Process for the purification of acrylic acid or methacrylic acid by crystallization and distillation

摘要

The invention relates to a method for purifying acrylic acid or methacrylic acid by crystallization and distillation, which consists of the following steps: (a) crystallization of a mixture containing the acrylic acid or methacrylic acid, resulting in formation of a product crystallizate enriched with acrylic acid or methacrylic acid and a mother liquor; (b) distillation of at least part of the mother liquor obtained under step (a) to obtain a distillation bottom which is at least partly extracted and an overhead; (c) crystallization of at least part of the overhead obtained under step (b) so as to obtain a crystallization residue which is extracted and a crystallizate; and (d) recirculation of the crystallizate obtained under step (c) into the crystallization process (a).