectivity over nitrobenzene. The effects of various parameters such as nitric acid/benzene volume ratio, temperature and time of reaction have also been systematically studied.

  10. Rice Husk Supported Catalysts for Degradation of Chlorobenzenes in Capillary Microreactor

    OpenAIRE

    Abdulelah Thabet; Chanbasha Basheer; Than Htun Maung; Hasan Ali Al-Muallem; Abdul Nasar Kalanthoden

    2015-01-01

    Chlorinated organic pollutants are persistent, toxic, and ubiquitously distributed environmental contaminants. These compounds are highly bioaccumulative and adversely affect the ozone layer in the atmosphere. As such, their widespread usage is a major cause of environmental and health concern. Therefore, it is important to detoxify such compounds by environment friendly methods. In this work, rice husk supported platinum (RHA-Pt) and titanium (RHA-Ti) catalysts were used, for the first time,...

  11. Polymer Supported Heterogenous Catalysts for Direct Synthesis of Hydrogen Peroxide in Absence of Selectivity Enhancers

    OpenAIRE

    Sterchele, Stefano

    2013-01-01

    The research program developed during the Ph.D. School is focused on the study of metal catalysts supported on cross-linked functional polymers (CFPs) for the direct synthesis of hydrogen peroxide. In the last twenty years this compound has become a commodity with a constant increasing demand because of its strong oxidant properties and the formation of water as the reduction byproduct. In particular, H2O2 is widely employed as environmentally-friendly bleaching and cleaning agent. The...

  12. Ceria catalyst for inert-substrate-supported tubular solid oxide fuel cells running on methane fuel

    Science.gov (United States)

    Zhao, Kai; Kim, Bok-Hee; Du, Yanhai; Xu, Qing; Ahn, Byung-Guk

    2016-05-01

    A ceria catalyst is applied to an inert-substrate supported tubular single cell for direct operation on methane fuel. The tubular single cell comprises a porous yttria-stabilized zirconia (YSZ) supporter, a Ni-Ce0.8Sm0.2O1.9 anode, a YSZ/Ce0.8Sm0.2O1.9 bi-layer electrolyte, and a La0.6Sr0.4Co0.2Fe0.8O3-δ cathode. The ceria catalyst is incorporated into the porous YSZ supporter layer by a cerium nitrate impregnation. The effects of ceria on the microstructure and electrochemical performance of the tubular single cell are investigated with respect to the number of impregnations. The optimum number of impregnations is determined to be four based on the maximum power density and polarization property of the tubular single cell in hydrogen and methane fuels. At 700 °C, the tubular single cell shows similar maximum power densities of ∼260 mW cm-2 in hydrogen and methane fuels, respectively. Moreover, the ceria catalyst significantly improves the performance stability of the cell running on methane fuel. At a current density of 350 mA cm-2, the single cell shows a low degradation rate of 2.5 mV h-1 during the 13 h test in methane fuel. These results suggest the feasibility of applying the ceria catalyst to the inert-substrate supported tubular single cell for direct operation on methane fuel.

  13. Activated carbon and tungsten oxide supported on activated carbon catalysts for toluene catalytic combustion.

    Science.gov (United States)

    Alvarez-Merino, M A; Ribeiro, M F; Silva, J M; Carrasco-Marín, F; Maldonado-Hódar, F J

    2004-09-01

    We have used activated carbon (AC) prepared from almond shells as a support for tungsten oxide to develop a series of WOx/AC catalysts for the catalytic combustion of toluene. We conducted the reaction between 300 and 350 degrees C, using a flow of 500 ppm of toluene in air and space velocity (GHSV) in the range 4000-7000 h(-1). Results show that AC used as a support is an appropriate material for removing toluene from dilute streams. By decreasing the GHSV and increasing the reaction temperature AC becomes a specific catalyst for the total toluene oxidation (SCO2 = 100%), but in less favorable conditions CO appears as reaction product and toluene-derivative compounds are retained inside the pores. WOx/AC catalysts are more selective to CO2 than AC due to the strong acidity of this oxide; this behavior improves with increased metal loading and reaction temperature and contact time. The catalytic performance depends on the nonstoichiometric tungsten oxide obtained during the pretreatment. In comparison with other supports the WOx/AC catalysts present, at low reaction temperatures, higher activity and selectivity than WO, supported on SiO2, TiO2, Al2O3, or Y zeolite. This is due to the hydrophobic character of the AC surface which prevents the adsorption of water produced from toluene combustion thus avoiding the deactivation of the active centers. However, the use of WOx/AC system is always restricted by its gasification temperature (around 400 degrees C), which limits the ability to increase the conversion values by increasing reaction temperatures. PMID:15461177

  14. Effect of water vapour on the molecular structures of supported vanadium oxide catalysts at elevated temperatures

    NARCIS (Netherlands)

    Jehng, Jih-Mirn; Deo, G.; Weckhuysen, B.M.; Wachs, I.E.

    2001-01-01

    The effect of water vapor on the molecular structures of V2O3-supported catalysts (SiO2, Al2o3, TiO2, and CeO2) was investigated by in situ Raman spectroscopy as a function of temperature (from 500°C to 120°C). Under dry conditions only isolated surface VO4 species are present on the dehydrated SiO2

  15. Carbon/H-ZSM-5 composites as supports for bi-functional Fischer-Tropsch synthesis catalysts

    NARCIS (Netherlands)

    Valero-Romero, M.J.; Sartipi, S.; Sun, X.; Rodríguez-Mirasol, J.; Cordero, T.; Kapteijn, F.; Gascon, J.

    2016-01-01

    Mesoporous H-ZSM-5–carbon composites, prepared via tetrapropylammonium hydroxide (TPAOH) post treatment of H-ZSM-5 followed by deposition of pyrolytic carbon, have been used as the support for the preparation of Co-based Fischer–Tropsch catalysts. The resulting catalysts display an improved performa

  16. Mechanistic and kinetic analysis of the oxidative dehydrogenation of ethane via novel supported alkali chloride catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Gaertner, C.; Veen, A.C. van; Lercher, J.A. [Technische Universitaet Muenchen (Germany). Catalysis Research Center

    2013-11-01

    The oxidative dehydrogenation of ethane over advanced catalysts is promising to selectively produce ethylene, an essential building block for the chemical industry. In this way, ethane from shale gas can be efficiently valorized. Supported alkali chloride catalysts are investigated in this work. Essential feature of those materials is the presence of a solid core (magnesium oxide in part doped with Dy{sub 2}O{sub 3}) covered under reaction conditions with a molten alkali chloride shell. It is shown that especially the lowered melting point of eutectic mixtures of LiCl with other alkali/alkaline earth metals is the key to taylor highly efficient materials. Elucidating the ODH reaction mechanism is essential to understand the reactivity of this novel catalyst class and provides the basis for improving performances. Information about elementary steps and the rate determining step were extracted from kinetic measurements, both in steady state and in transient configuration. Furthermore, isotopic labelling studies were performed, i.e. SSITKA studies and temperature programmed isotopic exchange experiments. Step experiments showed a significant oxygen uptake by the catalysts. Retained oxygen reacted quantitatively with ethane at nearly 100% selectivity to ethylene and conversion rates were comparable with rates observed during steady state operation. Thus, chemically bound oxygen in the melt is the active and selective intermediate in the ODH. Therefore, it is required to consider an intermediate and the activation is concluded to relate to the oxygen dissociation. The total concentration of stored oxygen can be correlated to the steady-state activity, while the viscosity of the melts mainly influences the selectivity towards ethene. Properties of the solid core impact on the catalyst efficiency suggesting that the oxygen species forms at the interface between support and overlayer. The quantity of retained oxygen additionally depends on the properties of the chloride

  17. Natural phosphate-supported palladium: A highly efficient and recyclable catalyst for the suzuki-miyaura coupling under microwave irradiation

    KAUST Repository

    Hassine, Ayoub

    2015-01-19

    This report explores Suzuki-Miyaura coupling under microwave irradiation, using a new generation of catalyst that is based on natural phosphate (NP) impregnated by palladium. This catalyst was prepared by the treatment of natural phosphate with bis(benzonitrile)palladium(II) chloride in acetone at room temperature. The catalyst displayed high catalytic activity for the Suzuki-Miyaura coupling of aryl bromides and chlorides with aryl boronic acids in pure water and with the use of microwave irradiation. The low-cost and availability of the solid support, mild reaction conditions, high yields of desired products, recyclability of the catalyst and short reaction times are the notable features of these methods.

  18. NiO-PTA supported on ZIF-8 as a highly effective catalyst for hydrocracking of Jatropha oil

    OpenAIRE

    Jing Liu; Jing He; Luying Wang; Rong Li; Pan Chen; Xin Rao; Lihong Deng; Long Rong; Jiandu Lei

    2016-01-01

    Nickel oxide (NiO) and phosphotungstic acid (PTA) supported on a ZIF-8 (NiO-PTA/ZIF-8) catalyst was first synthesized and it showed high activity and good selectivity for the hydrocracking of Jatropha oil. The catalyst was characterized by SEM, SEM-EDS, TEM, N2 adsorption, FT-IR, XRD and XPS. Compared with the NiO-PTA/Al2O3 catalyst, the selectivity of C15-C18 hydrocarbon increased over 36%, and catalytic efficiency increased 10 times over the NiO-PTA/ZIF-8 catalyst. The prepared NiO-PTA/ZIF-...

  19. Supported Copper, Nickel and Copper-Nickel Nanoparticle Catalysts for Low Temperature Water-Gas-Shift Reaction

    Science.gov (United States)

    Lin, Jiann-Horng

    Hydrogen is being considered worldwide as a future replacement for gasoline, diesel fuel, natural gas in both the transportation and non-transportation sectors. Hydrogen is a versatile energy carrier that can be produced from a variety of widely available primary energy sources, including coal, natural gas, biomass, solar, wind, and nuclear power. Coal, the most abundant fossil fuel on the planet, is being looked at as the possible future major source of H2, due to the development of the integrated gasification combined cycle (IGCC) and integrated gasification fuel cell technologies (IGFC). The gasification of coal produces syngas consisting of predominately carbon monoxide and hydrogen with some remaining hydrocarbons, carbon dioxide and water. Then, the water-gas shift reaction is used to convert CO to CO2 and additional hydrogen. The present work describes the synthesis of model Cu, Ni and Cu-Ni catalysts prepared from metal colloids, and compares their behavior in the WGS reaction to that of traditional impregnation catalysts. Initially, we systematically explored the performance of traditional Cu, Ni and Cu-Ni WGS catalysts made by impregnation methods. Various bimetallic Cu-Ni catalysts were prepared by supported impregnation and compared to monometallic Cu and Ni catalysts. The presence of Cu in bimetallic catalysts suppressed undesirable methanation side reaction, while the Ni component was important for high WGS activity. Colloidal Cu, Ni and Cu-Ni alloy nanoparticles obtained by chemical reduction were deposited onto alumina to prepare supported catalysts. The resulting Cu and Ni nanoparticle catalysts were found to be 2.5 times more active in the WGS reaction per unit mass of active metal as compared to catalysts prepared by the conventional impregnation technique. The powder XRD and HAADF-STEM provided evidence supporting the formation of Cu-Ni particles containing the Cu core and Cu-Ni alloy shell. The XPS data indicated surface segregation of Cu in

  20. Using supported Au nanoparticles as starting material for preparing uniform Au/Pd bimetallic catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Villa, Alberto [Universita di Milano, Italy; Prati, Laura [Universita di Milano, Italy; Su, Dangshen [Fritz Haber Institute of the Max Planck Society, Berlin, Germany; Wang, Di [Fritz Haber Institute of the Max Planck Society, Berlin, Germany; Veith, Gabriel M [ORNL

    2010-01-01

    One of the best methods for producing bulk homogeneous (composition) supported bimetallic AuPd clusters involves the immobilization of a protected Au seed followed by the addition of Pd. This paper investigates the importance of this gold seed in controlling the resulting bimetallic AuPd clusters structures, sizes and catalytic activities by investigating three different gold seeds. Uniform Au-Pd alloy were obtained when a steric/electrostatic protecting group, poly(vinyl alcohol) (PVA), was used to form the gold clusters on activated carbon (AC). In contrast Au/AC precursors prepared using Au nanoparticles with only electrostatic stabilization (tetrakis(hydroxypropyl)phosphonium chloride (THPC)), or no stabilization (magnetron sputtering) produced inhomogeneous alloys and segregation of the gold and palladium. The uniform alloyed catalyst (Pd{at}Au{sub PVA}/AC) is the most active and selective catalyst, while the inhomogenous catalysts are less active and selective. Further study of the PVA protected Au clusters revealed that the amount of PVA used is also critical for the preparation of uniform alloyed catalyst, their stability, and their catalytic activity.

  1. Catalytic oxidation of pulping effluent by activated carbon-supported heterogeneous catalysts.

    Science.gov (United States)

    Yadav, Bholu Ram; Garg, Anurag

    2016-01-01

    The present study deals with the non-catalytic and catalytic wet oxidation (CWO) for the removal of persistent organic compounds from the pulping effluent. Two activated carbon-supported heterogeneous catalysts (Cu/Ce/AC and Cu/Mn/AC) were used for CWO after characterization by the following techniques: temperature-programmed reduction, Fourier transform infrared spectroscopy and thermo-gravimetric analysis. The oxidation reaction was performed in a batch high-pressure reactor (capacity = 0.7  L) at moderate oxidation conditions (temperature = 190°C and oxygen pressure = 0.9 MPa). With Cu/Ce/AC catalyst, the maximum chemical oxygen demand (COD), total organic carbon (TOC) and lignin removals of 79%, 77% and 88% were achieved compared to only 50% removal during the non-catalytic process. The 5-day biochemical oxygen demand (BOD5) to COD ratio (a measure for biodegradability) of the pulping effluent was improved to 0.52 from an initial value of 0.16. The mass balance calculations for solid recovered after CWO reaction showed 8% and 10% deduction in catalyst mass primarily attributed to the loss of carbon and metal leaching. After the CWO process, carbon deposition was also observed on the recovered catalyst which was responsible for around 3-4% TOC reduction. PMID:26508075

  2. Carbon nanotubes/tin oxide nanocomposite-supported Pt catalysts for methanol electro-oxidation.

    Science.gov (United States)

    Li, Xingwei; Wei, Jiadi; Chai, Yuzheng; Zhang, Shuo

    2015-07-15

    Carbon nanotubes/tin oxide nanocomposite (MWCNTs-SnO2) was obtained via the hydrolysis of SnCl4 in the presence of multi-walled carbon nanotubes (MWCNTs) and subsequent calcinations. And carbon nanotubes/tin oxide nanocomposite-supported Pt catalysts (Pt/MWCNTs-SnO2) were prepared by in-situ liquid phase reduction using H2PtCl6 as a metal precursor. As-prepared catalysts were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM), and their catalytic performances were evaluated by chronoamperometry (CA) and cyclic voltammetry (CV). Desirable catalytic performance for methanol electro-oxidation was observed with a reduced size and an improved dispersion of Pt catalysts on the MWCNTs-SnO2 nanocomposite. The calcination temperature of MWCNTs-SnO2 nanocomposite was a key factor for controlling the catalytic performance of Pt/MWCNTs-SnO2 catalysts. PMID:25801135

  3. Vapor phase carbonylation of dimethyl ether and methyl acetate with supported transition metal catalysts

    International Nuclear Information System (INIS)

    The synthesis of acetic acid (AcOH) from methanol (MeOH) and carbon monoxide has been performed industrially in the liquid phase using a rhodium complex catalyst and an iodide promoter. The selectivity to AcOH is more than 99% under mild conditions (1750C, 28 atm). The homogeneous rhodium catalyst has been also effective for the synthesis of acetic anhydride (Ac2O) by carbonylation of dimethyl ether (DME) or methyl acetate (AcOMe). However, rhodium is one of the most expensive metals and its proved reserves are quite limited. It is highly desired, therefore, to develop a new catalyst as a substitute for rhodium. The authors have already reported that nickel supported on active carbon exhibits an excellent activity for the vapor phase carbonylation of MeOh in the presence of iodide promoter and under moderately pressurized conditions. In addition, corrosive attack on reactors by iodide compounds is expected to be negligible in the vapor phase system. In the present work, vapor phase carbonylation of DME and AcOMe on nickel-active carbon (Ni/A.C.) and molybdenum-active carbon (Mo/A.C.) catalysts was studied

  4. CeO_2-supported vanadium oxide catalysts for soot oxidation:the roles of molecular structure and nanometer effect

    Institute of Scientific and Technical Information of China (English)

    刘坚; 赵震; 徐春明; 段爱军; 姜桂元

    2010-01-01

    The nanometer CeO2 powder was prepared by the method of microwave-assisted heating hydrolysis,and the nanometer CeO2-supported or ordinary CeO2-supported vanadia catalysts with different vanadium loadings(atomic ratios:100V/Ce=0.1,1,4,10,and 20) were prepared by an incipient-wetness impregnation method.Spectroscopic techniques(XRD,FT-IR,Raman and UV-Vis DRS) were utilized to characterize the structures of VOx/CeO2 catalysts.The results showed that the structures of CeO2-supported vanadium oxide catalysts de...

  5. Catalytic hydrolysis of ammonia borane for hydrogen generation using cobalt nanocluster catalyst supported on polydopamine functionalized multiwalled carbon nanotube

    International Nuclear Information System (INIS)

    Hydrogen was generated from ammonia borane complex by hydrolysis using cobalt nanocluster catalyst supported on polydopamine functionalized MWCNTs (multi-walled carbon nanotubes). The impregnation-chemical reduction method was used for the preparation of the supported catalyst. The nanocluster catalyst support was formed by in-situ oxidative polymerization of dopamine on the MWCNTs in alkaline solution at room temperature. The structural and physical–chemical properties of the nanocluster catalyst were characterized by FT-IR (Fourier transform infrared spectroscopy), EDX (energy-dispersive X-ray spectroscopy), SEM (scanning electron microscope), XRD (X-ray diffraction) and TEM (transmission electron microscopy). The nanocluster catalyst showed good catalytic activity for the hydrogen generation from aqueous ammonia borane complex. A reusability test to determine the practical usage of the catalyst was also investigated. The result revealed that the catalyst maintained an appreciable catalytic performance and stability in terms of its reusability after three cycle of reuse for the hydrolysis reaction. Also, the activation energy for the hydrolysis of ammonia borane complex was estimated to be 50.41 kJmol−1, which is lower than the values of some of the reported catalyst. The catalyst can be considered as a promising candidate in developing highly efficient portable hydrogen generation systems such as PEMFC (proton exchange membrane fuel cells). - Highlights: • Co/Pdop-o-MWCNT (Pdop functionalized MWCNT supported cobalt nanocluster) catalyst was synthesized for hydrogen generation. • It is an active catalyst for hydrogen generation via hydrolysis of ammonia borane. • It showed good stability in terms of reusability for the hydrogen generation

  6. Catalytic partial oxidation of methane over porous silica supported VO{sub x} catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Pirovano, C.; Schoenborn, E.; Kalevaru, V.N.; Wohlrab, S.; Luecke, B.; Martin, A. [University Rostock e.V., Rostock (Germany). Leibniz Inst. for Catalysis

    2011-07-01

    High surface area mesoporous siliceous MCM-41 and SBA-15 materials have been used as supports to disperse vanadium oxide species using wet impregnation and incipient wetness impregnation methods. These materials were used as catalysts for the partial oxidation of methane (POM) to formaldehyde. The physico-chemical properties of the solids were studied by means of BET, DR-UV/Vis spectroscopy, Py-FTIR and TEM. The influence of support and the preparation method on the dispersion of VOx is also investigated. The catalytic properties of the catalysts were examined in a fixed bed stainless steel reactor at 923 K. So far a maximum production of formaldehyde can be detected on SBA-15 supported VOx-catalysts prepared by incipient wetness impregnation. On this V/SBA-15 material a covalent attachment of catalytic active molecular vanadium species dominates, which in turn leads to a lower activation temperature and thereby reduced over-oxidation. From the best case, the space time yield of HCHO could be reached close to 775 g{sub HCHO} Kg{sub cat}{sup -1} h{sup -1}. (orig.)

  7. A Deep Investigation of the Thermal Decomposition Process of Supported Silver Catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Jun; Xu, Tianhao; Li, Yaping; Lei, Xiaodong; Zhang, Hui; Evans, D. G.; Sun, Xiaoming; Duan, Xue [Beijing Univ. of Chemical Technology, Beijing (China)

    2014-06-15

    A deep understanding of the metallic silver catalysts formation process on oxide support and the formation mechanism is of great scientific and practical meaning for exploring better catalyst preparing procedures. Herein the thermal decomposition process of supported silver catalyst with silver oxalate as the silver precursor in the presence of ethylenediamine and ethanolamine is carefully investigated by employing a variety of characterization techniques including thermal analysis, in situ diffuse reflectance infrared Fourier transform spectroscopy, scanning electron microscopy, and X-ray diffraction. The formation mechanism of supported silver particles was revealed. Results showed that formation of metallic silver begins at about 100 .deg. C and activation process is essentially complete below 145 .deg. C. Formation of silver was accompanied by decomposition of oxalate group and removal of organic amines. Catalytic performance tests using the epoxidation of ethylene as a probe reaction showed that rapid activation (for 5 minutes) at a relatively low temperature (170 .deg. C) afforded materials with optimum catalytic performance, since higher activation temperatures and/or longer activation times resulted in sintering of the silver particles.

  8. A Deep Investigation of the Thermal Decomposition Process of Supported Silver Catalysts

    International Nuclear Information System (INIS)

    A deep understanding of the metallic silver catalysts formation process on oxide support and the formation mechanism is of great scientific and practical meaning for exploring better catalyst preparing procedures. Herein the thermal decomposition process of supported silver catalyst with silver oxalate as the silver precursor in the presence of ethylenediamine and ethanolamine is carefully investigated by employing a variety of characterization techniques including thermal analysis, in situ diffuse reflectance infrared Fourier transform spectroscopy, scanning electron microscopy, and X-ray diffraction. The formation mechanism of supported silver particles was revealed. Results showed that formation of metallic silver begins at about 100 .deg. C and activation process is essentially complete below 145 .deg. C. Formation of silver was accompanied by decomposition of oxalate group and removal of organic amines. Catalytic performance tests using the epoxidation of ethylene as a probe reaction showed that rapid activation (for 5 minutes) at a relatively low temperature (170 .deg. C) afforded materials with optimum catalytic performance, since higher activation temperatures and/or longer activation times resulted in sintering of the silver particles

  9. Cobalt salophen complex supported on imidazole functionalized magnetic nanoparticles as a recoverable catalyst for oxidation of alkenes

    Energy Technology Data Exchange (ETDEWEB)

    Afshari, Mozhgan, E-mail: m.afshari@iau-shoushtar.ac.ir [Department of Chemistry, Shoushtar Branch, Islamic Azad University, Shoushtar (Iran, Islamic Republic of); Gorjizadeh, Maryam [Department of Chemistry, Shoushtar Branch, Islamic Azad University, Shoushtar (Iran, Islamic Republic of); Nazari, Simin [Department of Chemistry, Sousangerd Branch, Islamic Azad University, Sousangerd (Iran, Islamic Republic of); Naseh, Mohammad [Department of Chemistry, Dezful Branch, Islamic Azad University, Dezful (Iran, Islamic Republic of)

    2014-08-01

    A new magnetically separable catalyst consisting of Co(II) salophen complex covalently supported on imidazole functionalized silica coated cobalt ferrite was prepared. The synthesized catalyst was characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), vibrating sample magnetometry (VSM), thermogravimetric analysis (TGA), inductively coupled plasma atomic emission spectroscopy (ICP-AES) and Fourier transform infrared (FT-IR). The immobilized catalyst was shown to be an efficient heterogeneous catalyst for the oxidation of some alkenes using hydrogen peroxide (H{sub 2}O{sub 2}) as oxidant. The catalyst could be easily and efficiently isolated from the final product solution by magnetic decantation and be reused for 5 consecutive reactions without showing any significant activity degradation. - Highlights: • A new magnetic catalyst consisting of Co(II) salophen complex was prepared. • The catalyst was shown to be an efficient catalyst for the oxidation of alkenes. • The catalyst could be easily isolated from the product by magnetic decantation. • The catalyst is reused 5 times without a significant loss of activity.

  10. Electrochemically Stable Titanium Oxy-Nitride Support for Platinum Electro-Catalyst for PEM Fuel Cell Applications

    International Nuclear Information System (INIS)

    Titanium Oxy-Nitride is prepared by an in-situ urea-based sol-gel method as a support for the platinum electro-catalyst for the oxygen reduction reaction (ORR). XRD, BET, SEM and EDX are used to analyze the physicochemical properties of the prepared Pt/TiON catalyst; and its electrochemical properties are evaluated by CV and RDE tests. Electrochemical active surface area is determined and compared to that of the commercial Pt/C electro-catalyst. Pt/TiON electro-catalyst showed a better electrochemical stability than those of the commercial Pt/C electro-catalyst. It is also found that the ORR proceeds via four electron transfer mechanism on both Pt/C and Pt/TiON electro-catalysts

  11. Carbon Nanotubes Supported Pt-Ru-Ni as Methanol Electro-Oxidation Catalyst for Direct Methanol Fuel Cells

    Institute of Scientific and Technical Information of China (English)

    Fei Ye; Shengzhou Chen; Xinfa Dong; Weiming Lin

    2007-01-01

    Carbon nanotubes (CNTs) supported Pt-Ru and Pt-Ru-Ni catalysts were prepared by chemical reduction of metal precursors with sodium borohydride at room temperature. The crystallographic properties and composition of the catalysts were characterized by X-ray diffraction (XRD) and energy dispersive X-ray (EDX) analysis, and the catalytic activity and stability for methanol electro-oxidation were measured by electrochemical impedance spectroscopy (EIS), linear sweep voltammetries (LSV), and chronoamperometry (CA). The results show that the catalysts exhibit face-centered cubic (fcc) structure.The particle size of Pt-Ru-Ni/CNTs catalyst is about 4.8 nm. The catalytic activity and stability of the Pt-Ru-Ni/CNTs catalyst are higher than those of Pt-Ru/CNTs catalyst.

  12. Carbon Aerogel-Supported Pt Catalysts for the Hydrogenolysis and Isomerization of n-Butane: Influence of the Carbonization Temperature of the Support and Pt Particle Size

    Directory of Open Access Journals (Sweden)

    Marta B. Dawidziuk

    2012-10-01

    Full Text Available Carbon aerogels prepared at different carbonization temperatures and with varying mesopore volumes were used as supports for Pt catalysts to study the n-C4H10/H2 reaction. Mean Pt particle size depended on the mesopore volume of the support, showing a linear decrease when the mesopore volume increased. The turnover frequency (TOF for hydrogenolysis was much higher than for isomerization in catalysts supported on carbon aerogels obtained at 900–950 °C. However, both TOF values were similar in catalysts supported on the carbon aerogel obtained at 500 °C. TOF for hydrogenolysis and isomerization were related to the mean Pt particle size in catalysts supported on carbon aerogels obtained at 900–950 °C. In addition, both reactions showed a compensation effect between the activation energy and pre-exponential factor, indicating that they have the same intermediate, i.e., the chemisorbed dehydrogenated alkane.

  13. Facial synthesis of porous hematite supported Pt catalyst and its photo enhanced electrocatalytic ethanol oxidation performance

    International Nuclear Information System (INIS)

    Graphical Abstract: A porous α-Fe2O3 supported Pt catalyst has been synthesized by a facial thermal treatment assisted precipitation method and the materials show a illumination enhanced performance for ethanol oxidation. Display Omitted -- Highlights: •A porous α-Fe2O3 supported Pt catalyst has been synthesized for the first time. •With the addition of α-Fe2O3, the current density of Pt/C grows about 51% under illumination and 32% in the dark compared with unsupported catalyst. •The current increases under illuminationin chronoamperometric experiments at a given potential of 0.7 V due to the photons from light provide energy for CO stripping. •This work demostrates an optical strategy to accelerate electrode reactions towards ethanol oxidation reaction. -- Abstract: The porous α-Fe2O3 supported Pt catalyst is synthesized by a facial thermal treatment assisted precipitation method. The particle size of Pt is less than 3 nm. The pore diameters of α-Fe2O3 particles are concentrated to 2.46 nm in a mesooporous scale. Its electrochemical performance is tested. The ethanol oxidation current of the Pt/Fe2O3 catalsyt obviously improves under illumination, compared with that in the dark, during the optical switching operation. Moreover, with the addition of α-Fe2O3, the ethanol oxidation current of Pt/C grows about 51% under illumination and 32% in the dark; the onset potential shifts negtively for about 20 mV. This work demostrates an optical strategy which can be a potential alternative to accelerate electrode reactions towards ethanol oxidation reaction

  14. Synthesis, characterization, and catalytic activity in Suzuki coupling and catalase-like reactions of new chitosan supported Pd catalyst.

    Science.gov (United States)

    Baran, Talat; Inanan, Tülden; Menteş, Ayfer

    2016-07-10

    The aim of this study is to analyze the synthesis of a new chitosan supported Pd catalyst and examination of its catalytic activity in: Pd catalyst was synthesized using chitosan as a biomaterial and characterized with FTIR, TG/DTG, XRD, (1)H NMR, (13)C NMR, SEM-EDAX, ICP-OES, Uv-vis spectroscopies, and magnetic moment, along with molar conductivity analysis. Biomaterial supported Pd catalyst indicated high activity and long life time as well as excellent turnover number (TON) and turnover frequency (TOF) values in Suzuki reaction. Biomaterial supported Pd catalyst catalyzed H2O2 decomposition reaction with considerable high activity using comparatively small loading catalyst (10mg). Redox potential of biomaterial supported Pd catalyst was still high without negligible loss (13% decrease) after 10 cycles in reusability tests. As a consequence, eco-friendly biomaterial supported Pd catalyst has superior properties such as high thermal stability, long life time, easy removal from reaction mixture and durability to air, moisture and high temperature. PMID:27106147

  15. Effects of microwave power and polyvinyl pyrrolidone on microwave polyol process of carbon-supported Cu catalysts for CO oxidation

    International Nuclear Information System (INIS)

    Highlights: → The microwave polyol process is a simple preparation for AC-supported catalyst. → PVP may as an unconsidered protecting agent for catalyst preparation. → The AC-supported Cu0 catalyst showed high activity for CO oxidation at 175 deg. C. - Abstract: The purpose of this study was to prepare an activated carbon (AC)-supported copper catalyst by a simple method - the microwave polyol process - and to evaluate the effects of microwave power and protecting agent on the resulting catalyst activity. The catalysts were characterized by Brunauer-Emmett-Teller (BET) surface area, X-ray diffraction (XRD), and field-emission scanning electron microscopy (FESEM). Experimental results indicated that a microwave power of 700 W was highly effective, and that copper particles (60 (±18) nm) dispersed well on the AC support, even in the absence of the protecting agent poly-vinyl pyrrolidone (PVP). The AC-supported Cu0 catalyst generated high catalytic activity for CO oxidation (90% CO conversion at 175 oC).

