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Journal ArticleDOI

Studies on the ketonization of acetic acid on chromia: I. The adsorbate-catalyst interaction

01 Aug 1969-Journal of Catalysis (Academic Press)-Vol. 14, Iss: 4, pp 348-354
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.
About: This article is published in Journal of Catalysis.The article was published on 1969-08-01. It has received 20 citations till now. The article focuses on the topics: Benzyl alcohol & Acetic acid.
Citations
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Journal ArticleDOI
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

Journal ArticleDOI
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

Journal ArticleDOI
TL;DR: In this paper, the authors investigated condensation reactions of propanal over CexZr1−xO2 mixed oxides as a model reaction to produce gasoline range molecules from short aldehydes found in bio-oil mixtures.
Abstract: Vapor phase condensation reactions of propanal were investigated over CexZr1−xO2 mixed oxides as a model reaction to produce gasoline range molecules from short aldehydes found in bio-oil mixtures. Several operating parameters were investigated. These included the type of carrier gas used (H2 or He) and the incorporation of acids and water in the feed. Propanal is converted to higher carbon chain oxygenates on CexZr1−xO2 by two pathways, aldol condensation and ketonization. The major products of these condensation reactions include 3-pentanone, 2-methyl-2-pentenal, 2-methylpentanal, 3-heptanone and 4-methyl-3-heptanone. It is proposed that the primary intermediate for the ketonization path is a surface carboxylate. The presence of acids in the feed inhibits the aldol condensation pathway by competitive adsorption that reduces the aldehyde conversion. Water also promotes ketonization and inhibits aldol condensation by increasing the concentration of surface hydroxyl groups that enhance the formation of surface carboxylates with the aldehyde. Hydrogen enhances cracking and production of light oxygenates and hydrocarbons. The light oxygenates may in turn be reincorporated into the reaction path, giving secondary products. However, the hydrocarbons do not react further. Analysis of the fresh and spent catalysts by XPS showed varying degrees of reduction of the oxide under different operating conditions that were consistent with the reaction results. Changing the proportion of the parent oxides showed that increased Zr favored formation of aldol products while increased Ce favored ketonization. This occurs by shifting the balance of the acid–base properties of the active sites. © 2010 Elsevier B.V. All rights reserved.

97 citations

Journal ArticleDOI
TL;DR: In this article, the authors evaluated the kinetics of thermal decarboxylation of aqueous solutions of acetic acid and sodium acetate at 335 and 355°C in contact with various surfaces as potential catalysts.

89 citations

Journal ArticleDOI
TL;DR: In this paper, a mesoporous base catalysts (CM-HMS and CM-MCM-41) were synthesized by generating uniform particles of cerium and manganese oxides (MnO x /CeO 2 ) in situ within hexagonal meshoporous silica.

66 citations

References
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Book
01 Jan 1963

108 citations

Journal ArticleDOI
TL;DR: In this paper, the effect of doping semiconductor oxides can be simulated by mixing reactants with other substances, such as acetic acid or hydrogen, in the light of the effect the chemisorption of various compounds has on the electronic character of the catalyst.

7 citations