Catalyst

Distribution by Scientific Domains
Distribution within Chemistry

Kinds of Catalyst

  • Grubb catalyst
  • Lewi acid catalyst
  • Lewi base catalyst
  • acid catalyst
  • acidic catalyst
  • active catalyst
  • additional catalyst
  • al2o3 catalyst
  • amine catalyst
  • anode catalyst
  • asymmetric catalyst
  • base catalyst
  • basic catalyst
  • benign catalyst
  • best catalyst
  • bifunctional catalyst
  • bimetallic catalyst
  • biological catalyst
  • c catalyst
  • carbene catalyst
  • carbon catalyst
  • cathode catalyst
  • chiral catalyst
  • chiral phase-transfer catalyst
  • cobalt catalyst
  • commercial catalyst
  • complex catalyst
  • conventional catalyst
  • copper catalyst
  • cr catalyst
  • crabtree catalyst
  • cu catalyst
  • dendritic catalyst
  • different catalyst
  • diimine catalyst
  • effective catalyst
  • efficient catalyst
  • efficient heterogeneous catalyst
  • enantioselective catalyst
  • epoxidation catalyst
  • excellent catalyst
  • fe catalyst
  • fi catalyst
  • generation Grubb catalyst
  • generation catalyst
  • geometry catalyst
  • gold catalyst
  • good catalyst
  • green catalyst
  • heterogeneous catalyst
  • heterogeneous gold catalyst
  • heterogeneous palladium catalyst
  • highly active catalyst
  • highly efficient catalyst
  • highly enantioselective catalyst
  • homogeneous catalyst
  • hoveyda catalyst
  • hybrid catalyst
  • hydrogenation catalyst
  • imidazolidinone catalyst
  • immobilized catalyst
  • iridium catalyst
  • iron catalyst
  • key catalyst
  • metal catalyst
  • metallocene catalyst
  • metathesis catalyst
  • model catalyst
  • molybdenum catalyst
  • nanoparticle catalyst
  • natta catalyst
  • new catalyst
  • ni catalyst
  • nickel catalyst
  • noble metal catalyst
  • novel catalyst
  • nucleophilic catalyst
  • olefin metathesis catalyst
  • organic catalyst
  • other catalyst
  • oxidation catalyst
  • oxide catalyst
  • palladium catalyst
  • pd catalyst
  • phase transfer catalyst
  • phase-transfer catalyst
  • pincer catalyst
  • platinum catalyst
  • polymerization catalyst
  • porphyrin catalyst
  • powerful catalyst
  • recoverable catalyst
  • recoverable phase-transfer catalyst
  • recyclable catalyst
  • reusable catalyst
  • rh catalyst
  • rhodium catalyst
  • ru catalyst
  • ruthenium catalyst
  • second-generation catalyst
  • selective catalyst
  • silver catalyst
  • single-site catalyst
  • solid acid catalyst
  • solid base catalyst
  • solid catalyst
  • stable catalyst
  • stereoselective catalyst
  • suitable catalyst
  • supported catalyst
  • supramolecular catalyst
  • thiourea catalyst
  • titanium catalyst
  • transfer catalyst
  • transfer hydrogenation catalyst
  • transition metal catalyst
  • transition-metal catalyst
  • used catalyst
  • vanadium catalyst
  • versatile catalyst
  • very active catalyst
  • very effective catalyst
  • very efficient catalyst
  • whole-cell catalyst
  • wilkinson catalyst
  • zeolite catalyst
  • ziegler-natta catalyst
  • zinc catalyst
  • zirconium catalyst
  • zirconocene catalyst
  • zn catalyst
  • zsm-5 catalyst

