A kind of refining method of caprolactam

Abstract

The invention relates to the field of caprolactam production, and discloses a caprolactam refining method. The method comprises the following steps: (1) reduced pressure distillation is carried out ona caprolactam crude product containing impurities with a boiling point higher than the boiling point of caprolactam and impurities with a boiling point lower than the boiling point of caprolactam, sothat impurities with the boiling point lower than he boiling point of caprolactam is removed, and a light removed product is obtained; (2) the light removed product is mixed with a crystallization solvent, and then crystallizing is carried out to obtain a crystal; and (3) a hydrogenation reaction is carried out on the crystal, wherein the reduced pressure distillation is carried out under a condition of variable temperature and variable pressure, and the mass ratio of the crystallization solvent to the light removed product is (0.2-5):1. Premium-grade caprolactam can be obtained through the method provided by the invention, a heavy removal step is omitted, the process flow is simple, and the method is easy for industrial implementation.

Description

technical field

[0001] The invention relates to the field of caprolactam production, in particular to a method for refining caprolactam. Background technique

[0002] Caprolactam is one of the important raw materials for synthetic fibers and synthetic resins, mainly used in the manufacture of polyamide fibers (nylon 6), resins and films. The known production methods of caprolactam include cyclohexanone oxime liquid-phase Beckmann rearrangement method using oleum as catalyst, cyclohexanone oxime gas-phase Beckmann rearrangement method using solid zeolite as catalyst, and methods such as depolymerization of waste polymers. . The gas-phase Beckmann rearrangement reaction of cyclohexanone oxime on solid acid catalyst is a new process to realize the sulfur-free ammonization of caprolactam, which has the problems of no equipment corrosion and no environmental pollution, and the separation and purification of products will be greatly simplified, so no sulfur The new gas-phase Bec...