Effect of water content on the homogeneous catalytic process of N-vinyl pyrrolidone synthesis from acetylene

The acetylene method is presently the most frequently employed technique for producing N-vinyl pyrrolidone (NVP). However, when using pyrrolidone potassium salt as the catalytically active substance in the conventional process, the water in the reaction system has a great impact on the catalyst activity and selectivity of the homogeneous process. This study comprehensively investigates the influence of water on the reaction within the conventional process of synthesizing NVP in an autoclave, and obtains a highly active homogeneous catalytic active substance through strict water removal. The main reaction and catalyst deactivation mechanisms are further clarified through DFT calculations. Based on the understanding of the mechanism, a one-step synthesis of NVP using KOH directly as the catalyst without removing water has been realized by introducing solvents into the stop-flow micro-tubing (SFMT) reactor with enhanced gas-liquid mass transfer to increase the amount of acetylene in the liquid phase.