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Showing papers on "Dehydrogenation published in 1985"


Journal ArticleDOI
TL;DR: In this article, the zinc-exchanged (ZSM-5-Zn) and proton exchange (Proton exchange 5-H) forms of ZSM 5 zeolite have been studied for the conversion of propane to aromatic hydrocarbons at temperatures in the range 730-820 K.

292 citations


Journal ArticleDOI
TL;DR: In this paper, it was shown that when glucose is brought into contact with a platinum electrode, the catalytic decomposition of glucose molecules occurs in addition to the formation of strongly chemisorbed particles.

282 citations



Journal ArticleDOI
TL;DR: Comportement photochimique de polyoxometalates (W, Mo, V, Nb, Ta) en presence d'eau et de divers alcools, amides, ethers, aldehydes, acides carboxyliques, nitriles, cetones et urees as discussed by the authors.
Abstract: Comportement photochimique de polyoxometalates (W, Mo, V, Nb, Ta) en presence d'eau et de divers alcools, amides, ethers, aldehydes, acides carboxyliques, nitriles, cetones et urees

185 citations



Journal ArticleDOI
TL;DR: In this article, the authors investigated the reversibility of 14C-containing carbonaceous deposits on the platinum surface for hydrogenation and hydrogen transfer with unlabeled hydrocarbons, showing that the inactive fraction increased with increasing adsorption temperature as the surface species became more hydrogen deficient.

147 citations


Journal ArticleDOI
TL;DR: In this paper, extra-fine crystallite of brookite TiO2, prepared by air oxidation of TiCl3 in aqueous HCl solution, exhibited marked photocatalytic activity for both dehydrogenation of propan-2-ol and Ag metal deposition in silver sulfate solution.

129 citations


Journal ArticleDOI
TL;DR: In this article, a mechanism of oxidative dehydrogenation converting ethylbenzene to styrene on V2O5/MgO catalysts is suggested, and the nature and structure of the VVVIV active centres are discussed on the basis of physicochemical properties.

106 citations



Journal ArticleDOI
TL;DR: In this paper, allyl alkyl carbonates were converted into ketones by decarboxylation-dehydrogenation; the ruthenium catalyst was the most active in this reaction.

100 citations


Journal ArticleDOI
TL;DR: In this paper, a catalytic cycle is proposed for bimolecular dehydrogenation of primary alcohols to esters and also of secondary alcohol to ketones with evolution of H 2.

Journal ArticleDOI
TL;DR: In this article, the authors used the early dissociation of the CC1 bond to study the CH n species and their stepwise dehydrogenation without interference, showing that the peak maxima used for identification are generated by the respective single species and not by superimposition of two or more peaks of species drifting through the dehydration process.

Journal ArticleDOI
TL;DR: In this paper, the authors used ab initio quantum chemical calculations (generalized valence bond) to examine the reactions mechanism for H3COH + 1 2 O2→H2CO + H2O as catalyzed by MoO3.

Journal ArticleDOI
TL;DR: In this article, the authors studied the active sites for ethane dehydrogenation over chromium supported on silica gel and showed that the number but not the type of sites changed upon dehydration at elevated temperatures.

Book ChapterDOI
TL;DR: In this paper, a variation of the selective chemisorption technique is used that makes use of the reactivity of the active sites to determine the existence and the densities of different active sites.
Abstract: Publisher Summary This chapter discusses the selective oxidative dehydrogenation of butenes on ferrite catalysts. A common method for determining the existence and the densities of different active sites is selective chemisorption. A variation of the selective chemisorption technique can be used that makes use of the reactivity of the active sites. The technique is temperature programmed desorption and reaction or thermal desorption and reaction. A reactant molecule is adsorbed at low temperatures on an active site. The temperature is then raised in a controlled manner, and the evolution of the reaction products is monitored. If the various products are evolved independent of each other, they must be formed on independent sites. The separation of the two sets of desorption products may indicate that they are from different sites. As the products of the thermal desorption experiments are directly correlated with the active sites, it is possible to measure the number of active sites by measuring the quantities of desorbed products, provided that each and every active site produces only one molecule of reaction product.

Journal ArticleDOI
TL;DR: In this article, the photochemical dehydrogenation of cyclo-octane both in the presence and absence of a hydrogen-acceptor was investigated in the absence of hydrogen acceptors.
Abstract: [IrH2(CF3CO2)(Pcy3)2](cy = cyclohexyl) catalyses the photochemical dehydrogenation of cyclo-octane both in the presence and absence of a hydrogen-acceptor.