  16. Catalytic incineration of CO and VOC emissions over supported metal oxide catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Larsson, Per-Olof

    1999-05-01

    Catalytic incineration is one of the methods to reduce the emissions of CO and VOCs. Low operation temperature and low catalyst cost are essential parameters for catalytic incinerators. Pt/Al{sub 2}O{sub 3} catalysts are frequently used today, but the cheaper metal oxide catalysts can be very competitive if comparable overall activity is obtained. This thesis concerns how it is possible to decrease the operation temperature for supported metal oxide catalysts by using different supports, active metal oxides and additives. In the thesis it is demonstrated that different copper oxide based catalysts have the best activity and durability for complete oxidation among several tested metal oxide catalysts. CuO{sub x} supported on TiO{sub 2} and Al{sub 2}O{sub 3} showed increased activity with the CuO{sub x} loading up to the threshold coverage for formation of crystalline CuO particles, which is 12 {mu}mol/m{sup 2} on TiO{sub 2} and 6 {mu}mol/m{sup 2} on Al{sub 2}O{sub 3}. Up to the threshold coverage for CuO formation, well dispersed copper oxide species were formed on TiO{sub 2}, and a dispersed copper aluminate surface phase was formed on Al{sub 2}O{sub 3}. Durability tests showed accelerated sintering of TiO{sub 2} by copper, but stabilisation was possible by modification of the TiO{sub 2} with CeO{sub x} before the deposition of CuO{sub x}. The stabilisation was obtained by formation of a Ce-O-Ti surface phase. Addition of CeO{sub x} also enhanced the activity of the copper oxide species thanks to favourable interaction between the active copper oxide species and the CeO{sub x} on the support, which could be seen as increased reducibility in TPR experiments. The increased activity and reducibility was also observed for CuO{sub x} supported on ceria modified Al{sub 2}O{sub 3}. In this regard it was shown that CuO{sub x} deposited on CeO{sub 2}(001) surfaces was substantially more active for CO oxidation than copper oxide deposited on CeO{sub 2}(111) Surfaces. This

  17. Highly Active Carbon Supported Pd-Ag Nanofacets Catalysts for Hydrogen Production from HCOOH.

    Science.gov (United States)

    Wang, Wenhui; He, Ting; Liu, Xuehua; He, Weina; Cong, Hengjiang; Shen, Yangbin; Yan, Liuming; Zhang, Xuetong; Zhang, Jinping; Zhou, Xiaochun

    2016-08-17

    Hydrogen is regarded as a future sustainable and clean energy carrier. Formic acid is a safe and sustainable hydrogen storage medium with many advantages, including high hydrogen content, nontoxicity, and low cost. In this work, a series of highly active catalysts for hydrogen production from formic acid are successfully synthesized by controllably depositing Pd onto Ag nanoplates with different Ag nanofacets, such as Ag{111}, Ag{100}, and the nanofacet on hexagonal close packing Ag crystal (Ag{hcp}). Then, the Pd-Ag nanoplate catalysts are supported on Vulcan XC-72 carbon black to prevent the aggregation of the catalysts. The research reveals that the high activity is attributed to the formation of Pd-Ag alloy nanofacets, such as Pd-Ag{111}, Pd-Ag{100}, and Pd-Ag{hcp}. The activity order of these Pd-decorated Ag nanofacets is Pd-Ag{hcp} > Pd-Ag{111} > Pd-Ag{100}. Particularly, the activity of Pd-Ag{hcp} is up to an extremely high value, i.e., TOF{hcp} = 19 000 ± 1630 h(-1) at 90 °C (lower limit value), which is more than 800 times higher than our previous quasi-spherical Pd-Ag alloy nanocatalyst. The initial activity of Pd-Ag{hcp} even reaches (3.13 ± 0.19) × 10(6) h(-1) at 90 °C. This research not only presents highly active catalysts for hydrogen generation but also shows that the facet on the hcp Ag crystal can act as a potentially highly active catalyst. PMID:27454194

  18. Heterogeneous activation of peroxymonosulphate by supported ruthenium catalysts for phenol degradation in water

    International Nuclear Information System (INIS)

    Highlights: ► RuO2/ZSM5 and RuO2/AC exhibited higher activity in Oxone activation with stable performance. ► RuO2/AC presented higher activity than RuO2/ZSM5. ► Phenol degradation on RuO2/AC and RuO2/ZSM5 followed first order kinetics. - Abstract: Activated carbon (AC) and Zeolite Socony Mobil-5 (ZSM5) supported ruthenium oxide catalysts were prepared and tested to degrade aqueous phenol in the presence of peroxymonosulphate. The physicochemical properties of ruthenium oxide based catalysts were characterised by several techniques such as XRD (X-ray diffraction), SEM-EDS (scanning electron microscopy-energy dispersive X-ray spectroscopy), and N2 adsorption. It was found that RuO2/AC was highly effective in heterogeneous activation of peroxymonosulphate to produce sulphate radicals, presenting higher reaction rate in phenol degradation compared with RuO2/ZSM-5. Degradation efficiency of phenol could be achieved at 100% of phenol decomposition and 60% of total organic carbon (TOC) removal in 1 h at the conditions of 50 ppm phenol, 0.2 g catalyst, 1 g Oxone® in 500 mL solution at 25 °C using the two catalysts. It was also found that phenol degradation was strongly influenced by catalyst loading, phenol concentration, Oxone® concentration and temperature. Kinetic studies proved that a pseudo first order kinetics would fit to phenol decomposition and the activation energies for RuO2/AC and RuO2/ZSM5 were obtained to be 61.4 and 42.2 kJ/mol, respectively.

  19. Pristine and supported ZnO-based catalysts for phenazopyridine degradation with direct solar light

    Science.gov (United States)

    Hilal, Hikmat S.; Al-Nour, Ghazi Y. M.; Zyoud, Ahed; Helal, Muath H.; Saadeddin, Iyad

    2010-04-01

    In search for safe techniques to manage waste pharmaceutical compounds drained in water, solar-driven degradation of phenazopyridine (a model drug) was investigated in aqueous media using different ZnO-based catalyst systems. Naked ZnO, CdS-sensitized ZnO (ZnO/CdS) and activated carbon-supported ZnO (AC/ZnO) have been studied. Both naked ZnO and AC/ZnO were highly efficient in mineralizing phenazopyridine, reaching complete removal in ˜50 min, with AC/ZnO having the higher edge. The ZnO/CdS system showed lower efficiency, due to screening of light by CdS. Moreover, the tendency of CdS to leach out Cd 2+ ions discouraged the use of CdS as sensitizer in this work. In both ZnO and AC/ZnO systems, the photo-degradation reaction was induced by the UV tail of the solar light. The visible region, with wavelength longer than 400 nm, failed to induce photo-degradation. The reaction was faster with higher catalyst loading, until a maximum efficiency was reached at a certain concentration. The rate of reaction increased with higher drug concentrations up to a certain limit. The effect of pH value was studied, and the catalysts showed highest efficiencies at pH close to 7. Stability of ZnO to degradation was studied. Both catalyst systems showed lowered efficiencies on recovery and reuse. The results suggest that complete mineralization of waste drugs, commonly dumped in sewage water, with direct solar light is a potentially feasible strategy using the AC/ZnO catalyst.

  20. Studies of supported metal catalysts. Progress report, September 1, 1979-August 31, 1980

    International Nuclear Information System (INIS)

    Research was carried out on four separate catalyst systems: Co-Al2O3; Mo-Al2O3; Co/Mo/Al2O3; and Ni. Work was completed on the interactions between cobalt and γ-Al2O3. Work was begun on the combined Co/Mo/Al2O3 system. A separate study is in progress on support interactions between nickel and a variety of supports; particular emphasis has been on the effect of preparation method

  1. Kinetics of the Bray-Liebhafsky oscillatory reaction perturbed by polymer supported cobalt catalyst

    Directory of Open Access Journals (Sweden)

    Maksimović J.P.

    2011-01-01

    Full Text Available The Bray-Liebhafsky (BL oscillatory reaction generated in the batch reactor at 62- 68 oC was perturbed by cobalt(II-nitrate, supported on the macroreticular copolymer of poly-4-vinylpyridine with divinylbenzene (Co-PVPDVB. The kinetic data was analyzed of the complex pathways of the hydrogen peroxide decomposition in the examined BL reaction. The obtained results confirm that the kinetics of the BL reaction in the presence Co-PVPDVB comes partially from the Co-catalyst and partially from the macroreticular copolymer support.

  2. Oxide-supported PtCo alloy catalyst for intermediate temperature polymer electrolyte fuel cells

    OpenAIRE

    Stassi, Alessandro; Gatto, Irene; Baglio, Vincenzo; Passalacqua, Enza; Aricò, Antonino S.

    2013-01-01

    International audience A Pt-Co alloy catalyst supported on a Ta-doped Ti-oxide was investigated for the oxygen reduction reaction in a polymer electrolyte fuel cell (PEMFC) operating between 80° and 110 °C at different relative humidity (100% and 33% R.H.). A crystalline Anatase phase was obtained for the Ta-doped Ti-oxide support with BET surface area of about 150 m2/g. Pt and Pt3Co1 nanoparticles dispersed on the Ta-doped Ti-oxide showed a crystallite size of 3.9 and 2.9 nm, respectively...

  3. Methanol synthesis from CO2 hydrogenation over Cu based catalyst supported on zirconia modified γ-Al2O3

    International Nuclear Information System (INIS)

    The effect of zirconia modification on γ-Al2O3 support to the Cu based catalyst was studied. It is found that the catalytic activity and methanol selectivity of the catalyst after Zr addition are both improved. The influences of reaction temperature, space velocity and the molar ratio of H2:CO2 on Cu/γ-Al2O3 and 12Cu10Zr/γ-Al2O3 catalyst were also studied. The results indicate that low temperature, high space velocity and proper molar ratio of H2/CO2 are advantageous to methanol synthesis. The XRD and TPR characterization show that the addition of Zr enhances the dispersion of CuO species, which is responsible for the enhanced catalytic performance of Cu based catalyst supported on zirconia modified γ-Al2O3 catalyst

  4. Towards rational design of catalysts supported on a topological insulator substrate

    CERN Document Server

    Xiao, Jianping; Yam, Chi-Yung; Frauenheim, Thomas; Yan, Binghai

    2015-01-01

    Exotic and robust metallic surface states of topological insulators (TIs) have been expected to provide a promising platform for novel surface chemistry and catalysis. However, it is still an unprecedented field how TIs affect the activity of catalysts. In this work, we study the effects of topological surface states (TSSs) on the activity of transition metal clusters (Au, Ag, Cu, Pt, and Pd), which are supported on a TI Bi2Se3 substrate. It was found the adsorption energy of oxygen on the supported catalysts can be always enhanced due to the TSSs. However, it does not necessarily mean an increase of the activity in catalytic oxidation reaction. Rather, the enhanced adsorption behavior in the presence of TSSs exhibits dual effects, determined by the intrinsic reactivity of these catalysts with oxygen. For the Au case, the activity of catalytic oxidation can be improved because the intrinsic binding between Au and O is relatively weak. In contrast, a negative effect is found for the Pt and Pd clusters since th...

  5. N-doped mesoporous carbons supported palladium catalysts prepared from chitosan/silica/palladium gel beads.

    Science.gov (United States)

    Zeng, Minfeng; Wang, Yudong; Liu, Qi; Yuan, Xia; Feng, Ruokun; Yang, Zhen; Qi, Chenze

    2016-08-01

    In this study, a heterogeneous catalyst including palladium nanoparticles supported on nitrogen-doped mesoporous carbon (Pd@N-C) is synthesized from palladium salts as palladium precursor, colloidal silica as template, and chitosan as carbon source. N2 sorption isotherm results show that the prepared Pd@N-C had a high BET surface area (640m(2)g(-1)) with large porosity. The prepared Pd@N-C is high nitrogen-rich as characterized with element analysis. X-ray photoelectron spectroscopy (XPS), high-resolution transmission electron microscopy (HR-TEM), and Raman spectroscopy characterization of the catalyst shows that the palladium species with different chemical states are well dispersed on the nitrogen-containing mesoporous carbon. The Pd@N-C is high active and shows excellent stability as applied in Heck coupling reactions. This work supplies a successful method to prepare Pd heterogeneous catalysts with high performance from bulk biopolymer/Pd to high porous nitrogen-doped carbon supported palladium catalytic materials. PMID:27155234

  6. RuCu nanoparticles supported on graphene: A highly efficient catalyst for hydrolysis of ammonia borane

    Energy Technology Data Exchange (ETDEWEB)

    Cao, Nan; Hu, Kai [College of Chemistry and Molecular Sciences, Wuhan University, Wuhan, Hubei 430072 (China); Luo, Wei, E-mail: wluo@whu.edu.cn [College of Chemistry and Molecular Sciences, Wuhan University, Wuhan, Hubei 430072 (China); Suzhou Institute of Wuhan University, Suzhou, Jiangsu, 215123 (China); Cheng, Gongzhen, E-mail: gzcheng@whu.edu.cn [College of Chemistry and Molecular Sciences, Wuhan University, Wuhan, Hubei 430072 (China)

    2014-03-25

    Graphical abstract: Well dispersed RuCu/graphene nanoparticles exerted satisfied catalytic activity and recycle stability towards the hydrolysis of ammonia borane. Highlights: • One-step in situ synthesis of graphene supported RuCu NPs. • The catalysts exhibit excellent catalytic activity toward hydrolysis of AB. • Graphene supported NPs exhibit the highest catalytic activity. -- Abstract: Well dispersed RuCu nanoparticles (NPs) supported on graphene were in situ synthesized by a one-step co-reduction of aqueous solution of ruthenium (III) chloride, cupric (II) chloride, and graphite oxide (GO) with ammonia borane (AB) under ambient condition. The nature of the NPs was fully characterized by TEM, HRTEM, XRD, energy dispersive spectroscopy (EDX), and X-ray photoelectron spectroscopy (XPS). The as-synthesized NPs exhibit much higher catalytic activity for hydrolytic dehydrogenation of AB than the monometallic Ru and Cu, bimetallic RuCu/graphene reduced by NaBH{sub 4}, and graphene free RuCu counterparts. Additionally, the as-synthesized NPs supported on graphene exhibit higher catalytic activity than the catalysts with other conventional supports, such as SiO{sub 2}, γ-Al{sub 2}O{sub 3}, and carbon black. The activity of Ru{sub 1}Cu{sub 7.5}/graphene NPs in terms of turnover frequency (TOF) is 135 mol H{sub 2} min{sup −1} (mol Ru){sup −1}, which is higher than Ru/graphene, and most reported Ru-based or other noble metal-based NPs for the catalytic hydrolysis of AB. The activation energy for hydrolysis of AB in the presence of Ru{sub 1}Cu{sub 7.5}/graphene NPs was determined as 30.59 kJ mol{sup −1}, which is lower than most of the reported catalysts. Furthermore, the as-prepared NPs exert satisfied durable stability for the hydrolytic dehydrogenation of AB.

  7. Aluminum Oxide Formation On Fecral Catalyst Support By Electro-Chemical Coating

    Directory of Open Access Journals (Sweden)

    Yang H.S.

    2015-06-01

    Full Text Available FeCrAl is comprised essentially of Fe, Cr, Al and generally considered as metallic substrates for catalyst support because of its advantage in the high-temperature corrosion resistance, high mechanical strength, and ductility. Oxidation film and its adhesion on FeCrAl surface with aluminum are important for catalyst life. Therefore various appropriate surface treatments such as thermal oxidation, Sol, PVD, CVD has studied. In this research, PEO (plasma electrolytic oxidation process was applied to form the aluminum oxide on FeCrAl surface, and the formed oxide particle according to process conditions such as electric energy and oxidation time were investigated. Microstructure and aluminum oxide particle on FeCrAl surface after PEO process was observed by FE-SEM and EDS with element mapping analysis. The study presents possibility of aluminum oxide formation by electro-chemical coating process without any pretreatment of FeCrAl.

  8. Electroreductive dechlorination of chlorophenols with Pd catalyst supported on solid electrode.

    Science.gov (United States)

    Caixia; Matsunaga, Atsushi; Tezuka, Meguru

    2013-12-01

    Electroreductive dechlorination of chlorophenols with Pd catalyst supported on solidelectrode was studied. As solid electrodes, carbon cloth (CC), carbon felt (CF) and titanium mesh were used, and palladium was plated on solid electrodes by either electrolytic or electroless method. On each electrode with Pd, chlorophenols were qualitatively dechlorinated to phenol, while they were entirely intact on electrodes without Pd. Moreover, neither base electrode nor plating method significantly affected the activity of Pd as far as it was sufficiently loaded on the electrode. Based on the results in the experiments using one electrode repeatedly, Pd catalyst proved to possess a satisfactory duarability under the present condition. It was suggested that the reactive species responsinble for the dechlorination of chlorophenols could be formed during preliminary electrolysis. Thus, (Pd)x-H resulting from the adsorption of electrogenerated hydrogen on metallic Pd might be assumed most probable. PMID:25078820

  9. Degradation of trichloroethylene by hydrodechlorination using formic acid as hydrogen source over supported Pd catalysts.

    Science.gov (United States)

    Yu, Xin; Wu, Ting; Yang, Xue-Jing; Xu, Jing; Auzam, Jordan; Semiat, Raphael; Han, Yi-Fan

    2016-03-15

    An advanced method for the degradation of trichloroethylene (TCE) over Pd/MCM-41 catalysts through a hydrogen-transfer was investigated. Formic acid (FA) was used instead of gaseous H2 as the hydrogen resource. As a model H-carrier compound, FA has proven to yield less by-products and second-hand pollution during the reaction. Several factors have been studied, including: the property of catalyst supports, Pd loading and size, temperature, initial concentrations of FA and TCE (potential impact on the reaction rates of TCE degradation), and FA decomposition. The intrinsic kinetics for TCE degradation were measured, while the apparent activation energies and the reaction orders with respect to TCE and FA were calculated through power law models. On the basis of kinetics, we assumed a plausible reaction pathway for TCE degradation in which the catalytic degradation of TCE is most likely the rate-determining step for this reaction. PMID:26685065

  10. Size control of rhodium particles of silica-supported catalysts using water-in-oil microemulsion

    Science.gov (United States)

    Kishida, Masahiro; Hanaoka, Toshiaki; Kim, Won Young; Nagata, Hideo; Wakabayashi, Katsuhiko

    1997-11-01

    Effects of components of water-in-oil microemulsions on rhodium particle sizes of silica-supported rhodium catalysts were investigated in the catalyst preparation method using microemulsion. In the case of the microemulsion of polyoxyethylene(23)dodecyl ether/ n-alcohols/RhCl 3 aq., the rhodium particle size increased from 3.4 to 5.0 nm as the specific permittivity of the organic solvent increased. The chain length of hydrophilic group of polyoxyethylene- p-nonylphenyl ether ( n = 5 to 15) employed as surfactants had an effect on the rhodium particle size where the rhodium size ranged between 2.0 and 3.6 nm. The rhodium particle size was 1.5 nm in the case of sodium bis(2-ethylhexyl) sulfocuccinate and this value was found to be the smallest. These results could be interpreted in terms of the adsorption of the surfactant on rhodium-hydrazine particle surface.

  11. Durability of ZSM5 supported Co-Pd catalysts in the reduction of NOx with methane

    International Nuclear Information System (INIS)

    Selective catalytic reduction of NO with CH4 was studied over ZSM5-based cobalt (Co) and palladium (Pd) catalysts in the presence of oxygen and water. Pore volume impregnation of cobalt was found to be more efficient and much simpler than the common (wet) ion-exchange method. In the case of Pd, wet ion-exchange was found to give superior activity. As compared to alternative catalytic systems reported in literature for CH-4-SCR in the presence of water, ZSM5 supported Co-Pd combination catalysts are very active and selective. The activity of the ZSM5-based Co-Pd combination catalysts, however, decreases strongly with time on stream. Strikingly, this deactivation is not (predominantly) caused by steam dealumination of the zeolites: loss of SCR activity with time on stream occurs irrespective of the presence or absence of water in the feed. The higher the temperature of calcination the lower the initial activity and the faster the deactivation. In addition to this, the deactivation is also more pronounced at higher reaction temperatures. These observations are consistent with a temperature-induced mechanism of ion migration and sintering as also confirmed by TPR analysis. The role of water in this migration process is not obvious. Hence, the limited thermal stability of ZSM5 supported metal (ion) catalysts leads to two demands, which have yet to be made for application of zeolites in CH4-SCR: (1) stabilisation of the ionic phases in zeolite pores of different geometry and (2) further improved activity and selectivity allowing one to operate at temperatures that do not exceed 350-400C, where deactivation is not significant

  12. Durability of ZSM5-supported Co-Pd catalysts in the reduction of NOx with methane

    International Nuclear Information System (INIS)

    Selective catalytic reduction (SCR) of NO with CH4 was studied over ZSM5-based cobalt and palladium catalysts in the presence of oxygen and water. Pore volume impregnation of cobalt was found to be more efficient and much simpler than the common (wet) ion-exchange method. In the case of Pd, wet ion-exchange was found to give superior activity. As compared to alternative catalytic systems reported in literature for CH4-SCR in the presence of water, ZSM5-supported Co-Pd combination catalysts are very active and selective. The activity of the ZSM5-based Co-Pd combination catalysts, however, decreases strongly with time-on-stream. Strikingly, this deactivation is not (predominantly) caused by steam dealumination of the zeolites: loss of SCR activity with time-on-stream occurs irrespective of the presence or absence of water in the feed. The higher the temperature of calcination the lower the initial activity and the faster the deactivation. In addition to this, the deactivation is also more pronounced at higher reaction temperatures. These observations are consistent with a temperature-induced mechanism of ion migration and sintering as also confirmed by TPR analysis. The role of water in this migration process is not obvious. Hence, the limited thermal stability of ZSM5-supported metal (ion) catalysts leads to two demands, which have yet to be made for application of zeolites in CH4-SCR: (1) stabilisation of the ionic phases in zeolite pores of different geometry; and (2) further improved activity and selectivity allowing one to operate at temperatures that do not exceed 350-400C, where deactivation is not significant

  13. The effect of CeO2 support upon activity and selectivity of Ru and Co Fischer Tropsh catalysts

    International Nuclear Information System (INIS)

    Some CeO2 supported Ru and Co catalysts with 5% metal loading were prepared by impregnation methods, and characterised by temperature programmed reduction techniques (TPR). Their catalytic activities and selectivities were tested in H2 + CO reactions and compared with a Ru on SiO2 catalyst in the range of 1-9 atmospheres at 2600C. Ru/SiO2 and Co/SiO2 catalysts gave CH4 only at 1 atm., and = 70% CH4 at 9 atms., whilst CeO2 supported Ru and Co gave significantly smaller quantities (20-80%) of CH4 over the same pressure range

  14. Titania–supported silver nanoparticles: An efficient and reusable catalyst for reduction of 4-nitrophenol

    Energy Technology Data Exchange (ETDEWEB)

    Deshmukh, S.P. [Department of Chemistry, Dr. Babasaheb Ambedkar Marathwada University, Aurangabad, Sub-campus Osmanabad 413 501, M.S. (India); Department of Chemistry, D.B.F. Dayanand College of Arts and Science, Solapur 413 001, M.S. (India); Dhokale, R.K. [Department of Chemistry, Dr. Babasaheb Ambedkar Marathwada University, Aurangabad, Sub-campus Osmanabad 413 501, M.S. (India); Yadav, H.M. [Department of Chemistry, Dr. Babasaheb Ambedkar Marathwada University, Aurangabad, Sub-campus Osmanabad 413 501, M.S. (India); Center for Interdisciplinary Research, D.Y. Patil University, Kolhapur 416 005, M.S. (India); Achary, S.N. [Chemistry Division, Bhabha Atomic Research Center, Mumbai 400 085, M.S. (India); Delekar, S.D., E-mail: sddelekar7@rediffmail.com [Department of Chemistry, Dr. Babasaheb Ambedkar Marathwada University, Aurangabad, Sub-campus Osmanabad 413 501, M.S. (India); Department of Chemistry, Shivaji University, Kolhapur 416 001, M.S. (India)

    2013-05-15

    Supported silver nanoparticles were synthesized via in situ sol–gel followed by reduction method with dextrose as reductant and sodium dodecyl sulfate as stabilizer. The synthesized nanoparticles were characterized by X–ray diffraction, transmission electron microscopy, Fourier transform Infra-Red spectroscopy and UV–visible measurements. The XRD peaks confirm the metallic face-centered cubic silver particles. The formation of silver nanoparticles was confirmed from the appearance of surface plasmon absorption maxima at 412 nm; which shifted to the longer wavelengths after supported on titania host lattice. TEM showed the spherical nanoparticles with size in the range of 18–23 nm. An efficient and simple method was reported for the reduction of 4-nitrophenol using titania-supported silver nanoparticles at room temperature. The reaction was first order with respect to the concentration of 4-nitrophenol with higher efficiency. Titania supported silver nanoparticles are reusable and stable heterogeneous catalyst.

  15. Titania-supported silver nanoparticles: An efficient and reusable catalyst for reduction of 4-nitrophenol

    Science.gov (United States)

    Deshmukh, S. P.; Dhokale, R. K.; Yadav, H. M.; Achary, S. N.; Delekar, S. D.

    2013-05-01

    Supported silver nanoparticles were synthesized via in situ sol-gel followed by reduction method with dextrose as reductant and sodium dodecyl sulfate as stabilizer. The synthesized nanoparticles were characterized by X-ray diffraction, transmission electron microscopy, Fourier transform Infra-Red spectroscopy and UV-visible measurements. The XRD peaks confirm the metallic face-centered cubic silver particles. The formation of silver nanoparticles was confirmed from the appearance of surface plasmon absorption maxima at 412 nm; which shifted to the longer wavelengths after supported on titania host lattice. TEM showed the spherical nanoparticles with size in the range of 18-23 nm. An efficient and simple method was reported for the reduction of 4-nitrophenol using titania-supported silver nanoparticles at room temperature. The reaction was first order with respect to the concentration of 4-nitrophenol with higher efficiency. Titania supported silver nanoparticles are reusable and stable heterogeneous catalyst.

  16. Titania–supported silver nanoparticles: An efficient and reusable catalyst for reduction of 4-nitrophenol

    International Nuclear Information System (INIS)

    Supported silver nanoparticles were synthesized via in situ sol–gel followed by reduction method with dextrose as reductant and sodium dodecyl sulfate as stabilizer. The synthesized nanoparticles were characterized by X–ray diffraction, transmission electron microscopy, Fourier transform Infra-Red spectroscopy and UV–visible measurements. The XRD peaks confirm the metallic face-centered cubic silver particles. The formation of silver nanoparticles was confirmed from the appearance of surface plasmon absorption maxima at 412 nm; which shifted to the longer wavelengths after supported on titania host lattice. TEM showed the spherical nanoparticles with size in the range of 18–23 nm. An efficient and simple method was reported for the reduction of 4-nitrophenol using titania-supported silver nanoparticles at room temperature. The reaction was first order with respect to the concentration of 4-nitrophenol with higher efficiency. Titania supported silver nanoparticles are reusable and stable heterogeneous catalyst.

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

    International Nuclear Information System (INIS)

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

  18. Supported Catalysts Useful in Ring-Closing Metathesis, Cross Metathesis, and Ring-Opening Metathesis Polymerization

    OpenAIRE

    Jakkrit Suriboot; Hassan S. Bazzi; Bergbreiter, David E.

    2016-01-01

    Ruthenium and molybdenum catalysts are widely used in synthesis of both small molecules and macromolecules. While major developments have led to new increasingly active catalysts that have high functional group compatibility and stereoselectivity, catalyst/product separation, catalyst recycling, and/or catalyst residue/product separation remain an issue in some applications of these catalysts. This review highlights some of the history of efforts to address these problems, first discussing th...

  19. Low-temperature steam-reforming of ethanol over ZnO-supported Ni and Cu catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Homs, Narcis; Llorca, Jordi; De la Piscina, Pilar Ramirez [Departament de Quimica Inorganica, Universitat de Barcelona, C/Marti i Franques 1-11, 08028 Barcelona (Spain)

    2006-08-15

    ZnO-supported Ni and Cu as well as bimetallic Co-Ni and Co-Cu catalysts containing ca. 0.7wt% sodium promoter and prepared by the co-precipitation method were tested in the ethanol steam-reforming reaction at low temperature (523-723K), using a bioethanol-like mixture diluted in Ar. Monometallic ZnO-supported Cu or Ni samples do not exhibit good catalytic performance in the steam-reforming of ethanol for hydrogen production. Copper catalyst mainly dehydrogenates ethanol to acetaldehyde, whereas nickel catalyst favours ethanol decomposition. However, the addition of Ni to ZnO-supported cobalt has a positive effect both on the production of hydrogen at low temperature (<573K), and on catalyst stability. Evidence for alloy formation as well as mixed oxides at the microstructural level was found in the bimetallic systems after running the ethanol steam-reforming reaction by HRTEM-EELS. (author)

  20. SnO2 nanocluster supported Pt catalyst with high stability for proton exchange membrane fuel cells

    International Nuclear Information System (INIS)

    Tin oxide nanocluster (SnO2) with parallel nanorods was synthesized via a hard template method and explored as the anode catalyst support for proton exchange membrane fuel cells (PEMFCs). Single cell test demonstrated that SnO2 supported Pt catalyst (Pt/SnO2) exhibited comparable anode performance with conventional Pt/C. Electrochemical measurements showed that Pt/SnO2 exhibited significantly enhanced electrochemical stability than Pt/C under high potential electro-oxidation and potential cycling. The Pt/SnO2 catalyst reserved most of its electrochemically active surface area (ECA) under 10 h potential hold at 1.6 V while its ECA degradation rate was one order of magnitude lower than Pt/C under potential cycling between 0.6 and 1.2 V. Therefore, SnO2 nanocluster can be considered as a promising alternative anode catalyst support for PEMFCs

  1. Partial Oxidation of Hydrocarbons in a Segmented Bed Using Oxide-based Catalysts and Oxygen-conducting Supports

    Science.gov (United States)

    Smith, Mark W.

    Two objectives for the catalytic reforming of hydrocarbons to produce synthesis gas are investigated herein: (1) the effect of oxygen-conducting supports with partially substituted mixed-metal oxide catalysts, and (2) a segmented bed approach using different catalyst configurations. Excess carbon deposition was the primary cause of catalyst deactivation, and was the focus of the experiments for both objectives. The formation and characterization of deposited carbon was examined after reaction for one of the selected catalysts to determine the quantity and location of the carbon on the catalyst surface leading to deactivation. A nickel-substituted barium hexaaluminate (BNHA), with the formula BaAl 11.6Ni0.4O18.8, and a Rh-substituted lanthanum zirconate pyrochlore (LCZR) with the formula La1.89Ca0.11 Zr1.89Rh0.11, were combined with two different doped ceria supports. These supports were gadolinium-doped ceria (GDC) and zirconium-doped ceria (ZDC). The active catalyst phases were combined with the supports in different ratios using different synthesis techniques. The catalysts were characterized using several different techniques and were tested under partial oxidation (POX) of n-tetradecane (TD), a diesel fuel surrogate. It was found that the presence of GDC and ZDC reduced the formation of carbon for both catalysts; the optimal ratio of catalyst to support was different for the hexaaluminate and the pyrochlore; a loading of 20 wt% of the pyrochlore with ZDC produced the most stable performance in the presence of common fuel contaminants (>50 h); and, the incipient wetness impregnation synthesis method of applying the active catalyst to the support produced more stable product yields than the catalyst prepared by a solid-state mixing technique. Different hexaaluminate and pyrochlore catalysts were used in different configurations in a segmented bed approach. The first strategy was to promote the indirect reforming mechanism by placing a combustion catalyst in the

  2. Based on a new support for synthesis of highly efficient palladium/hydroxyapatite catalyst for ethanol electrooxidation

    International Nuclear Information System (INIS)

    Based on a new support, hydroxyapatite (HAP), a facile and low–cost preparation of palladium/hydroxyapatite catalyst for ethanol electrooxidation is introduced in this paper through a solvothermal reaction without additives. HAP was employed as the catalyst support for its hydroxyl–rich surface in order to increase the stability and utilization ratio of catalyst. According to transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM) and X–ray diffraction (XRD) measurements, the as–prepared Pd nanoparticles with face–centered cubic crystal structure were evenly deposited on the surface of HAP. Cyclic voltammetry and chronoamperometry tests demonstrated that the Pd/HAP catalyst possessed a much higher current density (246 mA cm−2) than the Pd/C catalyst (109 mA cm−2) towards ethanol electrooxidation, and better stability as well. In the direct ethanol fuel cell (DEFC) test, Pd/HAP catalyst gives better performance than that with Pd/C in terms of both open-circuit voltage (OCV) and power density. These results indicate that the HAP is a better support and the catalyst developed in this study may be a better candidate for DEFCs. A possible mechanism consistent with the experimental is also proposed

  3. A novel TiO2 nanofiber supported PdAg catalyst for methanol electro-oxidation

    International Nuclear Information System (INIS)

    A novel PdAg/TiO2 nanofiber electrocatalyst for methanol oxidation was fabricated by using TiO2 nanofiber as support. The structural and electrochemical properties of the PdAg/TiO2 nanofiber catalyst were characterized by XRD (X-ray diffraction), TEM (the transmission electron microscopy) and electrochemical analysis. The experiment results showed that the large surface area and porous structure of TiO2 nanofiber were preferable to the dispersion of nanosized PdAg alloy on the surface of TiO2 nanofiber support. The electrocatalytic activity for methanol oxidation of the PdAg/TiO2 nanofiber catalyst has shown promising electrocatalytic and anti-poisoning capabilities. The methanol oxidation mechanism of the PdAg/TiO2 nanofiber catalyst was mainly resulted from the photocatalytic function of the composite TiO2 material that had high catalytic activity without UV light illumination. The PdAg/TiO2 catalyst might become a promising candidate for direct methanol fuel cell. - Highlights: • Novel non-Pt catalyst of PdAg/TiO2 nanofiber for methanol oxidation is fabricated. • PdAg alloy is dispersed uniformly on the surface of TiO2 nanofiber support. • The novel catalyst shows promising electrocatalytic activity and anti-poisoning ability. • The methanol oxidation mechanism of the catalyst results from photocatalytic mechanism of TiO2

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

    International Nuclear Information System (INIS)

    A new carbon black supported palladium catalyst for direct formic acid fuel cell applications has been prepared and characterized by X-ray diffraction. Bi-modal distribution of Pd crystallite sizes was observed. The average Pd size for crystallites in small size and large size ranges were about 2.7 nm and 11.2 nm, respectively. The initial activity of the catalyst in the oxidation of formic acid tested in a fuel cell was similar to a commercial well dispersed 20 wt.% Pd/Vulcan. The rates of the fuel cell power decay were measured for formic acid of two purities for various current loadings. The results showed that various mechanisms contribute to the decrease of cell power with time. In direct formic acid fuel cell (DFAFC) fed with a very pure HCOOH accumulation of CO2 gas bubbles in anode catalyst layer is responsible for observed power decay. In DFAFC fed with a pure for analysis (p.a.) grade formic acid the formation of COads poison from the formic acid impurities is the main deactivation reason.

