Paper HC+SS-MoM2
Theoretical Study of Acetic Acid Decomposition on Pd (111) using Density Functional Theory

Monday, October 21, 2019, 8:40 am, Room A212

Acetic acid decomposition on Pd (111) and the effects of water on the decomposition are good model systems for the study of solvent effects on small oxygenates. Numerous studies have found that solvents influence the selectivity and rate of heterogenous catalytic reactions, so fundamental understanding of how water affects OC-O, C-OH, CO-H, C-H and C-C bond cleavages will give us valuable insight into how water influences selectivity of oxygenates decomposition, further enabling bottom up design of effective catalyst and catalyst system. Here we present density functional theory calculations of the decomposition of acetic acid on Pd (111) and the effects of water on the reaction mechanism. Our results suggest that the most favorable decarboxylation (DCX) and decarbonylation (DCN) mechanisms in vacuum proceed through dehydrogenation of acetic acid (CH₃COOH) to acetate (CH₃COO), followed by dehydrogenation of CH₃COO to CH₂COO. The competition between the most favorable DCN and DCX pathway depends on two endothermic elementary steps, the deoxygenation of CH₂COO to ketene (CH₂CO) and dehydrogenation of the carboxylmethylidene (CH₂COO) to carboxylmethylidyne (CHCOO). Water can affect the different elementary steps by changing the stability of the initial, transition and/or final state or by providing new reaction paths such as through hydrogen shuttling, which can lead to changes in the selectivity of a complex reaction network as presented herein. Here we will discuss how water influences different critical reaction steps and how that effects the overall reaction network.