  • Terms modified by Catalyst

  • catalyst Support
  • catalyst activity
  • catalyst amount
  • catalyst complex
  • catalyst concentration
  • catalyst containing
  • catalyst deactivation
  • catalyst design
  • catalyst efficiency
  • catalyst layer
  • catalyst lead
  • catalyst loading
  • catalyst material
  • catalyst particle
  • catalyst performance
  • catalyst precursor
  • catalyst preparation
  • catalyst productivity
  • catalyst property
  • catalyst ratio
  • catalyst recycling
  • catalyst separation
  • catalyst structure
  • catalyst support
  • catalyst surface
  • catalyst synthesis
  • catalyst system
  • catalyst system consisting
  • catalyst system.
  • catalyst used

  • Selected Abstracts


    BEYOND THE ECONOMIC CATALYST DEBATE: CAN PUBLIC CONSUMPTION BENEFITS JUSTIFY A MUNICIPAL STADIUM INVESTMENT?

    JOURNAL OF URBAN AFFAIRS, Issue 5 2007
    CHARLES A. SANTO
    ABSTRACT:,A host of empirical studies have indicated that stadiums and arenas have no significant impact on metropolitan area income or employment. In light of this evidence, the continued proliferation of public investment in sports facilities begs the question: Is there some other justification for this spending, or are policymakers simply acting against the public interest (either irrationally, or in response to political-economic influences)? A possibility that has not been fully explored is the notion that stadiums and teams generate tangible and intangible consumption benefits that could support some level of public investment. This research builds on a small foundation of literature that is moving discussion beyond the economic catalyst debate by providing an empirical measure of the consumption benefits that accrue to a region as the result of hosting a major league sports team. A contingent valuation survey is used to quantify the consumption benefits that would be associated with the relocation of a major league baseball team to Portland, Oregon. An empirical measure of the region's aggregate willingness to pay for the benefits associated with hosting a team is disaggregated into option and existence values, which can then be compared to any proposed level of public contribution to a new stadium. The findings indicate that consumption benefits would only support a capital investment of approximately $74 million; a figure far smaller than the typical stadium subsidy. The majority of projected benefits are associated with expected public goods and externalities, rather than anticipated attendance, indicating that an equitable financing plan should employ nonuser revenue sources. The level of projected benefits does not vary by locality within the metropolitan area, which argues for a regional cost-sharing approach. The willingness of residents to pay for stadium construction is tempered by a concern about other pressing social needs in the Portland area and a reaction to the current tax climate. [source]


    TRUST IN HEALTH PROVIDERS AS A CATALYST FOR MALARIA PREVENTION: HETEROGENEOUS IMPACTS OF HEALTH EDUCATION IN RURAL GHANA

    THE DEVELOPING ECONOMIES, Issue 3 2010
    Thomas De HOOP
    O12; I18; I39 Although knowledge about effectiveness of insecticide-treated bed nets (ITNs) is fairly widespread in Ghana, their use remains far from universal. We test and validate the hypothesis that health education of hospitals and health centers in rural Ghana is more effective for groups that display relatively high trust to health providers. We estimate heterogeneous impacts of health education on ITN and/or bed net use and on fever as a crude proxy for malaria in the Brong Ahafo and Upper East regions in Ghana, with help of propensity-adjusted regression. The degree of trust in health providers appears to be a key factor in determining the effectiveness of health education in both regions. The effect is not ruled out by controlling for general trust. There are indications of nonlinear effects. The Kassena-Nankana seems to be an exception to this rule,despite low trust in health providers, health education is highly effective for this ethnic group. [source]


    EARLY ISLAMIC CHARITIES AS CATALYSTS OF INSTITUTIONAL INNOVATION

    ECONOMIC AFFAIRS, Issue 3 2010
    Benedikt Koehler
    Islamic societies may appear unsuitable catalysts for fostering individual enterprise and institutional innovation. This view is challenged by examination of the evolution of charities in early Islam, the so-called waqf. Mohammed's prescription of providing alms engendered an extensive and varied range of charitable institutions. One example is the creation of Islam's earliest centres of higher learning, madrasahs. Key concepts of Common Law, such as trusts, may have copied Islamic legal concepts; the constitutions of the earliest colleges of Oxford and Cambridge universities replicated the design of charitable madrasahs. [source]