  5. Catalytic oxidation of albendazole using molybdenum supported on carbon nanotubes as catalyst

    International Nuclear Information System (INIS)

    The catalytic oxidation reaction of the thioether group (-S-) in the structure to the drug albendazole (C12H15N3O2S) was studied in order to obtain a pharmacologically active molecule known as albendazole sulfoxide. With this purpose, three heterogeneous catalysts were prepared using molybdenum (Mo) as active phase and carbon nanotubes as a multiple-layer catalyst support. The incorporation of the active phase was performed by wet impregnation, with subsequent calcination for 4 hours at 400 oC. For the catalytic oxidation reaction was employed hydrogen peroxide-urea (H2NCONH2·H2O2) as oxidizing agent and methanol (CH3OH) as reaction medium. The textural and morphology characterization of carbon nanoparticles and catalysts was carried out by adsorption-desorption of N2 (BET) and scanning electron microscopy (SEM). The identification and quantification of the reaction products were followed by Fourier transform infrared spectroscopy (FTIR) and high performance liquid chromatography (HPLC), respectively. With the yield, selectivity and conversion higher than 90% after 60 minutes of reaction, albendazole sulphoxide was obtained as major product of oxidation reaction. (author)

  6. Hydrogen production from lignin with supported nickel catalysts through supercritical water gasification

    International Nuclear Information System (INIS)

    The production of hydrogen through the gasification of lignin was examined with nickel supported magnesium oxide catalysts in supercritical water at 673 K. In the absence of nickel (MgO only), the amount of gases were very low and almost all of lignin were decomposed to THF insoluble. The increase in the amount of nickel on catalyst leaded to the increase in the amount of gases. In this reaction, the magnesium oxide decomposed the lignin to lower molecular components. The nickel probably promoted the participation of hydrogen and oxygen atom to form gases through the gasification of lignin. The gas yield was attained almost 80% in a carbon basis at 673 K and 0.3 g/cm3 of water density. The main gas components were methane, carbon dioxide, hydrogen and these composition were about 54%, 40% and 6%, respectively. These results indicate that the biomass can be converted to gases including hydrogen by using nickel catalyst at low temperature region. (authors)

  7. Preparation and characterization of silica-supported Ni/Pt catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Raab, C.; Lercher, J.A. (Universitaet Wien, Vienna (Austria)); Goodwin, J.G. Jr. (Univ. of Pittsburgh, PA (USA)); Shyu, J.Z. (Amoco Research Center, Naperville, IL (USA))

    1990-04-01

    The formation of a series of Ni/Pt catalysts was investigated by means of temperature programmed reduction (TPR) of the chloride precursor, hydrogen chemisorption, x-ray diffraction, scanning electron microscopy, XPS, and magnetic measurements. An alloy between Pt and Ni was formed. The minority constituent of the series of bimetallic catalysts was always found to be quantitatively alloyed or in close contact with the more abundant metal. For several samples, the stoichiometric NiPt compound was observed. With Ni-rich samples a nonstoichiometric alloy (rich in Ni) was concluded to exist. At all concentration levels the presence of Pt facilitated the reduction of Ni{sup 2+} significantly. Temperature-programmed reduction of the Ni/Pt catalyst with 50 mol% and higher concentrations of Pt did not differ from that of pure Pt. Based on XPS and magnetic measurements it is concluded that a constant fraction (approximately 10-15%) of Ni was highly dispersed and interacted strongly with the support. 30 refs.

  8. Cerium Modified Pillared Montmorillonite Supported Cobalt Catalysts for Fischer Tropsch Synthesis

    International Nuclear Information System (INIS)

    Fischer-Tropsch (FT) synthesis was accomplished over Al-pillared Montmorillonite supported 20 wt% Co modified with different weight% of cerium catalysts. These catalysts were prepared by impregnation method while structural characterizations of the prepared samples were performed by XRD, TPR, NH/sub 3/TPD, TGA, BET, XRF and SEM techniques. The Fischer Tropsch reaction was studied in fixed bed micro catalytic reactor at temperature range of 220, 260 and 275 degree C and at different pressure (1, 5 and 10 bars). From the activity results, it was found that by pillaring NaMMT with Al higher catalytic activity and lower methane selectivity of NaMMT was achieved. Furthermore, the results of FT synthesis reaction revealed that cerium incorporation increased the dispersion of Co/sub 3/O/sub 4/ on the surface and consequently resulted in enhanced catalytic activity. Additionally, the C/sub 5/-C/sub 12/ hydrocarbons and methane selectivity increased while C/sub 22+/ hydrocarbons selectivity was decreased over cerium modified catalysts. Higher reaction temperature (>220 degree C) resulted in significant enhancement in CO conversion and methane selectivity. Though, increase in pressure from 1 to 10 bars eventually resulted in increase in C/sub 5+/ hydrocarbons and decrease in methane and C/sub 2/-C/sub 5/ hydrocarbons selectivity. (author)

  9. The application of inelastic neutron scattering to investigate the steam reforming of methane over an alumina-supported nickel catalyst

    Science.gov (United States)

    McFarlane, Andrew R.; Silverwood, Ian P.; Norris, Elizabeth L.; Ormerod, R. Mark; Frost, Christopher D.; Parker, Stewart F.; Lennon, David

    2013-12-01

    An alumina-supported nickel catalyst, previously used in methane reforming experiments employing CO2 as the oxidant, is applied here in the steam reforming variant of the process. Micro-reactor experiments are used to discern an operational window compatible with sample cells designed for inelastic neutron scattering (INS) experiments. INS spectra are recorded after 6 h reaction of a 1:1 mixture of CH4 and H2O at 898 K. Weak INS spectra are observed, indicating minimal hydrogen retention by the catalyst in this operational regime. Post-reaction, the catalyst is further characterised by powder X-ray diffraction, transmission electron microscopy and Raman scattering. In a comparable fashion to that seen for the ‘dry’ reforming experiments, the catalyst retains substantial quantities of carbon in the form of filamentous coke. The role for hydrogen incorporation by the catalyst is briefly considered.

  10. One-pot Synthesis of Pt Catalysts Supported on Al-modified TiO2

    Directory of Open Access Journals (Sweden)

    Rebecca Olsen

    2014-10-01

    Full Text Available A facile, industrially viable, one-pot synthesis of 0.5-8 wt% Pt supported on 22 mol% Al-modified ana-tase with high surface area and thermal stability is presented. Four pathways were studied to deter-mine the effects of support properties on catalyst dispersion, and the highest dispersions were observed for high surface area materials containing 5-coordinate anatase. Systematic study of preparation vari-ables shows that low drying temperatures, slow calcination ramp rates, and slow reduction ramp rates further increased Pt dispersion and resulted in a more uniform Pt size distribution. Pt dispersions as high as 54% have been obtained using the one-pot method and 59% for Pt catalysts synthesized by dry impregnation. Statistically designed studies are needed to more completely determine the effects of synthesis variables and to optimize the dispersion and reduction of Pt supported on Al-modified ana-tase. Results presented in this paper show that this one-pot method and dry impregnation method us-ing our Al-modified anatase support are promising syntheses of highly dispersed Pt supported on stabi-lized titania. Our results demonstrate that the alumina-stabilized anatase support is superior to other anatase supports for (1 obtaining high Pt dispersions, i.e. more efficiently utilizing this expensive pre-cious metal, and (2 processes in which thermal stability is important due to its constant phase and pore structures at high temperatures. © 2014 BCREC UNDIP. All rights reservedReceived: 20th April 2014; Revised: 14th May 2014; Accepted: 10th June 2014How to Cite: Olsen, R.E., Bartholomew,C.H., Enfield, D.B., Woodfield, B.F. (2014. One-pot Synthesis of Pt Catalysts Supported on Al-modified TiO2. Bulletin of Chemical Reaction Engineering & Catalysis, 9 (3: 156-167. (doi:10.9767/bcrec.9.3.6734.156-167Permalink/DOI: http://dx.doi.org/10.9767/bcrec.9.3.6734.156-167

  11. Novel growth method of carbon nanotubes using catalyst-support layer developed by alumina grit blasting

    Science.gov (United States)

    Watanabe, Hiromichi; Ishii, Juntaro; Ota, Keishin

    2016-08-01

    We propose an efficient method of growing carbon nanotube (CNT) arrays on a variety of metals, alloys, and carbon materials using chemical vapor deposition (CVD) assisted by a simple surface treatment of the materials. The main feature of this method is the application of grit blasting with fine alumina particles to the development of a catalyst-support layer required for the growth of CNTs on various conductive materials, including ultra-hard metals such as tungsten. Auger electron spectroscopy shows that grit blasting can form a non-continuous layer where alumina nanoparticles are embedded as residues in the blasting media left on the treated surfaces. This work reveals that such a non-continuous alumina layer can behave as the catalyst-support layer, which is generally prepared by sputter or a vacuum evaporation coating process that considerably restricts the practical applications of CNTs. We have attempted to grow CNTs on grit-blasted substrates of eighteen conventionally used conductive materials using CVD together with a floating iron catalyst. The proposed method was successful in growing multi-walled CNT arrays on the grit-blasted surfaces of all the examined materials, demonstrating its versatility. Furthermore, we found that the group IV metal oxide films thermally grown on the as-received substrates can support the catalytic activity of iron nanoparticles in the CVD process just as well as the alumina film developed by grit blasting. Spectral emissivity of the CNT arrays in the visible and infrared wavelength ranges has been determined to assess the applicability of the CNT arrays as a black coating media.

  12. Novel growth method of carbon nanotubes using catalyst-support layer developed by alumina grit blasting.

    Science.gov (United States)

    Watanabe, Hiromichi; Ishii, Juntaro; Ota, Keishin

    2016-08-19

    We propose an efficient method of growing carbon nanotube (CNT) arrays on a variety of metals, alloys, and carbon materials using chemical vapor deposition (CVD) assisted by a simple surface treatment of the materials. The main feature of this method is the application of grit blasting with fine alumina particles to the development of a catalyst-support layer required for the growth of CNTs on various conductive materials, including ultra-hard metals such as tungsten. Auger electron spectroscopy shows that grit blasting can form a non-continuous layer where alumina nanoparticles are embedded as residues in the blasting media left on the treated surfaces. This work reveals that such a non-continuous alumina layer can behave as the catalyst-support layer, which is generally prepared by sputter or a vacuum evaporation coating process that considerably restricts the practical applications of CNTs. We have attempted to grow CNTs on grit-blasted substrates of eighteen conventionally used conductive materials using CVD together with a floating iron catalyst. The proposed method was successful in growing multi-walled CNT arrays on the grit-blasted surfaces of all the examined materials, demonstrating its versatility. Furthermore, we found that the group IV metal oxide films thermally grown on the as-received substrates can support the catalytic activity of iron nanoparticles in the CVD process just as well as the alumina film developed by grit blasting. Spectral emissivity of the CNT arrays in the visible and infrared wavelength ranges has been determined to assess the applicability of the CNT arrays as a black coating media. PMID:27389659

  13. Metal (Fe, Co, Ni) supported on different aluminas as Fischer-Tropsch catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Dahlan [Chemistry Education Study Program, Universitas Halu Oleo, Jl. HEA Mokodompit, Kendari 93232 (Indonesia); Marsih, I. Nyoman, E-mail: nyoman@chem.itb.ac.id; Ismunandar [Inorganic and Physical Chemistry Division, Departement of Chemistry, Institut Teknologi Bandung, Jl. Ganesha 10, Bandung 40132 (Indonesia); Makertihartha, I. G. B. N. [Department of Chemical Engineering, Institut Teknologi Bandung, Jl. Ganesha 10, Bandung 40132 (Indonesia); Praserthdam, Piyasan; Panpranot, Joongjai [Center of Excellence on Catalysis and Catalytic Reaction Engineering, Department of Chemical Engineering, Chulalongkorn University, 254 Phayathai Road, Bangkok 10330 (Thailand)

    2015-09-30

    This research aimed to compare the physico-chemical properties of the same metal M (M = iron, cobalt, nickel) supported on aluminas with different morphology and pore size as Fischer-Tropsch catalyst. The aluminas applied as support were alumina synthesized through hydrothermal process, alumina formed by pretreatment of catapal and commercial alumina which named as Ahy, Aca, and Aco respectively. Ahy has uniform morphology of nanotubes while Aca and Aco showed non-uniform morphology of particle lumps. The particle lumps of Aca were larger than those of Aco. Ahy, Aca, and Aco respectively has average pore diameter of 2.75, 2.86 and 2.9 nm. Metals were deposited on the supports by incipient-wetness impregnation method. The catalysts were characterized by XRD, H{sub 2}-TPR, and H{sub 2} chemisorption. Catalyst acitivity test for Fischer-Tropsch reaction was carried out in a micro reactor at 200 °C and 1 atm, and molar ratio of H{sub 2}/CO = 2:1. The metal oxide particle size increased in the order M/Aco < M/Aca < M/Ahy. The catalysts reducibility also increased according to the order M/Aco < M/Aca < M/Ahy suggesting that the larger metal oxide particles are more reducible. The number of active site was not proportional to the reducibility because during the reduction, larger metal oxide particles were converted into larger metal particles. On the other hand, the number of active sites was inversely proportional to the particle sizes. The number of active site increased in the order M/Ahy < M/Aco < M/Aca. The catalytic activity also increased in the following order M/Ahy < M/Aco < M/Aca. The activity per active site increased according to the order M/Aca < M/Aco < M/Ahy meaning that for M/Ahy, a little increase in active site will lead to a significance increase in catalytic activity. It showed that Ahy has potential for the better support.

  14. Carbon monoxide adsorption and hydrogenation of deposited carbon on alumina supported modified surface catalyst

    International Nuclear Information System (INIS)

    The catalytic behavior of series of Ru/Al/sub 2/O/sub 2/ catalysts promoted with various levels of Au were investigated in the CO-hydrogenation reaction and have been the subject of numerous investigations. Catalytic activities and product selectivities reveal that no significant ensembles or electronic effect is produced by the addition of Au to Ru/Al/sub 2/O/sub 3/ system. It is suggested that a significant fraction of added Au species interacts with the support rather with the Ru metal. (author)

  15. Oxygen reduction on carbon supported platinum catalysts in high temperature polymer electrolytes

    DEFF Research Database (Denmark)

    Qingfeng, Li; Hjuler, Hans Aage; Bjerrum, Niels

    2000-01-01

    Oxygen reduction on carbon supported platinum catalysts has been investigated in H3PO4, H3PO4-doped Nafion and polybenzimidazole (PBI) polymer electrolytes in a temperature range up to 190 degrees C. Compared with pure H3PO4, the combination of H3PO4 and polymer electrolytes can significantly...... improve the oxygen reduction kinetics due to increased oxygen solubility and suppressed adsorption of phosphoric acid anions. Further enhancement of the catalytic activity can be obtained by operating the polymer electrolytes at higher temperatures. Efforts have been made to develop a polymer electrolyte...

  16. Preparation of supported copper catalyst by spray pyrolysis of copper acetate on HEU zeolite

    International Nuclear Information System (INIS)

    Bulgarian natural clinoptilolite was coated with copper and its oxides via spray pyrolysis method. D.C. arc-AES method revealed the presence of copper atoms. XRD patterns showed that after loading the Heulandite-type (HEU-type) structure is preserved. It is also proved that several copper phases exist on the zeolite: Cu, CuO and Cu2O. The chemical content of natural and coated zeolite forms has been proved by XPS analysis. Scanning Electron Microscopy (SEM) revealed Cu nanoparticles situated over the zeolite surface as agglomerates. The ozone conversion on the copper supported catalyst reaches 87% and does not change with the course of time

  17. On the preparation and characterisation of MCM-41 supported heterogeneous nickel and molybdenum catalysts

    OpenAIRE

    Lensveld, Dennis

    2003-01-01

    MCM-41 is an ordered mesoporous material, displaying a honeycomb-like structure of uniform mesopores (3 nm in diameter) running through a matrix of amorphous silica. Because of the high porosity (pore volume » 1.0 ml g-1) and concomitant large surface area (approximately 1,000 m2 g-1) MCM-41 is in principle ideally suited to be used as a support material for heterogeneous catalysts, as it offers the possibility to apply (precursors of) active phases in a highly dispersed fashion. Unfortunatel...

  18. Supported Potassium-Doped Co3O4 Catalysts for N2O Decomposition

    Czech Academy of Sciences Publication Activity Database

    Klyushina, A.; Kovanda, F.; Jirátová, Květa; Obalová, L.

    Praha: Česká společnost chemická, 2014, s. 814-815. ISSN 0009-2770. [Sjezd asociací českých a slovenských chemických společností /66./. Ostrava (CZ), 07.09.2014-10.09.2014] R&D Projects: GA ČR GA14-13750S Grant ostatní: GA MŠMT(CZ) LO1208; GA MŠMT(CZ) SP2014/48 Institutional support: RVO:67985858 Keywords : cobalt nitrate solution * catalysts * potassium Subject RIV: CI - Industrial Chemistry, Chemical Engineering http://hdl.handle.net/11104/0235805

  19. Kinetics of the Bray-Liebhafsky oscillatory reaction perturbed by polymer supported cobalt catalyst

    OpenAIRE

    Maksimović J.P.; Čupić Ž.D.; Lončarević D.; Pejić N.; Vasiljević-Radović D.; Anić S.

    2011-01-01

    The Bray-Liebhafsky (BL) oscillatory reaction generated in the batch reactor at 62- 68 oC was perturbed by cobalt(II)-nitrate, supported on the macroreticular copolymer of poly-4-vinylpyridine with divinylbenzene (Co-PVPDVB). The kinetic data was analyzed of the complex pathways of the hydrogen peroxide decomposition in the examined BL reaction. The obtained results confirm that the kinetics of the BL reaction in the presence Co-PVPDVB comes partially from the Co-catalyst and partially ...

  20. Metal (Fe, Co, Ni) supported on different aluminas as Fischer-Tropsch catalyst

    International Nuclear Information System (INIS)

    This research aimed to compare the physico-chemical properties of the same metal M (M = iron, cobalt, nickel) supported on aluminas with different morphology and pore size as Fischer-Tropsch catalyst. The aluminas applied as support were alumina synthesized through hydrothermal process, alumina formed by pretreatment of catapal and commercial alumina which named as Ahy, Aca, and Aco respectively. Ahy has uniform morphology of nanotubes while Aca and Aco showed non-uniform morphology of particle lumps. The particle lumps of Aca were larger than those of Aco. Ahy, Aca, and Aco respectively has average pore diameter of 2.75, 2.86 and 2.9 nm. Metals were deposited on the supports by incipient-wetness impregnation method. The catalysts were characterized by XRD, H2-TPR, and H2 chemisorption. Catalyst acitivity test for Fischer-Tropsch reaction was carried out in a micro reactor at 200 °C and 1 atm, and molar ratio of H2/CO = 2:1. The metal oxide particle size increased in the order M/Aco < M/Aca < M/Ahy. The catalysts reducibility also increased according to the order M/Aco < M/Aca < M/Ahy suggesting that the larger metal oxide particles are more reducible. The number of active site was not proportional to the reducibility because during the reduction, larger metal oxide particles were converted into larger metal particles. On the other hand, the number of active sites was inversely proportional to the particle sizes. The number of active site increased in the order M/Ahy < M/Aco < M/Aca. The catalytic activity also increased in the following order M/Ahy < M/Aco < M/Aca. The activity per active site increased according to the order M/Aca < M/Aco < M/Ahy meaning that for M/Ahy, a little increase in active site will lead to a significance increase in catalytic activity. It showed that Ahy has potential for the better support

  1. Nanocrystalline Anatase Titania Supported Vanadia Catalysts: Facet-dependent Structure of Vanadia

    Energy Technology Data Exchange (ETDEWEB)

    Li, Wei-Zhen; Gao, Feng; Li, Yan; Walter, Eric D.; Liu, Jun; Peden, Charles HF; Wang, Yong

    2015-07-09

    Titania supported vanadia, a classic heterogeneous catalyst for redox reactions, typically has nonhomogeneous vanadia species on various titania facets, making it challenging not only to determine and quantify each species but also to decouple their catalytic contributions. We prepared truncated tetragonal bipyramidal (TiO2-TTB) and rod-like (TiO2-Rod) anatase titania with only {101} and {001} facets at ratios of about 80:20 and 93:7, respectively, and used them as supports of sub-monolayer vanadia. The structure and redox properties of supported vanadia were determined by XRD, TEM, XPS, EPR, Raman, FTIR and TPR, etc. It was found that vanadia preferentially occupy TiO2 {001} facets and form isolated O=V4+(O-Ti)2 species, and with further increase in vanadia surface coverage, isolated O=V5+(O-Ti)3 and oligomerized O=V5+(O-M)3 (M = Ti or V) species form on TiO2 {101} facets. The discovery on support facet-dependent structure of vanadia on anatase titania is expected to enable the elucidation of structure-function correlations on high surface area TiO2 supported vanadia catalysts. This work was supported by U. S. Department of Energy (DOE), Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Biosciences and Geosciences. The research was performed in the Environmental Molecular Sciences Laboratory (EMSL), a national scientific user facility sponsored by the DOE Office of Biological and Environmental Research, and located at Pacific Northwest National Laboratory (PNNL). PNNL is operated for DOE by Battelle.

  2. Carbon Nanotubes and Other Nanostructures as Support Material for Nanoparticulate Noble-Metal Catalysts in Fuel Cells

    DEFF Research Database (Denmark)

    Larsen, Mikkel Juul; Veltzé, Sune; Skou, Eivind Morten

    platinum-alloy catalysts in the electrodes are required. To maximize the utilization of the noble metal it is frequently deposited as nanoparticles (1-5 nm) on a stabilizing support of carbon black. Carbon black provides good anchoring of the catalyst particles, but is prone to severe destructive oxidation...... fuel-cell electrodes. However, the low concentration of structural defects also poses challenges with regard to anchoring of the catalyst particles on the CNT surface. Thus, activation treatments introducing surface functional groups may be necessary. Also, the surface properties are responsible for...

  3. Carbon nanotubes and other nanostructures as support material for nanoparticulate noble-metal catalysts in fuel cells

    DEFF Research Database (Denmark)

    Veltzé, Sune; Larsen, Mikkel Juul; Elina, Yli-Rantala;

    platinum-alloy catalysts in the electrodes are required. To maximize the utilization of the noble metal it is frequently deposited as nanoparticles (1–5 nm) on a stabilizing support of carbon black. Carbon black provides good anchoring of the catalyst particles, but is prone to severe destructive oxidation...... fuel-cell electrodes. However, the low concentration of structural defects also poses challenges with regard to anchoring of the catalyst particles on the CNT surface. Thus, activation treatments introducing surface functional groups may be necessary. Also, the surface properties are responsible for...

  4. CuO/CeO2 catalysts prepared with different cerium supports for CO oxidation at low temperature

    International Nuclear Information System (INIS)

    The activity of a catalyst depends on the nature of its support, its active site, and its preparation method. This study aimed to employ various types of CeO2 supports such as commercial CeO2 and self-prepared CeO2 for the preparation of copper catalysts. The CuO/CeO2 catalysts were prepared using the polyol process and impregnation method. The catalysts were characterized using Brunauer–Emmett–Teller analysis, scanning electron microscopy, and X-ray analysis, and their catalytic activity for CO removal was evaluated in a microcatalytic reactor. The experimental results showed that the catalytic activity of the CuO/CeO2 catalysts with different calcination temperatures decreased in the following order: 500 °C > 300 °C > 700 °C. Compared to the impregnation method, the polyol process generated well-dispersed metal particles over the support and showed higher CO removal efficiency with low activation energy. Compared to CuO/CeO2 catalysts with commercial CeO2, those with CeO2 that was self-prepared by pyrolysis had a large pore volume and good crystal structure of CeO2 and showed good performance. The catalytic activity for CO removal was in the following order: CuO/CeO2-P (pyrolysis) > CuO/CeO2-C (commercial) > CuO/CeO2-D (deposition precipitation). CuO/CeO2-P catalysts showed good activity even at low temperature. The CuO/CeO2-P(300)-P-120 min catalyst was found to possess the good CO removal rate when the oxygen content was 6%, CO concentration was 500 ppm, catalyst weighed 1.0 g, pollutant gas velocity was 500 mL min−1, SV was 3.7 × 104 h−1, and reaction temperature was 150 °C. - Highlights: • CuO/CeO2 catalysts were prepared using polyol and impregnation methods. • The supports of catalyst were self-prepared cerium oxide and commercial cerium oxide. • Pyrolysis and deposition precipitation methods were used for cerium preparation. • Catalytic activity of CuO/CeO2 catalysts were evaluated by the removal of CO

  5. Studies on Zeolite-Supported Mo and Re Catalysts : Catalytic Performance in Methane Aromatization Reaction and Their Structural Characterization

    OpenAIRE

    Wang, Linsheng

    1999-01-01

    The main achievements in the present studies are summarized as 4 key points: 1) HZSM-5 supported Mo and Re catalysts are found to be quite active and selective for directly conyerting methane to benzene, naphthalene and C2 hydrocarbons. A great progress for methane aromatization has been made because of the discover of the two new catalysts. 2) Coke deposition on the catalyst for non-oxidative conversion of methane is solved by varying methane pressure combined with addition of CO2 in methane...

  6. Titania Supported Pt and Pt/Pd Nano-particle Catalysts for the Oxidation of Sulfur Dioxide

    DEFF Research Database (Denmark)

    Koutsopoulos, Sotiris; Johannessen, Tue; Eriksen, Kim Michael;

    2006-01-01

    Several types of titania (anatase) were used as supports for pure platinum and Pt–Pd bimetallic alloy catalysts. The preparation methods, normal wet impregnation technique and flame aerosol synthesis, obtained metal loadings of 2% by weight. The prepared catalysts were tested for SO2 oxidation...... activity at atmospheric pressure in the temperature range 250–600 °C. The SO2 to SO3 conversion efficiency of the Pt–Pd alloy was significantly higher than that of the individual metals. The effects of the preparation method and the titania type used on the properties and activity of the resulting catalyst...

  7. CuO/CeO{sub 2} catalysts prepared with different cerium supports for CO oxidation at low temperature

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Chi-Yuan [School of Public Health, Chung Shan Medical University, Taichung 402, Taiwan, ROC (China); Department of Occupational Medicine, Chung Shan Medical University Hospital, Taichung 402, Taiwan, ROC (China); Chang, Wen-Chi [Department of Environmental Engineering, National Chung Hsing University, Taichung 402, Taiwan, ROC (China); Wey, Ming-Yen, E-mail: mywey@dragon.nchu.edu.tw [Department of Environmental Engineering, National Chung Hsing University, Taichung 402, Taiwan, ROC (China)

    2013-08-15

    The activity of a catalyst depends on the nature of its support, its active site, and its preparation method. This study aimed to employ various types of CeO{sub 2} supports such as commercial CeO{sub 2} and self-prepared CeO{sub 2} for the preparation of copper catalysts. The CuO/CeO{sub 2} catalysts were prepared using the polyol process and impregnation method. The catalysts were characterized using Brunauer–Emmett–Teller analysis, scanning electron microscopy, and X-ray analysis, and their catalytic activity for CO removal was evaluated in a microcatalytic reactor. The experimental results showed that the catalytic activity of the CuO/CeO{sub 2} catalysts with different calcination temperatures decreased in the following order: 500 °C > 300 °C > 700 °C. Compared to the impregnation method, the polyol process generated well-dispersed metal particles over the support and showed higher CO removal efficiency with low activation energy. Compared to CuO/CeO{sub 2} catalysts with commercial CeO{sub 2}, those with CeO{sub 2} that was self-prepared by pyrolysis had a large pore volume and good crystal structure of CeO{sub 2} and showed good performance. The catalytic activity for CO removal was in the following order: CuO/CeO{sub 2}-P (pyrolysis) > CuO/CeO{sub 2}-C (commercial) > CuO/CeO{sub 2}-D (deposition precipitation). CuO/CeO{sub 2}-P catalysts showed good activity even at low temperature. The CuO/CeO{sub 2}-P(300)-P-120 min catalyst was found to possess the good CO removal rate when the oxygen content was 6%, CO concentration was 500 ppm, catalyst weighed 1.0 g, pollutant gas velocity was 500 mL min{sup −1}, SV was 3.7 × 10{sup 4} h{sup −1}, and reaction temperature was 150 °C. - Highlights: • CuO/CeO{sub 2} catalysts were prepared using polyol and impregnation methods. • The supports of catalyst were self-prepared cerium oxide and commercial cerium oxide. • Pyrolysis and deposition precipitation methods were used for cerium preparation.

  8. Controlled radical polymerization of vinyl acetate in presence of mesoporous silica supported TiCl4 heterogeneous catalyst

    Indian Academy of Sciences (India)

    M A Semsarzadeh; S Amiri; M Azadeh

    2012-10-01

    The heterogeneous TiCl4 catalysts supported on mesoporous mobile composition of matter (MCM-41) and mesoporous silicone particles synthesized from block copolymer of PPG–PEG–PPG (SPB) complexed with dimethyl formamide (DMF) ligand were used in a controlled free radical reaction with benzoyl peroxide (BPO) initiator in bulk polymerization of vinyl acetate (VAc). In this polymerization process, mesoporous particle of SPB increased the reactivity of TiCl4 catalyst with DMF ligand. The active site formed on the surface and the pores of the catalyst produced specific sequences of VAc on the chain with different thermal and microstructural properties and crystallinity.

  9. Catalytic Transfer Hydrogenation of Furfural to Furfuryl Alcohol over Nitrogen-Doped Carbon-Supported Iron Catalysts.

    Science.gov (United States)

    Li, Jiang; Liu, Jun-Ling; Zhou, Hong-Jun; Fu, Yao

    2016-06-01

    Iron-based heterogeneous catalysts, which were generally prepared by pyrolysis of iron complexes on supports at elevated temperature, were found to be capable of catalyzing the transfer hydrogenation of furfural (FF) to furfuryl alcohol (FFA). The effects of metal precursor, nitrogen precursor, pyrolysis temperature, and support on catalytic performance were examined thoroughly, and a comprehensive study of the reaction parameters was also performed. The highest selectivity of FFA reached 83.0 % with a FF conversion of 91.6 % under the optimal reaction condition. Catalyst characterization suggested that iron cations coordinated by pyridinic nitrogen functionalities were responsible for the enhanced catalytic activity. The iron catalyst could be recycled without significant loss of catalytic activity for five runs, and the destruction of the nitrogen-iron species, the presence of crystallized Fe2 O3 phase, and the pore structure change were the main reasons for catalyst deactivation. PMID:27144965

  10. Nickel catalysts supported on MgO with different specific surface area for carbon dioxide reforming of methane

    Institute of Scientific and Technical Information of China (English)

    Luming; Zhang; Lin; Li; Yuhua; Zhang; Yanxi; Zhao; Jinlin; Li

    2014-01-01

    In this paper, three kinds of MgO with different specific surface area were prepared, and their effects on the catalytic performance of nickel catalysts for the carbon dioxide reforming of methane were investigated. The results showed that MgO support with the higher specific surface area led to the higher dispersion of the active metal, which resulted in the higher initial activity. On the other hand, the specific surface area of MgO materials might not be the dominant factor for the basicity of support to chemisorb and activate CO2, which was another important factor for the performance of catalysts. Herein, Ni/MgO(CA) catalyst with proper specific surface area and strong ability to activate CO2exhibited stable catalytic property and the carbon species deposited on the Ni/MgO(CA) catalyst after 10 h of reaction at 650 ?C were mainly activated carbon species.

  11. Heterogeneous catalytic ozonation of ciprofloxacin in water with carbon nanotube supported manganese oxides as catalyst

    International Nuclear Information System (INIS)

    Highlights: ► Ciprofloxacin in water was degraded by heterogeneous catalytic ozonation. ► MnOx were supported on MWCNTs to serve as catalyst for ozonation. ► MnOx/MWCNT exhibited highly catalytic activity on ozonation of ciprofloxacin in water. ► MnOx/MWCNT resulted in effective antibacterial activity inhibition on ciprofloxacin. ► MnOx/MWCNT promoted the generation of hydroxyl radicals. - Abstract: Carbon nanotube-supported manganese oxides (MnOx/MWCNT) were used as catalysts to assist ozone in degrading ciprofloxacin in water. Manganese oxides were successfully loaded on multi-walled carbon nanotube surfaces by simply impregnating the carbon nanotube with permanganate solution. The catalytic activities of MnOx/MWCNT in ciprofloxacin ozonation, including degradation, mineralization effectiveness, and antibacterial activity change, were investigated. The presence of MnOx/MWCNT significantly elevated the degradation and mineralization efficiency of ozone on ciprofloxacin. The microbiological assay with a reference Escherichia coli strain indicated that ozonation with MnOx/MWCNT results in more effective antibacterial activity inhibition of ciprofloxacin than that in ozonation alone. The effects of catalyst dose, initial ciprofloxacin concentration, and initial pH conditions on ciprofloxacin ozonation with MnOx/MWCNT were surveyed. Electron spin resonance trapping was applied to assess the role of MnOx/MWCNT in generating hydroxyl radicals (HO·) during ozonation. Stronger 5,5-dimethyl-1-pyrroline-N-oxide–OH signals were observed in the ozonation with MnOx/MWCNT compared with those in ozonation alone, indicating that MnOx/MWCNT promoted the generation of hydroxyl radicals. The degradation of ciprofloxacin was studied in drinking water and wastewater process samples to gauge the potential effects of water background matrix on MnOx/MWCNT catalytic ozonation.