Journal ArticleDOI
TL;DR: In this paper, the photocatalytic activity of anatase TiO2 depended significantly on the amount of metal or metal oxide present; the effect on the activity increased in the order platinum black ≫ platinum powder > ruthenium dioxide.
Abstract: Photoirradiation (λex > 300 nm) of Ar-purged aqueous propan-2-ol solution gave hydrogen and acetone in the presence of platinum- and/or ruthenium dioxide-loaded TiO2. The photocatalytic activity of anatase TiO2 depended significantly on the amount of metal or metal oxide present; the effect on the activity increased in the order platinum black ≫ platinum powder > ruthenium dioxide. The photocatalytic activity of rutile TiO2 was negligible even when loaded with platinum black. The effective wavelengths for the photocatalytic dehydrogenation of propan-2-ol were below ca. 390 nm, in agreement with the u.v. absorption spectrum of anatase TiO2. In a similar way primary, secondary and tertiary aliphatic alcohols underwent photocatalytic oxidation, accompanied by hydrogen liberation, by the platinized TiO2. The primary and secondary alcohols gave the corresponding carbonyl derivatives, while 2-methylpropan-2-ol and acetone gave dimeric products accompanied by stoichiometric hydrogen evolution. The initial rate of dehydrogenation in these photocatalytic systems was in proportion to the rate constants of hydrogen abstraction by hydroxyl radical in the homogeneous systems.

Journal ArticleDOI
TL;DR: In this paper, a theoretical study has been made of acetylene and ethylene adsorption and rearrangement reactions on Pt(111) and the structures, energies, and transition states are determined for the reaction scheme and compared with results of numerous experimental studies.

Journal ArticleDOI
TL;DR: The alkylammonium and ammonium 12-heteropolyates of general formula A3XM12O40, where A is the monovalent ammonium cation, X is the central or heteropoly ion (P5+ or As5+), and M is the metal cation (Mo6+ or W6+), have been studied in this paper.

Journal ArticleDOI
TL;DR: Deuterium labeling has been used to study the processes occurring during the conversion of methanol to methyl formate over copper catalysts at 180-210 °C and pressures of 0.3 to 1 atm.

Journal ArticleDOI
TL;DR: In this paper, the performance of different catalysts for hydrogenation, hydrogenolysis, dehydrogenation, decarbonylation, CH x insertion, and CO insertion was studied by the addition of various probe molecules (C 2 H 4, CH 3 CH 2 OH, and CH 3 CHO) to the reaction stream under synthesis conditions.

Journal ArticleDOI
TL;DR: In this paper, the isomerization of 1-hexene on 60 80 -mesh ZSM-5 zeolite was studied in the temperature range 200-280 °C and the results were compared with those previously obtained for HY at 200 °C.

Journal ArticleDOI
TL;DR: In this paper, a homogeneous ruthenium complex is used as a catalysts for methanol catalytic de-hydrogenation, which can be isolated from the reaction solution as catalysts.
Abstract: Catalytic dehydrogenation of methanol occurs in solution by use of a homogeneous ruthenium complex,[Ru2(OAc)4Cl]–t-phosphine, or mononuclear ruthenium(II) complexes, which can be isolated from the reaction solution as catalysts.

Journal ArticleDOI
TL;DR: Patients with multiple acyl-CoA dehydrogenation deficiencies have been found in whom the defect has been located to ETF and/or ETFDH, which indicates a defect related to the metabolism of FAD.
Abstract: The key reaction in the β-oxidation of fatty acids is the acyl-CoA dehydrogenation, catalyzed by short chain, medium chain, and long chain acyl-CoA dehydrogenases. Acyl-CoA dehydrogenation reactions are also involved in the metabolism of the branched chain amino acids, where isovaleryl-CoA and 2-methylbutyryl-CoA dehydrogenases are involved and in the metabolism of lysine, 5-hydroxylysine and tryptophan, where glutaryl-CoA dehydrogenase functions. In all of these dehydrogenation systems reducing equivalents are transported to the main respiratory chain by electron transfer flavoprotein (ETF) and electron transfer flavoprotein dehydrogenase (ETFDH), which are common to all the dehydrogenation systems. The acyl-CoA dehydrogenation enzymes are dependent on flavin adenine dinucleotide (FAD) as coenzyme, for which riboflavin is the precursor. Patients with multiple acyl-CoA dehydrogenation deficiencies have been found in whom the defect has been located to ETF and/or ETFDH. A few patients with multiple acyl-CoA dehydrogenation deficiencies have been described, in whom no defects in acyl-CoA dehydrogenases, ETF or ETFDH have been found but who respond clinically and biochemically to pharmacological doses of riboflavin. This indicates a defect related to the metabolism of FAD. An uptake defect of riboflavin or a synthesis defect of FAD from riboflavin have been excluded byin vivo andin vitro studies. A mitochondrial transport defect of FAD or a defect in the binding FAD to ETF and/or ETFDH remains possible.

