(214c) Selective Activation of Methyl Acetate On Pd Surfaces

Ester hydrogenolysis for the production of alcohols is an important class of catalytic process frequently encountered in industrial polymer synthesis and biomass feedstock processing. The reactions are typically catalyzed by Cu and Cu compounds, which require high temperature and pressure. Transition metals including Pd and Rh can reduce the severity of the reaction conditions but generally suffer low selectivity for alcohols. Although ester hydrogenolysis has been extensively studied experimentally for decades, what governs the selective conversion of esters to alcohols remains poorly understood. We have performed density functional theory (DFT) calculations to investigate the activation of a model ester, methyl acetate, on palladium surfaces. We find that clean Pd(111) preferentially catalyzes C-H bond scission which is liable to generate unwanted decomposition products and fundamentally limits the selectivity to alcohols. However, surface structure, reaction conditions, and alloying can all influence the balance between C-H and ester C-O bond scission and therefore affect product selectivity. These effects will be discussed. The atomic-level insights into methyl acetate activation that our study identifies may provide clues for devising selective catalysts and catalytic processes for oxygenate conversion in general.