(628g) Catalytic Process Intensification for the Synthesis of N-Vinylpyrrolidone from Acetylene

N-vinyl pyrrolidone (NVP) is one of the high value-added chemical products, which can be polymerized into polyvinylpyrrolidone (PVP), a nonionic water-soluble polymer. PVP is widely used in medicine and health, daily chemicals, pigments and coatings, office stationery, beverages and food industries. 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 research comprehensively investigates the main reaction mechanism of the process through experiments and theoretical computations, and clarifies the effect of water on catalyst deactivation. Based on the understanding of the mechanism, a one-step KOH-catalyzed synthesis of NVP without removing water has been realized by introducing solvent into the Stop-Flow Micro-Tubing (SFMT) reactor with enhanced gas-liquid mass transfer to increase the amount of acetylene in the liquid phase, thus promoting the main reaction. In addition, this study takes advantage of the ability of macrocyclic polyethers to selectively complex cations by using 15-crown-5, 18-crown-6 and 2.2.2-crypt as promoters of the reaction process to reduce the amount of solvent. The catalytic mechanism of macrocyclic polyethers as promoters is clarified by characterization and theoretical computations, which increases the anionic amount of pyrrolidone and the nucleophilicity of N in the anion by complexing with K⁺. The introduction of solvents and the use of promoters realize the intensification of the catalytic reaction process of NVP synthesis by acetylene method.