Mechanism of initial activation of carbon-oxygen bonds for deoxidation of acetic acid

Producing valuable fuel-ranged hydrocarbons from cellulosic biomass is an effective approach to addressing potential energy issues. However, the cellulose-derived bio-oil may contain carboxylic acid components that contribute to the unfavorable acidic and corrosive nature, which necessitates upgrading through the hydrodeoxygenation (HDO) treatment using heterogeneous catalysis. Here, we performed reactive force -field molecular dynamics (ReaxFF-MD) to study the hydrogenolysis, dehydrogenation and decarboxylation mechanisms of the acetic acid model compound on the Ni -based catalyst. Comparative analysis of the activation of C-O and C=O bonds was presented, followed by an examination of the associative desorption of H2 and the dynamic evolution of main intermediates. Furthermore, the conversion pathways of key intermediates were determined and four main pathways for ethanol generation and the temperature-response mechanism for coking formation were proposed. This mechanism diagram explains the strong effects of a hydrogen environment in biomass-related reactions, highlighting the dynamic mechanism of selective hydrogenation and deoxygenation of carbon-oxygen bonds.