    Interdisciplinary Heterogeneity as a Catalyst for Product Innovativeness of Entrepreneurial Teams

    CREATIVITY AND INNOVATION MANAGEMENT, Issue 2 2007
    Daniel Henneke
    Although more and more ventures are successfully founded by entrepreneurial teams, the specific benefits of the team-based founding approach have received little attention in extant empirical studies. This study explores the relationship between the level of interdisciplinary heterogeneity in entrepreneurial teams and the level of product innovativeness in high-tech ventures. It is proposed that an interdisciplinary new venture team composition impacts the quality of the strategic planning process (scanning activities, planning openness) and thereby indirectly shapes product innovativeness. The hypotheses are investigated using data from a sample of Canadian high-tech ventures. The findings provide support for the proposed relationship between team heterogeneity, strategic planning and product innovativeness. Venture capitalists, university faculty and incubator institutions are therefore well advised to direct their attention towards fostering a heterogeneous composition of founding teams. [source]


    Prussian Blue-Modified Titanate Nanotubes: A Novel Nanostructured Catalyst for Electrochemical Reduction of Hydrogen Peroxide

    ELECTROANALYSIS, Issue 19 2010
    Damir Ivekovi
    Abstract Prussian blue (PB) modified titanate nanotubes (PB-TiNT) have been synthesized by the reaction of Fe2+ -modified TiNT with hexacyanoferrate(III) ions. The rate constant for heterogeneous catalytic reaction between PB-TiNT and H2O2 was found to be k=2×104,dm3,mol,1,s,1, which is an order of magnitude higher than the values of k reported for conventionally prepared, electrochemically deposited PB films. On the PB-TiNT modified electrode with subnanomolar surface concentration of PB (,(PB)=2.8×10,11,mol/cm2), a stable, reproducible and linear response towards H2O2 was obtained in the concentration range 0.02,4,mM, with the sensitivity of 0.10,AM,1,cm,2 at ,150,mV. [source]


    Synthesis of Ionic Liquid Functionalized SBA-15 Mesoporous Materials as Heterogeneous Catalyst toward Knoevenagel Condensation under Solvent-Free Conditions

    EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 15 2006
    Yong Liu
    Abstract 1-Methyl-3-propylimidazolium chloride (MPImCl) and 1-propylpyridinium chloride (PPyCl) ionic liquid functionalized SBA-15 mesoporous materials were synthesized and used as heterogeneous catalysts in Knoevenagel reactions with excellent yields and reusability. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source]


    Incorporation of a (Cyclopentadienyl)molybdenum Oxo Complex in MCM-41 and Its Use as a Catalyst for Olefin Epoxidation

    EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 24 2004
    Marta Abrantes
    Abstract The tricarbonyl complex [(,5 -C5H4 -COOMe)Mo(CO)3Cl] was prepared from the reaction of sodium (methoxycarbonyl)cyclopentadienide, (C5H4 -CO2Me)Na, with (Bu4N)[Mo(CO)5I]. Heating the ester with 3-(triethoxysilyl)propylamine gave the amide derivative {[,5 -C5H4 -CONH-C3H6Si(OEt)3]Mo(CO)3Cl}. The functionalised tricarbonyl complex was immobilised in the ordered mesoporous silica MCM-41 with a loading of 13 wt.-% Mo (1.4 mmol·g,1) by carrying out a grafting reaction in dichloromethane. Powder X-ray diffraction and nitrogen adsorption,desorption analysis indicated that the structural integrity of the support was preserved during the grafting and that the channels remained accessible, despite significant reductions in surface area, pore volume and pore size. The success of the coupling reaction was confirmed by 29Si and 13C (CP) MAS NMR spectroscopy. A supported dioxo complex of the type [(,5 -C5H4R)MoO2Cl] was subsequently prepared by oxidative decarbonylation of the tethered tricarbonyl complex using tert -butyl hydroperoxide (TBHP). The oxidised material is an active catalyst for the liquid phase epoxidation of cyclooctene with TBHP as the oxygen source. Similar catalytic results were obtained using the tethered tricarbonyl complex directly as a pre-catalyst since fast oxidative decarbonylation occurs under the reaction conditions used. For both systems, the desired epoxide was the only product and the initial activities were about 13 mol·molMo,1·h,1. The solid catalysts were recycled several times. Some activity was lost between the first and second runs but thereafter tended to stabilise. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source]