  12. Heterogeneous catalytic ozonation of ciprofloxacin in water with carbon nanotube supported manganese oxides as catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Sui, Minghao, E-mail: suiminghao.sui@gmail.com [State Key Laboratory of Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai 200092 (China); Xing, Sichu; Sheng, Li; Huang, Shuhang; Guo, Hongguang [State Key Laboratory of Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai 200092 (China)

    2012-08-15

    Highlights: Black-Right-Pointing-Pointer Ciprofloxacin in water was degraded by heterogeneous catalytic ozonation. Black-Right-Pointing-Pointer MnOx were supported on MWCNTs to serve as catalyst for ozonation. Black-Right-Pointing-Pointer MnOx/MWCNT exhibited highly catalytic activity on ozonation of ciprofloxacin in water. Black-Right-Pointing-Pointer MnOx/MWCNT resulted in effective antibacterial activity inhibition on ciprofloxacin. Black-Right-Pointing-Pointer MnOx/MWCNT promoted the generation of hydroxyl radicals. - Abstract: Carbon nanotube-supported manganese oxides (MnOx/MWCNT) were used as catalysts to assist ozone in degrading ciprofloxacin in water. Manganese oxides were successfully loaded on multi-walled carbon nanotube surfaces by simply impregnating the carbon nanotube with permanganate solution. The catalytic activities of MnOx/MWCNT in ciprofloxacin ozonation, including degradation, mineralization effectiveness, and antibacterial activity change, were investigated. The presence of MnOx/MWCNT significantly elevated the degradation and mineralization efficiency of ozone on ciprofloxacin. The microbiological assay with a reference Escherichia coli strain indicated that ozonation with MnOx/MWCNT results in more effective antibacterial activity inhibition of ciprofloxacin than that in ozonation alone. The effects of catalyst dose, initial ciprofloxacin concentration, and initial pH conditions on ciprofloxacin ozonation with MnOx/MWCNT were surveyed. Electron spin resonance trapping was applied to assess the role of MnOx/MWCNT in generating hydroxyl radicals (HO{center_dot}) during ozonation. Stronger 5,5-dimethyl-1-pyrroline-N-oxide-OH signals were observed in the ozonation with MnOx/MWCNT compared with those in ozonation alone, indicating that MnOx/MWCNT promoted the generation of hydroxyl radicals. The degradation of ciprofloxacin was studied in drinking water and wastewater process samples to gauge the potential effects of water background matrix on

  13. NO oxidation on Zeolite Supported Cu Catalysts: Formation and Reactivity of Surface Nitrates

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Hai-Ying; Wei, Zhehao; Kollar, Marton; Gao, Feng; Wang, Yilin; Szanyi, Janos; Peden, Charles HF

    2016-04-18

    The comparative activities of a small-pore Cu-CHA and a large-pore Cu-BEA catalyst for the selective catalytic reduction (SCR) of NOx with NH3, and for the oxidation of NO to NO2 and the subsequent formation of surface nitrates were investigated. Although both catalysts are highly active in SCR reactions, they exhibit very low NO oxidation activity. Furthermore, Cu-CHA is even less active than Cu-BEA in catalyzing NO oxidation but is clearly more active for SCR reactions. Temperature-programed desorption (TPD) experiments following the adsorption of (NO2 + NO + O2) with different NO2:NO ratios reveal that the poor NO oxidation activity of the two catalysts is not due to the formation of stable surface nitrates. On the contrary, NO is found to reduce and decompose the surface nitrates on both catalysts. To monitor the reaction pathways, isotope exchange experiments were conducted by using 15NO to react with 14N-nitrate covered catalyst surfaces. The evolution of FTIR spectra during the isotope exchange process demonstrates that 14N-nitrates are simply displaced with no formation of 15N-nitrates on the Cu-CHA sample, which is clearly different from that observed on the Cu-BEA sample where formation of 15N-nitrates is apparent. The results suggest that the formal oxidation state of N during the NO oxidation on Cu-CHA mainly proceeds from its original +2 to a +3 oxidation state, whereas reaching a higher oxidation state for N, such as +4 or +5, is possible on Cu-BEA. The authors at PNNL gratefully acknowledge the US Department of Energy (DOE), Energy Efficiency and Renewable Energy, Vehicle Technologies Office for the support of this work. The research described in this paper was performed at the Environmental Molecular Sciences Laboratory (EMSL), a national scientific user facility sponsored by the DOE’s Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory (PNNL). PNNL is operated for the US DOE by Battelle.

  14. Oxygen-deficient titania as alternative support for Pt catalysts for the oxygen reduction reaction

    Institute of Scientific and Technical Information of China (English)

    Anqi Zhao; Justus Masa; Wei Xia

    2014-01-01

    Insufficient electrochemical stability is a major challenge for carbon materials in oxygen reduction reaction (ORR) due to carbon corrosion and insufficient metal-support interactions. In this work, titania is explored as an alternative support for Pt catalysts. Oxygen deficient titania samples including TiO2−x and TiO2−xNy were obtained by thermal treatment of anatase TiO2 under flowing H2 and NH3, respectively. Pt nanoparticles were deposited on the titania by a modified ethylene glycol method. The samples were characterized by N2-physisorption, X-ray diffraction and X-ray photoelectron spectroscopy. The ORR activity and long-term stability of supported Pt catalysts were evaluated using linear sweep voltammetry and chronoamperometry in 0.1 mol/L HClO4. Pt/TiO2−x and Pt/TiO2−xNy showed higher ORR activities than Pt/TiO2 as indicated by higher onset potentials. Oxygen deficiency in TiO2−x and TiO2−xNy contributed to the high ORR activity due to enhanced charge transfer, as disclosed by electrochemical impedance spectroscopy studies. Electrochemical stability studies revealed that Pt/TiO2−x exhibited a higher stability with a lower current decay rate than commercial Pt/C, which can be attributed to the stable oxide support and strong interaction between Pt nanoparticles and the oxygen-deficient TiO2−x support.

  15. Size and Promoter Effects on Stability of Carbon-Nanofiber-Supported Iron-Based Fischer–Tropsch Catalysts

    Science.gov (United States)

    2016-01-01

    The Fischer–Tropsch Synthesis converts synthesis gas from alternative carbon resources, including natural gas, coal, and biomass, to hydrocarbons used as fuels or chemicals. In particular, iron-based catalysts at elevated temperatures favor the selective production of C2–C4 olefins, which are important building blocks for the chemical industry. Bulk iron catalysts (with promoters) were conventionally used, but these deactivate due to either phase transformation or carbon deposition resulting in disintegration of the catalyst particles. For supported iron catalysts, iron particle growth may result in loss of catalytic activity over time. In this work, the effects of promoters and particle size on the stability of supported iron nanoparticles (initial sizes of 3–9 nm) were investigated at industrially relevant conditions (340 °C, 20 bar, H2/CO = 1). Upon addition of sodium and sulfur promoters to iron nanoparticles supported on carbon nanofibers, initial catalytic activities were high, but substantial deactivation was observed over a period of 100 h. In situ Mössbauer spectroscopy revealed that after 20 h time-on-stream, promoted catalysts attained 100% carbidization, whereas for unpromoted catalysts, this was around 25%. In situ carbon deposition studies were carried out using a tapered element oscillating microbalance (TEOM). No carbon laydown was detected for the unpromoted catalysts, whereas for promoted catalysts, carbon deposition occurred mainly over the first 4 h and thus did not play a pivotal role in deactivation over 100 h. Instead, the loss of catalytic activity coincided with the increase in Fe particle size to 20–50 nm, thereby supporting the proposal that the loss of active Fe surface area was the main cause of deactivation. PMID:27330847

  16. Mechanistic understanding and kinetic studies of highly selective oxidative dehydrogenation of ethane over novel supported molten chloride catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Gaertner, C.; Veen, A.C. van; Lercher, J.A. [Technische Univ. Muenchen, Garching (Germany). Dept. of Chemistry

    2012-07-01

    Ethene is one of the most important feedstocks for chemical industry, nowadays mainly produced via steam cracking. However, oxidative dehydrogenation becomes a more important process route, allowing to produce ethene selectively and at lower temperatures. Supported alkali chloride catalysts are promising materials. However, the ODH mechanism of this class of catalysts is not well investigated so far. The investigation of the reaction mechanism is thus the aim of this contribution. (orig.)

  17. Nanoparticles of TiAlZr mixed oxides as supports of hydrodesulfurization catalysts: Synthesis and characterization

    Energy Technology Data Exchange (ETDEWEB)

    Kraleva, E., E-mail: ekraleva@gmail.com [Institute of Biodiversity and Ecosystems Research, Bulgarian Academy of Sciences, Sofia, Gagarin st.2 (Bulgaria); Spojakina, A. [Institute of Catalysis, Bulgarian Academy of Sciences, 1113 Sofia (Bulgaria); Saladino, M.L. [Dipartimento di Chimica ' S. Cannizzaro' , Universita di Palermo and INSTM-Udr Palermo, Parco d' Orleans II Viale delle Scienze pad 17, I-90128 Palermo,Italy (Italy); Caponetti, E. [Dipartimento di Chimica ' S. Cannizzaro' , Universita di Palermo and INSTM-Udr Palermo, Parco d' Orleans II Viale delle Scienze pad 17, I-90128 Palermo,Italy (Italy); Centro Grandi Apparecchiature - UniNetLab, Universita di Palermo, Via F. Marini 14, I-90128 Palermo (Italy); Nasillo, G. [Centro Grandi Apparecchiature - UniNetLab, Universita di Palermo, Via F. Marini 14, I-90128 Palermo (Italy); Jiratova, K. [Institute of Chemical Process Fundamentals, 16502 Prague 6 (Czech Republic)

    2012-02-05

    Highlights: Black-Right-Pointing-Pointer Preparation of ternary mixed oxide by sol-gel method. Black-Right-Pointing-Pointer Catalytic properties of the three-mixed oxides. Black-Right-Pointing-Pointer Heteropolyacid H{sub 3}PMo{sub 12}O{sub 40} and its cobalt salt Co{sub 1.5}PMo{sub 12}O{sub 40} that of active components in catalytic systems for thiophene hydrodesulfurization (HDS). - Abstract: TiAlZr mixed oxides, synthesized using sol-gel method, were characterized and used as supports of hydrodesulfurization catalysts (12 wt% Mo) prepared by impregnation either with molybdenum heteropolyacid H{sub 3}PMo{sub 12}O{sub 40} or its cobalt salt Co{sub 1.5}PMo{sub 12}O{sub 40}. Structure, morphology and textural properties of oxides and catalysts were characterized using X-ray powder diffraction (XRD), Raman spectroscopy, Nitrogen adsorption porosimetry, TEM-EDS, temperature-programmed desorption (TPD) and temperature-programmed reduction (TPR) techniques. Activity of the catalytic systems was tested in thiophene hydrodesulfurization (HDS). No formation of a new oxide phase was revealed in the synthesized mixed materials. However the effect of separated oxides on the structure of ternary oxides was observed. Maximum in HDS activity of Mo containing samples was determined by optimum content of alumina in the mixed oxides. Incorporation of cobalt into the heteropolyacid increased the HDS activity about two times and masked the effect of the support composition.

  18. Nanoparticles of TiAlZr mixed oxides as supports of hydrodesulfurization catalysts: Synthesis and characterization

    International Nuclear Information System (INIS)

    Highlights: ► Preparation of ternary mixed oxide by sol–gel method. ► Catalytic properties of the three-mixed oxides. ► Heteropolyacid H3PMo12O40 and its cobalt salt Co1.5PMo12O40 that of active components in catalytic systems for thiophene hydrodesulfurization (HDS). - Abstract: TiAlZr mixed oxides, synthesized using sol–gel method, were characterized and used as supports of hydrodesulfurization catalysts (12 wt% Mo) prepared by impregnation either with molybdenum heteropolyacid H3PMo12O40 or its cobalt salt Co1.5PMo12O40. Structure, morphology and textural properties of oxides and catalysts were characterized using X-ray powder diffraction (XRD), Raman spectroscopy, Nitrogen adsorption porosimetry, TEM-EDS, temperature-programmed desorption (TPD) and temperature-programmed reduction (TPR) techniques. Activity of the catalytic systems was tested in thiophene hydrodesulfurization (HDS). No formation of a new oxide phase was revealed in the synthesized mixed materials. However the effect of separated oxides on the structure of ternary oxides was observed. Maximum in HDS activity of Mo containing samples was determined by optimum content of alumina in the mixed oxides. Incorporation of cobalt into the heteropolyacid increased the HDS activity about two times and masked the effect of the support composition.

  19. Enhanced stability of multilayer graphene-supported catalysts for polymer electrolyte membrane fuel cell cathodes

    Science.gov (United States)

    Marinkas, A.; Hempelmann, R.; Heinzel, A.; Peinecke, V.; Radev, I.; Natter, H.

    2015-11-01

    One of the biggest challenges in the field of polymer electrolyte membrane fuel cells (PEMFC) is to enhance the lifetime and the long-term stability of PEMFC electrodes, especially of cathodes, furthermore, to reduce their platinum loading, which could lead to a cost reduction for efficient PEMFCs. These demands could be achieved with a new catalyst support architecture consisting of a composite of carbon structures with significant different morphologies. A highly porous cathode catalyst support layer is prepared by addition of various carbon types (carbon black particles, multi-walled carbon nanotubes (MWCNT)) to multilayer graphene (MLG). The reported optimized cathodes shows extremely high durability and similar performance to commercial standard cathodes but with 89% lower Pt loading. The accelerated aging protocol (AAP) on the membrane electrode assemblies (MEA) shows that the presence of MLG increases drastically the durability and the Pt-extended electrochemical surface area (ECSA). In fact, after the AAP slightly enhanced performance can be observed for the MLG-containing cathodes instead of a performance loss, which is typical for the commercial carbon-based cathodes. Furthermore, the presence of MLG drastically decreases the ECSA loss rate. The MLG-containing cathodes show up to 6.8 times higher mass-normalized Pt-extended ECSA compared to the commercial standard systems.

  20. Atomic-Scale Studies of Oxides Supported Catalysts by X-ray and Imaging Methods

    Science.gov (United States)

    Feng, Zhenxing

    2011-12-01

    Oxide supported metal and metal oxide catalysts have been synthesized by molecular beam epitaxy (MBE) and atomic-layer deposition (ALD). To obtain a general idea of how a catalyst behaves chemically and structurally during reduction-oxidization (redox) reaction at atomic-scale, oxide single crystals with well-defined surfaces are used as supports to grow monolayer (ML) and sub-ML catalysts. Several model catalysis systems are investigated: Pt/SrTiO 3(001), WOX/alpha-Fe2O3(0001), VO X/alpha-TiO2(110) and mixed VOX/WOX/alpha-TiO 2(110). For purposes of comparison the catalysts include a noble metal (Pt), inert oxide (WOX) and active oxide (VOX). The oxide supports are categorized as a reducible substrate, alpha-Fe2 O3(0001), and non-reducible substrates, alpha-TiO 2(110) and SrTiO3(001). To obtain in situ information, a variety of X-ray and scanning imaging methods have been applied together to study the atomic-scale surface morphology, structure and cation dynamics during chemical reactions. These characterization techniques are: X-ray standing wave (XSW), grazing-incident small angle X-ray scattering (GISAXS), X-ray absorption fine structure (XAFS), X-ray reflectivity (XRR), X-ray fluorescence (XRF), X-ray photoelectron spectroscopy (XPS), atomic-force microscopy (AFM) and scanning electron microscopy (SEM). Our studies show that different combinations of catalysts and substrates give distinct structural and chemical state changes in redox reactions. For MBE deposited sub-monolayer (sub-ML) Pt on the 2 x 1 SrTiO 3(001) surface, AFM shows the formation of nanoparticles and XSW atomic imaging shows that these nanoparticles are composed of Pt face-centered-cubic nanocrystals with cube-on-cube epitaxy coherent to the substrate unit cell. Different Pt coverages lead to differences in the observed XSW image of the interfacial structure, which is explained by the Pt-Pt interaction becoming stronger than the Pt-substrate interaction as the coverage is increased from 0.2 to

  1. Alumina-Supported Manganese Catalysts for Soot Combustion Prepared by Thermal Decomposition of KMnO4

    Directory of Open Access Journals (Sweden)

    Agustin Bueno-López

    2012-09-01

    Full Text Available Alumina-supported manganese catalysts with cryptomelane and/or birnessite structure have been prepared using a simple method based on the thermal decomposition of potassium permanganate. The samples have been characterized by XRD, FTIR, TGA, DSC, N2 adsorption at −196 °C, SEM, H2-TPR and XPS, and their catalytic activity for soot combustion has been tested and compared to that of a reference Pt/alumina catalyst. The thermal decomposition of alumina-supported KMnO4 yields a mixture of supported birnessite and potassium manganate which is the most effective, among those prepared, to lower the soot combustion temperature. However, this material is not useful for soot combustion because the accelerating effect is not based on a catalytic process but on the oxidation of soot by potassium manganate. A suitable soot combustion catalyst is obtained after potassium manganate is removed by water washing, yielding only the birnessite phase on the γ-Al2O3 support. This birnessite phase can be transformed into cryptomelane by calcination at 600 °C. These two samples, γ-Al2O3-supported birnessite and cryptomelane are suitable catalysts for soot combustion in NOx/O2 mixtures, as their catalytic activity is based on the NO2-assited mechanism, that is, both catalysts accelerate the oxidation of NO to NO2 and NO2 promotes soot oxidation. The soot combustion temperatures obtained with these birnessite/cryptomelane alumina-supported catalysts are similar to that obtained with the reference Pt/alumina catalyst.

  2. Characterization and reactivity of 11-molybdo-1-vanadophosphoric acid catalyst supported on zirconia for dehydration of glycerol to acrolein

    Indian Academy of Sciences (India)

    Balaga Viswanadham; Amirineni Srikanth; Komandur V R Chary

    2014-03-01

    A series of vanadium-substituted phosphomolybdic acid (HPA) catalysts supported on zirconia were prepared by impregnation method with varying the HPA active phase content from 10 to 50 wt% on the support. The calcined catalysts were characterized by X-ray diffraction, Raman spectroscopy, temperatureprogrammed desorption of NH3, FT-IR spectra of pyridine adsorption and surface area measurements. XRD results suggest that the active phase of heteropolyacid is present in a highly dispersed state at lower loadings and as a crystalline phase at higher HPA loadings and these findings are well-supported by the results of FT-IR and Raman spectra. Calcination of the samples did not affect the Keggin ion structure of HPA. The ammonia TPD results suggest that acidity of the catalysts was found to increase with increase of HPA loading up to 40 wt% and decreases at higher loadings. FT-IR spectra of pyridine adsorption show that the Brønsted acidic sites increase with increase of HPA loadings up to 40 wt% catalyst. However, Lewis acid sites decrease with increase ofHPA loading. Catalytic properties were evaluated during vapour phase dehydration of glycerol to acrolein. The catalyst with 40 wt% HPA has exhibited excellent selectivity towards acrolein formation with complete conversion of glycerol at 225°C under atmospheric pressure. Catalytic performances during dehydration of glycerol are well-correlated with acidity of the catalysts.

  3. X-ray photoelectron spectroscopy investigation over supported palladium catalysts prepared using water-in-oil microemulsion

    International Nuclear Information System (INIS)

    Supported palladium catalysts have been prepared using water n il microemulsions consisting of Pd(NO3)2 aq, Brij 30 (surfactant) and n-hexane (oil). The binding energies of palladium from those catalysts were measured using x-ray photoelectron spectroscopy (XPS) and were compared with that of the catalysts prepared by conventional impregnation method. It was observed that the majority of the palladium is present at a binding energy shifted between 0.8 to 1.0 eV higher than the impregnation catalysts observed for PdO. Such shift appeared to be associated with a metal support interaction where the palladium was very small in size and highly dispersed. These findings were supported with a much higher activity in methane combustion under lean conditions. However, not only the size and dispersity of palladium that determined their catalytic performance, it was found that the active phase or state of the catalysts that existed during the reaction has great influence on the catalyst activity. The result showed PdO was the most active state for methane combustion but it did not rule out the possibilities of a mixed phase, Pd0/PdOx. (Author)

  4. Synthesis of a highly active carbon-supported Ir-V/C catalyst for the hydrogen oxidation reaction in PEMFC

    Energy Technology Data Exchange (ETDEWEB)

    Li, B.; Qiao, J.; Yang, D.; Lv, H.; Zheng, J.; Ma, J. [Tongji Univ., Shanghai (China). School of Automotive Studies, Clean Energy Automotive Engineering Center; Zhang, J.; Wang, H. [National Research Council, Vancouver, BC (Canada). Inst. for Fuel Cell Innovation

    2009-07-01

    Non-platinum catalysts are interesting candidates for use in fuel cell systems, particularly for long-term consideration. Iridium-based catalysts such as IrSn, IrOx and IrCo have very good corrosion resistance, electrical conductivity, and resistance to carbon monoxide poisoning. They also have platinum-like behaviour for the chemisorptions of hydrogen and oxygen. The Ir-based catalysts are also less expensive than platinum. In this study, carbon-supported Ir and Ir-V nanoclusters were synthesized via an ethylene glycol (EG) method using IrCl3 and NH4 VO3 as the Ir and V precursors. The nanoparticle catalysts were characterized by X-ray diffraction (XRD) and high resolution transmission electron microscope (TEM). These carbon-supported catalysts had better characteristic for hydrogen oxidation reaction. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) techniques were used to characterize the electrochemical properties of fuel cells by applying Ir/C and Ir-V/C as anode catalysts. According to the discharge characteristics of the fuel cell, the Ir/C and Ir-V/C catalysts affected the performance of electrocatalysts considerably. In this experiment, the catalyst Ir-V/C at 40 wt per cent exhibited the best catalytic activity to hydrogen oxidation reaction. A cell performance of 20 wt per cent higher than that for commercially available Pt/C catalysts was achieved. In addition, there was no significant deterioration in performance of the fuel cell following a 100 hour fuel cell life test at a constant current density of 1000 mA/cm{sup 2} in H{sub 2}/O{sub 2} conditions. 3 refs., 2 figs.

  5. Ceria maintains smaller metal catalyst particles by strong metal-support bonding.

    Science.gov (United States)

    Farmer, Jason A; Campbell, Charles T

    2010-08-20

    The energies of silver (Ag) atoms in Ag nanoparticles supported on different cerium and magnesium oxide surfaces, determined from previous calorimetric measurements of metal adsorption energies, were analyzed with respect to particle size. Their stability was found to increase with particle size below 5000 atoms per particle. Silver nanoparticles of any given size below 1000 atoms had much higher stability (30 to 70 kilojoules per mole of silver atoms) on reduced CeO2(111) than on MgO(100). This effect is the result of the very large adhesion energy (approximately 2.3 joules per square meter) of Ag nanoparticles to reduced CeO2(111), which we found to be a result of strong bonding to both defects and CeO2(111) terraces, apparently localized by lattice strain. These results explain the unusual sinter resistance of late transition metal catalysts when supported on ceria. PMID:20724631

  6. Ethylenediamine-modified multiwall carbon nanotubes as a Pt catalyst support

    International Nuclear Information System (INIS)

    Highlights: → Multi-walled carbon nanotubes (MWCNTs) were used as a support for Pt nanoparticles. → Modification of oxidized MWCNTs by ethylenediamine is necessary for high Pt loading. → Pt nanoparticles are homogenously distributed on the support without agglomeration. → The activity of the catalyst for oxygen reduction matches the commercial catalyst. - Abstract: Multi-walled carbon nanotubes (MWCNTs) were used as a support for Pt nanoparticles prepared by the microwave-assisted polyol method. The MWCNTs were pretreated by chemical oxidation (o-MWCNTs) followed by modification by ethylenediamine (eda-MWCNTs). Characterization of both oxidized and eda-modified materials by UV-spectroscopy, cyclic voltammetry and electrochemical impedance spectroscopy revealed that the modification by eda leads to (i) agglomeration of the MWCNTs, (ii) a decrease in the capacitance of the material and (iii) reduced rate of electron transfer between the MWCNTs and solution species. However, the Pt loading of Pt/o-MWCNTs was only 2 mass% while the loading of Pt/eda-MWCNTs was 20 mass%. Much higher efficiency of Pt deposition on eda-MWCNTs than on o-MWCNTs was ascribed to the shift in pHpzc value of the MWCNT surface from 2.43 to 5.91 upon modification by eda. Transmission electron microscopy revealed that the mean diameter of the Pt particles in Pt/eda-MWCNTs is 2.5 ± 0.5 nm and that their distribution on the support is homogenous with no evidence of pronounced particle agglomeration. Cyclic voltammetry of a Pt/eda-MWCNT thin film indicated a clean Pt surface with well-resolved peaks characteristic of polycrystalline Pt. Its electrocatalytic activity for oxygen reduction was examined and the results corresponded to the commercial Pt nanocatalyst. This study shows that modification of o-MWCNTs by eda helps to achieve homogenous distribution of small Pt nanoparticles and does not impede its electrocatalytic activity.

  7. Supported catalysts based on layered double hydroxides for catalytic oxidation and hydrogenation: general functionality and promising application prospects.

    Science.gov (United States)

    Feng, Junting; He, Yufei; Liu, Yanan; Du, Yiyun; Li, Dianqing

    2015-08-01

    Oxidation and hydrogenation catalysis plays a crucial role in the current chemical industry for the production of key chemicals and intermediates. Because of their easy separation and recyclability, supported catalysts are widely used in these two processes. Layered double hydroxides (LDHs) with the advantages of unique structure, composition diversity, high stability, ease of preparation and low cost have shown great potential in the design and synthesis of novel supported catalysts. This review summarizes the recent progress in supported catalysts by using LDHs as supports/precursors for catalytic oxidation and hydrogenation. Particularly, partial hydrogenation of acetylene, hydrogenation of dimethyl terephthalate, methanation, epoxidation of olefins, elimination of NOx and SOx emissions, and selective oxidation of biomass have been chosen as representative reactions in the petrochemical, fine chemicals, environmental protection and clean energy fields to highlight the potential application and the general functionality of LDH-based catalysts in catalytic oxidation and hydrogenation. Finally, we concisely discuss some of the scientific challenges and opportunities of supported catalysts based on LDH materials. PMID:25962432

  8. 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.

  9. SUPPORTED LIQUID CATALYSTS FOR REMOVAL OF HIGH TEMPERATURE FUEL CELL CONTAMINANTS

    Energy Technology Data Exchange (ETDEWEB)

    Alan W. Weimer (PI); Peter Czerpak; Patrick Hilbert

    2000-01-01

    A novel catalytic synthesis gas oxidation process using molten carbonate salts supported on compatible fluidized iron oxide particles (supported-liquid-phase-catalyst (SLPC) fluidized bed process) was investigated. This process combines the advantages of large scale fluidized bed processing with molten salt bath oxidation. Molten salt catalysts can be supported within porous fluidized particles in order to improve mass transfer rates between the liquid catalysts and the reactant gases. Synthesis gas can be oxidized at reduced temperatures resulting in low NO{sub x} formation while trace sulfides and halides are captured in-situ. Hence, catalytic oxidation of synthesis gas can be carried out simultaneously with hot gas cleanup. Such SLPC fluidized bed processes are affected by inter-particle liquid capillary forces that may lead to agglomeration and de-fluidization of the bed. An understanding of the origin and strength of these forces is needed so that they can be overcome in practice. Process design is based on thermodynamic free energy minimization calculations that indicate the suitability of eutectic Na{sub 2}CO{sub 3}/K{sub 2}CO{sub 3} mixtures for capturing trace impurities in-situ (< 1 ppm SO{sub x} released) while minimizing the formation of NO{sub x}(< 10 ppm). Iron oxide has been identified as a preferred support material since it is non-reactive with sodium, is inexpensive, has high density (i.e. inertia), and can be obtained in various particle sizes and porosities. Force balance modeling has been used to design a surrogate ambient temperature system that is hydrodynamically similar to the real system, thus allowing complementary investigation of the governing fluidization hydrodynamics. The primary objective of this research was to understand the origin of and to quantify the liquid capillary interparticle forces affecting the molten carbonate SLPC fluidized bed process. Substantial theoretical and experimental exploratory results indicate process

  10. Silica (NPs) supported Fe (III) as a reusable heterogeneous catalyst for the one-pot synthesis of 1, 4-dihydropyridines under mild conditions

    Indian Academy of Sciences (India)

    Javad Safaei-Ghomi; Abolfazl Ziarati; Safura Zahedi

    2012-07-01

    A cheap and recyclable silica (NPs) supported Fe (III) was prepared as heterogeneous catalyst for the synthesis of various substituted 1,4-dihydropyridines via condensation of aldehydes with ethyl acetoacetate and ammonium acetate in ethanol. The products were separated from the catalyst simply by filtration and the catalyst could be recycled and reused for several times without noticeable decrease in the catalytic activity.

  11. The application of inelastic neutron scattering to investigate the steam reforming of methane over an alumina-supported nickel catalyst

    International Nuclear Information System (INIS)

    Highlights: • Inelastic neutron scattering has been used to investigate a Ni/alumina catalyst. • The extent of hydrogen retention by the catalyst has been determined. • Filamentous carbon is identified as a by-product. - Abstract: An alumina-supported nickel catalyst, previously used in methane reforming experiments employing CO2 as the oxidant, is applied here in the steam reforming variant of the process. Micro-reactor experiments are used to discern an operational window compatible with sample cells designed for inelastic neutron scattering (INS) experiments. INS spectra are recorded after 6 h reaction of a 1:1 mixture of CH4 and H2O at 898 K. Weak INS spectra are observed, indicating minimal hydrogen retention by the catalyst in this operational regime. Post-reaction, the catalyst is further characterised by powder X-ray diffraction, transmission electron microscopy and Raman scattering. In a comparable fashion to that seen for the ‘dry’ reforming experiments, the catalyst retains substantial quantities of carbon in the form of filamentous coke. The role for hydrogen incorporation by the catalyst is briefly considered

  12. The application of inelastic neutron scattering to investigate the steam reforming of methane over an alumina-supported nickel catalyst

    Energy Technology Data Exchange (ETDEWEB)

    McFarlane, Andrew R.; Silverwood, Ian P. [School of Chemistry, Joseph Black Building, University of Glasgow, Glasgow G12 8QQ (United Kingdom); Norris, Elizabeth L.; Ormerod, R. Mark [Department of Chemistry, School of Physical and Geographical Sciences, Keele University, Staffs ST5 5BG (United Kingdom); Frost, Christopher D.; Parker, Stewart F. [ISIS Facility, STFC Rutherford Appleton Laboratory, Chilton, Didcot, Oxon OX11 0QX (United Kingdom); Lennon, David, E-mail: David.Lennon@glasgow.ac.uk [School of Chemistry, Joseph Black Building, University of Glasgow, Glasgow G12 8QQ (United Kingdom)

    2013-12-12

    Highlights: • Inelastic neutron scattering has been used to investigate a Ni/alumina catalyst. • The extent of hydrogen retention by the catalyst has been determined. • Filamentous carbon is identified as a by-product. - Abstract: An alumina-supported nickel catalyst, previously used in methane reforming experiments employing CO{sub 2} as the oxidant, is applied here in the steam reforming variant of the process. Micro-reactor experiments are used to discern an operational window compatible with sample cells designed for inelastic neutron scattering (INS) experiments. INS spectra are recorded after 6 h reaction of a 1:1 mixture of CH{sub 4} and H{sub 2}O at 898 K. Weak INS spectra are observed, indicating minimal hydrogen retention by the catalyst in this operational regime. Post-reaction, the catalyst is further characterised by powder X-ray diffraction, transmission electron microscopy and Raman scattering. In a comparable fashion to that seen for the ‘dry’ reforming experiments, the catalyst retains substantial quantities of carbon in the form of filamentous coke. The role for hydrogen incorporation by the catalyst is briefly considered.

