Theoretical insight into the generation mechanism of vinyl acrylate in the production of vinyl acetate on PdAu(100)

Abstract

In the industrial production of vinyl acetate, the by-product vinyl acrylate is difficult to separate, and shows extremely strong reaction activity and may have adverse effects on the main reaction process, catalyst and downstream products of vinyl acetate. However, studies on this topic are rare. In this work, the DFT method and the kMC method are combined to study how vinyl acrylate is produced during the production of vinyl acetate by the ethylene method. The calculation result shows that the active site on the surface of the PdAu(100) catalyst is Pd; CH₂O and CH₂CHCOOH are critical intermediates, and the reaction pathway CO₂ → HCOO → HCOOH → H₂COOH → CH₂O → CH₂CH₂COOH → CH₂CHCOOH → CH₂CHCOOCHCH₂ is the most probable way to produce vinyl acrylate. CH₂CHCOOH can further produce vinyl acrylate as a final by-product using a one-step or two-step reaction. The energy barrier of the one-step reaction is 1.23 eV; in the two-step reaction method, the energy barriers are 0.88 eV and 1.43 eV, respectively. The two-step method used to generate the final by-product vinyl acrylate is more advantageous than the one-step method.