Studies on the ketonization of acetic acid on chromia: II. The surface reaction
TL;DR: In this paper, a mechanism for the surface reaction of acetic acid on chromia is suggested and discussed based on a comparison of the energies of activation and the previously established fact that both the dehydration and dehydrogenation activity of chromia are required for the ketonization reaction.
About: This article is published in Journal of Catalysis.The article was published on 1970-03-01. It has received 37 citations till now. The article focuses on the topics: Chromia & Acetic acid.
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TL;DR: In this article, the conversion of methanol and other O-compounds to C 2 ǫC 10 hydrocarbons using a new class of shape-selective zeolites is reported.
1,250 citations
TL;DR: The role of α-hydrogen has been proven as a critical requirement for ketonization over catalysts that are active for surface Ketonization and serves as the initial basis for the discussion as mentioned in this paper.
Abstract: Ketonization is a reaction in which two carboxylic acids convert into a ketone, carbon dioxide, and water. While this reaction once found its industrial application for acetone production, it is regaining interest for its value in the upgrading of biomass-derived oxygenates, for example, bio-oils obtained from the fast pyrolysis of biomass. Namely, ketonization is crucial to reduce the detrimental effects of carboxylic acids in bio-oil. This review addresses reaction mechanisms, families of materials that catalyze the reaction (metal oxides and zeolites), and current applications of ketonization in the upgrading of biomass-derived oxygenates. A variety of mechanisms have been proposed to explain the ketonization reaction, and these proposals are critically discussed. The role of the α-hydrogen has been proven as a critical requirement for ketonization over catalysts that are active for surface ketonization and serves as the initial basis for the discussion. The role of crucial reaction intermediates such ...
287 citations
TL;DR: This review surveys both the biological and chemical catalytic routes to producing platform chemicals from renewable sources and describes advances in condensation chemistry and strategies for the conversion of these platform chemicals into fuels and high-value chemicals.
281 citations
TL;DR: In this paper, the ketonization of propanoic acid to form 3-pentanone over CeO 2 -based composite oxides at temperatures of 300-425°C was investigated.
Abstract: The ketonization of propanoic acid to form 3-pentanone over CeO 2 -based composite oxides at temperatures of 300–425 °C was investigated. A CeO 2 -based solid solution, CeO 2 –Mn 2 O 3 , was effective for the ketonization. The citrate process was the most appropriate method for preparing a well-dispersed solid solution. In the ketonization of propanoic acid with another linear carboxylic acid, an asymmetric ketone together with two symmetric ketones was formed, and the ketone composition was approximated by a binomial distribution. The reactivity of the carboxylic acid was slightly decreased as its chain length was increased. In contrast to linear aliphatic acids, branched acids were less reactive. Methyl group substituents at the α- and β-positions of carboxylic acids decreased their reactivities in both homo- and cross-ketonization. The lack of an α-hydrogen or the increase in steric hindrance was surmised to be the cause of the decrease in reactivity.
150 citations
TL;DR: In this paper, the key issue of the catalysts for hydrogenation of aromatic and aliphatic carboxylic acids to the corresponding aldehydes was reviewed, and a new aspect of direct hydrogenation catalysts was briefly reviewed.
Abstract: In this article, the key issue of the catalysts for hydrogenation of aromatic and aliphatic carboxylic acids to the corresponding aldehydes was reviewed. For the hydrogenation of aromatic carboxylic acids, metal oxides, such as ZrO2, CeO2, ZnO and MnO, show high activity and selectivity to aldehydes. On the other hand, for aliphatic carboxylic acids which have two -hydrogen atoms, these metal oxides show low selectivity for hydrogenation, because undesirable ketonization occurs. For the hydrogenation of aliphatic carboxylic acids, Cr 2O3 and the partially reduced Fe2O3 show high selectivity. Especially, the highly pure Cr2O3 exhibits superior chemo-selectivity to aldehyde without C=C bond migration or ketonization. The chromium-modified ZrO2 catalyst for manufacturing aromatic aldehydes and the highly pure Cr2O3 catalyst for manufacturing aliphatic aldehydes have been commercially used in industrial processes. A new aspect of direct hydrogenation catalysts is briefly reviewed, and the reaction mechanism for hydrogenation of carboxylic acids is also discussed. © 2001 Elsevier Science B.V. All rights reserved.
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TL;DR: In this paper, the ketonization of acetic acid has been studied on a chromia catalyst at 460 °C and at a contact time of 0.7 sec at various partial pressures in presence of tertiary butyl alcohol and benzyl alcohol.
20 citations
15 citations
TL;DR: Experiments with mixed molybdenum oxide–silica (MoO2–SiO2) catalysts, in this laboratory, were discontinued because of the unavoidable presence of metallic molyBdenum in such preparations.
Abstract: SOME examples of relations between the activity and the electrical conductivity of catalyst surfaces have been described, notably by Garner, Gray and Stone1 for copper and copper oxide films. Measurements with a similar degree of accuracy have not been recorded for precipitated catalysts. Experiments with mixed molybdenum oxide–silica (MoO2–SiO2) catalysts, in this laboratory, were discontinued because of the unavoidable presence of metallic molybdenum in such preparations2.
14 citations
9 citations