Patent ID: 7884231

Claim:
A process to produce an enriched composition suitable for use in the production of step-growth polymers, said process comprising: (a) oxidizing an aromatic feedstock comprising para-xylene in a primary oxidation zone to form a crude carboxylic acid composition comprising terephthalic acid; (b) optionally subjecting said crude carboxylic acid composition to a liquid displacement zone to form a slurry composition; (c) oxidizing said slurry composition or said crude carboxylic acid composition in a staged oxidation zone to form a staged oxidation composition; (d) cooling and optionally enriching said staged oxidation composition in a cooling zone to form a cooled carboxylic acid composition; (e) subjecting said cooled carboxylic acid composition, a wash feed, and optionally an enrichment feed to a catalyst removal zone to form a post catalyst removal composition, a wash liquor, a catalyst rich liquor and optionally a depleted enrichment feed; and (f) contacting in an enrichment zone, said post catalyst removal composition comprising terephthalic acid in an amount greater than 50% by weight with an enrichment feed to form said enriched composition; wherein said enrichment feed comprises at least one compound selected from the group consisting of isophthalic acid, phthalic acid, benzene-tricarboxylic acid isomers, hydroxybenzoic acid isomers, hydroxymethylbenzoic acid isomers, dicarboxybiphenyl isomers, dicarboxystilbene isomers, tricarboxybiphenyl isomers, tricarboxybenzophenone isomers, dicarboxybenzophenone isomers, dicarboxybenzil isomers, form-acet-hydroxybenzoic acid isomers, acet-hydroxymethylbenzoic acid isomers, and phthaldehyde isomers.