  13. Hydrogenation of CO and CO2 over rhodium catalysts supported on various metal oxides

    International Nuclear Information System (INIS)

    The formation of hydrocarbons in the reaction of CO + H2 and CO2 + H2 was studied over rhodium catalysts supported on ZrO2, Al2O3, SiO2, and MgO. Among those catalysts, Rh on ZrO2 was most active and Rh-MgO was least active for the above reactions. Over Rh-ZrO2, the CO2 + H2 reaction took place even at 500C, whereas the CO + H2 reaction occurred only at temperature higher than 1300C. The reaction of CO2 + H2 produced only methane at temperatures up to 2000C, but a small amount of CO formed along with methane in the reverse water gas shift reaction above 2000C. In the case of the CO + H2 reaction, the higher molecular weight hydrocarbons (C2 approx. C4) as well as CH4 formed. The inverse kinetic isotope effect was observed in both reactions of CO + H2(D2) and CO2 + H2(D2) over Rh-ZrO2. However, the isotope effect was not observed in the CO2 + H2(D2) reaction over Rh-Al2O3 whose effect in the CO + H2 reaction was still inverse. The activity for the CO + H2 reaction over the oxidized Rh-ZrO2 and Rh-Al2O3 was almost 2 to 10 times higher than that on the reduced catalyst. The reaction mechanisms of the above reactions are discussed. 2 figures, 4 tables

  14. Catalytic performance of cement clinker supported nickel catalyst in glycerol dry reforming

    Institute of Scientific and Technical Information of China (English)

    Hua Chyn Lee; Kah Weng Siew; Maksudur R. Khan; Sim Yee Chin; Jolius Gimbun; Chin Kui Cheng

    2014-01-01

    The paper reports the development of cement clinker-supported nickel (with metal loadings of 5 wt%, 10 wt%, 15 wt%and 20 wt%) catalysts for glycerol dry (CO2) reforming reaction. XRF results showed that CaO constituted 62.0%of cement clinker. The physicochemical character-ization of the catalysts revealed 32-folds increment of BET surface area (SBET) with the addition of nickel metal into the cement clinker, which was also corroborated by FESEM images. Significantly, XRD results suggested different types of Ni oxides formation with Ni loading, whilst Ca3SiO5 and Ca2Al0.67Mn0.33FeO5 were the main crystallite species for pure cement clinker. Temperature-programmed reduction analysis yielded three domains of H2 reduction peaks, viz. centered at approximately 750 K referred to as type-I peaks, another peaks at 820 K denoted as type-II peaks and the highest reduction peaks, type-III recorded at above 1000 K. 20 wt%Ni was found to be the best loading with the highest XG and H2 yield, whilst the lowest methanation activity. Syngas with lower H2/CO ratios (0.6 to 1.5) were readily produced from glycerol dry reforming at CO2-to-Glycerol feed ratio (CGR) of unity. Nonetheless, carbon deposit comprised of whisker type (Cv) and graphitic-like type (Cc) species were found to be in majority on 20 wt%Ni/CC catalysts.

  15. 4,6-Dimethyl-dibenzothiophene conversion over Al2O3-TiO2-supported noble metal catalysts

    International Nuclear Information System (INIS)

    Research highlights: → Al2O3 and Al2O3-TiO2 (molar ratio Al/Ti = 2, AT2) mixed oxides were pore-filling impregnated to obtain Pd, Pt and Pd-Pt catalysts with ∼1 wt% nominal metal loading. → Reduced catalysts were tested in the 4,6-dimethyl-dibenzothiophene hydrodesulfurization (HDS). → In Pd-containing materials, TiO2 incorporation into the alumina support was favorable to the catalytic activity of noble metal catalysts. → Enhanced intrinsic activity (per exposed metallic site) was obtained in Pt-containing catalysts supported on the AT2 mixed oxide. → Yield to different products over various catalysts seemed to be strongly influenced by metallic particles dispersion. - Abstract: Al2O3 and Al2O3-TiO2 (molar ratio Al/Ti = 2, AT2) mixed oxides were synthesized using a low-temperature sol-gel method and were further pore-filling impregnated to obtain Pd and Pt catalysts with ∼1 wt% nominal metal loading. Simultaneous impregnation was used to prepare bimetallic materials at Pd:Pt = 80:20. Solids characterization was carried out by N2-physisorption, high-resolution transmission electron microscopy (HR-TEM and E-FTEM), X-ray diffraction, temperature-programmed reduction and CO-chemisorption. Reduced (350 deg. C, H2 flow) catalysts were tested in the 4,6-dimethyl-dibenzothiophene hydrodesulfurization (HDS) (in n-dodecane, at 300 deg. C and 5.5 MPa, batch reactor). In Pd-containing materials, TiO2 incorporation into the alumina support was favorable to the catalytic activity of noble metal catalysts, where bimetallic Pd-Pt with AT2 carrier had the highest organo-S compound conversion. Enhanced intrinsic activity (per exposed metallic site) was obtained in Pt-containing catalysts supported on the AT2 mixed oxide (as compared to alumina-supported ones). Yield to different products over various catalysts seemed to be strongly influenced by metallic particles dispersion.

  16. Preparation of IrO2 nanoparticles with SBA-15 template and its supported Pt nanocomposite as bifunctional oxygen catalyst

    Science.gov (United States)

    Kong, Fan-Dong; Liu, Jing; Ling, Ai-Xia; Xu, Zhi-Qiang; Wang, Hui-Yun; Kong, Qing-Sheng

    2015-12-01

    In the present work, we report the syntheses of IrO2 nanoparticles with SBA-15 template (s-IrO2), and s-IrO2 supported Pt nanocomposite (Pt/s-IrO2) as bifunctional oxygen catalyst. Physical characterizations including X-ray diffraction and transmission electron microscopy demonstrate that s-IrO2 catalyst has excellent uniformity and regularity in particle shape and much ordered distribution in geometric space, and Pt/s-IrO2 catalyst shows a uniform Pt dispersion on the surface of the s-IrO2 particles. Electrochemical analyses prove that s-IrO2 catalyst possesses superior OER activity at operating potentials; and that Pt/s-IrO2 catalyst, in comparison to Pt/commercial IrO2, has higher ESA value and ORR catalytic performance with a mechanism of four-electron pathway and a high ORR efficiency. And as a bifunctional oxygen catalyst, Pt/s-IrO2 also exhibits more remarkable OER performance than the commercial one. The s-IrO2 nanoparticles will be a promising active component (for OER), and suitable for Pt support (for ORR).

  17. Highly efficient, quick and green synthesis of biarlys with chitosan supported catalyst using microwave irradiation in the absence of solvent.

    Science.gov (United States)

    Baran, Talat; Açıksöz, Eda; Menteş, Ayfer

    2016-05-20

    The aim of this study was to develop a quick reaction that had high activity with a small amount of catalyst, which could be an eco-friendly alternative technique for the synthesis of biarlys in Suzuki coupling reactions. First, a novel chitosan Schiff base supported Pd(II) catalyst was synthesized, and its structure was illuminated with FTIR, (1)H NMR, (13)C NMR, TG/DTG, SEM/EDAX, XRD, ICP-OES, UV-vis, magnetic moment, and molar conductivity techniques. Subsequently, the catalytic activity of the catalyst was tested in Suzuki CC reactions under microwave irradiation using a solvent-free reaction condition. The catalytic tests showed an excellent activity with a small load of the catalyst (0.02mol%) in 4min. The catalyst showed seven runs without loss of activity, and high values of turnover numbers (TON) and turnover frequency (TOF) were obtained. The novel biopolymer supported Pd(II) catalyst provided much faster reaction times, higher yields, and reusability under microwave heating compared to classic heating methods. PMID:26917390

  18. Mechanism and kinetics of Fischer-Tropsch synthesis over supported ruthenium catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Kellner, C.S.

    1981-06-01

    A detailed study of the kinetics of the Fischer-Tropsch synthesis of hydrocarbons, methanol, and acetaldehyde, over alumina- and silica-supported ruthenium catalysts has been carried out over a broad range of reaction conditions. Based on these results and information taken from the literature, mechanisms for the formation of normal paraffins, ..cap alpha..-olefins, methanol, and acetaldehyde have been proposed. Rate data were obtained between 448 and 548K, 1 and 10 atm, and H/sub 2//CO ratios between 1 and 3, utilizing a micro flow reactor operated at very low conversions. In addition to the studies performed with H/sub 2//CO mixtures, a series of experiments were carried out utilizing D/sub 2//CO mixtures. These studies were used to help identify rate limited steps and steps that were at equilibrium. A complementary investigation, carried out by in situ infrared spectroscopy, was performed using a Fourier Transform spectrometer. The spectra obtained were used to identify the modes of CO adsorption, the CO coverage, and the relative reactivity of different forms of adsorbed CO. It was established that CO adsorbs on alumina-supported Ru in, at least, two forms: (i) Ru-CO and (ii) OC-Ru-CO. Only the first of these forms participates in CO hydrogenation. The coverage of this species is described by a simple Langmuir isotherm. A reaction mechanism is presented for interpreting the kinetics of hydrocarbon synthesis, the olefin to paraffin ratio for each product, and the probability of chain propagation. Rate expressions based on this mechanism are reasonably consistent with the experimental data. Acetaldehyde, obtained mainly over silica-supported Ru, appears to be formed by a mechanism related to that for hydroformulation of olefins. The effect of the dispersion of Ru/Al/sub 2/O/sub 3/ catalysts on their specific activity and selectivity was also investigated. The specific activity for all products decreased rapidly with increasing dispersions.

  19. Nanoporous carbon supported platinum-copper nanocomposites as anode catalysts for direct borohydride-hydrogen peroxide fuel cell

    International Nuclear Information System (INIS)

    Highlights: • NPC supported Pt-Cu nanocomposites are used firstly as anode catalysts for DBHFC. • The average size of the Pt-Cu nanocrystals is around 2.3 nm. • The DBHFC with Pt2Cu/NPC anode shows the maximum power density of 89 mW cm−2. -- Abstract: Nanoporous carbon (NPC) supported Pt-Cu nanocomposites (PtxCu/NPC) with different Pt/Cu molar ratios have been successfully synthesized via NaBH4 reduction method and used as anode catalysts for direct borohydride-hydrogen peroxide fuel cell (DBHFC). The as-synthesized PtxCu/NPC electrocatalysts are characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), cyclic voltammetry (CV), chronoamperometry (CA), rotating disc electrode (RDE) and fuel cell test. It has been found that the PtCu nanoparticles are uniformly dispersed on the surface of the NPC support with average size of about 2.3 nm. Besides, the PtxCu/NPC catalysts show higher activities for borohydride oxidation than that of monometallic Pt/NPC and Vulcan XC-72 carbon supported Pt2Cu (Pt2Cu/XC-72) catalysts. Especially, the DBHFC equipped with Pt2Cu/NPC as anode catalyst shows the maximum power density of 89 mW cm−2 at 25 °C

  20. Ultrafine porous carbon fiber and its supported platinum catalyst for enhancing performance of proton exchange membrane fuel cells

    International Nuclear Information System (INIS)

    The enhancement of electrocatalytic activity of carbon-supported platinum catalysts has been essential for improving the performance of proton exchange membrane fuel cells (PEMFCs). In this paper, one kind of grounded ultrafine porous carbon fiber (UPCF), with an average diameter of the order of 100 nm and pore sizes of 5–30 nm, was used as a novel compound carbon support (CCS) to prepare a supported Pt catalyst (Pt/CCS) for the electrode catalyst layer in a PEMFC, and its associated membrane electrode assembly (MEA). The fabricated MEA was also tested in a single fuel cell to validate this Pt/CCS catalyst. The electrochemical surface area (ECSA) of Pt was determined to be 71.9 m2.g−1 for the CCS, which is much larger than the 54.6 m2.g−1 known to apply for carbon black support. Both the onset potential and half-wave potential of Pt/CCS were all positively shifted in comparison with Pt/C, based on linear sweep voltammetry (LSV). The performance of a single fuel cell catalyzed by Pt/CCS showed 1.25 times higher power density than that catalyzed by Pt/C at room temperature. The cross-sectional morphology of the electrode indicated the chopped-fiber-form UPCF might construct a loose three-dimensionally layer-like catalyst that could reduce mass transform resistance and allow the water produced to escape easily

  1. Role of metal-support interactions on the activity of Pt and Rh catalysts for reforming methane and butane

    International Nuclear Information System (INIS)

    For residential fuel cell systems, reforming of natural gas is one option being considered for providing the H(sub 2) necessary for the fuel cell to operate. Industrially, natural gas is reformed using Ni-based catalysts supported on an alumina substrate, which has been modified to inhibit coke formation. At Argonne National Laboratory, we have developed a new family of catalysts derived from solid oxide fuel cell technology for reforming hydrocarbon fuels to generate H(sub 2). These catalysts consist of a transition metal supported on an oxide-ion-conducting substrate, such as ceria, that has been doped with a small amount of a non-reducible element, such as gadolinium, samarium, or zirconium. Unlike alumina, the oxide-ion-conducting substrate has been shown to induce strong metal-support interactions. Metal-support interactions are known to play an important role in influencing the catalytic activity of many metals supported on oxide supports. Based on results from temperature-programmed reduction/oxidation and kinetic reaction studies, this paper discusses the role of the metal and the substrate in the metal-support interactions, and how these interactions influence the activity and the selectivity of the catalyst in reforming methane and butane to hydrogen for use in fuel cell power systems

  2. Palladium catalysts supported on novel CexY1-xO washcoats for toluene catalytic combustion

    Institute of Scientific and Technical Information of China (English)

    JIN Lingyun; HE Mai; LU Jiqing; LUO Mengfei; GAO Libiao; HE Jun

    2008-01-01

    Novel CexY1-xO washcoats adhered on the cordierite honeycomb, used as supports for Pd catalysts, were prepared by an impregnation method. It was found that the CexY1-xO washcoats had better adhesion and higher adsorption efficiency of H2PdCl4, and the optimal component of the washcoat was Ce0.8Y0.2O. Model reaction of catalytic combustion of toluene was chosen to evaluate the performance of the developed Pd/CexY1-xO/substrate catalysts. The results showed that the catalytic performance of the Pd/CexY1-xO/substrate catalysts depended on the component of the washcoats, with the Pd/Ce0.8Y0.2O/ substrate catalyst giving the best catalytic activity and thermal stability.

  3. Synthesis of 3D structured graphene as a high performance catalyst support for methanol electro-oxidation

    Science.gov (United States)

    Li, Yecheng; Zhang, Lei; Hu, Zhuofeng; Yu, Jimmy C.

    2015-06-01

    A simple process for preparing 3D structured graphene (3D-G) by a solution combustion method is reported. The product was deposited with platinum and used for methanol electro-oxidation. The catalyst shows a considerable enhancement in both the activity and stability towards methanol electro-oxidation reaction. Characterization reveals that the Pt/3D-G catalyst has a more negative onset potential as well as a higher electrochemically active specific surface area than a commercial Pt/C catalyst. Moreover, the catalyst exhibits higher tolerance to corrosion than carbon black. This work provides an efficient way for preparing 3D-G as a promising support for the oxidation of small organic molecules in fuel cells.

  4. Effects of CO2 content on the activity and stability of nickel catalyst supported on mesoporous nanocrystalline zirconia

    Institute of Scientific and Technical Information of China (English)

    M.Rezaei; S.M.Alavi; S.Sahebdelfar; Zi-Feng Yan

    2008-01-01

    The effects of carbon dioxide content on the catalytic performance and coke formation of nickel catalyst supported on mesoporous nanocrystalline zirconia with high surface area and pure tetragonaI crystalline phase were investigated in methane reforming with carbon dioxide.The samples were characterized bV XRD,BET,PR,TPO,TPH,TEM,and SEM techniques.The catalyst prepared showed high surface area and a mesoporous structure with a narrow pore size distribution.The obtained results revealed that the increase in CO2 content increased the methane conversion and stability of the catalyst and significantly reduced the coke deposition.The TPH analysis showed that several species of carbon with different reactivities toward hydrogenation were deposited on the spent catalysts employed under different CO2 contents.

  5. Silica gel-Supported Palladium Catalyst for the Acyl Sonogashira Reaction

    Energy Technology Data Exchange (ETDEWEB)

    Hossain, Shahin; Park, Jihoon; Park, Minkyu; Jin, Myungjong [Inha Univ., Incheon (Korea, Republic of)

    2013-06-15

    We have demonstrated an efficient and eco-friendly procedure for the synthesis of ynones using silica supported thiol-palladium complex as a recyclable catalyst under copper free mild reaction conditions. The material was synthesized by post grafting of 3-mercaptopropyltrimethoxysilane on amorphous silica and subsequently Pd(II) attached onto thiol groups. This synthetic method has notable advantages because it involves easily available, less costly and produces an easily recyclable catalyst in high yields of the products. The mild reaction conditions encouraged us to further extension for the development of novel multicomponent reactions. Thus we have explained the three component synthesis of pyrazoles in one-pot fashion with good yields. Specifically, this simple procedure for the ynone synthesis and this approach to synthesize N-containing heterocycles may be valuable tool in future. The acyl Sonogashira reaction between acyl chlorides and terminal alkynes is one of the most useful method for the preparation of ynones which are important intermediates to prepare versatile pharmaceutically and biologically active heterocyclic compounds such as pyrroles, pyrazoles, furans, furanones, isoxazoles, pyrimidines, quinolines, indolizidinones.

  6. Rice Husk Supported Catalysts for Degradation of Chlorobenzenes in Capillary Microreactor

    Directory of Open Access Journals (Sweden)

    Abdulelah Thabet

    2015-01-01

    Full Text Available Chlorinated organic pollutants are persistent, toxic, and ubiquitously distributed environmental contaminants. These compounds are highly bioaccumulative and adversely affect the ozone layer in the atmosphere. As such, their widespread usage is a major cause of environmental and health concern. Therefore, it is important to detoxify such compounds by environment friendly methods. In this work, rice husk supported platinum (RHA-Pt and titanium (RHA-Ti catalysts were used, for the first time, to investigate the detoxification of chlorobenzenes in a glass capillary microreactor. High potential (in kV range was applied to a reaction mixture containing buffer solution in the presence of catalyst. Due to high potential, hydroxyl and hydrogen radicals were produced, and the reaction was monitored by gas chromatography-mass spectrometry. The main advantage of this capillary reactor is the in situ generation of hydrogen for the detoxification of chlorobenzene. Various experimental conditions influencing detoxification were optimized. Reaction performance of capillary microreactor was compared with conventional catalysis. Only 20 min is sufficient to completely detoxify chlorobenzene in capillary microreactor compared to 24 h reaction time in conventional catalytic method. The capillary microreactor is simple, easy to use, and suitable for the detoxification of a wide range of chlorinated organic pollutants.

  7. Supported PtAu catalysts with different nano-structures for ethanol electrooxidation

    International Nuclear Information System (INIS)

    Two bimetallic Pt-Au catalysts supported on carbon, namely core-shell structured nanoparticles (Au@Pt/C) and alloy-like nanoparticles (AuPt/C), were synthesized and tested for ethanol electro-oxidation in acidic environment. The catalysts were characterized by X-ray diffraction; X-ray photoelectron spectroscopy and transmission electron microscopy. Catalytic activity was quantified by anodic CO-stripping voltammetry, and cyclic voltammetry of ethanol electro-oxidation. The electronic interaction between Pt and Au was demonstrated by X-ray photoelectron spectroscopy and the effect was found to be more prominent in the alloy-like PtAu nanoparticles. X-ray diffraction revealed expanded Pt lattice parameter and interatomic distance in the PtAu nanoparticles. The interaction between Pt and Au of PtAu/C and Au@Pt/C samples was the main cause of the enhanced CO tolerance. The stronger Pt-Au interaction and the expanded Pt lattice parameter in alloyed PtAu/C contributed to the higher specific activity towards ethanol electro-oxidation of PtAu/C compared to Au@Pt/C

  8. Stability analysis of hydrophobic catalysts in presence of tritiated water. Evaluation of polydivynilbenzene support stability

    International Nuclear Information System (INIS)

    The behaviour of hydrophobic catalysts in the isotopic exchange reactions H/D/T was analyzed by quantum chemistry methods. The primary radiolytic effect was analyzed using a two-step radiolytic mechanism: a) the ionization of molecule and spatial redistribution of atoms in order to reach a minimum value of energy, characteristic to the new quantum state; b) the neutralization of molecule by capture of an electron and its rapid dissociation in free radicals. Time period between the capture of electron and molecule dissociation in free radicals is shorter than the time required for geometric reoptimization. Chemical bonds suspected to break are located in the distribution region of LUMO orbital and have minimal bond energy. Evaluation of secondary effects taking place in polymeric structure in the presence of water was carried out through the study of the transition state (activated complex) resulted after the attack of HO· radicals formed in the radiolysis of water. In the case of catalyst on styrene-divinylbenzene copolymer support, the quantum chemistry analysis reveals a good stability of the polymer to the primary radiolytic effect. The secondary effects affect the polymeric structure due to the HO· radicals attack at the benzilic position. These attacks are accompanied by fragmentation of polymeric chain and induction of hydrophobic groups on the chain. Occurrence of these processes is much lower as compared to those taking place in the polytetrafluoroethylene substrate. (authors)

  9. Silica gel-Supported Palladium Catalyst for the Acyl Sonogashira Reaction

    International Nuclear Information System (INIS)

    We have demonstrated an efficient and eco-friendly procedure for the synthesis of ynones using silica supported thiol-palladium complex as a recyclable catalyst under copper free mild reaction conditions. The material was synthesized by post grafting of 3-mercaptopropyltrimethoxysilane on amorphous silica and subsequently Pd(II) attached onto thiol groups. This synthetic method has notable advantages because it involves easily available, less costly and produces an easily recyclable catalyst in high yields of the products. The mild reaction conditions encouraged us to further extension for the development of novel multicomponent reactions. Thus we have explained the three component synthesis of pyrazoles in one-pot fashion with good yields. Specifically, this simple procedure for the ynone synthesis and this approach to synthesize N-containing heterocycles may be valuable tool in future. The acyl Sonogashira reaction between acyl chlorides and terminal alkynes is one of the most useful method for the preparation of ynones which are important intermediates to prepare versatile pharmaceutically and biologically active heterocyclic compounds such as pyrroles, pyrazoles, furans, furanones, isoxazoles, pyrimidines, quinolines, indolizidinones

  10. Hydrogenation of Anthracene in Supercritical Carbon Dioxide Solvent Using Ni Supported on Hβ-Zeolite Catalyst

    Directory of Open Access Journals (Sweden)

    Ashraf Aly Hassan

    2012-01-01

    Full Text Available Catalytic hydrogenation of anthracene was studied over Ni supported on Hβ-zeolite catalyst under supercritical carbon dioxide (sc-CO2 solvent. Hydrogenation of anthracene in sc-CO2 yielded 100% conversion at 100 °C, which is attributed to the reduced mass transfer limitations, and increased solubility of H2 and substrate in the reaction medium. The total pressure of 7 MPa was found to be optimum for high selectivity of octahydroanthracene (OHA. The conversion and selectivity for OHA increased with an increase in H2 partial pressure, which is attributed to higher concentration of hydrogen atoms at higher H2 pressures. The selectivity reduced the pressure below 7 MPa because of enhanced desorption of the tetrahydro-molecules and intermediates from Ni active sites, due to higher solubility of the surface species in sc-CO2. The selectivity of OHA increased with the increase in catalyst weight and reaction time. The rate of hydrogenation of anthracene was compared with that found for napthalene and phenanthrene. The use of acetonitrile as co-solvent or expanded liquid with CO2 decreased the catalytic activity.

  11. Supported nano gold as a recyclable catalyst for green, selective and efficient oxidation of alcohol using molecular oxygen

    Directory of Open Access Journals (Sweden)

    Bashir Dar

    2011-09-01

    Full Text Available The myth that gold cannot act as a catalyst has been discarded in view of recent studies, which have demonstrated the high catalytic efficiency of pure nano-gold and supported nano-gold catalysts. In recent years, numerous papers have described the use of supported nano-gold particles for catalysis in view of their action on CO and O2 to form CO2, as well as a variety of other reactions. Special emphasis is placed on the oxidation studies undertaken on model nano-Au systems. In this work a solvent free oxidation of 1-phenyl ethanol was carried out using gold supported on ceria-silica, ceria-titania, ceria- zirconia and ceria-alumina at 160 0C. Almost 88-97% conversion was obtained with >99% selectivity. Temperature screening was done from 70 to 160 0C.Catalysts were prepared by deposition co-precipitation method and deposition was determined by EDEX analysis.

  12. 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)

    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 150-200oC and free from difficult problems of SOx-deactivation and hydrothermal ageing of the NOx-absorption-reduction catalyst. (author)

  13. Alumina-supported CuO-CeO2-ZrO2 catalysts for CO oxidation - preparation and characterization

    International Nuclear Information System (INIS)

    The effect of catalyst samples, prepared by different methods, having the composition (CuCe5.17Zr3.83Ox/γ-Al2O3 (20 wt%) was studied in the present work for carbon monoxide (CO) oxidation. Cu(NO3)23H2O was used as a precursor for the preparation of the catalysts. Catalysts were prepared by four methods: co-impregnation, citric acid sol-gel, urea nitrate combustion and urea gelation co-precipitation methods. Prepared catalysts were characterized by BET specific surface area, X-ray diffraction, thermogravimetric analysis/differential scanning calorimetry (TGA/DSC) and scanning electron microscopy (SEM) techniques. The oxidation of CO was carried out in a tubular fixed bed reactor at atmospheric pressure and at temperature ranging from ambient to 250 ℃. A fixed weight (100 mg) of the catalyst was taken and 2.5% CO in air at a total feed rate of 60 ml/min was used in the reactor. It was observed that the performance of the catalysts in CO oxidation was influenced by the preparation methods. The catalyst prepared by sol-gel method that calcined at 500 ℃ exhibited excellent activity for CO oxidation with total conversion at 210℃. The ranking order of the alumina supporting CuO-CeO2-ZrO2 catalysts was as follows: sol-gel > co-impregnation > urea gelation > urea nitrate combustion. The four catalysts prepared did not show deactivation of catalytic activity for 50 h of continuous runs. (author)

  14. Gas phase polymerization of ethylene with a silica-supported metallocene catalyst: influence of temperature on deactivation

    OpenAIRE

    Roos, Peter; Meier, Gerben B.; Samson, Job Jan C.; Weickert, Günter; Westerterp, K. Roel

    1997-01-01

    Ethylene was polymerized at 5 bar in a stirred powder bed reactor with silica supported rac-Me2Si[Ind]2ZrCl2/methylaluminoxane (MAO) at temperatures between 40°C and 80°C using NaCl as support bed and triethylaluminium (TEA) as a scavenger for impurities. For this fixed recipe and a given charge of catalyst. the average catalyst activity is reproducible within 10% for low temperatures. The polymerization rate and the rate of deactivation increase with increasing temperature. The deactivation ...

  15. Preparation and characterization of titanium dioxide nanotube array supported hydrated ruthenium oxide catalysts

    Science.gov (United States)

    Giang, Thi Phuong Ly; Tran, Thi Nhu Mai; Le, Xuan Tuan

    2012-03-01

    This work aimed at preparing and characterizing TiO2 nanotube supported hydrated ruthenium oxide catalysts. First of all, we succeeded in preparing TiO2 nanotube arrays by electrochemical anodization of titanium metal at 20 V for 8 h in a 1M H3PO4+0.5 wt% HF solution as evidenced from scanning electron microscopy (SEM) and x-ray photoelectron spectroscopy (XPS) results. The hydrated ruthenium oxide was then deposited onto TiO2 nanotubes by consecutive exchange of protons by Ru3+ ions, followed by formation of hydrated oxide during the alkali treatment. Further XPS measurements showed that the modified samples contain not only hydrated ruthenium oxide but also hydrated ruthenium species Ru(III)-OH.

  16. Chitosan-coated Silica Nanoparticles - A Potential Support for Metal Particles used as Heterogeneous Catalyst

    International Nuclear Information System (INIS)

    In this work a strategy to immobilize noble metal nanoparticles on silica microspheres is proposed. In order to achieve this, monodispersed silica nanoparticles of an average size of 63.5±6.7 nm were synthesized via sol-gel method. Then chitosan was coated onto the silica to create a core/ shell composite with the size range of 66.56±9.78 nm to 79.18±11.87 nm. The noble metal nanoparticles were then synthesized on the shell of the composite through coordination of the respective metal ions to the polymer followed by the subsequent reduction. In this way, the silver particles of average size 6.17±1.83 nm, 9.85±2.60 nm, and 11.80±4.26 nm have been synthesized on the shell successfully. The optimized supported metal particles can be used as a potential heterogeneous catalyst. (author)

  17. Electro-synthesis of novel nanostructured PEDOT films and their application as catalyst support

    Directory of Open Access Journals (Sweden)

    Yan Yushan

    2011-01-01

    Full Text Available Abstract Poly(3,4-ethylenedioxythiophene (PEDOT films doped with nitric and chlorine ions have been electrochemically deposited simply by a one-step electrochemical method in an aqueous media in the absence of any surfactant. The fabricated PEDOT films were characterized by scanning electron microscopy, transmission electron microscopy, and Raman spectroscopy. The results indicate that the hierarchical structured PEDOT film doped with nitric ions displays a 'lunar craters' porous morphology consisting of PEDOT nano-sheets with a thickness of less than 2 nm. The effect of counter ions on the electro-polymerization, the electrochemistry, and the morphology of the polymer film was studied. Compared with PEDOT film doped with nitric acid, PEDOT film deposited in the presence of chlorine ions shows irregular morphology and less electrochemical activity. The specific nanostructure of the polymer was further studied as catalyst support for platinum nanoparticles to methanol electro-oxidation.

  18. Fabrication of Novel Titanium-supported Ni-Sn Catalysts for Methanol Electro-oxidation

    Institute of Scientific and Technical Information of China (English)

    YI Qing-Feng; HUANG Wu; YU Wen-Qiang; LI Lei; LIU Xiao-Ping

    2008-01-01

    Novel titanium-supported Ni-Sn/Ti electrodes (Ni8Sn/Ti, Ni7Sn3/Ti and Ni/Ti) have been prepared using a hydrothermal method by a one step process. The scanning electron microscopy (SEM) images show that the catalyst particles are present as nano-scale flakes. Their electrochemical activity for methanol oxidation in 1 mol·L-1 NaOH was evaluated using voltammetric techniques, chronoamperometric measurements and electrochemical impedance spectra (EIS). It was found that the Ni8Sn/Ti electrode presents higher anodic currents and lower onset potential for methanol oxidation than Ni7Sn3/Ti, Ni/Ti and polycrystalline Ni electrodes. The EIS data indicate that under condi- tions of various anodic potentials and methanol concentrations, the Ni8Sn/Ti electrode displays significantly lower charge transfer resistances and high electrocatalytic activity towards methanol oxidation.

  19. Shake-Rattle-and-Roll: A Model of Dynamic Structural Disorder in Supported Nanoscale Catalysts

    CERN Document Server

    Rehr, J J

    2013-01-01

    We investigate the effects of "dynamic structural disorder" (DSD) on the behavior of supported nano-scale catalysts. DSD refers to the intrinsic fluctuating, inhomogeneous structure of such nano-scale systems. In contrast to bulk materials, nano-scale systems exhibit substantial fluctuations in energy, charge, and other extensive quantities as well as large surface effects. The DSD is driven by the stochastic librational motion of the center of mass and fluxional bonding at the nanoparticle surface due to thermal coupling with the substrate. Our approach for calculating DSD is based on a combination of statistical mechanics, transient coupled-oscillator models, and real-time DFT/MD simulations. This approach treats thermal and dynamic effects over multiple time-scales, including bond-stretching and -bending vibrations, DSD, and transient tethering to the substrate at longer ps time-scales. Model calculations of molecule-cluster interactions and molecular dissociation reaction paths are presented in which the ...

