Process for producing a high purity aromatic polycarboxylic acid

摘要

The invention relates to a process for producing a high purity aromatic polycarboxylic acid. <??>A high aromatic polycarboxylic acid is produced by purifying a crude aromatic polycarboxylic acid in accordance with the following steps. (I) a step of forming a salt which comprises forming an amine salt of an aromatic polycarboxylic acid from the crude polycarboxylic acid and an amine; (II) a step of decomposing a salt which comprises continuously conducting in a salt decomposition reactor three operations of (i) supplying an aqueous solution of the amine salt of an organic polycarboxylic acid formed in the step of forming a salt, (ii) removing the amine and water by distillation under heating and (iii) taking out a slurry containing crystallized aromatic polycarboxylic acid; and (III) a step of separating crystals which comprises separating and recovering crystals of the aromatic polycarboxylic acid from a slurry which is taken out in the step of decomposing a salt. <??>The invention further provides a process for producing a high purity aromatic polycarboxylic acid whereby in the step of decomposing a salt, the slurry in the salt decomposition reactor which comprises the aqueous solution of the amine salt and the aromatic polycarboxylic acid formed by the decomposition is circulated through a heat exchanger, heat is supplied in the heat exchanger while a pressure of the slurry is kept at a vapor pressure of the slurry or higher, a mixture of the amine and water is removed by distillation in the salt decomposition reactor, and the aromatic polycarboxylic acid is crystallized in the salt decomposition reactor. <IMAGE>