Experimental and Theoretical Research on One-Step Oxidative Esterification of Methyl Acrolein with Methanol

As a promising competitive route to synthesize methyl methacrylate (MMA), direct oxidative esterification with Au-based catalysts is widely studied. However, the reaction kinetics of the generation of MMA and other side products, such as methacrylic acid and methyl acrolein (MAL) dimethyl acetal, has not been clearly elucidated. The corresponding theoretical calculations of side products are also less reported. In this regard, kinetic experiments and kinetic models, along with molecular simulations, are utilized to acquire the detailed reaction mechanism in this paper. The chemical reaction rates at 363 and 373 K with different reactant concentrations are investigated, and the macroscopic kinetic models of primary and side reactions are fully established. Meanwhile, the intermediates, reaction energy, and activation barrier are evaluated by density functional theory calculations, as well, illustrating the fact that MMA is the main product with lowest activation energy. The calculated reaction pathway is found to be in qualitative agreement with the experimental results and kinetic models. The results could provide a solid theoretical foundation and useful reference for the future design and optimization of the industrial process of MAL oxidative esterification to MMA.