    Allylic Amination of Internal Alkynes with Aromatic and Aliphatic Amines Using Polymer-Supported Triphenylphosphane,Palladium Complex as a Heterogeneous and Recyclable Catalyst

    EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 26 2010
    Yogesh S. Wagh
    Abstract A facile and novel protocol for the allylic amination of internal alkynes with amines by using a polymer-supported triphenylphosphane,palladium complex [PS,TPP,Pd] as a highly active heterogeneous reusable catalyst was developed. The catalyst exhibited remarkable activity and is reusable over five consecutive cycles. The protocol was applicable for a variety of hindered and functionalized aromatic/aliphatic amines and afforded the desired allylic products in good to excellent yield. [source]


    Lanthanum(III) Oxide as a Recyclable Catalyst for the Synthesis of Diaryl Sulfides and Diaryl Selenides

    EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 34 2009
    Sabbavarapu Narayana Murthy
    Abstract La2O3 as a new and efficient recyclable catalyst in coupling various aryl halides with aromatic/alkyl thiols and diphenyl diselenide in combination with KOH as a base and DMEDA as a ligand in DMSO at 110 °C is reported. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source]


    Efficient Diphosphane-Based Catalyst for the Palladium-Catalyzed Suzuki Cross-Coupling Reaction of 3-Pyridylboronic Acids

    EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 13 2009
    Xing-Li Fu
    Abstract A highly active catalyst system derived from PdCl2 and2,2,,6,6,-tetramethoxy-4,4,-bis(diphenylphosphanyl)-3,3,-bipyridine (P-Phos) has been developed for the Suzuki cross-coupling reaction of pyridylboronic acid with a variety of aryl halides in good to excellent yields, even in the presence of hindered and functional groups. In addition, P-Phos also exhibited high activity in the palladium-catalyzed Suzuki reaction of 2,6-dimethoxypyridylboronic acid in excellent yields with a fast rate. The steric and electronic effects of the P-Phos,palladium complex to this cross-coupling reaction were also discussed.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source]


    A Magnetically Separable Heterogeneous Deallylation Catalyst: [CpRu(,3 -C3H5)(2-pyridinecarboxylato)]PF6 Complex Supported on a Ferromagnetic Microsize Particle Fe3O4@SiO2

    EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 6 2009
    Takuya Hirakawa
    Abstract The highly reactive and chemoselective homogeneousdeallylation catalyst CpRu(,3 -C3H5)(4-substituted-2-pyridinecarboxylato) was immobilized on microsize spherical Fe3O4@SiO2 particles. The resultant heterogeneous catalyst displays high saturation magnetization, weak coercive forces and high levels of dispersibility. The catalyst has increased the utility of deallylation by allowing the reaction to be conducted without extra additives. The only co-product of the reaction is a volatile allyl ether compound. Here, we demonstrate the efficient deallylation and separation of highly polar multifunctional compounds as well as multiple rounds of catalyst recycling without significant loss of reactivity. The usefulness of this catalyst has been confirmed by the synthesis of a triribonucleotide 3,5 U. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source]


    The Use of a Bifunctional Copper Catalyst in the Cross-Coupling Reactions of Aryl and Heteroaryl Halides with Terminal Alkynes

    EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 23 2008
    Minyan Wu
    Abstract Copper-catalyzed cross-coupling reactions of aryl halides and heteroaryl halides with terminal alkynes were carried out in DMF at 110,130 °C to provide the corresponding coupling products in satisfactory-to-good yields by using inexpensive 8-hydoxyquinoline as the ligand. Noteworthy is that the bifunctional copper catalyst was successfully applied in this alkynylation reaction for the first time.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source]


