Theoretical study on the synthesis of vinyl acetate from acetylene and acetic acid over nonmetallic catalysts with different carbon-nitrogen ratios

Abstract

At present, the acetylene acetic acid reaction catalysts studied are metal catalysts. Whether there are non-metallic materials that can catalyze the reaction is very worth exploring. In this study, we used density functional theory (DFT) to calculate the feasibility of preparing vinyl acetate (VAc) on four CN non-metallic materials (C2N, C3N, C4N and C5N) under the reaction conditions of 1 atm, 393.15–493.15 K at B3LYP/6-31G(d, p) level. It is found that after considering the reaction temperature, only C2N and C3N show good adsorption capacity for acetylene and acetic acid, and C3N has stronger adsorption capacity for reactants. After that, we calculated and simulated the reaction process of acetylene acetic acid reaction catalyzed by four CN materials. It is found that among the four CN materials, the energy barrier of the reaction rate control step of C3N is the lowest (the free energy barrier of the rate control step is only 30.57 kcal/mol at 393.15 K), and the interior of CN non-metallic materials has higher activity than the boundary of hydrogen sealing. We also found that the reaction process on CN non-metallic material is consistent with the acid catalysis mechanism, which shows that the non-metallic catalyst is theoretically feasible for catalyzing the acetic acid acidification of acetylene, and the two-dimensional C3N material is likely to be a potential non-metallic catalyst for the preparation of vinyl acetate by acetylene gas phase method.