Patent ID: 9096516
Filing Date: 2015-08-04
Classification: B01D,C07D

Abstract:
1. A method for producing N-vinyl-2-pyrrolidone by crystallization comprising: controlling a water content in a feed N-vinyl-2-pyrrolidone solution at an inlet of a crystallizer so as to be not lower than 0.7% by weight and not higher than 10% by weight based on the total weight of the N-vinyl-2-pyrrolidone solution; adjusting the pH value of the feed N-vinyl-2-pyrrolidone solution before supplying to a crystallization process to be within the range of from 10.8 to 12.0; and supplying the resulting pH-adjusted feed N-vinyl-2-pyrrolidone solution to the crystallization process, wherein a temperature of the feed N-vinyl-2-pyrrolidone solution before supplying to the crystallization process is within the range of from 9.0° C. to 25.0° C., wherein the N-vinyl-2-pyrrolidone solution resulting from the method has a purity of more than 99%.