Acetic acid and propionic acid decarboxylation on Mg(OH) 2 nanoclusters: a density functional theory study
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Acetic acid and propionic acid decarboxylation on Mg(OH)2 nanoclusters: a density functional theory study Duwage C. Perera1
1 2
, Jinasena W. Hewage2
, and Jayendran C. Rasaiah1,*
Department of Chemistry, University of Maine, Orono, USA Department of Chemistry, University of Ruhuna, Matara, Sri Lanka
Received: 17 December 2019
ABSTRACT
Accepted: 30 August 2020
Theoretical analysis of the energetics and mechanism of a reaction can guide the selection of a catalyst from a set of similar candidates and avoid the need for lengthy experimental trials. In this work, a catalyst for the decarboxylation of acetic acid (AA) to methane and carbon dioxide was selected from a set of related magnesium hydroxide [Mg(OH)2]n (n = 1–9) nanoclusters. Density functional theory (DFT) was used to follow the energetics, mechanism, and stereochemical details of the reaction. It was found that the n = 5 nanocluster had the best performance of the set. For this nanocluster, the decarboxylation reaction proceeded through a single transition state (TS), in contrast to an intermediate and two TSs for the free gas-phase catalytic reaction or decarboxylation with a (MgO)4 catalyst. Inspection of AA adsorbed on the [Mg(OH)2]5 cluster shows the favorable structural orientation of the acid, which facilitated decarboxylation via a single activated state, bypassing the intermediate and one of the TSs. We hypothesized that the decarboxylation of propionic acid to ethane and carbon dioxide should also occur via a single TS with the same catalyst, which was confirmed by a separate DFT study. The [Mg(OH)2]5 clusters have potential use as a coating for textiles to catalyze the decomposition of propionic acid in sweat.
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Springer Science+Business
Media, LLC, part of Springer Nature 2020
Handling Editor: Yaroslava Yingling.
Address correspondence to E-mail: [email protected]
https://doi.org/10.1007/s10853-020-05196-z
J Mater Sci
GRAPHIC ABSTRACT
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Introduction The catalytic behavior and adsorption properties of carboxylic acid on metal and metal oxide surfaces have drawn the attention of researchers across the globe. Biomass is one of the most sustainable green energy resources to overcome the problem of fossil fuel depletion along with environmental pollution. One potential problem is the presence of an excessive amount of acids, alcohols, and ether in the bio-oil produced from thermochemical conversions of lignocellulosic biomass. This causes some major drawbacks such as high viscosity, low stability, low heating value, and low pH in the production of highquality fuel. Therefore, it is important to upgrade biooil by reducing/eliminating these compounds. Acetic acid (AA) can be considered as a model acid present in unprocessed bio-oil. Therefore, studying the decomposition of AA is important in upgrading the quality of bio-oil [1, 2]. Acetic acid is a typical weak acid and an important starting material for the production of vinyl acetate and acetic anhydride for the synthesis of long
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