Patent ID: 7358392

Claim:
A process to produce a purified carboxylic acid composition said process comprising: (a) oxidizing an aromatic feedstock in a primary oxidation zone to form a crude carboxylic acid slurry; (b) oxidizing said crude carboxylic acid slurry in a staged oxidation zone to form a staged oxidation composition; wherein said staged oxidation zone comprises at least one staged oxidation reactor operated at a temperature of about 150° C. to about 280° C.; (c) crystallizing in a crystallization zone said staged oxidation composition to form a crystallized composition; (d) removing in a solid liquid displacement zone impurities from said crystallized composition to form said purified carboxylic acid slurry; wherein said impurities comprise 4-carboxybenzaldehyde, trimellitic acid, and 2,6-dicarboxyfluorenone; wherein said solid liquid displacement zone comprises a solid liquid separator that is operated at a temperature between 110° C. and 200° C.; (e) cooling said purified carboxylic acid slurry in a cooling zone to form a cooled purified carboxylic acid slurry; and (f) filtering and drying said cooled purified carboxylic slurry in a filtration and drying zone to produce said purified carboxylic acid composition.