Catalysis Letters
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Methane oxidation using Au/MgO catalysts
Catalysis Letters - Tập 50 - Trang 211-218 - 1998
A series of Au/MgO(0.04-15 wt%) catalysts have been investigated for the oxidation of methane. Detailed electron microscopy and Mössbauer spectroscopy studies show that two distinct Au morphologies can be observed: (a) two-dimensional Au rafts and (b) discrete three-dimensional Au particles (5-10 nm in diameter). The two-dimensional rafts are observed as the main form of Au at low loadings and, in......
On the physicochemical and catalytic properties of H5PV2Mo10O40 supported on silica
Catalysis Letters - Tập 25 - Trang 225-240 - 1994
Properties of H5PV2Mo10O40 (HPVMo) heteropolyacid supported on high area silica (375 m2 g−1) were investigated. At low loadings interaction with surface OH groups leads to hydrolysis of Keggin anions into “triads” of edge-sharing octahedra strongly bound to the surface. Characteristic acidity is lost and methanol is oxidized to formaldehyde. At high loading unperturbed Keggin anions are present at......
Silylation of Ti‐MCM‐41 by trimethylsilyl‐imidazole and its effect on the olefin epoxidation with aqueous H2O2
Catalysis Letters - Tập 66 Số 4 - Trang 245-249 - 2000
Ti‐MCM‐41 catalyst was silylated with a new silylating agent, N‐trimethylsilyl‐imidazole (TMSI). TMSI was found to be more effective to improve the hydrophobicity and the catalytic performance of Ti‐MCM‐41 than other silylating agents. Different levels of silylation were obtained by varying the silylation time. A linear relationship was observed between the degree of silylation and each of the int......
A technique for simultaneous in situ MAS NMR and on-line gas chromatographic studies of hydrocarbon conversions on solid catalysts under flow conditions
Catalysis Letters - Tập 57 - Trang 199-204 - 1999
A new technique is introduced allowing simultaneous in situ MAS NMR investigations of hydrocarbon conversions on solids under flow conditions and on-line gas chromatography. For adsorption of methanol on zeolite HBeta, equal amounts of adsorbed molecules were determined by both analytical methods. Studying the synthesis of methyl tertiary-butyl ether (MTBE) on zeolite HBeta using an MAS NMR rotor ......
CAL-B-Catalyzed Enantioselective Deacetylation of Some Benzylic Acetate Derivatives Via Alcoholysis in Non-aqueous Media
Catalysis Letters - Tập 145 - Trang 1054-1061 - 2015
Enantioselective deacetylation of a set of benzylic acetates via alcoholysis catalyzed by Lipase B from Candida antarctica (CAL-B), under mild conditions is described. A systematic study allows to determine the appropriate combination nucleophile/organic solvent and also to explain the influence of these parameters on the enzymatic catalytic reaction. In all cases, (R)-alcohols are obtained with ......
Adsorbate (substrate)-induced restructuring of active transition metal sites of heterogeneous and enzyme catalysts
Catalysis Letters - Tập 59 - Trang 89-91 - 1999
Adsorbate-induced restructuring of transition metal surfaces and those of transition metal clusters embedded in metalloproteins has been shown to be a dominant phenomenon by LEED surface crystallography and X-ray crystallography studies, respectively. The restructuring is thermodynamically driven and is more facile for low-coordination metal sites (surface defects, steps and kinks, and nanocluster......
Preparation of Rosin Pentaerythritol Ester Over an Fe3O4-Supported ZnO Catalyst
Catalysis Letters - Tập 150 - Trang 3359-3367 - 2020
Conversion of rosin to its pentaerythritol ester provides a means of improving its water resistance, alkali resistance, and oxidation resistance, thereby increasing its stability. Rosin pentaerythritol ester is much more amenable to industrial applications than the parent compound. To overcome the difficulty of catalyst recovery and its associated high cost during the synthesis of rosin pentaeryth......
LaCo1−x Pd x O3 Perovskite-Type Oxides: Synthesis, Characterization and Simultaneous Removal of NO x and Diesel Soot
Catalysis Letters - Tập 130 - Trang 613-621 - 2009
A series of naometric perovskite catalysts LaCo1−x
Pd
x
O3 (x = 0, 0.01, 0.03) were prepared via a solution combustion synthesis route using metal nitrates as oxidizers and urea as fuel. It is essential to add a certain amount of ammonia aqueous solution to Pd2+ ions solution in the catalyst preparation process. Homogeneous nanoparticles La......
Asymmetric Biginelli Reaction Catalyzed by Silicon, Titanium and Aluminum Oxides
Catalysis Letters - Tập 146 - Trang 493-498 - 2015
The asymmetric Biginelli reaction was investigated in the presence of N-[(2S,4R)-4-hydroxyprolyl]-(S)-1-phenylethylamine as chiral inducer and silicon, titanium or aluminum oxides (individual and mixed, bulk and nanosized) as heterogeneous catalysts. It has been shown that all studied oxides improve chemo- and stereoselectivity of the Biginelli reaction.
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A Comparison of Catalytic Oxidative Dehydrogenation of Ethane Over Mixed V-Mg Oxides and Over Those Prepared via a Mesoporous V-Mg-O Pathway
Catalysis Letters - Tập 88 - Trang 147-154 - 2003
The catalytic oxidative dehydrogenation of ethane was investigated in a fixed-bed tubular microreactor at 500, 550 and 600 °C and a space velocity of 35 027ml g-1h-1. Two kinds of V-Mg oxides catalysts containing various V/Mg atomic ratios were employed. One group of catalysts was prepared by the solid reaction between fine powders of vanadium pentoxide and magnesium nitrate and the other ones wer......
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