Development of a new production process for N-vinyl-2-pyrrolidone

We describe the first continuous production process for N-vinyl-2-pyrrolidone (NVP). The starting materials are gamma-butyrolactone (GBL) and monoethanolamine (MEA). The process consists of two stages: the synthesis of N-(2-hydroxyethyl)-2-pyrrolidone (HEP) from GBL and MEA, and the vapor-phase dehydration of HEP to NVP. The key features of this technology are the dehydration catalyst and the vapor-phase reaction system. The catalyst is of very simple composition, being alkali (or alkaline earth) metal oxides-SiO2. Though its acid and base strengths are very weak, its catalytic performance is high. We presume that the excellent catalytic performance is due to the selective adsorption of HEP to the catalyst. Moreover, an IR spectroscopic study of the HEP-adsorbed catalyst indicated that the isolated silanol of the catalyst surface plays an important role. This account describes the progress made from the laboratory study to the industrial process, along with the experimental results and discussion.