Density Functional Theory Investigation on the Synthesis Mechanism of Vinyl Acetate from Acetylene and Acetic Acid Catalyzed by Ordered Mesoporous Carbon-Supported Zinc Acetate

The formation mechanism of vinyl acetate in the reaction of acetylene and acetic acid, which was catalyzed by ordered mesoporous carbon (OMC) supported zinc acetate, was investigated using density functional theory (DFT). Since the surface functional groups of carbon support influence the reaction significantly and play an important role in catalysis designing, we calculate the elementary steps on pristine ordered mesoporous carbon and carbon modified with carboxyl, carbonyl, and hydroxyl, respectively. After calculation, we find that carbonyl shifts to the epoxy group, which indicates the instability of carbonyl on the catalyst support. We propose the possible reaction mechanism and find that the reaction mechanism is not exactly the same with different functional groups. A remarkably acetate shift will occur in the existence of carboxyl and the activation barrier of rate-limiting steps in this case is also reduced, while the hydroxyl and epoxy groups will increase the barrier to some extent. Therefore, when designing the industrial catalysis for this reaction, we can modify the surface of catalysis support directionally, to enhance the reaction efficiency.