Journal ArticleDOI
TL;DR: These results provide the first direct evidence for carbanion formation via abstraction of a C-2 hydrogen by a base in the enzyme, as the first step of the catalytic pathway of acyl-CoA dehydrogenation, and indicate that the hydride ion transfer from C-3 of the substrate to the enzyme-FAD is not yet complete in the charge-transfer complex.

Journal ArticleDOI
TL;DR: In situ measurements of electrical conductivities were performed on MoO3, Bi2Mo2O9, and Bi 2MoO6 (koechlinite), the latter either as such or doped with small amounts of Mo or Bi.

Journal ArticleDOI
TL;DR: In this paper, the absorption and reaction of C 2 H 4 on clean and oxygen covered Pd(100) was studied with temperature programmed reaction spectroscopy (TPRS) and high resolution electron energy loss spectrum (EELS) and it was found that two oxygen atoms were required to block the reaction of one ethylene molecule.

Journal ArticleDOI
TL;DR: In the presence of substrats organiques comme cyclohexadiene, aldehydes, methylstyrene, sulfures sulfoxydes and phosphines, Fe(II)-H 2 O 2 -CH 3 CN conduit a des produits de deshydrogenation.
Abstract: En presence de substrats organiques comme cyclohexadiene-1,4 diphenyl-1,2hydrazine, catechols, thiols le systeme Fe(II)-H 2 O 2 -CH 3 CN conduit a des produits de deshydrogenation. Avec des substrats tels que alcools, aldehydes, methylstyrene, sulfures sulfoxydes et phosphines le compose d'addition Fe(II)(H 2 O 2 ) 2+ favorise leur monooxygenation en aldehydes, acides carboxyliques, epoxydes, sulfoxydes, sulfones et phosphine oxydes respectivement

Journal ArticleDOI
TL;DR: In this article, the decomposition of formic acid was studied on supported Rh catalysts in a flow reactor at 380-520 K and the dominant process was the dehydrogenation reaction which followed first-order kinetics.

Journal Article
TL;DR: The excretion pattern of organic acids in urine from patients with acyl-CoA dehydrogenation deficiencies - as measured by means of gas chromatography/mass spectrometry - offers in most cases a tentative diagnosis of the enzyme defect.
Abstract: Acyl-CoA dehydrogenation deficiencies are defined as disorders of the metabolism of branched chain and straight chain acyl-CoA esters and of glutaryl-CoA. The acyl-CoA dehydrogenation process is comprised of three enzymes, i.e. acyl-CoA dehydrogenase (isovaleryl-CoA, isobutyryl-CoA/2-Me-butyryl-CoA, short-chain acyl-CoA, general (medium-chain) acyl-CoA, long-chain acyl-CoA or glutaryl-CoA), electron transfer flavoprotein (ETF) and electron transfer flavoprotein dehydrogenase (ETF DH). Patients with isovaleryl-CoA dehydrogenase deficiency, glutaryl-CoA dehydrogenase deficiency and general (medium-chain) acyl-CoA dehydrogenase deficiency have been reported. Assays for the enzymatic diagnosis in cells from such patients (especially cultured skin fibroblasts) have been developed and the different methods are reviewed. Patients with apparent defects in all acyl-CoA dehydrogenation processes, designated multiple acyl-CoA dehydrogenation deficiencies, have also been found. I. e. glutaric aciduria type II, ethylmalonicadipic aciduria and riboflavin responsive multiple acyl-CoA dehydrogenation defect. The enzymatic diagnosis has not yet been performed in any of these cases, but the different approaches in this respect are discussed. The excretion pattern of organic acids in urine from patients with acyl-CoA dehydrogenation deficiencies - as measured by means of gas chromatography/mass spectrometry - offers in most cases a tentative diagnosis of the enzyme defect. These excretion patterns are characterized by the presence in urine of different compounds originating from the primary accumulated acyl-CoA ester(s). The most important biochemical processes involved in the formation of these patterns seem to be glycine conjugation, omega-and omega-1-oxidation, carboxylation and dioxygenation. The enzymatic basis for these processes is discussed with respect to the enzyme affinities for acyl-CoA esters relevant to the acyl-CoA dehydrogenation deficiencies. And the knowledge gained from such affinity studies is used to explain the excretion pattern in the different patients, thus increasing the diagnostic power of the gas chromatographic/mass spectrometric analyses. The pathophysiological manifestations in patients with acyl-CoA dehydrogenation deficiencies resemble in many respect those seen in patients with Reye's syndrome, in which the fatty acid oxidation also seems to be compromised. Ethiological factors have not been identified in Reye's syndrome, but in many patients blood accumulation of short- and medium-chain fatty acids has been found.(ABSTRACT TRUNCATED AT 400 WORDS)