Studies on the surface interaction of acetic acid on iron oxide
TL;DR: In this paper, the activation energy of the reaction depends on the region of temperature in which the reaction is carried out, indicating the dependence of the mechanism of ketonization on temperature.
About: This article is published in Journal of Catalysis.The article was published on 1977-11-01. It has received 48 citations till now. The article focuses on the topics: Catalysis & Acetic acid.
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TL;DR: This critical review examines transition metal-catalyzed decarboxylative couplings that have emerged within recent years as a powerful strategy to form carbon-carbon or carbon-heteroatom bonds starting from carboxylic acids.
Abstract: This critical review examines transition metal-catalyzed decarboxylative couplings that have emerged within recent years as a powerful strategy to form carbon–carbon or carbon–heteroatom bonds starting from carboxylic acids. In these reactions, C–C bonds to carboxylate groups are cleaved, and in their place, new carbon–carbon bonds are formed. Decarboxylative cross-couplings constitute advantageous alternatives to traditional cross-coupling or addition reactions involving preformed organometallic reagents. Decarboxylative reaction variants are also known for Heck reactions, direct arylation processes, and carbon–heteroatom bond forming reactions.
1,104 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: In this article, a series of laboratory experiments were conducted to measure the rate constants for the decomposition of acetate (acetic acid and sodium acetate) in the presence of titanium, silica, stainless steel, gold, and magnetite.
146 citations
TL;DR: In this article, the active and selective catalysts for the hydrogenation of acetic acid to acetaldehyde were described. But they were not discussed in detail, except that the catalysts were prereduced and the hydrogen/acid ratio must be higher than four.
134 citations
TL;DR: In this article, the present level of understanding of the bonding modes of carboxylic acids (acetic acid in particular) on the TiO2 and ZrO2 surfaces as obtained from DFT calculations is discussed.
Abstract: Carboxylic acids play a fundamental role in the transformation of biomass into liquid fuels and other useful chemicals. In order to reduce the O/C content of biofuels, carboxylic acids need to be decomposed by decarboxylation, dehydroxylation, or decarbonylation unimolecular reactions, or they need to be converted into ketones via complex bimolecular reaction mechanisms. Ketonization, that is, the transformation of carboxylic acids into ketones, carbon dioxide, and water, is promoted by heterogeneous catalysts based on oxide materials. Among the most active catalysts are titania and zirconia surfaces. In recent years, a large body of experimental data has been complemented by specific investigations performed with first-principles electronic structure calculations based on density functional theory (DFT). In this review, I discuss the present level of understanding of the bonding modes of carboxylic acids (acetic acid in particular) on the TiO2 and ZrO2 surfaces as obtained from DFT calculations. Enolizat...
133 citations
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TL;DR: In this article, a thermocouple is used to measure the sample temperature in a Stanton HT-D thermobalance, the bead of which is positioned in or near the sample, depending on crucible design.
Abstract: THE use of thermogravimetric data to evaluate kinetic parameters of solid-state reactions involving weight loss (or gain) has been investigated by a number of workers1–4. Freeman and Carroll2 have stated some of the advantages of this method over conventional isothermal studies. To these reasons may be added the advantage of using one single sample for investigation. However, the importance of procedural details, such as crucible geometry, heating rate, pre-history of sample, and particle size, on the parameters has yet to be fully investigated. It is also necessary to ensure accurate temperature measurement, both for precision and also to detect any departure from a linear heating rate due to endo- or exo-thermic reactions. (The effect of these may be largely eliminated by the use of small samples.) In our present work (using a Stanton HT–D thermobalance) the sample temperature is measured directly by means of a thermocouple the bead of which is positioned in or near the sample, depending on crucible design, the wires of which run down a twin-bore rise rod. The connexion between the end of the thermocouple wires on the balance arm and the terminal block is made by 0.001 in. platinum and platinum/rhodium wires5. It has been shown that these wires do not affect the performance of the balance but act merely as a subsidiary damping. From the terminal block compensated cable leads to the cold junction and a potentiometric arrangement for direct measurement of the thermocouple output.
5,770 citations
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.
37 citations
31 citations
17 citations