Patent ID: 7132566
Filing Date: 2006-11-07
Classification: C07C

Abstract:
1. A process to produce a purified carboxylic acid composition comprising: (a) oxidizing an aromatic feed stock in a primary oxidation zone at an oxidizing temperature to form a crude carboxylic acid slurry composition; wherein said crude carboxylic acid slurry composition comprises at least one carboxylic acid; wherein there is less than 5% by weight terephthalic acid and isophthalic acid in said crude carboxylic acid slurry composition; (b) removing in a solid-liquid displacement zone impurities from said crude carboxylic acid slurry composition to form a slurry composition; and wherein said impurities comprise 4-carboxybenzaldehyde, trimellitic acid, or 2,6-dicarboxyfluorenone; (c) oxidizing said slurry composition in a staged oxidation zone to form a staged oxidation composition; wherein said oxidizing is conducted at an oxidizing temperature between about 190° C. to about 280° C.; wherein said oxidizing temperature in said staged oxidation zone is higher than the oxidizing temperature in said primary oxidation zone; (d) crystallizing said staged oxidation composition in a crystallization zone to form a crystallized composition; (e) cooling said crystallized composition in a cooling zone to form a cooled purified carboxylic acid slurry composition; and (f) filtering and optionally drying said cooled purified carboxylic slurry composition in a filtration and drying zone to produce said purified carboxylic acid composition.