  20. Alumina supported/unsupported mixed oxides of Ca and Mg as heterogeneous catalysts for transesterification of Nannochloropsis sp. microalga’s oil

    International Nuclear Information System (INIS)

    Highlights: • Biodiesel made from oleaginous microalgae through transesterification process. • Effects of methanol/oil molar ratio, catalyst amount, reaction temperature and reaction time were optimized. • High biodiesel yields (75% and 85%) achieved at 60 °C. • The supported catalyst was very sustainable in high water content feedstocks. • The catalysts were characterized using TGA, XRD, FTIR, TPD-CO2 and SEM. - Abstract: In this study, calcium magnesium (CaMgO) and alumina (Al2O3) supported CaMgO mixed oxide catalysts were prepared via pH-controlled co-precipitation (Na2CO3 and NaOH as a precipitant) for transesterification of crude Nannochloropsis oculata (N. oculata) oil with methanol. The catalysts were characterized by means of Thermogravimetric analyses (TGA), X-ray diffraction (XRD), Fourier transform-infrared (FTIR), Temperature programmed desorption of CO2 (CO2-TPD), Inductively coupled plasma–atomic emission spectrometer (ICP–AES) and Scanning electron microscopy (SEM) analysis. At optimization condition, CaMgO mixed oxide catalyst showed 75.2% of fatty acid methyl ester (FAME) yield with catalyst loading of 20 wt.% at 3 h. Meanwhile, the supported CaMgO mixed oxide catalyst gave a higher FAME yield of 85.3% with catalyst loading of 10 wt.% at same conditions. Besides, the reusability study of catalyst was performed to investigate the stability and durability of supported/unsupported catalysts. The high content of Ca2+ and Mg2+ precipitated on Al2O3 supported CaMgO mixed oxide catalyst tend to increase the total basicity and provide more active sites for transesterification reaction. Moreover, better moisture resistant on the Al2O3 supported CaMgO mixed oxide catalyst compared with CaMgO mixed oxide catalyst, which is favourable for transesterification reaction on high water content microalgae oil

  1. Reverse Micelle Synthesis and Characterization of Supported Pt/Ni Bimetallic Catalysts on gamma-Al2O3

    Energy Technology Data Exchange (ETDEWEB)

    B Cheney; J Lauterbach; J Chen

    2011-12-31

    Reverse micelle synthesis was used to improve the nanoparticle size uniformity of bimetallic Pt/Ni nanoparticles supported on {gamma}-Al{sub 2}O{sub 3}. Two impregnation methods were investigated to optimize the use of the micelle method: (1) step-impregnation, where Ni nanoparticles were chemically reduced in microemulsion and then supported, followed by Pt deposition using incipient wetness impregnation, and (2) co-impregnation, where Ni and Pt were chemically reduced simultaneously in microemulsion and then supported. Transmission electron microscopy (TEM) was used to characterize the particle size distribution. Atomic absorption spectroscopy (AAS) was used to perform elemental analysis of bimetallic catalysts. Extended X-ray absorption fine structure (EXAFS) measurements were utilized to confirm the formation of the Pt-Ni bimetallic bond in the step-impregnated catalyst. CO pulse chemisorption and Fourier transform infrared spectroscopy (FTIR) studies of 1,3-butadiene hydrogenation in a batch reactor were performed to determine the catalytic activity. Step-impregnated Pt/Ni catalyst demonstrated enhanced hydrogenation activity over the parent monometallic Pt and Ni catalysts due to bimetallic bond formation. The catalyst synthesized using co-impregnation showed no enhanced activity, behaving similarly to monometallic Ni. Overall, our results indicate that reverse micelle synthesis combined with incipient wetness impregnation produced small, uniform nanoparticles with bimetallic bonds that enhanced hydrogenation activity.

  2. TiN@nitrogen-doped carbon supported Pt nanoparticles as high-performance anode catalyst for methanol electrooxidation

    Science.gov (United States)

    Zhang, Jun; Ma, Li; Gan, Mengyu; Fu, Shenna; Zhao, Yi

    2016-08-01

    In this paper, TiN@nitrogen-doped carbons (NDC) composed of a core-shell structure are successfully prepared through self-assembly and pyrolysis treatment using γ-aminopropyltriethoxysilane as coupling agent, polyaniline as carbon and nitrogen source, respectively. Subsequently, TiN@NDC supporting Pt nanoparticles (Pt/TiN@NDC) are obtained by a microwave-assisted polyol process. The nitrogen-containing functional groups and TiN nanoparticles play a critical role in decreasing the average particle size of Pt and improving the electrocatalytic activity of Pt/TiN@NDC. Transmission electron microscope results reveal that Pt nanoparticles are uniformly dispersed in the TiN@NDC surface with a narrow particle size ranging from 1 to 3 nm in diameter. Moreover, the Pt/TiN@NDC catalyst shows significantly improved catalytic activity and high durability for methanol electrooxidation in comparison with Pt/NDC and commercial Pt/C catalysts, revealed by cyclic voltammetry and chronoamperometry. Strikingly, this novel Pt/TiN@NDC catalyst reveals a better CO tolerance related to Pt/NDC and commercial Pt/C catalysts, which due to the bifunctional mechanism and strong metal-support interaction between Pt and TiN@NDC. In addition, the probable reaction steps for the electrooxidation of CO adspecies on Pt NPs on the basis of the bifunctional mechanism are also proposed. These results indicate that the TiN@NDC is a promising catalyst support for methanol electrooxidation.

  3. Kinetics of carbon monoxide oxidation over modified supported CuO catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Loc, Luu Cam; Tri, Nguyen; Cuong, Hoang Tien; Thoang, Ho Si [Vietnam Academy of Science and Technology (VAST), Ho Chi Minh City (Viet Nam). Inst. of Chemical Technology; Agafonov, Yu.A.; Gaidai, N.A.; Lapidus, A.L. [Russian Academy of Sciences, Moscow (Russian Federation). N.D. Zelinsky Institute of Organic Chemistry

    2013-11-01

    The following supported on {gamma}-Al{sub 2}O{sub 3} catalysts: 10(wt.)%CuO (CuAl), 10%CuO+10%Cr{sub 2}O{sub 3} (CuCrAl) and 10%CuO+20%CeO{sub 2} (CuCeAl) were under the investigation. Physico-chemical characteristics of the catalysts were determined by the methods of BET, X-ray Diffraction (XRD), and Temperature-Programmed Reduction (TPR). A strong interaction of copper with support in CuAl resulted in the formation of low active copper aluminates. The bi-oxide CuCrAl was more active than CuAl owing to the formation of high catalytically active spinel CuCr{sub 2}O{sub 4}. The fact of very high activity of the sample CuCeAl can be explained by the presence of the catalytically active form of CuO-CeO{sub 2}-Al{sub 2}O{sub 3}. The kinetics of CO total oxidation was studied in a gradientless flow-circulating system at the temperature range between 200 C and 270 C. The values of initial partial pressures of carbon monoxide (P{sup o}{sub CO}), oxygen (P{sup o}{sub O2}), and specially added carbon dioxide (P{sup o}{sub CO{sub 2}}) were varied in ranges (hPa): 10 / 45; 33 / 100, and 0 / 30, respectively. (orig.)

  4. Synthesis of boron and nitrogen doped graphene supporting PtRu nanoparticles as catalysts for methanol electrooxidation

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Jiming; Zhou, Yingke, E-mail: zhouyk888@hotmail.com; Tian, Xiaohui; Xu, Xiao; Zhu, Hongxi; Zhang, Shaowei; Yuan, Tao

    2014-10-30

    Highlights: • A single-step heat treatment approach is developed to synthesize boron and nitrogen doped graphene supporting PtRu nanocatalysts. • The introduction of boron or nitrogen containing function groups into graphene can modulate the particle size and dispersion of the supporting PtRu nanoparticles. • The optimized catalysts present high electrocatalytic activity and excellent stability for methanol oxidation reaction. - Abstract: In this study, we demonstrate a single-step heat treatment approach to synthesize boron and nitrogen doped graphene supporting PtRu electrocatalysts for methanol electro-oxidation reaction. The reduction of graphene oxide, boron or nitrogen doping of graphene and loading of PtRu nanoparticles happened simultaneously during the reaction process. The morphologies and microstructures of the as-prepared catalysts were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The electrocatalytic methanol oxidation activity and durability of the obtained catalysts were evaluated by the cyclic voltammetry and chronoamperometric techniques. The results reveal that the boron and nitrogen doped graphene supporting PtRu electrocatalysts can be successfully prepared by the single step heat treatment technique, and the introduction of boron or nitrogen containing function groups into the reduced graphene sheets could modulate the particle size and dispersion of the supporting PtRu nanoparticles and improve the electrocatalytic performance of methanol oxidation reaction. The optimal annealing temperature is 800 °C, the preferable heat treatment time is 60 min for the nitrogen-doped catalysts and 90 min for the boron-doped catalysts, and the catalysts prepared under such conditions present superior catalytic activities for methanol oxidation than those prepared under other heat treatment conditions.

  5. Synthesis of boron and nitrogen doped graphene supporting PtRu nanoparticles as catalysts for methanol electrooxidation

    International Nuclear Information System (INIS)

    Highlights: • A single-step heat treatment approach is developed to synthesize boron and nitrogen doped graphene supporting PtRu nanocatalysts. • The introduction of boron or nitrogen containing function groups into graphene can modulate the particle size and dispersion of the supporting PtRu nanoparticles. • The optimized catalysts present high electrocatalytic activity and excellent stability for methanol oxidation reaction. - Abstract: In this study, we demonstrate a single-step heat treatment approach to synthesize boron and nitrogen doped graphene supporting PtRu electrocatalysts for methanol electro-oxidation reaction. The reduction of graphene oxide, boron or nitrogen doping of graphene and loading of PtRu nanoparticles happened simultaneously during the reaction process. The morphologies and microstructures of the as-prepared catalysts were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The electrocatalytic methanol oxidation activity and durability of the obtained catalysts were evaluated by the cyclic voltammetry and chronoamperometric techniques. The results reveal that the boron and nitrogen doped graphene supporting PtRu electrocatalysts can be successfully prepared by the single step heat treatment technique, and the introduction of boron or nitrogen containing function groups into the reduced graphene sheets could modulate the particle size and dispersion of the supporting PtRu nanoparticles and improve the electrocatalytic performance of methanol oxidation reaction. The optimal annealing temperature is 800 °C, the preferable heat treatment time is 60 min for the nitrogen-doped catalysts and 90 min for the boron-doped catalysts, and the catalysts prepared under such conditions present superior catalytic activities for methanol oxidation than those prepared under other heat treatment conditions

  6. Studies on accelerated deactivation of ruthenium-promoted alumina-supported alkalized cobalt Fischer-Tropsch synthesis catalyst

    Institute of Scientific and Technical Information of China (English)

    Shohreh Tehrani; Mohamad Irani; Ahmad Tavasoli; Yadollah Mortazavi; Abbas A.Khodadadi; Ali Nakhaei Pour

    2011-01-01

    Accelerated deactivation of ruthenium-promoted alumina-supported alkalized cobalt(K-Ru-Co/-γ-Al2O3)Fischer-Tropsch(FT)synthesis catalyst along the catalytic bed over 120 h of time-on-stream(TOS)was investigated.Catalytic bed was divided into three parts and structural changes of the spent catalysts collected from each catalytic bed after FT synthesis were studied using different techniques.Rapid deactivation was observed during the reaction due to high reaction temperature and low feed flow rates.The physico-chemical properties of the catalyst charged in the Bed #1 of the reactor did not change significantly.Interaction of cobalt with alumina and the formation of CoAl2O4 increased along the catalytic bed.Reducibility percentage decreased by 4.5%,7.5% and 12.9% for the catalysts in the Beds #1,#2 and #3,respectively.Dispersion decreased by 8.8%,14.4% and 26.6% for the catalysts in the Beds #1,#2 and #3,respectively.Particle diameter increased by 0.6%,2.4% and 10.4% for the catalysts in the Beds #1,#2 and #3,respectively,suggesting higher rate of sintering at the last catalytic bed.The amount of coke at the last catalytic bed was significantly higher than those of Beds #1 and #2.

  7. Impact of carbon on the surface and activity of silica-carbon supported copper catalysts for reduction of nitrogen oxides

    Science.gov (United States)

    Spassova, I.; Stoeva, N.; Nickolov, R.; Atanasova, G.; Khristova, M.

    2016-04-01

    Composite catalysts, prepared by one or more active components supported on a support are of interest because of the possible interaction between the catalytic components and the support materials. The supports of combined hydrophilic-hydrophobic type may influence how these materials maintain an active phase and as a result a possible cooperation between active components and the support material could occur and affects the catalytic behavior. Silica-carbon nanocomposites were prepared by sol-gel, using different in specific surface areas and porous texture carbon materials. Catalysts were obtained after copper deposition on these composites. The nanocomposites and the catalysts were characterized by nitrogen adsorption, TG, XRD, TEM- HRTEM, H2-TPR, and XPS. The nature of the carbon predetermines the composite's texture. The IEPs of carbon materials and silica is a force of composites formation and determines the respective distribution of the silica and carbon components on the surface of the composites. Copper deposition over the investigated silica-carbon composites leads to formation of active phases in which copper is in different oxidation states. The reduction of NO with CO proceeds by different paths on different catalysts due to the textural differences of the composites, maintaining different surface composition and oxidation states of copper.

  8. The effect of CeO sub 2 support upon activity and selectivity of Ru and Co Fischer Tropsh catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Al-Shammary, A.F.Y.; Caga, I.T.; Tata, A.Y.; Winterbottom, J.M. (Birmingham Univ. (UK))

    1991-01-01

    Some CeO{sub 2} supported Ru and Co catalysts with 5% metal loading were prepared by impregnation methods, and characterised by temperature programmed reduction techniques (TPR). Their catalytic activities and selectivities were tested in H{sub 2} + CO reactions and compared with a Ru on SiO{sub 2} catalyst in the range of 1-9 atmospheres at 260{sup 0}C. Ru/SiO{sub 2} and Co/SiO{sub 2} catalysts gave CH{sub 4} only at 1 atm., and = 70% CH{sub 4} at 9 atms., whilst CeO{sub 2} supported Ru and Co gave significantly smaller quantities (20-80%) of CH{sub 4} over the same pressure range.

  9. STUDIES ON THE STATE OF PALLADIUM AND HYDROGENATION ACTIVITY OF RESIN SUPPORTED PALLADIUM—TIN OXIDE CATALYSTS

    Institute of Scientific and Technical Information of China (English)

    HuWeibing; ZhangShengming; 等

    1994-01-01

    Sereral Pd-SnO2/D3520 and Pd-PbO/D3520 catalysts with Pd/D3520,SnO2/D3520 and PbO/D3520 catalysts as reference were studied by means of IR and XPS.Interaction between Pd and the second metal or between metal and support was observed.Results show that there is a strong interaction between Pd and the second metal,but there is not an obvious interaction between metal and support.The active constituent is Pd.Hydrogenation activity of the catalysts is altered because of the interaction between Pd and the second metal.The activity of the catalysis for hydrogenation has relation to outer layer valence electron density of Pd.

  10. Carbon nanotubes-Nafion composites as Pt-Ru catalyst support for methanol electro-oxidation in acid media

    Institute of Scientific and Technical Information of China (English)

    Shengzhou Chen; Fei Ye; Weiming Lin

    2009-01-01

    Carbon nanotubes-Nafion (CNTs-Nafion) composites were prepared by impregnated CNTs with Nafion in ethanol solution and characterized by FT-IR. Pt-Ru catalysts supported on CNTs-Nafion composites were synthesized by microwave-assisted polyol process. The physical and electrochemical properties of the catalysts were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), CO stripping voltammetry, cyclic voltammetry (CV) and chronoamperometry (CA). The results showed that the Nafion incorporation in CNTs-Nafion composites did not significantly alter the oxygen-containing groups on the CNTs surface. The Pt-Ru catalyst supported on CNTs-Nafion composites with 2 wt% Nafion showed good dispersion and the best CO oxidation and methanol electro-oxidation activities.

  11. Catalytic upgrading of oleic acid into biofuel using Mo modified zeolite supported Ni oxalate catalyst functionalized with fluoride ion

    International Nuclear Information System (INIS)

    Highlights: • Modification of zeolite with freshly prepared molybdenum oxalate. • Functionalization of Ni oxalate with HF and incorporation into Mo modified zeolite. • Characterization of synthesized Mo modified zeolite supported Ni oxalate catalyst. • Deoxygenation of oleic acid with the synthesized zeolite supported catalyst. • Reusability study on the synthesized zeolite supported catalyst. - Abstract: In this study, fluoride ion functionalized nickel oxalate supported on molybdenum modified zeolite (NiMoFOx/Zeol) catalyst was synthesized, characterized and tested on the hydrodeoxygenation (HDO) of oleic acid (OA) into paraffinic fuel. The NiMoFOx/Zeol characterization results confirmed the presence of both Ni and Mo as well as the formation of NiMoO4 which is a highly HDO reactive specie at 2θ value of 43.6° according to the XRD result. NiMoFOx/Zeol also showed loss in crystallinity and reduction in the average particle size leading to increase in the pore volume and specific surface area due to the combined effects of fluoride ion presence, oxalic acid functionalization and calcination. The effect of temperature, pressure and NiMoFOx/Zeol loading studied showed that initial increase in their values increased the yield of the target fractions until some points where reduction was observed. The best observed experimental conditions to hydrodeoxygenate 40 g (∼45 mL) of OA into 75% n-C18 and 23% i-C18 were 360 °C, 30 mg NiMoFOx/Zeol loading and 20 bar using 100 mL H2/min. The presence of i-C18 was due to the functionalization of the catalyst with fluoride ion. The catalyst reusability result displayed excellent qualities with marginal loss of only 2% in activity after third reuse due to the improved synthesis protocol that employed organometallic precursor. The results are strongly encouraging for further studies toward industrialization of HDO process

  12. Electro-oxidation of Ethanol on Carbon Supported PtSn and PtSnNi Catalysts

    Directory of Open Access Journals (Sweden)

    Nur Hidayati

    2016-03-01

    Full Text Available Even though platinum is known as an active electro-catalyst for ethanol oxidation at low temperatures (< 100 oC, choosing the electrode material for ethanol electro-oxidation is a crucial issue. It is due to its property which easily poisoned by a strong adsorbed species such as CO. PtSn-based electro-catalysts have been identified as better catalysts for ethanol electro-oxidation. The third material is supposed to improved binary catalysts performance. This work presents a study of the ethanol electro-oxidation on carbon supported Pt-Sn and Pt-Sn-Ni catalysts. These catalysts were prepared by alcohol reduction. Nano-particles with diameters between 2.5-5.0 nm were obtained. The peak of (220 crystalline face centred cubic (fcc Pt phase for PtSn and PtSnNi alloys was repositioned due to the presence of Sn and/or Ni in the alloy. Furthermore, the modification of Pt with Sn and SnNi improved ethanol and CO electro-oxidation. Copyright © 2016 BCREC GROUP. All rights reserved Received: 10th November 2015; Revised: 1st February 2016; Accepted: 1st February 2016 How to Cite: Hidayati, N., Scott, K. (2016. Electro-oxidation of Ethanol on Carbon Supported PtSn and PtSnNi Catalysts. Bulletin of Chemical Reaction Engineering & Catalysis, 11 (1: 10-20. (doi:10.9767/bcrec.11.1.394.10-20 Permalink/DOI: http://dx.doi.org/10.9767/bcrec.11.1.394.10-20

  13. Selective catalytic oxidation of H2S over iron oxide supported on alumina-intercalated Laponite clay catalysts

    International Nuclear Information System (INIS)

    Graphical abstract: The catalytic reaction and deactivation mechanisms for H2S selective oxidation over Fe/Al-Lap catalysts are shown in the illustration. The catalytic reaction follows Mars–van Krevelen mechanism. Moreover, the interaction between iron oxide and alumina, the strong acidity of the catalysts and the well dispersion of iron oxide improve the catalytic performance efficiently. Meanwhile, the catalyst deactivation is mainly due to the formation of Fe2(SO4)3 and elemental sulfur deposits on the surface. -- Highlights: • Fe/Al-Lap catalysts with mesoporous structure were synthesized. • Iron oxide mainly exists in form of isolate Fe3+ in an oxidic environment. •Fe/Al-Lap catalysts show high catalytic activities at low temperature. •The high catalytic activities are ascribed to the interaction between iron oxide and alumina. •The formed Fe2(SO4)3 and elemental sulfur deposits on surface cause catalyst deactivation. -- Abstract: A series of iron oxide supported on alumina-intercalated clay catalysts (named Fe/Al-Lap catalysts) with mesoporous structure and high specific surface area were prepared. The structural and chemical properties were studied by nitrogen sorption isotherms, X-ray diffraction (XRD), UV–vis diffuse reflectance spectra (UV–vis DRS), X-ray photoelectron spectra (XPS), Fourier transform infrared spectroscopy (FTIR), H2 temperature-programmed reduction (H2-TPR) and NH3 temperature-programmed desorption (NH3-TPD) techniques. It was realized that iron oxide mainly existed in the form of isolated Fe3+ in an oxidic environment. Fe/Al-Lap catalysts showed high catalytic activities in the temperature range of 120–200 °C without the presence of excessive O2. This can be attributed to the interaction between iron oxide and alumina, which improve the redox property of Fe3+ efficiently. In addition, the strong acidity of catalysts and good dispersion of iron oxide were also beneficial to oxidation reaction. Among them, 7% Fe

  14. SISGR-Fundamental Experimental and Theoretical Studies on a Novel Family of Oxide Catalyst Supports for Water Electrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Kumta, Prashant [University of Pittsburgh

    2014-10-03

    Identification and development of non-noble metal based electro-catalysts or electro-catalysts with significant reduction of expensive noble metal contents (E.g. IrO2, Pt) with comparable electrochemical performance as the standard noble metal/metal oxide for proton exchange membrane (PEM) based water electrolysis would constitute a major breakthrough in the generation of hydrogen by water electrolysis. Accomplishing such a system would not only result reduction of the overall capital costs of PEM based water electrolyzers, but also help attain the targeted hydrogen production cost [< $ 3.0 / gallon gasoline equivalent (gge)] comparable to conventional liquid fuels. In line with these goals, it was demonstrated that fluorine doped IrO2 thin films and nanostructured high surface area powders display remarkably higher electrochemical activity, and comparable durability as pure IrO2 electro-catalyst for the oxygen evolution reaction (OER) in PEM based water electrolysis. Furthermore, corrosion resistant SnO2 and NbO2 support has been doped with F and coupled with IrO2 or RuO2 for use as an OER electro-catalyst. A solid solution of SnO2:F or NbO2:F with only 20 - 30 mol.% IrO2 or RuO2 yielding a rutile structure in the form of thin films and bulk nanoparticles displays similar electrochemical activity and stability as pure IrO2/RuO2. This would lead to more than 70 mol.% reduction in the noble metal oxide content. Novel nanostructured ternary (Ir,Sn,Nb)O2 thin films of different compositions FUNDAMENTAL STUDY OF NANOSTRUCTURED ELECTRO-CATALYSTS WITH REDUCED NOBLE METAL CONTENT FOR PEM BASED WATER ELECTROLYSIS 4 have also been studied. It has been shown that (Ir0.40Sn0.30Nb0.30)O2 shows similar electrochemical activity and enhanced chemical robustness as compared to pure IrO2. F doping of the ternary (Ir,Sn,Nb)O2 catalyst helps in further decreasing the noble metal oxide content of the catalyst. As a result, these reduced noble metal oxide catalyst systems would

  15. Production of biodiesel by transesterification of soybean oil using calcium supported tin oxides as heterogeneous catalysts

    International Nuclear Information System (INIS)

    Highlights: • Heterogeneous catalysts were prepared by an impregnation method with different conditions. • The catalysts were efficient in the soybean oil transesterification. • The catalytic activity and stability of the catalyst were investigated. - Abstract: The main objective of this work was to develop an environmentally benign process for the production of biodiesel by using a stable solid base catalyst. To this purpose, different heterogeneous CaO–SnO2 catalysts have been prepared by means of impregnation methods. Various techniques such as X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, thermogravimetric and differential thermal analysis (TG-DTA), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) were applied for the catalyst characterization. The transesterification of soybean oil with methanol, to produce biodiesel, was carried out under batch conditions at refluxed methanol over the CaO–SnO2 catalysts. The catalytic activity is found to be highly dependent on the Ca/Sn ratio and calcination temperature. The solid catalyst with the Ca/Sn molar ratio of 4:1 and calcined at a temperature of 973 K, performed the best activity, reaching the conversion to methyl esters of 89.3% after 6 h of reaction at methanol reflux temperature (343 K) when a methanol/oil molar ratio of 12:1 and catalyst dosage of 8 wt.% were employed. Further, the solid catalyst is proved to be stable and durable for the transesterification reaction

  16. Designing supported palladium-on-gold bimetallic nano-catalysts for controlled hydrogenation of acetylene in large excess of ethylene

    Science.gov (United States)

    Malla, Pavani

    Ethylene is used as a starting point for many chemical intermediates in the petrochemical industry. It is predominantly produced through steam cracking of higher hydrocarbons (ethane, propane, butane, naphtha, and gas oil). During the cracking process, a small amount of acetylene is produced as a side product. However, acetylene must be removed since it acts as a poison for ethylene polymerization catalysts at even ppm concentrations (>5 ppm). Thus, the selective hydrogenation of acetylene to ethylene is an important process for the purification of ethylene. Conventional, low weight loading Pd catalysts are used for this selective reaction in high concentration ethylene streams. Gold was initially considered to be catalytically inactive for a long time. This changed when gold was seen in the context of the nanometric scale, which has indeed shown it to have excellent catalytic activity as a homogeneous or a heterogeneous catalyst. Gold is proved to have high selectivity to ethylene but poor at conversion. Bimetallic Au and Pd catalysts have exhibited superior activity as compared to Pd particles in semi-hydrogenation. Hydrogenation of acetylene was tested using this bimetallic combination. The Pd-on-Au bimetallic catalyst structure provides a new synthesis approach in improving the catalytic properties of monometallic Pd materials. TiO 2 as a support material and 0.05%Pd loading on 1%Au on titania support and used different treatment methods like washing plasma and reduction between the two metal loadings and was observed under 2:1 ratio. In my study there were two set of catalysts which were prepared by a modified incipient wetness impregnation technique. Out of all the reaction condition the catalyst which was reduced after impregnating gold and then impregnating palladium which was further treated in non-thermal hydrogen plasma and then pretreated in hydrogen till 250°C for 1 hour produced the best activity of 76% yield at 225°C. Stability tests were conducted

  17. Effect of Surface Oxygen Containing Groups on the Catalytic Activity of Multi-walled Carbon Nanotube Supported Pt Catalyst

    Energy Technology Data Exchange (ETDEWEB)

    X Wang; N Li; J Webb; L Pfefferle; G Haller

    2011-12-31

    Multi-walled carbon nanotubes (MWNT) supported platinum catalysts were employed to study the support functionalization on their catalytic performances. The MWNT were subjected to HNO{sub 3} functionalization, in which oxygen-containing-groups (OCGs) were introduced to improve Pt dispersion. The MWNT supports were characterized by nitrogen physisorption and NEXAFS, and the Pt supported on differently functionalized MWNT characterized by X-ray absorption, TEM and both hydrogen and CO chemisorption. Compared to the as received MWNT supports, Pt dispersion is improved on the HNO3 treated MWNT supports, but the turnover frequency (TOF) of aqueous phase reforming decreases by half. The TOF can be recovered by removing the OCGs via high temperature annealing. To further investigate the OCGs effect, different probe reactions, including both steam reforming and liquid phase reforming of hydrocarbon oxygenates and dehydrogenation of alkanes in the liquid and gas phases, have been performed on the MWNT supported catalysts with different OCGs. A comparison of these reaction results suggests that OCGs are only detrimental to reactions in a binary mixture with two components of different hydrophilicity due to their competitive adsorption on the catalyst supports.

  18. Influence of the Synthesis Method for Pt Catalysts Supported on Highly Mesoporous Carbon Xerogel and Vulcan Carbon Black on the Electro-Oxidation of Methanol

    OpenAIRE

    Cinthia Alegre; María Elena Gálvez; Rafael Moliner; María Jesús Lázaro

    2015-01-01

    Platinum catalysts supported on carbon xerogel and carbon black (Vulcan) were synthesized with the aim of investigating the influence of the characteristics of the support on the electrochemical performance of the catalysts. Three synthesis methods were compared: an impregnation method with two different reducing agents, sodium borohydride and formic acid, and a microemulsion method, in order to study the effect of the synthesis method on the physico-chemical properties of the catalysts. X-ra...

  19. Catalysts with Cu base supported in mixed oxides to generate H2: reformed of methanol in oxidant atmosphere

    International Nuclear Information System (INIS)

    In this work, the characterization of Cu supported in CeO2-ZrO2, for to generate H2 starting from the one reformed of methanol with water vapor and oxygen is presented. The sol-gel technique and classic impregnation for the obtaining of the supports and catalysts respectively were used. The materials were characterized by XRD, SEM, adsorption- desorption of N2 and TPR. The catalytic materials presented crystalline phases associated with the zircon (tetragonal and monoclinic phase) and the ceria (cubic phase) depending on the CeO2/ZrO2 relationship. The morphology of the catalysts was analyzed by SEM being observed semispheric particles for the rich materials in ZrO2 and added planars in the rich materials in CeO2. The ceria addition to the zircon favors the specific area of the mixed oxides CeO2-ZrO2 and it promotes the reducibility of the copper oxide at low temperatures. The rich catalysts in ceria also showed high activity in the methanol transformation and bigger selectivity toward the production of H2. This result is associated with the presence of copper species that decrease to low temperature present in the rich catalysts in ceria and that they are not present in the rich catalysts in zircon. (Author)

  20. A core-shell structured, metal-ceramic composite-supported Ru catalyst for methane steam reforming

    Science.gov (United States)

    Lee, Hyun Chul; Potapova, Yulia; Lee, Doohwan

    2012-10-01

    Methane steam reforming on a metal-ceramic composite-supported ruthenium catalyst is studied at high temperatures. The core-shell structured Al2O3@Al composite consisting primarily of an Al metal core with a high surface area γ-Al2O3 overlayer is obtained by hydrothermal oxidation. Under the synthesis condition, primary Al2O3@Al particles aggregate to form a hierarchal secondary structure with macrosize inter-pores. This core-shell composite support enhances the heat conductivity and provides a high surface area for fine dispersion of a catalytic Ru component on the γ-Al2O3 overlayer. The Ru/Al2O3@Al catalyst exhibits significantly higher CH4 conversion than the conventional Ru/Al2O3 catalyst, indicating its superior properties for methane steam reforming at high temperatures contributed due to the fine Ru dispersion and facilitated heat and mass transfer via the unique catalyst structure. This metal-ceramic composite catalyst is stable in the reforming reaction for an extended time, suggesting reasonable stability in its physicochemical properties.

  1. Effects of supported metallocene catalyst active center multiplicity on antioxidant-stabilized ethylene homo- and copolymers

    KAUST Repository

    Atiqullah, Muhammad

    2014-10-09

    © 2014 Akadémiai Kiadó, Budapest, Hungary. A silica-supported bis(n-butylcyclopentadienyl) zirconium dichloride [( n BuCp)2ZrCl2] catalyst was synthesized. This was used to prepare an ethylene homopolymer and an ethylene-1-hexene copolymer. The active center multiplicity of this catalyst was modeled by deconvoluting the copolymer molecular mass distribution and chemical composition distribution. Five different active site types were predicted, which matched the successive self-nucleation and annealing temperature peaks. The thermo-oxidative melt stability, with and without Irganox 1010 and Irgafos 168, of the above polyethylenes was investigated using nonisothermal differential scanning calorimetric (DSC) experiments at 150 °C. This is a temperature that ensures complete melting of the samples and avoids the diffusivity of oxygen to interfere into polyethylene crystallinity and its thermo-oxidative melt degradation. The oxidation parameters such as onset oxidation temperature, induction period, protection factor, and S-factor were determined by combining theoretical modeling with the DSC experiments. Subsequently, these findings were discussed considering catalyst active center multiplicity and polymer microstructure, particularly average ethylene sequence length. Several insightful results, which have not been reported earlier in the literature, were obtained. The antioxidant effect, for each polymer, varied as (Irganox + Irgafos) ≈ Irganox > Irgafos > Neat polymer. The as-synthesized homopolymer turned out to be almost twice as stable as the corresponding copolymer. The antioxidant(s) in the copolymer showed higher antioxidant effectiveness (AEX) than those in the homopolymer. Irganox exhibited more AEX than Irgafos. To the best of our knowledge, such findings have not been reported earlier in the literature. However, mixed with Irganox or Irgafos, their melt oxidation stability was comparable. The homopolymer, as per the calculated S-factor, showed Irganox

  2. A Phenomenological Study on the Synergistic Role of Precious Metals and the Support in the Steam Reforming of Logistic Fuels on Monometal Supported Catalysts

    Directory of Open Access Journals (Sweden)

    Abdul-Majeed Azad

    2010-01-01

    Full Text Available Clean power source utilizing vast logistic fuel reserves (jet fuels, diesel, and coal would be the main driver in the 21st century for high efficiency. Fuel processors are required to convert these fuels into hydrogen-rich reformate for extended periods in the presence of sulfur, and deliver hydrogen with little or no sulfur to the fuel cell stack. However, the jet and other logistic fuels are invariably sulfur-laden. Sulfur poisons and deactivates the reforming catalyst and therefore, to facilitate continuous uninterrupted operation of logistic fuel processors, robust sulfur-tolerant catalysts ought to be developed. New noble metal-supported ceria-based sulfur-tolerant nanocatalysts were developed and thoroughly characterized. In this paper, the performance of single metal-supported catalysts in the steam-reforming of kerosene, with 260 ppm sulfur is highlighted. It was found that ruthenium-based formulation provided an excellent balance between hydrogen production and stability towards sulfur, while palladium-based catalyst exhibited rapid and steady deactivation due to the highest propensity to sulfur poisoning. The rhodium supported system was found to be most attractive in terms of high hydrogen yield and long-term stability. A mechanistic correlation between the role of the nature of the precious metal and the support for generating clean desulfurized H2-rich reformate is discussed.

