Patent ID: 7880032

Claim:
A process for treating a purge feed stream produced in a terephthalic acid (TPA) production process or in an isophthalic acid (IPA) production process; wherein said purge feed stream comprises impurities, produced in an oxidation step from said terephthalic acid (TPA) production process or in said isophthalic acid (IPA) production process, and one or more catalyst components, wherein said impurities comprise mono-functional impurities and non-mono-functional impurities, wherein said mono-functional impurities comprise at least one compound selected from the group consisting of benzoic acid (BA), bromo-benzoic acid, bromo-acetic acid, 4-CBA, p-TAc, monocarboxyfluorenones, and monocarboxyfluorenes; and wherein said non-mono-functional impurities comprise at least one compound selected from the group consisting of isophthalic acid, trimellitic acid, 2,5,4″-tricarboxybiphenyl, 2,5,4″-tricarboxybenzophenone, and dicarboxyfluorenones; said process comprising: (a) separating said purge feed stream into (i) a mono-functional impurity rich stream containing catalyst that is rich in at least one of said mono-functional impurities; and (ii) a non-mono-functional impurity rich stream that is rich in at least one of said non-mono-functional impurities; and (b) separating said non-mono-functional impurity rich stream into (i) a wash liquor stream; and (ii) a mono-functional impurity depleted stream; wherein a portion of said mono-functional impurity depleted stream is subsequently combined with a TPA and/or IPA product stream to form a combined stream.