Comparative Kinetic Monte Carlo Study of Acetic Acid Decomposition to Surface Carbon Species and Undesirable Byproducts on Pd(100) and Pd/Au(100) from Density Functional Theory-Based Calculations

Abstract

Acetic acid decomposition on Pd(100) and Pd/Au(100) during vinyl acetate (VA) synthesis from ethylene acetoxylation is the primary source of such undesirable byproducts as methanol (CH3OH), acetaldehyde (CH3CHO), ketene (CH2CO), acetone (CH3COCH3), and methane (CH4), and also one possible source of surface carbon formation, which will lead to the deactivation of the catalyst. In this work, density functional theory (DFT) calculations and kinetic Monte Carlo (kMC) simulation were performed to probe the mechanism of acetic acid decomposition on Pd(100) and Pd/Au(100) at the molecular level. The corresponding adsorption of relevant species involved in acetic acid decomposition on Pd(100) and Pd/Au(100) was investigated, and the transition states of the elementary reactions involved were identified. The results show that the most probable pathway of acetic acid decomposition on Pd/Au(100) is CH3COOH → CH3COO+H → CO2+CH3+H → CO2+CH4, followed by CH3COOH → CH3COO+H → CO2+CH3+H → CO2+CH2+2H → CO2+CH+3H → CO2+C+4...