    Silica-Immobilized NHC,CuI Complex: An Efficient and Reusable Catalyst for A3 -Coupling (Aldehyde,Alkyne,Amine) under Solventless Reaction Conditions

    EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 13 2008
    Min Wang
    Abstract A novel silica-immobilized NHC,CuI complex was developed and used as a highly efficient catalyst in the three-component coupling reactions of aldehydes, alkynes and amines (A3 -coupling). The reactions were applicable to aromatic and aliphatic aldehydes, alkynes and amines, and generated the corresponding propargylamines in good yields only in the presence of SiO2,NHC,CuI (2 mol-%) at room temp. under solvent-free reaction conditions. Moreover, the catalyst was quantitatively recovered from the reaction mixture by a simple filtration and reused for ten cycles with almost consistent activity.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source]


    Effect of Varying the Anionic Component of a Copper(I) Catalyst on Homologation of Arylacetylenes to Allenes by the Mannich Reaction

    EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 1 2008
    Vipan Kumar
    Abstract The effect of varying the anionic component of a copper(I) catalyst in the homologation of terminal arylacetylenes to allenes by the Mannich reaction was investigated. Varying amounts of allenes, Mannich bases and dimers were obtained depending on the nature of the anionic component of the copper catalyst. On the other hand, Eglinton,Glaser dimerizations were achieved in high yields with 0.5 equiv. of triethylamine. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source]


    Hydrophobically Directed Aldol Reactions: Polystyrene-Supported L -Proline as a Recyclable Catalyst for Direct Asymmetric Aldol Reactions in the Presence of Water,

    EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 28 2007
    Michelangelo Gruttadauria
    Abstract A simple synthetic methodology for the preparation of a polystyrene-supported L -proline material is reported, and this material has been used as catalyst in direct asymmetric aldol reactions between several ketones and arylaldehydes to furnish aldol products in high yields and stereoselectivities. Screening of solvents showed that these reactions take place only in the presence of water or methanol, at lower levels of conversion in the latter case. This solvent effect, coupled with the observed high stereoselectivities, has been explained in terms of the formation of a hydrophobic core in the inner surface of the resin, whereas the hydrophilic proline moiety lies at the resin/water interface. Such a microenvironment both promotes the aldol reaction and increases the stereoselectivity. Recycling investigations have shown that this material can be reused, without loss in levels of conversion and stereoselectivity, for at least five cycles. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source]


    Polystyrene-Supported 1,5,7-Triazabicyclo[4.4.0]dec-5-ene as an Efficient and Reusable Catalyst for the Thiolysis of 1,2-Epoxides under Solvent-Free Conditions

    EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 5 2006
    Francesco Fringuelli
    Abstract Polystyrene-supported 1,5,7-triazabicyclo[4.4.0]dec-5-ene (PS-TBD) is an effective basic catalyst for the thiolysis of the 1,2-epoxides 1a,e by the aryl- and alkyl-substituted thiols 2A,E under solvent-free conditions while its activity is remarkably reduced in MeCN. The reactions are totally anti -diastereoselective and generally highly C-, regioselective. The corresponding hydroxy sulfides have been isolated in excellent yields and the catalyst has been easily recovered and reused with no loss in terms of efficiency and selectivity of the process. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source]


    A C2 -Chiral Bis(amidinium) Catalyst for a Diels,Alder Reaction Constituting the Key Step of the Quinkert,Dane Estrone Synthesis

    EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 9 2003
    Svetlana B. Tsogoeva
    Abstract A novel C2 -chiral bis(amidinium) salt 12 has been synthesised from 5-(tert -butyl)isophthalic acid. The hydrogen-bond-mediated association of dienophiles 3a and 3b with the chiral host molecule 12 accelerates the Diels,Alder reactions with diene 2 by more than three orders of magnitude. In addition, enantioselective formation of the desired adducts is observed under catalysis with 12. Good ratios of 4a(b) + ent - 4a(b)/5a(b) + ent - 5a(b) from 1:10 to 1:22 were found in all reactions. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source]