  3. Ferric hydrogen sulfate supported on silica-coated nickel ferrite nanoparticles as new and green magnetically separable catalyst for 1,8-dioxodecahydroacridine synthesis

    Institute of Scientific and Technical Information of China (English)

    Amir Khojastehnezhad; Mohammad Rahimizadeh; Hossein Eshghi; Farid Moeinpour; Mehdi Bakavoli

    2014-01-01

    A new magnetically separable catalyst consisting of ferric hydrogen sulfate supported on sili-ca-coated nickel ferrite nanoparticles was prepared. The synthesized catalyst was characterized using vibrating sample magnetometry, X-ray diffraction, transmission electron microscopy, scan-ning electron microscopy, and Fourier transform infrared spectroscopy. This new magnetic catalyst was shown to be an efficient heterogeneous catalyst for the synthesis of 1,8- dioxodecahydroacri-dines under solvent-free conditions. The catalyst is readily recovered by simple magnetic decanta-tion and can be recycled several times with no significant loss of catalytic activity.

  4. Selective Aerobic Oxidation of 5-Hydroxymethylfurfural in Water Over Solid Ruthenium Hydroxide Catalysts with Magnesium-Based Supports

    DEFF Research Database (Denmark)

    Gorbanev, Yury; Kegnæs, Søren; Riisager, Anders

    2011-01-01

    Solid catalyst systems comprised of ruthenium hydroxide supported on magnesium-based carrier materials (spinel, magnesium oxide and hydrotalcite) were investigated for the selective, aqueous aerobic oxidation of the biomass-derived chemical 5-hydroxymethylfurfural into 2,5-furandicarboxylic acid...

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

    OpenAIRE

    Monika Gupta; Rajive Gupta; Medha Anand

    2009-01-01

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

  6. Synthesis and characterization of molybdenum catalysts supported on γ-Al2O3-CeO2 composite oxides

    International Nuclear Information System (INIS)

    The physical and chemical properties of a catalyst play a vital role in various industrial applications. Molybdenum catalysts supported on γ-Al2O3 and γ-Al2O3-CeO2 mixed oxides with varying loading of CeO2 (5, 10, 15, 20 wt% with respect to γ-Al2O3) were prepared by wet impregnation method. The physiochemical properties of these synthesized Mo catalysts were studied with various characterization techniques such as X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), temperature-programmed reduction (TPR), field emission scanning electron microscopy-energy dispersive analysis (FESEM-EDX) and X-ray fluorescence spectrometer (XRF). The results showed that the addition of CeO2 into the support affected the binding energies of the elements and reducibility of the metal oxides formed after calcination of catalyst samples due to the change in metal-support interaction. Further, the characterization techniques showed that the active metal was well dispersed on the surface of support material.

  7. One-step Synthesis of n-Butanol from Ethanol Condensation over Alumina-supported Metal Catalysts

    Institute of Scientific and Technical Information of China (English)

    Ke Wu YANG; Xuan Zhen JIANG; Wei Chao ZHANG

    2004-01-01

    One-step synthesis of n-butanol from bimolecular condensation of ethanol was firstly achieved over nickel supported gamma alumina catalyst. A mechanism of dehydration path for the growth of carbon chain by eliminating a hydroxy group from one ethanol molecule with a α-H of other ethanol molecule rather than aldol condensation was verified.

  8. Effect of Al content on the gas-phase dehydration of glycerol over silica-alumina-supported silicotungstic acid catalysts

    International Nuclear Information System (INIS)

    The gas-phase dehydration of glycerol to acrolein was carried out over silicotungstic acid (H4SiW12O40·xH2O, HSiW) catalysts supported on SiO2, η-Al2O3, and silica-alumina with different Al contents. The HSiW catalysts supported on silica-alumina showed higher glycerol conversions and acrolein yields during the initial 2 h at 315.deg.C than did SiO2- and η-Al2O3-supported HSiW catalysts. Among the tested catalysts, HSiW/Si0.9Al0.1Ox exhibited the highest space-time yield during the initial 2 h. The loaded HSiW species can change the acid types and suppress the formation of carbonaceous species on Al-rich silica-alumina. The deactivated HSiW supported on silica-alumina can be fully regenerated after calcination in air at 500.deg.C. As long as the molar ratio between water and glycerol was in the range of 2-11, the acrolein selectivity increased significantly with increasing water content in the feed, while the surface carbon content decreased owing to the suppression of heavy compounds

  9. Effect of Al content on the gas-phase dehydration of glycerol over silica-alumina-supported silicotungstic acid catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Yong Tae; You, Su Jin; Park, Eun Duck [Ajou Univ., Suwon (Korea, Republic of); Jung, Kwangdeog [Korea Institute of Science and Technology, Seoul (Korea, Republic of)

    2012-07-15

    The gas-phase dehydration of glycerol to acrolein was carried out over silicotungstic acid (H{sub 4}SiW{sub 12}O{sub 40}{center_dot}xH{sub 2}O, HSiW) catalysts supported on SiO{sub 2}, {eta}-Al{sub 2}O{sub 3}, and silica-alumina with different Al contents. The HSiW catalysts supported on silica-alumina showed higher glycerol conversions and acrolein yields during the initial 2 h at 315.deg.C than did SiO{sub 2}- and {eta}-Al{sub 2}O{sub 3}-supported HSiW catalysts. Among the tested catalysts, HSiW/Si{sub 0.9}Al{sub 0.1Ox} exhibited the highest space-time yield during the initial 2 h. The loaded HSiW species can change the acid types and suppress the formation of carbonaceous species on Al-rich silica-alumina. The deactivated HSiW supported on silica-alumina can be fully regenerated after calcination in air at 500.deg.C. As long as the molar ratio between water and glycerol was in the range of 2-11, the acrolein selectivity increased significantly with increasing water content in the feed, while the surface carbon content decreased owing to the suppression of heavy compounds.

  10. Preparation of High-Activity MgO-Supported Co-Mo and Ni-Mo Sulfide Hydrodesulfurization Catalysts

    Czech Academy of Sciences Publication Activity Database

    Klicpera, Tomáš; Zdražil, Miroslav

    2002-01-01

    Roč. 206, č. 2 (2002), s. 314-320. ISSN 0021-9517 R&D Projects: GA ČR GA104/01/0544 Keywords : hydrodesulfurization * sulfide catalysts * MgO support Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 3.118, year: 2002

  11. Continuous fixed-bed gas-phase hydroformylation using supported ionic liquid-phase (SILP) Rh catalysts

    DEFF Research Database (Denmark)

    Riisager, Anders; Wasserscheid, Peter; Van Hal, R.; Fehrmann, Rasmus

    2003-01-01

    Continuous flow gas-phase hydroformylation of propene was performed using novel supported ionic liquid-phase (SILP) catalysts containing immobilized Rh complexes of the biphosphine ligand sulfoxantphos in the ionic liquids 1-n-butyl-3-methylimidazolium hexafluorophosphate and halogen-free 1-n-but...

  12. Rhodium nanoparticles supported on carbon nanofibers as an arene hydrogenation catalyst highly tolerant to a coexisting epoxido group.

    Science.gov (United States)

    Motoyama, Yukihiro; Takasaki, Mikihiro; Yoon, Seong-Ho; Mochida, Isao; Nagashima, Hideo

    2009-11-01

    Rhodium nanoparticles supported on a carbon nanofiber (Rh/CNF-T) show high catalytic activity toward arene hydrogenation under mild conditions in high turnover numbers without leaching the Rh species; the reaction is highly tolerant to epoxido groups, which often undergo ring-opening hydrogenation with conventional catalysts. PMID:19788269

  13. Inkjet printing of carbon supported platinum 3-D catalyst layers for use in fuel cells

    Science.gov (United States)

    Taylor, André D.; Kim, Edward Y.; Humes, Virgil P.; Kizuka, Jeremy; Thompson, Levi T.

    We present a method of using inkjet printing (IJP) to deposit catalyst materials onto gas diffusion layers (GDLs) that are made into membrane electrode assemblies (MEAs) for polymer electrolyte fuel cell (PEMFC). Existing ink deposition methods such as spray painting or screen printing are not well suited for ultra low (Monarch 700, Black Pearls 2000, etc.). Our ink jet printed MEAs with catalyst loadings of 0.020 mg Pt cm -2 have shown Pt utilizations in excess of 16,000 mW mg -1 Pt which is higher than our traditional screen printed MEAs (800 mW mg -1 Pt). As a further demonstration of IJP versatility, we present results of a graded distribution of Pt/C catalyst structure using standard Johnson Matthey (JM) catalyst. Compared to a continuous catalyst layer of JM Pt/C (20% Pt), the graded catalyst structure showed enhanced performance.

  14. Suzuki Reaction of Aryl Bromides Using a Phosphine-Free Magnetic Nanoparticle-Supported Palladium Catalyst

    Institute of Scientific and Technical Information of China (English)

    Nghia T. BUI; Trung B. DANG; Ha V. LE; Nam T. S. PHAN

    2011-01-01

    A palladium catalyst immobilized on superparaganetic nanoparticles was prepared with a palladium loading of 0.30 mmol/g.The catalyst was characterized using X-ray diffraction,scanning electron microscopy,transmission electron microscopy,vibrating sample magnetometry,thermogravimetric analysis,Fourier transform infrared,atomic absorption spectrophotometry,and nitrogen adsorption.The immobilized palladium catalyst was an efficient catalyst without added phosphine ligands for the Suzuki cross-coupling reaction of several aryl bromides with phenylboronic acid.The recovery of catalyst was simply by magnetic decantation in the presence of a magnet.The immobilized palladium catalyst can be reused many times without significant degradation in catalytic activity.No leaching of active palladium species into the reaction solution was detected.

  15. Preparation of Mesoporous Silica-Supported Palladium Catalysts for Biofuel Upgrade

    OpenAIRE

    Ling Fei; Harvind Kumar Reddy; Joshua Hill; Qianglu Lin; Bin Yuan; Yun Xu; Peter Dailey; Shuguang Deng; Hongmei Luo

    2012-01-01

    We report the preparation of two hydrocracking catalysts Pd/CoMoO4/silica and Pd/CNTs/CoMoO4/silica (CNTs, carbon nanotubes). The structure, morphologies, composition, and thermal stability of catalysts were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectroscopy, transmission electron microscopy (TEM), energy-dispersive X-ray (EDX), and thermogravimetric analysis (TGA). The catalyst activity was measured in a Parr reactor with camelina fatty acid methyl est...

  16. Efficient and selective chemical transformations under flow conditions: The combination of supported catalysts and supercritical fluids

    Directory of Open Access Journals (Sweden)

    M. Isabel Burguete

    2011-09-01

    Full Text Available This paper reviews the current trends in the combined use of supported catalytic systems, either on solid supports or in liquid phases and supercritical fluids (scFs, to develop selective and enantioselective chemical transformations under continuous and semi-continuous flow conditions. The results presented have been selected to highlight how the combined use of those two elements can contribute to: (i Significant improvements in productivity as a result of the enhanced diffusion of substrates and reagents through the interfaces favored by the scF phase; (ii the long term stability of the catalytic systems, which also contributes to the improvement of the final productivity, as the use of an appropriate immobilization strategy facilitates catalyst isolation and reuse; (iii the development of highly efficient selective or, when applicable, enantioselective chemical transformations. Although the examples reported in the literature and considered in this review are currently confined to a limited number of fields, a significant development in this area can be envisaged for the near future due to the clear advantages of these systems over the conventional ones.

  17. Characterization of platinum catalyst supported on carbon nanoballs prepared by solution plasma processing

    International Nuclear Information System (INIS)

    In order to improve the energy-conversion efficiency in fuel cells, the authors loaded Pt nanoparticles on carbon nanoballs (CNBs) by using solution plasma processing (SPP) involving CNB and Pt ion with a protection group. In this study, we employed poly(vinylpyrrolidone) (PVP) or sodium dodecyl sulfate (SDS) to prepare Pt nanoparticles supported on CNB (Pt/CNB) by the SPP, and the electrochemical properties as a catalyst was evaluated by cyclic voltammetry. The carbon nanoballs were prepared by thermal decomposition process of ethylene and hydrogen gases. Color of the solution changed from yellow to dark brown as synthesis time. This change indicates the improvement of dispersibility of CNB. Moreover, transmission electron microscopy images and elemental mapping images showed the Pt nanoparticles supported on CNB. A catalytic activity of the Pt/CNB in use of SDS was shown to be higher than the Pt/CNB prepared with PVP system. The SDS-containing Pt/CNB also showed the higher activity than that obtained by the conventional method.

  18. Synthesis and characterization of electrospun carbon nanofiber supported Pt catalyst for fuel cells

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • The functionalized and optimized e-CNF has been prepared. • Increasing functionalization period, the fiber morphology slightly affected. • The suitability of the Pt/fe-CNF was studied in the lab made set-ups of PEMFC. - Abstract: Polyacrylonitrile polymer nanofibers were prepared using an electrospinner. These nanofibers were subjected to stabilization and carbonization processes. The electrospun carbon nanofibers (e-CNF) were functionalized using sulfuric acid and nitric acid under three different refluxing periods (i.e., 1f, 3f, and 5f) to optimize the functionalization level. The thermal stability of the obtained carbon supports was characterized by TGA. The Pt loaded carbon supports (20 wt%) for the three functionalized (1fe, 3fe, and 5fe-CNF) samples were prepared using chloroplatinic acid with ethylene glycol as the reducing agent. The dispersion of platinum on e-CNF and the size of Pt nanoparticles were characterized by HRSEM and HRTEM and the crystalline nature was confirmed by XRD. The surface area and pore size distribution were calculated from Brunner Emmett Teller method. The performance of five different samples such as Pt/C, Pt/1fe, 3fe, 5fe-CNF and e-CNF as electrodes and laboratory prepared hydrocarbon based sulfonated poly ether ether ketone (SPEEK) as electrolyte were studied in proton exchange membrane fuel cells (PEMFC) and the results were compared with commercially available Pt/C catalyst and Nafion-117 membrane

  19. Combination of supported bimetallic rhodium–molybdenum catalyst and cerium oxide for hydrogenation of amide

    International Nuclear Information System (INIS)

    Hydrogenation of cyclohexanecarboxamide to aminomethylcyclohexane was conducted with silica-supported bimetallic catalysts composed of noble metal and group 6–7 elements. The combination of rhodium and molybdenum with molar ratio of 1:1 showed the highest activity. The effect of addition of various metal oxides was investigated on the catalysis of Rh–MoOx/SiO2, and the addition of CeO2 much increased the activity and selectivity. Higher hydrogen pressure and higher reaction temperature in the tested range of 2–8 MPa and 393–433 K, respectively, were favorable in view of both activity and selectivity. The highest yield of aminomethylcyclohexane obtained over Rh–MoOx/SiO2 + CeO2 was 63%. The effect of CeO2 addition was highest when CeO2 was not calcined, and CeO2 calcined at >773 K showed a smaller effect. The use of CeO2 as a support rather decreased the activity in comparison with Rh–MoOx/SiO2. The weakly-basic nature of CeO2 additive can affect the surface structure of Rh–MoOx/SiO2, i.e. reducing the ratio of Mo–OH/Mo–O− sites. (focus issue paper)

  20. Combination of supported bimetallic rhodium-molybdenum catalyst and cerium oxide for hydrogenation of amide

    Science.gov (United States)

    Nakagawa, Yoshinao; Tamura, Riku; Tamura, Masazumi; Tomishige, Keiichi

    2015-02-01

    Hydrogenation of cyclohexanecarboxamide to aminomethylcyclohexane was conducted with silica-supported bimetallic catalysts composed of noble metal and group 6-7 elements. The combination of rhodium and molybdenum with molar ratio of 1:1 showed the highest activity. The effect of addition of various metal oxides was investigated on the catalysis of Rh-MoOx/SiO2, and the addition of CeO2 much increased the activity and selectivity. Higher hydrogen pressure and higher reaction temperature in the tested range of 2-8 MPa and 393-433 K, respectively, were favorable in view of both activity and selectivity. The highest yield of aminomethylcyclohexane obtained over Rh-MoOx/SiO2 + CeO2 was 63%. The effect of CeO2 addition was highest when CeO2 was not calcined, and CeO2 calcined at >773 K showed a smaller effect. The use of CeO2 as a support rather decreased the activity in comparison with Rh-MoOx/SiO2. The weakly-basic nature of CeO2 additive can affect the surface structure of Rh-MoOx/SiO2, i.e. reducing the ratio of Mo-OH/Mo-O- sites.

  1. Suppression of methane formation during Fisher-Tropsch synthesis using manganese-cobalt oxide supported on H-5A zeolite as a catalyst

    Institute of Scientific and Technical Information of China (English)

    Syed Tajammul Hussain; Muhammad Mazhar; Muhammad Arif Nadeem

    2009-01-01

    In Fischer-Tropsch synthesis reaction, methane formation is one of the side reactions which must be suppressed in order to get better catalytic selectivity for light olefins. In the present study, we have modified cobalt based Fischer-Tropsch catalyst and developed a process to minimize methane production, consequently to produce maximum yield of light olefins. Manganese-cobalt oxide supported on H-5A zeolite catalyst was synthesized using modified H-5A zeolite, to increase its surface acid sites. Increased acidity of zeolite plays a major part in the suppression of methane formation during the Fischer-Tropsch reaction. The modified zeolite results in the electronic modification of catalyst surface by creating new active catalytic sites. The results are compared with other supported catalysts along with unmodified zeolite. Appreciable reduction in methane formation is achieved on modified zeolite supported catalyst in comparison with unsupported catalyst.

  2. Vanadium Oxide Supported on MSU-1 as a Highly Active Catalyst for Dehydrogenation of Isobutane with CO2

    OpenAIRE

    Guosong Sun; Qingze Huang; Shiyong Huang; Qiuping Wang; Huiquan Li; Haitao Liu; Shijie Wan; Xuewang Zhang; Jinshu Wang

    2016-01-01

    Vanadium oxide supported on MSU-1, with VOx loading ranging from 2.5 to 17.5 wt. %, was developed as a highly active catalyst in dehydrogenation of isobutane with CO2. The obtained catalysts of VOx/MSU-1 were characterized by X-ray diffraction (XRD), N2 adsorption-desorption, and H2-temperature programmed reduction (H2-TPR) methods and the results showed that the large surface area of MSU-1 was favorable for the dispersion of VOx species and the optimal loading of VOx was 12.0 wt. %. Meanwhil...

  3. Effective immobilisation of a metathesis catalyst bearing an ammonium-tagged NHC ligand on various solid supports.

    Science.gov (United States)

    Skowerski, Krzysztof; Białecki, Jacek; Czarnocki, Stefan J; Żukowska, Karolina; Grela, Karol

    2016-01-01

    An ammonium-tagged ruthenium complex, 8, was deposited on several widely available commercial solid materials such as silica gel, alumina, cotton, filter paper, iron powder or palladium on carbon. The resulting catalysts were tested in toluene or ethyl acetate, and found to afford metathesis products in high yield and with extremely low ruthenium contamination. Depending on the support used, immobilised catalyst 8 shows also additional traits, such as the possibility of being magnetically separated or the use for metathesis and subsequent reduction of the obtained double bond in one pot. PMID:26877803

  4. The Selective Oxidation of n-Butane to Maleic Anhydride : Comparison of Bulk and Supported V-P-O Catalysts

    OpenAIRE

    Koningsberger, D.C.; Ruitenbeek, M.; van Dillen, A.J.; BARBON, A; Faassen, E.E.H. van; Geus, John W.

    1998-01-01

    V P O catalysts supported on the surface of silica and titania particles were studied and compared with bulk V P O. The catalytic performance was tested in the n-butane oxidation reaction to maleic anhydride, and the structure of the equilibrated catalysts was characterised with X-ray absorption spectroscopy (EXAFS) and (low-temperature) ESR spectroscopy. Our results show considerable differences in catalytic performance between VPO/TiO_{2} on the one hand, and VPO/SiO_{2} and VPO/bulk on the...

  5. Co-production of hydrogen and carbon nanofibers from methane decomposition over zeolite Y supported Ni catalysts

    International Nuclear Information System (INIS)

    Highlights: • Methane cracking requires an optimum temperature range of 550–600 °C for H2 yield. • At 550 and 600 °C, catalyst showed longer activity for the whole test. • At 600 °C, a 614.25 gc/gNi of carbon was obtained using 30% Ni/Y zeolite catalysts. • Produced filamentous carbon has the same diameter as the metallic nickel itself. • VHSV has reverse and non-linear relevancy to the weight of Ni/Y zeolite catalyst. - Abstract: The objective of this paper is to study the influences of different operating conditions on the hydrogen formation and properties of accumulated carbon from methane decomposition using zeolite Y supported 15% and 30% Ni, respectively, at a temperature range between 500 and 650 °C in a pilot scale fixed bed reactor. The temperature ramp was showed a significant impact on the thermo-catalytic decomposition (TCD) of methane. An optimum temperature range of 550–600 °C were required to attain the maximum amount of methane conversion and revealed that at 550 and 600 °C, catalyst showed longer activity for the whole studied of experimental runs. Additionally, at 550 °C, the methane decomposition is two times longer for 30% Ni/Y zeolite than that for 15% Ni/Y zeolite catalyst, whereas it is almost three times higher at 500 °C. A maximum carbon yield of 614.25 and 157.54 gc/gNi were reported after end of the complete reaction at 600 °C with 30% and 15% Ni/Y zeolite catalyst, respectively. From BET, TPD, and XRD analysis, we had reported that how the chemistry between the TCD of methane and metal content of the catalysts could significantly affect the hydrogen production as well as carbon nano-fibers. TEM analysis ensured that the produced carbon had fishbone type structures with a hollow core and grew from crystallites of Ni anchored on the external surface of the catalysts and irrespective of the metal loadings, the whisker types of nano filaments were formed as confirmed from FESEM analysis. Nevertheless, the effect of

  6. Fundamental Studies of Butane Oxidation over Model-Supported Vanadium Oxide Catalysts: Molecular Structure-Reactivity Relationships

    NARCIS (Netherlands)

    Wachs, I.E.; Jehng, J.M.; Deo, G.; Weckhuysen, B.M.; Guliants, V.V.; Benziger, J.B.; Sundaresan, S.

    1997-01-01

    The oxidation of n-butane to maleic anhydride was investigated over a series of model-supported vanadia catalysts where the vanadia phase was present as a two-dimensional metal oxide overlayer on the different oxide supports (TiO2, ZrO2, CeO2, Nb2O5, Al2O3, and SiO2). No correlation was found betwee

  7. Gold catalysts supported on nanosized iron oxide for low-temperature oxidation of carbon monoxide and formaldehyde

    Science.gov (United States)

    Tang, Zheng; Zhang, Weidong; Li, Yi; Huang, Zuming; Guo, Huishan; Wu, Feng; Li, Jinjun

    2016-02-01

    This study aimed to optimize synthesis of gold catalyst supported on nanosized iron oxide and to evaluate the activity in oxidation of carbon monoxide and formaldehyde. Nanosized iron oxide was prepared from a colloidal dispersion of hydrous iron oxide through a dispersion-precipitation method. Gold was adsorbed onto nanosized iron oxide under self-generated basic conditions. Characterization results indicate that the iron oxide consisted of hematite/maghemite composite with primary particle sizes of 6-8 nm. Gold was highly dispersed on the surface of the support. The catalysts showed good activity in the oxidation of airborne carbon monoxide and formaldehyde. The optimal pH for their synthesis was ∼7. The catalytic performance could be enhanced by extending the adsorption time of gold species on the support within 21 h. The optimized catalyst was capable of achieving complete oxidation of 1% carbon monoxide at -20 °C and 33% conversion of 450 ppm formaldehyde at ambient temperature. The catalyst may be applicable to indoor air purification.

  8. Steam reforming of ethanol over Ni/support catalysts for generation of hydrogen for fuel cell applications

    Energy Technology Data Exchange (ETDEWEB)

    Denis, Andrzej; Grzegorczyk, Wieslaw; Gac, Wojciech; Machocki, Andrzej [University of Maria Curie-Sklodowska, Faculty of Chemistry, Department of Chemical Technology, 3 Maria Curie-Sklodowska Square, 20-031 Lublin (Poland)

    2008-09-30

    The paper reports experimental results concerning the influence of the support nature (TiO{sub 2}, ZnO, Al{sub 2}O{sub 3} and Al{sub 2}O{sub 3}-Fe{sub 2}O{sub 3}) of nickel catalysts on their activity, selectivity and coking phenomenon in the steam reforming of ethanol in the range of 570-870K. The chemical transformations of ethanol occurring on the catalyst support make its chemical nature an important factor affecting the productivity and selectivity of the process. It was found that the most suitable supports in nickel catalysts designed for hydrogen generation in the steam reforming of ethanol are ZnO and TiO{sub 2}. Taking into consideration both the efficiency of hydrogen generation and the intensity of carbon deposition, the optimum temperature of the process of the steam reforming of ethanol is below 750K. An improvement in the selectivity of hydrogen generation and diminishing of the formation of undesirable products may be obtained by promoting nickel catalysts with sodium. (author)

  9. A new generation of zirconia supported metal oxide catalysts for converting low grade renewable feedstocks to biodiesel.

    Science.gov (United States)

    Kim, Manhoe; DiMaggio, Craig; Salley, Steven O; Simon Ng, K Y

    2012-08-01

    A new class of zirconia supported mixed metal oxides (ZnO-TiO(2)-Nd(2)O(3)/ZrO(2) and ZnO-SiO(2)-Yb(2)O(3)/ZrO(2)) has demonstrated the ability to convert low quality, high free fatty acid (FFA) bio-oils into biodiesel. Pelletized catalysts of ZrO(2) supported metal oxides were prepared via a sol-gel process and tested in continuous flow packed bed reactors for up to 6 months. In a single pass, while operating at mild to moderate reaction conditions, 195 °C and 300 psi, these catalysts can perform simultaneous esterification and transesterification reactions on feedstock of 33% FFA and 67% soybean oil to achieve FAME yields higher than 90%. Catalytic activity of the ZrO(2) supported metal oxide catalysts was highly dependent on the metal oxide composition. These heterogeneous catalysts will enable biodiesel manufacturers to avoid problems inherent in homogeneous processes, such as separation and washing, corrosive conditions, and excessive methanol usage. PMID:22695144

  10. Boron-doped graphene as promising support for platinum catalyst with superior activity towards the methanol electrooxidation reaction

    Science.gov (United States)

    Sun, Yongrong; Du, Chunyu; An, Meichen; Du, Lei; Tan, Qiang; Liu, Chuntao; Gao, Yunzhi; Yin, Geping

    2015-12-01

    We report the synthesis of boron-doped graphene by thermally annealing the mixture of graphene oxide and boric acid, and its usage as the support of Pt catalyst towards the methanol oxidation reaction. The composition, structure and morphology of boron-doped graphene and its supported Pt nanoparticles (Pt/BG) are characterized by transmission electron microscopy, inductively coupled plasma mass spectrometry, Raman spectroscopy, X-ray diffraction and X-ray photoelectron spectroscopy. It is revealed that boron atoms are doped into graphene network in the form of BC2O and BCO2 bonds, which lead to the increase in defect sites and facilitate the subsequent deposition of Pt nanoparticles. Therefore, the Pt/BG catalyst presents smaller particle size and narrower size distribution than the graphene supported Pt (Pt/G) catalyst. When evaluated as the electrocatalyst for the methanol oxidation reaction, the Pt/BG catalyst exhibits excellent electrochemical activity and stability demonstrated by cyclic voltammetry and chronoamperometry tests. The enhanced activity is mainly ascribed to the electronic interaction between boron-doped graphene and Pt nanoparticles, which lowers the d-band center of Pt and thus weakens the absorption of the poisoning intermediate CO. Our work provides an alternative approach of improving the reaction kinetics for the oxidation of small organic molecules.

  11. New approach on the catalytic oxidation of methanol to formaldehyde over MoO3 supported on nano hydroxyapatite catalysts

    Science.gov (United States)

    Said, A. A.; Abd El-Wahab, M. M.; Alian, A. M.

    2014-08-01

    Molybdenum oxide (20 wt. %) supported on nano hydroxyapatite mixed was prepared by impregnation method and calcinated at 400° 500° 600° and 700°C in static air atmosphere. The catalysts were characterized by thermogravimetry (TG), differential thermal analysis (DTA), X-ray diffraction (XRD), Transmission Electron Microscope (TEM) and nitrogen sorption measurements. The gas-phase oxidation of methanol to formaldehyde was carried out in a conventional fixed flow bed reactor. The obtained results clearly revealed that the formation of CaMoO4 spinel nano particles was active and selective catalyst towards the formation of formaldehyde. The maximum yield of formaldehyde was 97% on the catalyst calcined at 400 ° C. Moreover, the yield of formaldehyde was found unaffected by increasing the calcination temperature up to 700° C.

  12. Carbon supported Cu-Pd nanoparticles as anode catalyst for direct borohydride-hydrogen peroxide fuel cells

    International Nuclear Information System (INIS)

    Carbon supported Cu-Pd bimetallic nanoparticles were prepared by a successive reduction method in aqueous solution and used as anode electrocatalyst for direct borohydride-hydrogen peroxide fuel cell (DBHFC). The physical and electrochemical properties of the as-prepared electrocatalysts are investigated by transmission electron microscopy (TEM), X-ray diffraction (XRD), cyclic voltammetry (CV), chronopotentiometry (CP), linear sweep voltammetry (LSV) and fuel cell test. The results show that the size of the crystallite is around 12.5 nm, the Cu1Pd1/C catalyst presents the highest catalytic activity among all the resultant catalysts, and the DBHFC using Cu1Pd1/C as anode catalyst and Pt mesh (1 cm × 1 cm) as cathode electrode obtains the maximum power density as high as 39.8 mW cm-2 at a discharge current density of 80.1 mA cm-2 at 20 °C

  13. Effect of reduction method on the performance of Pd catalysts supported on activated carbon for the selective oxidation of glucose

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The effect of the reduction method on the catalytic properties of palladium catalysts supported on activated carbon for the oxidation of D-glucose was examined.The reduction methods investigated include argon glow discharge plasma reduction at room temperature,reduction by flowing hydrogen at elevated temperature,and reduction by formaldehyde at room temperature.The plasma-reduced catalyst shows the smallest metal particles with a narrow size distribution that leads to a much higher activity.The catalyst characteristics show that the plasma reduction increases the amount of oxygen-containing functional groups,which significantly enhances the hydrophilic property of the activated carbon and improves the dispersion of the metal.

  14. Activated Carbons as Supports for Catalyst%作为催化剂载体的活性炭

    Institute of Scientific and Technical Information of China (English)

    赵波; 韩文锋; 霍超; 刘化章

    2004-01-01

      This paper introduces the advantages of activated carbons as supports for catalysts. The manufacture of the carbons is described briefly, together with their most important chemical and physical properties that are tightly related to catalysts manufacture and use of such catalysts. The treatment methods of activated carbons are also reviewed.%  介绍了活性炭作为催化剂载体的优点、了活性炭的生产方法以及与催化剂的生产和应用密切相关的活性炭的物理及化学性质,并介绍了活性炭的改性处理的方法。

  15. Kinetics and efficiency displayed by supported and suspended TiO2 catalysts applied to the disinfection of Escherichia coli

    Institute of Scientific and Technical Information of China (English)

    Majdi Kacem; Gael Plantard; Nathalie Wery; Vincent Goetz

    2014-01-01

    TiO2-mediated photocatalysis is widely used in a variety of applications and products in the envi-ronmental and energy fields, including photoelectrochemical conversion, self-cleaning surfaces, and especially water purification systems. The dimensionality of the structure of a TiO2 material can affect its properties, functions, and more specifically, its photocatalytic performance. In this work, the photocatalytic inactivation of Gram-negative Escherichia coli using three photocatalysts, differ-ing in their structure and other characteristics, was studied in a batch reactor under UVA light. The aim was to establish the disinfection efficiency of solid TiO2 compared with that of suspended cata-lysts, widely considered as reference cases for photocatalytic water disinfection. The bacterial inac-tivation profiles obtained showed that: (1) the photoinactivation was exclusively related to the quantity of photons retained per unit of treated volume, irrespective of the characteristics of the photocatalyst and the emitted light flux densities;(2) across the whole UV light range studied, each of the photocatalytic solids was able to achieve more than 2 log bacterial inactivation with less than 2 h UV irradiation;(3) none of the used catalysts achieved a total bacterial disinfection during the treatment time. For each of the catalysts the quantum yield has been assessed in terms of disinfec-tion efficiency, the 2D material showed almost the same performance as those of suspended cata-lysts. This catalyst is promising for supported photocatalysis applications.

