Patent ID: 7342128
Filing Date: 2008-03-11
Classification: C07C

Abstract:
1. A process to produce a crystallized post oxidation composition said process comprising the following steps in the order named: (a) oxidizing an aromatic feedstock at a temperature of about 110° C. to about 200° C. in a primary oxidation zone in the presence of a catalyst system to form a crude carboxylic acid composition; wherein said catalyst system comprises cobalt; (b) routing said crude carboxylic acid composition in a solid liquid displacement zone to form a slurry composition and a mother liquor; wherein at least a portion of said catalyst system in the crude carboxylic acid composition is removed in the mother liquor; wherein additional solvent is fed to said solvent liquid displacement zone; (c) oxidizing at a temperature of about 180° C. to about 280° C. in a post oxidation zone said crude carboxylic acid composition or said slurry composition in said post oxidation zone in the presence of added steam to form a post oxidation composition and an offgas stream; wherein said post oxidation zone comprises at least one post oxidation device; wherein said post oxidation composition comprises 4-carboxybenzaldehyde; and wherein said post oxidation zone results in at least 70% by weight conversion of said 4-carboxybenzaldehyde to terephthalic acid; and (d) crystallizing in a crystallization zone said post oxidation composition to form said crystallized post oxidation composition; wherein said crystallization zone comprises at least one crystallizer.