    Synthesis of Polysubstituted Alkenes by Heck Vinylation or Suzuki Cross-Coupling Reactions in the Presence of a Tetraphosphane,Palladium Catalyst

    EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 6 2003
    Florian Berthiol
    Abstract Through the use of [PdCl(C3H5)]2/cis,cis,cis -1,2,3,4-tetrakis[(diphenylphosphanyl)methyl]cyclopentane as a catalyst, a range of vinyl bromides undergo Suzuki cross-couplings with arylboronic acids in good yields. Furthermore, the catalyst can be used at low loadings, even for reactions of sterically hindered substrates. Mediated by this catalyst, stilbene and 1,1-diphenylethylene undergo Heck reactions with aryl halides to give triarylethylene derivatives. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source]


    Evaluation of RuxWySez Catalyst as a Cathode Electrode in a Polymer Electrolyte Membrane Fuel Cell

    FUEL CELLS, Issue 1 2010
    K. Suárez-Alcántara
    Abstract The oxygen reduction reaction (ORR) on RuxWySez is of great importance in the development of a novel cathode electrode in a polymer electrolyte membrane fuel cell (PEMFC) technology. The RuxWySez electrocatalyst was synthesised in an organic solvent for 3,h. The powder was characterised by transmission electron microscopy (TEM), and powder X-ray diffraction (XRD). The electrocatalyst consisted of agglomerates of nanometric size (,50,150,nm) particles. In the electrochemical studies, rotating disc electrode (RDE) and rotating ring-disc electrode (RRDE) techniques were used to determine the oxygen reduction kinetics in 0.5,M H2SO4. The kinetic studies include the determination of Tafel slope (112,mV,dec,1), exchange current density at 25,°C (1.48,×,10,4,mA,cm,2) and the apparent activation energy of the oxygen reaction (52.1,,,0.4,kJ,mol,1). Analysis of the data shows a multi-electron charge transfer process to water formation, with 2% H2O2 production. A single PEMFC with the RuxWySez cathode catalysts generated a power density of 180,mW,cm,2. Performance achieved with a loading of 1.4,mg,cm,2 of a 40,wt% RuxWySez and 60,wt% carbon Vulcan (i.e. 0.56,mg,cm,2 of pure RuxWySez). Single PEMFC working was obtained with hydrogen and oxygen at 80,°C with 30,psi. [source]


    Combinatorial Search for Quaternary Methanol Tolerant Oxygen Electro-Reduction Catalyst

    FUEL CELLS, Issue 1 2010
    M. K. Jeon
    Abstract A combinatorial library containing 645 different compositions was synthesised and characterised for methanol tolerant oxygen electro-reduction reaction (ORR) catalytic performance. The library was composed of compositions involving between 1 and 4 metals among Pt, Ru, Fe, Mo and Se. In an optical screening test, Pt(50)Ru(10)Fe(20)Se(10) composition exhibited the highest ORR activity in the presence of methanol. This composition was further investigated by synthesis and characterisation of a powder version catalyst [Pt(50)Ru(10)Fe(20)Se(10)/C]. At 0.85,V [vs. reversible hydrogen electrode (RHE)] in the absence of methanol, the Pt/C catalyst exhibited higher ORR current (0.0990,mA) than the Pt(50)Ru(10)Fe(20)Se(10)/C catalyst (0.0902,mA). But much higher specific activity (12.7 ,A cmpt,2) was observed in the Pt(50)Ru(10)Fe(20)Se(10)/C catalyst than for the Pt/C catalyst 6.51 ,A cmpt,2). In the presence of methanol, the ORR current decreased by 0.0343 and 0.247,mA for the Pt(50)Ru(10)Fe(20)Se(10)/C and Pt/C catalysts, respectively, which proved the excellent methanol tolerance of the Pt(50)Ru(10)Fe(20)Se(10)/C catalyst. [source]


