Patent ID: 7888530

Claim:
A process comprising: (a) providing a slurry comprising a solid phase and a liquid phase comprising a mother liquor, wherein said solid phase contains a first quantity of terephthalic acid, wherein said liquid phase contains a second quantity of terephthalic acid; (b) subjecting at least a portion of said first quantity of terephthalic acid to oxidation treatment to thereby produce oxidation-treated terephthalic acid; wherein said oxidation-treated terephthalic acid has a b* value of about 3.5 to about 10 and a 4-carboxybenzaldehyde (4-CBA) and para-toluic acid (p-TAc) content totaling greater than 700 ppmw; and (c) subjecting at least a portion of said mother liquor containing said second quantity of said terephthalic acid to evaporation treatment to form a concentrated slurry having more than about 10 weight % solid terephthalic acid particles, and subsequently subjecting said second quantity of terephthalic acid to hydrogenation treatment to thereby produce hydrogenation-treated terephthalic acid; wherein said hydrogenation-treated terephthalic acid has a b* value of less than 3.0 and a 4-CBA and p-TAc content totaling less than 700 ppmw; and; (d) combining at least a portion of said oxidation-treated terephthalic acid with at least a portion of said hydrogenation-treated terephthalic acid to produce a final composite acid suitable for use in the manufacture of polyesters; wherein the ratio of the amount of said oxygenation-treated terephthalic acid to said hydrogenation-treated terephthalic acid combined with one another is in the a range of from about 10:1 to about 1,000:1 by weight; wherein said process further comprises recovering solid particles of said second quantity of terephthalic acid prior to said hydrogenation treatment of step (c).