PRODUCTION METHOD OF &egr;-CAPROLACTAM

摘要

PROBLEM TO BE SOLVED: To provide a production method of ε-caprolactam, for producing high-quality ε-caprolactam, which has fewer impurities, with a good yield.

SOLUTION: The production method includes: an ε-caprolactam purification step A of obtaining purified ε-caprolactam from crude ε-caprolactam by applying a drop-crystallization method; a first-stage ε-caprolactam recovery step B of applying a vaporization crystallization method to a crystallization mother liquid obtained in the ε-caprolactam purification step A, to obtain a first recovered ε-caprolactam and a first recovered mother liquid; and a second-stage ε-caprolactam recovery step C of at least partially removing a solvent included in the first recovered mother liquid, applying a melting crystallization method to the concentrated first recovered mother liquid to obtain a second recovered purified ε-caprolactam. The first recovered ε-caprolactam is recovered as a raw material for the ε-caprolactam purification step A, and the second recovered purified ε-caprolactam is recovered as a raw material for any one of or both of the ε-caprolactam purification step A and the first-stage ε-caprolactam recovery step B.

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