Abstract:
PROBLEM TO BE SOLVED: To provide a method for producing ε-caprolactam, which produces high-quality ε-caprolactam containing less impurity in a high yield. SOLUTION: The method for producing ε-caprolactam includes an ε-caprolactam purification step A for obtaining purified ε-caprolactam from raw ε-caprolactam by applying a drop crystallization method, a first-stage ε-caprolactam recovery B for obtaining first recovered ε-caprolactam and a first recovered mother liquor by applying an evaporative crystallization method to a crystallization mother liquor obtained in the ε-caprolactam polymerization step A and a second-stage ε-caprolactam recovery step C for obtaining second recovered purified ε-caprolactam by applying a melt crystallization method to the first recovered mother liquor, first recovered ε-caprolactam being recovered as a raw material for the ε-caprolactam purification step A and second recovered purified ε-caprolactam being recovered as a raw material for the ε-caprolactam purification step A and/or the first-stage ε-caprolactam recovery step B. COPYRIGHT: (C)2012,JPO&INPIT
Abstract:
PROBLEM TO BE SOLVED: To improve purification yield of NVP (N-vinyl-2-pyrrolidone) in a method for purifying NVP by crystallization. SOLUTION: The method for purifying N-vinyl-2-pyrrolidone by crystallization comprises carrying out crystallization by making a stabilizer exist in a mother liquor composed of N-vinyl-2-pyrrolidone as a main component and containing impurities. COPYRIGHT: (C)2005,JPO&NCIPI