    Investigation of a Novel Catalyst Coated Membrane Method to Prepare Low-Platinum-Loading Membrane Electrode Assemblies for PEMFCs

    FUEL CELLS, Issue 2 2009
    X. Leimin
    Abstract In this work, a novel catalyst coated membrane (CCM) approach,a catalyst-sprayed membrane under irradiation (CSMUI),was developed to prepare MEAs for proton exchange membrane fuel cell (PEMFC) application. Catalyst ink was sprayed directly onto the membrane and an infrared light was used simultaneously to evaporate the solvents. The resultant MEAs prepared by this method yielded very high performance. Based on this approach, the preparation of low-platinum-content MEAs was investigated. It was found that for the anode, even if the platinum loading was decreased from 0.2 to 0.03,mg,cm,2, only a very small performance decrease was observed; for the cathode, when the platinum loading was decreased from 0.3 to 0.15,mg,cm,2, just a 5% decrease was detected at 0.7,V, but a 35% decrease was observed when the loading was decreased from 0.15 to 0.06,mg,cm,2. These results indicate that this approach is much better than the catalyst coated gas diffusion layer (GDL) method, especially for the preparation of low-platinum-content MEAs. SEM and EIS measurements indicated ample interfacial contact between the catalyst layer and the membrane. [source]


    Cu(II)-Azabis(oxazoline)-Complexes Immobilized on Superparamagnetic Magnetite@Silica-Nanoparticles: A Highly Selective and Recyclable Catalyst for the Kinetic Resolution of 1,2-Diols

    ADVANCED FUNCTIONAL MATERIALS, Issue 13 2009
    Alexander Schätz
    Abstract Two different types of azide functionalized magnetite@silica nanoparticles are synthesized, which are ideally suited as inexpensive supports for catalysts and reagents as demonstrated with the grafting of copper(II)-azabis(oxazoline) complexes via a copper(I) catalyzed azide/alkyne cycloaddition (CuAAC) reaction. The potential of the immobilized complexes as catalysts is tested in the desymmetrization of racemic 1,2-diols through asymmetric benzoylation. Compared to azabis(oxazolines) "clicked" to common polymeric supports such as MeOPEG or Merrifield resin, Fe3O4@SiO2 proves to be superior with respect to activity and selectivity, as exemplified by employing the catalysts in up to five runs with consistent high activity and selectivity. Recycling of the catalysts is achieved quantitatively by magnetic decantation. [source]


    Multicomponent Approach Towards the Synthesis of Substituted Pyrroles under Supramolecular Catalysis Using , -Cyclodextrin as a Catalyst in Water Under Neutral Conditions

    HELVETICA CHIMICA ACTA, Issue 10 2009
    Narayana Murthy, Sabbavarapu
    Abstract Synthesis of substituted pyrroles in H2O by using , -cyclodextrin as a supramolecular catalyst is described. This reaction has several advantages over existing methods and provides substituted pyrroles in good-to-excellent yields (79,89%). The supramolecular catalysis of the reaction was studied using 1H-NMR spectroscopy. , -Cyclodextrin can be recovered and reused several times without loss of activity. [source]


    Bottom-Imprint Method for VSS Growth of Epitaxial Silicon Nanowire Arrays with an Aluminium Catalyst

    ADVANCED MATERIALS, Issue 46 2009
    Zhang Zhang
    A bottom-imprint method to fabricate high-quality Si [100] nanowire arrays is described (see figure). This new approach combines the functions of a highly ordered anodic aluminum oxide (AAO) template that acts as both a stamp and a template. Vertically aligned, Al-catalyzed Si nanowire (NW) arrays are grown epitaxially on the Si substrate with a narrow size distribution. [source]


    Kinetics and mechanism of esterification of epoxy resin in presence of triphenylphosphine

    INTERNATIONAL JOURNAL OF CHEMICAL KINETICS, Issue 5 2004
    Neelam Pal
    The kinetics of esterification of bisphenol-A based epoxy resin with acrylic acid in presence of triphenylphosphine has been studied. The reaction exhibits a first-order rate dependence with respect to [Epoxy] and [Catalyst]. A first-order dependence of rate with respect to [Acid] has been observed during a particular kinetic run. However, a retarding effect of [Acid] on the rate has been observed by increasing the initial concentration of acid. A suitable mechanism consistent with the kinetic data is proposed and discussed. © 2004 Wiley Periodicals, Inc. Int J Chem Kinet 36: 280,285, 2004 [source]


    Cover Picture: Dendritic Nanowire Growth Mediated by a Self-Assembled Catalyst (Adv. Mater.

