关键词: N-乙烯基吡咯烷酮, 结晶, 纯化, 分离

Abstract: For the polymers of N-vinylpyrrolidone used in food and pharmaceutical fields, a purity of the N-vinylpyrrolidone monomer higher than 99.9% is required. However, it is often very difficult to meet the requirement by fractional distillation. To solve this problem, a crystallization process was applied to purify N-vinylpyrrolidone from industrial grade (99.5%) to pharmaceutical grade (99.9%). The effects of crystal seed addition amount, temperature of adding crystal seed, cooling rate, final crystallization temperature, crystallization time, heating rate, final sweating temperature, and sweating time on the purity and yield of the product were investigated. The appropriate operating conditions were obtained as follows:crystal seed addition amount is of 0.1% based on the weight of raw material, temperature of adding crystal seed of 11℃, cooling rate of 6℃/h, final crystallization temperature of 6℃, crystallization time of 20 min, heating rate of 6~8℃/h, final sweating temperature of 12℃, and sweating time of 30min. N-vinylpyrrolidone of industrial grade(99.5%) can be purified through single-stage crystallization to a purity more than 99.95% with a yield more than 74.5%. Compared to other separation methods, this method has obvious advantages.

Key words: N-vinylpyrrolidone, crystallization, purification, separation