Catalytic routes and mechanisms for vinyl acetate synthesis

Vinyl acetate is important as a building block for the production of added value chemicals and products. Here, we review studies on catalyst structure and reaction mechanisms for vinyl acetate synthesis via heterogeneous non-oxidative acetylene acetoxylation and homogeneous and heterogeneous oxidative ethylene acetoxylation. In doing so, we assess the complexity and similarities in all three systems and highlight the importance of combining experiment and computation to understand the mechanisms. In spite of many studies on the method currently used in industry, heterogeneous ethylene acetoxylation, the reaction and catalyst deactivation mechanisms and the role of promoters and alloy composition are not fully resolved. Aspects of reaction mechanism involving ethylene coupling with pre-adsorbed high-coverage acetates have been established via detailed surface science and DFT work, but other essential steps for steady state catalysis describing how coverages and rate liming steps change with conditions are not well-understood. Our recent kinetic, isotopic measurements and computations show that reaction orders, selectivity, and kinetic relevance of elementary steps change significantly with reactant pressures and surface coverage. Steps that account for kinetic coupling between acetate formation and consumption can fully capture these changes. Such a general mechanistic framework can guide the design and development of more active, selective, and stable catalysts for sustainable VA synthesis processes.