    ADVANCED MATERIALS, Issue 5 2005
    5/2005)
    Abstract The dendritic nanostructures shown on the cover background were generated by self-assembled Mn clusters deposited from the vapor phase during vapor,liquid,solid growth of InAs nanowires. By carefully controlling the timing and amount of the Mn precursor, on p.,598 Lauhon and co-workers demonstrate a route to the formation of ordered hierarchical nanowire structures shown from various perspectives in the cover insets. [source]


    A Bifunctional Cinchona Alkaloid-Squaramide Catalyst for the Highly Enantioselective Conjugate Addition of Thiols to trans -Chalcones

    ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 13 2010
    Le Dai
    Abstract A chiral squaramide catalysts-promoted asymmetric sulfa-Michael conjugated addition of thiols to trans -chalcones is presented. Moderate to excellent yields and high enantioselectivities (up to 99% ee) were achieved under mild conditions. [source]


    Redox-Active Catalyst Based on Poly(Anilinesulfonic Acid)- Supported Gold Nanoparticles for Aerobic Alcohol Oxidation in Water

    ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 13 2010
    Daisuke Saio
    Abstract The hybrid consisting of gold nanoparticles and poly(2-methoxyaniline-5-sulfonic acid), which works as a redox mediator for transferring protons and electrons, catalyzed the oxidation reaction of various alcohols in water under molecular oxygen. [source]


    Polystyrene-Supported Amino Acids as Efficient Catalyst for Chemical Fixation of Carbon Dioxide

    ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 11-12 2010
    Chaorong Qi
    Abstract Four new polystyrene-supported amino acids have been synthesized and applied to the chemical fixation of carbon dioxide for the first time. Two series of experiments with polystyrene-supported threonine (PS-Thr) and polystyrene-supported tyrosine (PS-Tyr) as catalyst, respectively, were conducted to study the effect of the reaction conditions on the carboxylation of propylene oxide/carbon dioxide. There was no considerable decrease in the yield of propylene carbonate after the polystyrene-supported amino acids were used five times, indicating that these catalysts are very stable. It was demonstrated that these catalysts were very efficient in the carboxylation of various epoxides and aziridines with carbon dioxide under mild conditions without any solvents. The mechanism for this carboxylation is also discussed. [source]


    One-Pot Suzuki/Heck Sequence for the Synthesis of (E)-Stilbenes Featuring a Recyclable Silica-Supported Palladium Catalyst via a Multi-Component Reaction in 1,3-Propanediol

    ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 11-12 2010
    Lionel Joucla
    Abstract The synthesis of (E)-stilbenes was performed following a one-pot Suzuki/Heck sequence through the use of potassium vinyltrifluoroborate. The combination of heterogeneous palladium/silica (Pd/SiO2) catalyst with potassium phosphate monohydrate (K3PO4,H2O) as base resulted in useful to good isolated yields regardless of the ortho- , meta- or para- substitution of the aryl halides employed. In a sustainable approach, we found that bio-sourced 1,3-propanediol could advantageously replace N -methylpyrrolidone (NMP) as similar yields were obtained. Moreover, the reactivity gap between aryl iodides and bromides resulting from the use of 1,3-propanediol allowed an efficient multi-component approach toward the synthesis of (E)-stilbenes. Furthermore, this heterogeneous catalyst was found to be extremely robust despite the use of aerobic conditions and was successfully re-used over several cycles. [source]