PROCESS FOR CONTINUOUSLY CLEANING RAW CAPROLACTAM MADE FROM 6-AMINO CAPRONITRILE

摘要

Cleaning raw caprolactam by hydration, subsequent treatment in an acid medium and final distillation in an alkaline medium, in which (a) 6-amino capronitrile is converted into raw caprolactam by reaction with water; (b) difficultly and easily boiling components are removed from the raw caprolactam from step (a); (c) the raw caprolactam from step (b) is treated with hydrogen at a temperature in the 50 to 150 DEG C range and a pressure in the 1.5 to 250 bar range in the presence of a hydration catalyst and, if desired, a solvent, to give a mixture A;(d1) mixture A is taken at a temperature in the 30 to 80 DEG C range and a pressure in the 1 to 5 bar range over an ion exchanger containing acid terminal groups to give a mixture B1 or (d2) mixture A is distilled in the presence of sulphuric acid, in which any solvent is removed before the addition of the sulphuric acid to give a mixture B2; and (e) mixture B1 or B2 is distilled in the presence of a base to yield pure caprolactam.