  16. In situ characterisation of supported iron-iridium catalysts by iron-57 and iridium-193 Moessbauer spectroscopy

    International Nuclear Information System (INIS)

    Some silica-supported iron-iridium catalysts with different iron to iridium ratios and formed by the incipient wetness technique have been examined in situ by 57Fe and 193Ir Moessbauer spectroscopy following pretreatment in hydrogen. The results show that the reduction of the iron component is enhanced by the presence of iridium metal. The pretreated catalysts were evaluated for the hydrogenation of carbon monoxide at 2700C and 50 atmospheres pressure. The presence of iridium, which was shown by Moessbauer spectroscopy to result in the formation of reduced iron, iridium, and iron iridium alloy in the pretreated catalyst, was found to increase the catalytic activity and also influence selectivity. However, the systematic variation of the iridium content which was shown by Moessbauer spectroscopy to determine the exact phase composition of the pretreated catalysts, appeared to have little effect on catalytic performance. The 57Fe Moessbauer spectra recorded from all the used catalysts showed the formation of large and small particle ε'-Fe2.2C under the high pressure of the catalytic reaction. The results suggest that the formation of iron carbides on reduced iron, perhaps at the surface, and the adsorption of hydrogen on reduced iridium are important features of this catalytic system. (orig.)

  17. Preparation, characterization of Mo catalysts supported on Ni- containing calcium deficient hydroxyapatite and reactivity for the thiophene HDS reaction

    Directory of Open Access Journals (Sweden)

    Cherif A.

    2013-09-01

    Full Text Available Ni-containing Calcium Hydroxyapatite (NiCaHAp; 3.31 wt.% Ni was synthesized by coprecipitation and used as catalyst support. Molybdenum was supported on NiCaHAp by impregnation using ammonium heptamolybdate. The prepared catalysts Mo(x/NiCaHAp (x: 2 to 8 wt % in Mo were characterized by elemental analysis, XRD, FT-IR, N2 adsorption-desorption and TEM-EDX. The catalysts were sulfided in-situ at 673 K under flowing H2S/H2 (15 Vol.% H2S and tested in hydrodesulfurization (HDS of thiophene at 673 K. The main XRD peaks of hydroxyapatite CaHAp phase were observed in all samples and a peak due probably to crystalline MoO3 phase was also identified from the results. However, no crystalline phase of NiO was found for the catalysts, which showed its Ni species were highly dispersed. The sulfided catalysts Mo(x/NiCaHAp presented are active in HDS of thiophene, despite the presence of some large MoO3 crystallites and incomplete sulfidation. This activity may be due to interaction of NiO and MoO3 on CaHAp resulting in the formation of Ni-Mo-S phase under flowing H2S/H2. When the molybdenum content increased the HDS activity increasead slightly, which was caused by the agglomeration of MoO3. The Mo(8/NiCaHAp catalyst is about two times less active for thiophene HDS than the commercial NiMoP/Al2O3.

  18. The effect of noble metals on catalytic methanation reaction over supported Mn/Ni oxide based catalysts

    Directory of Open Access Journals (Sweden)

    Wan Azelee Wan Abu Bakar

    2015-09-01

    Full Text Available Carbon dioxide (CO2 in sour natural gas can be removed using green technology via catalytic methanation reaction by converting CO2 to methane (CH4 gas. Using waste to wealth concept, production of CH4 would increase as well as creating environmental friendly approach for the purification of natural gas. In this research, a series of alumina supported manganese–nickel oxide based catalysts doped with noble metals such as ruthenium and palladium were prepared by wetness impregnation method. The prepared catalysts were run catalytic screening process using in-house built micro reactor coupled with Fourier Transform Infra Red (FTIR spectroscopy to study the percentage CO2 conversion and CH4 formation analyzed by GC. Ru/Mn/Ni(5:35:60/Al2O3 calcined at 1000 °C was found to be the potential catalyst which gave 99.74% of CO2 conversion and 72.36% of CH4 formation at 400 °C reaction temperature. XRD diffractogram illustrated that the supported catalyst was in polycrystalline with some amorphous state at 1000 °C calcination temperature with the presence of NiO as active site. According to FESEM micrographs, both fresh and used catalysts displayed spherical shape with small particle sizes in agglomerated and aggregated mixture. Nitrogen Adsorption analysis revealed that both catalysts were in mesoporous structures with BET surface area in the range of 46–60 m2/g. All the impurities have been removed at 1000 °C calcination temperature as presented by FTIR, TGA–DTA and EDX data.

  19. Application of carbon supported base metal carburized catalyst to fuel cell electrocatalyst

    Energy Technology Data Exchange (ETDEWEB)

    Izhar, S.; Otsuka, S.; Nagai, M. [Tokyo Univ. of Agriculture and Technology, Tokyo (Japan). Graduate School of Bio-applications and Systems Engineering

    2006-07-01

    Due to the high cost and potential for carbon monoxide poisoning, polymer electrolyte fuel cells using platinum (Pt) base catalysts pose serious problems. Transition metal carbides are highly regarded because of their high conductivity, high activity in hydrogenolysis reactions and high resistance to poisoning of the catalyst. A study was conducted in which nickel (Ni) molybdenum (Mo)/Ketjen carbon (KC) carbides were prepared with various Ni compositions and carburization temperatures. XRD, TPR and the cyclic voltammetric method were used to evaluate these catalysts through comparative evaluations with a Pt/C catalyst. These Ni-Mo/KC catalysts were evaluated for their electrocatalytic activity using a H{sub 2}O{sub 2} single stack cell and a 3-electrode cell in order to identify the active species. It was found that Ni{sub 0.5}Mo{sub 0.5} carbided at 873 K achieved the current density of 17 per cent of the Pt/C catalyst. Cyclic voltammetry measurements indicated that the Ni-Mo/KC carbide catalysts have a high activity towards the anodic electrooxidation of hydrogen. The activity is due to the amorphous Ni-Mo carbide measured by XRD and TPR. It was concluded that bimetallic carbides can reduce the manufacturing cost of fuel cells and are therefore a suitable material for Pt/C catalysts.

  20. Recent progress of ordered mesoporous silica-supported chiral metallic catalysts

    Directory of Open Access Journals (Sweden)

    LIU Rui

    2013-02-01

    Full Text Available Recently,ordered silica-based mesoporous chiral organometallics-functionalized heterogeneous catalysts have attracted extensive research interest due to their excellent properties,such as easy preparation,high activity and convenient recycle.This review mainly summarizesthe generally prepared strategy and the silica-based organometallics-functionalized heterogeneous catalysts reported in the literatures.

  1. Biodiesel production by methanolysis of soybean oil using calcium supported on mesoporous silica catalyst

    International Nuclear Information System (INIS)

    The transesterification of soybean oil with a CaO/mesoporous silica catalyst was achieved. The effects of CaO loading levels in the mesoporous silica catalyst, the amount of catalyst to substrate level and the reaction temperature and time on the conversion of soybean oil were investigated. Increasing the temperature and reaction time raised the total conversion of soybean oil attained. The optimized condition, found to be 15 wt.% of Ca loading on the mesoporous silica catalyst, a 5% (w/w) catalyst to oil level and a reaction temperature of 60 deg. C for 8 h, provided the highest yield of 95.2%. The fuel properties of the biodiesel obtained under these optimized conditions were acceptable under the biodiesel standards of Thailand.

  2. Conversion of biomass-derived sorbitol to glycols over carbon-materials supported Ru-based catalysts

    Science.gov (United States)

    Guo, Xingcui; Guan, Jing; Li, Bin; Wang, Xicheng; Mu, Xindong; Liu, Huizhou

    2015-11-01

    Ruthenium (Ru) supported on activated carbon (AC) and carbon nanotubes (CNTs) was carried out in the hydrogenolysis of sorbitol to ethylene glycol (EG) and 1,2-propanediol (1,2-PD) under the promotion of tungsten (WOx) species and different bases. Their catalytic activities and glycols selectivities strongly depended on the support properties and location of Ru on CNTs, owning to the altered metal-support interactions and electronic state of ruthenium. Ru located outside of the tubes showed excellent catalytic performance than those encapsulated inside the nanotubes. Additionally, the introduction of WOx into Ru/CNTs significantly improved the hydrogenolysis activities, and a complete conversion of sorbitol with up to 60.2% 1,2-PD and EG yields was obtained on RuWOx/CNTs catalyst upon addition of Ca(OH)2. Stability study showed that this catalyst was highly stable against leaching and poisoning and could be recycled several times.

  3. Pillar effects in MoS2 catalysts supported on Al and Zr pillared clays in a hydrotreatment reaction

    International Nuclear Information System (INIS)

    Molybdenum (Mo) supported on aluminum-pillared clay (Al-PILC) and zirconium-pillared clay (Zr-PILC) with contents of 0.6, 1.4 and 2.8 atoms of Mo/nm2 were prepared and tested in the hydrogenation (HYD) of naphthalene (NP). It was found that the molybdenum sulfide (MoS2) catalysts supported on Zr- pillared clays were more active than the samples supported on Al-pillared clays and catalysts supported on alumina. The catalysts were characterized by X-ray diffraction (XRD), thermogravimetric analysis, nitrogen adsorption and transmission electron microscopy (TEM). Characterization analysis clearly pointed out to a close interaction of MoS2 with ZrO2 in the pillared clays. Therefore, the highest hydrogenation activities can be related to the presence of an interaction of MoS2 with ZrO2, probably with a different electronic interaction between the active phase and the support, than that reported for the MoS2/Al2O3 system

  4. Synthesis and characterization of a catalyst containing vanadium supported on alumina

    Science.gov (United States)

    Aderdour, N.; Nohair, K.; Baalala, M.; Diouri, M.; Bensitel, M.

    2005-03-01

    This work describes the preparation, the characterization of the hysico chemical properties of catalyst containing vanadium supported on Al{2}O{3}, and study of its catalytic activity in the reaction of conversion of SO{2} to SO{3}, the synthesis of the alumine was carried out by hydrolysis of isopropoxyde aluminium in solution of isopropanol. Vanadium is introduced by impregnation with porous volume in several stages. The same technique is used for the SO{4}{}2-, K{2}O.followed of calcination under-air with 450° C. This solid is characterized by DRX, IR and analyzes elementary. IR highlighted the presence of the surface sulphated species, adsorption of the molecule probes 2,6-dimethylpyridine on V{2}O{5}/Al{2}O{3} followed by infra-red shows the presence of coordinated species (Lewis acidity) about 1580, 1470 and 1452 cm-1and protonic species (Brönsted acidity) characterized by vibrations infra-red about 1650 and 1620 cm-1.

  5. Catalytic Hydrotreatment of Humins in Mixtures of Formic Acid/2-Propanol with Supported Ruthenium Catalysts.

    Science.gov (United States)

    Wang, Yuehu; Agarwal, Shilpa; Kloekhorst, Arjan; Heeres, Hero Jan

    2016-05-10

    The catalytic hydrotreatment of humins, which are the solid byproducts from the conversion of C6 sugars (glucose, fructose) into 5-hydroxymethylfurfural (HMF) and levulinic acid (LA), by using supported ruthenium catalysts has been investigated. Reactions were carried out in a batch setup at elevated temperatures (400 °C) by using a hydrogen donor (formic acid (FA) in isopropanol (IPA) or hydrogen gas), with humins obtained from d-glucose. Humin conversions of up to 69 % were achieved with Ru/C and FA, whereas the performance for Ru on alumina was slightly poorer (59 % humin conversion). Humin oils were characterized by using a range of analytical techniques (GC, GC-MS, GCxGC, gel permeation chromatography) and were shown to consist of monomers, mainly alkyl phenolics (>45 % based on compounds detectable by GC) and higher oligomers. A reaction network for the reaction is proposed based on structural proposals for humins and the main reaction products. PMID:26836970

  6. New composite DMFC anode with PEDOT as a mixed conductor and catalyst support

    Energy Technology Data Exchange (ETDEWEB)

    Drillet, J.F.; Dittmeyer, R.; Juettner, K.; Li, L.; Mangold, K.M. [DECHEMA e.V., Karl-Winnacker-Institut, Theodor-Heuss-Allee 25, 60486 Frankfurt a. M. (Germany)

    2006-12-15

    The conducting polymer PEDOT is tested as a carbon substitute material for the DMFC anode. Electrochemical experiments are carried out in a three-electrode half-cell at room temperature. The first part of this paper focuses on the characterization of PEDOT and PEDOT-PSS as a diffusion layer material. PEDOT/C cyclic voltammograms are recorded in 1 M H{sub 2}SO{sub 4} in the range between the hydrogen evolution and polymer over-oxidation potentials. The incorporation of the PSS counter-ion into the polymer matrix leads to higher impedance values compared to PEDOT without PSS. The second part deals with the study of PEDOT as a Pt catalyst support. It is found that the partial over-oxidation of PEDOT enhances the activity of Pt for methanol oxidation. This can be explained by a change in the morphology of PEDOT that probably improves methanol diffusion within the reaction layer. The degradation of the conducting polymer is confirmed by SEM, EDX, and FTIR measurements. (Abstract Copyright [2006], Wiley Periodicals, Inc.)

  7. Transition Metal Phosphide Nanoparticles Supported on SBA-15 as Highly Selective Hydrodeoxygenation Catalysts for the Production of Advanced Biofuels.

    Science.gov (United States)

    Yang, Yongxing; Ochoa-Hernández, Cristina; de la Peña O'Shea, Víctor A; Pizarro, Patricia; Coronado, Juan M; Serrano, David P

    2015-09-01

    A series of catalysts constituted by nanoparticles of transition metal (M = Fe, Co, Ni and Mo) phosphides (TMP) dispersed on SBA-15 were synthesized by reduction of the corresponding metal phosphate precursors previously impregnated on the mesostructured support. All the samples contained a metal-loading of 20 wt% and with an initial M/P mole ratio of 1, and they were characterized by X-ray diffraction (XRD), N2 sorption, H2-TPR and transmission electron microscopy (TEM). Metal phosphide nanocatalysts were tested in a high pressure continuous flow reactor for the hydrodeoxygenation (HDO) of a methyl ester blend containing methyl oleate (C17H33-COO-CH3) as main component (70%). This mixture constitutes a convenient surrogate of triglycerides present in vegetable oils, and following catalytic hydrotreating yields mainly n-alkanes. The results of the catalytic assays indicate that Ni2P/SBA-15 catalyst presents the highest ester conversion, whereas the transformation rate is about 20% lower for MoP/SBA-15. In contrast, catalysts based on Fe and Co phosphides show a rather limited activity. Hydrocarbon distribution in the liquid product suggests that both hydrodeoxygenation and decarboxylation/decarbonylation reactions occur simultaneously over the different catalysts, although MoP/SBA-15 possess a selectivity towards hydrodeoxygenation exceeding 90%. Accordingly, the catalyst based on MoP affords the highest yield of n-octadecane, which is the preferred product in terms of carbon atom economy. Subsequently, in order to conjugate the advantages of both Ni and Mo phosphides, a series of catalysts containing variable proportions of both metals were prepared. The obtained results reveal that the mixed phosphides catalysts present a catalytic behavior intermediate between those of the monometallic phosphides. Accordingly, only marginal enhancement of the yield of n-octadecane is obtained for the catalysts with a Mo/Ni ratio of 3. Nevertheless, owing to this high selectivity

  8. Oxidative Dehydrogenation of n-Butane over LaV Catalysts Supported on TiO2

    Directory of Open Access Journals (Sweden)

    Le Minh Cam

    2013-01-01

    Full Text Available The catalytic performance of vanadia catalysts with 15 wt% V supported on TiO2 and (15 wt% V + 4.6 wt% La supported on TiO2 in oxidative dehydrogenation (ODH of n-butane was investigated. The catalysts were characterized by means of TPD-NH3, TPR-H2, UV-Vis, and BET. Testing of samples showed that vanadia catalysts were active for the reaction. It was found that La doping of V/TiO2 catalyst had a negative effect on the dispersion of V species and led to formation of V2O5 clusters. This resulted in a loss of activity. Although slight improvement of selectivity was observed in comparison to undoped V/TiO2 samples due to lower acidity of La-doped –V/TiO2, this could not compensate the loss of activity and finally did not lead to higher butene yields.

  9. Thermal stability and hcp-fcc allotropic transformation in supported Co metal catalysts probed near operando by ferromagnetic NMR.

    Science.gov (United States)

    Andreev, Andrey S; d'Espinose de Lacaillerie, Jean-Baptiste; Lapina, Olga B; Gerashenko, Alexander

    2015-06-14

    Despite the fact that cobalt based catalysts are used at the industrial scale for Fischer-Tropsch synthesis, it is not yet clear which cobalt metallic phase is actually at work under operando conditions and what is its state of dispersion. As it turns out, the different phases of metallic cobalt, fcc and hcp, give rise to distinct ferromagnetic nuclear magnetic resonance. Furthermore, within one Co metal particle, the occurrence of several ferromagnetic domains of limited sizes can be evidenced by the specific resonance of Co in multi-domain particles. Consequently, by ferromagnetic NMR, one can follow quantitatively the sintering and phase transitions of dispersed Co metal particles in supported catalysts under near operando conditions. The minimal size probed by ferromagnetic Co NMR is not precisely known but is considered to be in the order of 10 nm for supported Co particles at room temperature and increases to about 35 nm at 850 K. Here, in Co metal Fischer-Tropsch synthesis catalysts supported on β-SiC, the resonances of the fcc multi-domain, fcc single-domain and hcp Co were clearly distinguished. A careful rationalization of their frequency and width dependence on temperature allowed a quantitative analysis of the spectra in the temperature range of interest, thus reflecting the state of the catalysts under near operando conditions that is without the uncertainty associated with prior quenching. The allotropic transition temperature was found to start at 600-650 K, which is about 50 K below the bulk transition temperature. The phase transition was fully reversible and a significant part of the hcp phase was found to be stable up to 850 K. This anomalous behavior that was observed without quenching might prove to be crucial to understand and model active species not only in catalysts but also in battery materials. PMID:25970204

  10. Application of carbon supported NiMo carburized catalyst to fuel cell anode electrocatalyst

    Energy Technology Data Exchange (ETDEWEB)

    Izhar, S.; Otsuka, S.; Nagai, M. [Tokyo Univ. of Agriculture and Technology, Tokyo (Japan). Graduate School of Bio-applications and Systems Engineering

    2008-01-15

    The fabrication of polymer electrolyte fuel cells using platinum (Pt) base catalysts is a challenge due to the high cost of Pt and the potential for carbon monoxide poisoning. Transition metal carbides are highly regarded as a material substitute because of their high conductivity, high activity in hydrogenolysis reactions and high resistance to poisoning of the catalyst. A study was conducted in which nickel (Ni) molybdenum (Mo)/Ketjen carbon (KC) carbides were prepared with various Ni compositions and carburization temperatures. XRD, temperature programmed reduction and the cyclic voltammetric method were used to evaluate these catalysts through comparative evaluations with a Pt/C catalyst. The Ni-Mo/KC catalysts were evaluated for their electrocatalytic activity using a H{sub 2}O{sub 2} single stack cell and a 3-electrode cell in order to identify the active species. Cyclic voltammetry measurements indicated that the Ni-Mo/KC carbide catalysts have a high activity towards the anodic electrooxidation of hydrogen. The activity was attributed to the amorphous Ni-Mo carbide measured by XRD and temperature programmed reduction techniques. It was concluded that bimetallic carbides can reduce the manufacturing cost of fuel cells and are therefore a suitable material for Pt/C catalysts. 17 refs., 3 tabs., 7 figs.

  11. Synthesis of carbon-supported titanium oxynitride nanoparticles as cathode catalyst for polymer electrolyte fuel cells

    International Nuclear Information System (INIS)

    Highlights: • A sol–gel route for the synthesis of rutile TiO2 was modified to synthesize TiOxNy-C. • N atoms were doped into TiOx nanoparticles solely by the heat-treatment under N2 gas. • The N2-treatment produced sites more active toward ORR compared with NH3-treatment. • TiOx doped with a small amount of N atoms are suggested to be responsible for ORR. -- Abstract: For use as the oxygen reduction reaction (ORR) catalyst in polymer electrolyte fuel cell cathodes, carbon-supported titanium oxynitride (TiOxNy-C) nanoparticles with a size of approximately 5 nm or less were synthesized without using NH3 gas. A sol–gel route developed for the synthesis of pure rutile TiO2 nanopowders was modified to prepare the carbon-supported titanium oxide nanoparticles (TiOx-C). For the first time, N atoms were doped into TiOx solely by heating TiOx-C under an inexpensive N2 atmosphere at 873 K for 3 h, which could be due to carbothermal reduction. The TiOx-C powder was also heated under NH3 gas at various temperatures (873–1273 K) and durations (3–30 h). This step resulted in the formation of a TiN phase irrespective of the heating conditions. Both N2- and NH3-treated TiOxNy-C did not crystallize well; however, the former showed a mass activity more than three times larger than that of the latter at 0.74 V versus the standard hydrogen electrode. Thus, titanium oxide nanoparticles doped with a small amount of N atoms are suggested to be responsible for catalyzing ORR in the case of N2-treated TiOxNy-C

  12. Ethyl Acetate Abatement on Copper Catalysts Supported on Ceria Doped with Rare Earth Oxides.

    Science.gov (United States)

    Carabineiro, Sónia Alexandra Correia; Konsolakis, Michalis; Marnellos, George Emmanouil-Nontas; Asad, Muhammad Faizan; Soares, Olívia Salomé Gonçalves Pinto; Tavares, Pedro Bandeira; Pereira, Manuel Fernando Ribeiro; Órfão, José Joaquim de Melo; Figueiredo, José Luís

    2016-01-01

    Different lanthanide (Ln)-doped cerium oxides (Ce0.5Ln0.5O1.75, where Ln: Gd, La, Pr, Nd, Sm) were loaded with Cu (20 wt. %) and used as catalysts for the oxidation of ethyl acetate (EtOAc), a common volatile organic compound (VOC). For comparison, both Cu-free (Ce-Ln) and supported Cu (Cu/Ce-Ln) samples were characterized by N₂ adsorption at -196 °C, scanning/transmission electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy and temperature programmed reduction in H₂. The following activity sequence, in terms of EtOAc conversion, was found for bare supports: CeO₂ ≈ Ce0.5Pr0.5O1.75 > Ce0.5Sm0.5O1.75 > Ce0.5Gd0.5O1.75 > Ce0.5Nd0.5O1.75 > Ce0.5La0.5O1.75. Cu addition improved the catalytic performance, without affecting the activity order. The best catalytic performance was obtained for Cu/CeO₂ and Cu/Ce0.5Pr0.5O1.75 samples, both achieving complete EtOAc conversion below ca. 290 °C. A strong correlation was revealed between the catalytic performance and the redox properties of the samples, in terms of reducibility and lattice oxygen availability. Νo particular correlation between the VOC oxidation performance and textural characteristics was found. The obtained results can be explained in terms of a Mars-van Krevelen type redox mechanism involving the participation of weakly bound (easily reduced) lattice oxygen and its consequent replenishment by gas phase oxygen. PMID:27196886

  13. Single-site SBA-15 supported zirconium catalysts. Synthesis, characterization and toward cyanosilylation reaction

    International Nuclear Information System (INIS)

    Graphical abstract: Ligand-modified signal-site SBA-15 supported zirconium catalysts were synthesized by SOMC method and characterized by a variety of techniques. The zirconium surface complexes show high catalytic efficiency for cyanosilylation of benzaldehyde. - Highlights: • Some Zr active species have been anchored on the surface of SBA-15 by SOMC technique. • The structures of the Zr species have been characterized by a variety of techniques. • The anchored Zr species are single-sited surface complexes. • The Zr surface complexes are catalytic active for cyanosilylation of benzaldehyde. - Abstract: A successive anchoring of Zr(NMe2)4, cyclopentadiene and a O-donor ligand, 1-hydroxyethylbenzene (PEA), 1,1′-bi-2-naphthol (Binol) or 2,3-dihydroxybutanedioic acid diethyl ester (Tartrate), on dehydroxylated SBA-15 pretreated at 500 °C for 16 h (SBA-15-500) was conducted by SOMC strategy in moderate conditions. The dehydoxylation of SBA-15 was monitored by in situ Fourier transform infrared spectroscopy (in situ FT-IR). The ligand-modified SBA-15-500 supported zirconium complexes were characterized by in situ FT-IR, 13C CP MAS-NMR, X-ray photoelectron spectroscopy (XPS), inductively coupled plasma mass spectrometry (ICP-MAS) and elemental analysis in detail, verifying that the surface zirconium species are single-sited. The catalytic activity of these complexes was evaluated by cyanosilylation of benzaldehyde. The results showed that the catalytic activity is dependent strongly on the structure of surface species and the configuration of the ligands

  14. A Facile Preparation of Palladium Catalysts Supported on Hollow Polypyrrole Nanospheres for Ethanol Oxidation

    International Nuclear Information System (INIS)

    Graphical abstract: Ppy hollow nanospheres with uniform size have been successfully prepared and employed as the supports for Pd nanoparticles with smaller particle size and better dispersion. Electrochemical measurements demonstrate that the obtained Pd/H-ppy exhibits good electrocatalytic activity and stability for ethanol electrooxidation. - Highlights: • Ppy hollow nanospheres support provides new ways to develop catalyst materials as a result of its distorted structure and large surface area. • Ppy hollow nanospheres with uniform size have been successfully prepared through chemical oxidative polymerization of pyrrole in the presence of PS microspheres. • Pa nanoparticles have been successfully assembled on the surface of hollow ppy nanospheres. • Pd/H-ppy exhibits good electrocatalytic activity and stability for ethanol electrooxidation. - Abstract: A facile and low-cost preparation of Pd nanoparticles on the surface of hollow polypyrrole (ppy) nanospheres was introduced in this paper through solvothermal reaction. Herein, uniform polystyrene (PS) microspheres as sacrificial templates were rapidly prepared through a emulsion polymerization method, and then the hollow ppy nanospheres were obtained through chemical oxidative polymerization of pyrrole in the presence of PS microspheres. According to X-ray diffraction (XRD) and transmission electron microscopy (TEM) measurements, the novel Pd nanoparticles are well-dispersed on the surface of hollow ppy nanospheres with a relatively narrow particle size distribution. The diameters of hollow ppy nanospheres range from 240 to 280 nm, and the average shell thickness is about 15 nm. Electrochemical analysis results indicate that the as-prepared Pd nanoparticles on the surface of hollow ppy nanospheres (Pd/H-ppy) exhibit good electrocatalytic activity and stability for ethanol electrooxidation

  15. Single-site SBA-15 supported zirconium catalysts. Synthesis, characterization and toward cyanosilylation reaction

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Wei; Yu, Bo; Zhang, Ying; Chen, Xi; Zhang, Guofang, E-mail: gfzhang@snnu.edu.cn; Gao, Ziwei, E-mail: zwgao@snnu.edu.cn

    2015-01-15

    Graphical abstract: Ligand-modified signal-site SBA-15 supported zirconium catalysts were synthesized by SOMC method and characterized by a variety of techniques. The zirconium surface complexes show high catalytic efficiency for cyanosilylation of benzaldehyde. - Highlights: • Some Zr active species have been anchored on the surface of SBA-15 by SOMC technique. • The structures of the Zr species have been characterized by a variety of techniques. • The anchored Zr species are single-sited surface complexes. • The Zr surface complexes are catalytic active for cyanosilylation of benzaldehyde. - Abstract: A successive anchoring of Zr(NMe{sub 2}){sub 4}, cyclopentadiene and a O-donor ligand, 1-hydroxyethylbenzene (PEA), 1,1′-bi-2-naphthol (Binol) or 2,3-dihydroxybutanedioic acid diethyl ester (Tartrate), on dehydroxylated SBA-15 pretreated at 500 °C for 16 h (SBA-15{sub -500}) was conducted by SOMC strategy in moderate conditions. The dehydoxylation of SBA-15 was monitored by in situ Fourier transform infrared spectroscopy (in situ FT-IR). The ligand-modified SBA-15{sub -500} supported zirconium complexes were characterized by in situ FT-IR, {sup 13}C CP MAS-NMR, X-ray photoelectron spectroscopy (XPS), inductively coupled plasma mass spectrometry (ICP-MAS) and elemental analysis in detail, verifying that the surface zirconium species are single-sited. The catalytic activity of these complexes was evaluated by cyanosilylation of benzaldehyde. The results showed that the catalytic activity is dependent strongly on the structure of surface species and the configuration of the ligands.

  16. Performance of practical-sized membrane-electrode assemblies using titanium nitride-supported platinum catalysts mixed with acetylene black as the cathode catalyst layer

    Science.gov (United States)

    Shintani, Haruhiko; Kakinuma, Katsuyoshi; Uchida, Hiroyuki; Watanabe, Masahiro; Uchida, Makoto

    2015-04-01

    The performance of practical-sized membrane-electrode assemblies (MEAs) using titanium nitride-supported platinum (Pt/TiN) as the cathode catalysts was evaluated with the use of a practical single cell designed for microscale combined heat and power (CHP) applications. The performance can be controlled by adding acetylene black (AB), with the behavior being dominated by the percolation law. The electrical resistance of the MEAs drastically decreased for AB contents greater than 37 vol%. The Pt utilization percentage was close to 100% for Pt/TiN with percolated AB networks. It was also found that the percolated AB networks supplied effective gas transport pathways, which were not flooded by generated water, thus enhancing the oxygen mass transport. The practical-sized MEA using Pt/TiN + 47 vol% AB showed 1.5 times greater mass activity and a comparable performance under a practical operating condition for micro-CHP applications, compared with the MEA using a commercial graphitized carbon black-supported platinum catalyst.

  17. Kinetics and deactivation of the NO reduction by CO on Pt-supported catalysts

    OpenAIRE

    Frank, Brigitta; Renken, Albert

    1999-01-01

    Reaction kinetics and catalyst deactivation during the redn. of NO with CO on a 0.5%Pt-3.4%MoO3/a-Al2O3 catalyst were investigated. The reaction shows an ignition/quenching behavior. After ignition, the reaction kinetics (formation of N2 and N2O) obey the bimol. Langmuir-Hinshelwood equations, in accordance with a dissociative mechanism. A slow catalyst deactivation is obsd. under reductive conditions (pCO >> pNO). The proposed mechanism comprises the formation of electron-withdrawing isocyan...

  18. Transition metals supported on al-pilcs as catalysts for C6H5Cl oxidation

    Directory of Open Access Journals (Sweden)

    L.C.A. Oliveira

    2003-03-01

    Full Text Available In the present work, clays pillared with aluminium and impregnated with transition metals (Fe, Co and Cr were prepared, characterised and studied as catalysts in the oxidation of chlorobenzene. The pillared clay was synthesised using a natural montmorillonite from San Juan (Argentina as the starting material and an aluminium polycation solution. The catalysts were prepared by impregnating the pillared clay and then calcinating at 500ºC. The catalysts were characterised by XRD, temperature-programmed reduction (TPR and nitrogen adsorption isotherms. The samples were tested in the deep oxidation of chlorobenzene in some cases reaching more than 90% of total conversion.

  19. Silica Supported Methanesulfonic Acid as an Efficient and Reusable Heterogeneous Catalyst for the Synthesis of Amidoalkyl Naphthols%Silica Supported Methanesulfonic Acid as an Efficient and Reusable Heterogeneous Catalyst for the Synthesis of Amidoalkyl Naphthols

    Institute of Scientific and Technical Information of China (English)

    王敏; 梁艳; 张婷婷; 高晶晶

    2011-01-01

    A green protocol for the preparation of amidoalkyl naphthols from three-component one-pot condensation of 2-naphthol, aldehydes, amides or urea in the presence of silica supported methanesulfonic acid under thermal sol- vent-free conditions has been described. The catalyst is stable, efficient, easily prepared, and reusable. The remarkable features of this methodology are short reaction time, excellent yields, simple experimental and work-up procedures.

  20. Ethanol electrooxidation on novel carbon supported Pt/SnOx/C catalysts with varied Pt:Sn ratio

    International Nuclear Information System (INIS)

    Novel carbon supported Pt/SnOx/C catalysts with Pt:Sn atomic ratios of 5:5, 6:4, 7:3 and 8:2 were prepared by a modified polyol method and characterized with respect to their structural properties (X-ray diffraction (XRD) and transmission electron microscopy (TEM)), chemical composition (XPS), their electrochemical properties (base voltammetry, COad stripping) and their electrocatalytic activity and selectivity for ethanol oxidation (ethanol oxidation reaction (EOR)). The data show that the Pt/SnOx/C catalysts are composed of Pt and tin oxide nanoparticles with an average Pt particle diameter of about 2 nm. The steady-state activity of the Pt/SnOx/C catalysts towards the EOR decreases with tin content at room temperature, but increases at 80 deg. C. On all Pt/SnOx/C catalysts, acetic acid and acetaldehyde represent dominant products, CO2 formation contributes 1-3% for both potentiostatic and potentiodynamic reaction conditions. With increasing potential, the acetaldehyde yield decreases and the acetic acid yield increases. The apparent activation energies of the EOR increase with tin content (19-29 kJ mol-1), but are lower than on Pt/C (32 kJ mol-1). The somewhat better performance of the Pt/SnOx/C catalysts compared to alloyed PtSnx/C catalysts is attributed to the presence of both sufficiently large Pt ensembles for ethanol dehydrogenation and C-C bond splitting and of tin oxide for OH generation. Fuel cell measurements performed for comparison largely confirm the results obtained in model studies