Process for producing highly pure terephthalic acid

摘要

There is disclosed a process for producing highly pure terephthalic acid by subjecting a p-phenylene compound to liquid-phase oxidation in the presence of acetic acid as a solvent, producing highly pure terephthalic acid through the refining treatment of the crude terephthalic acid, separating water through the azeotropic distillation of the mother liquor from the oxidation reaction, and recycling the resultant water as a solvent for the liquid-phase oxidation which process is characterized by extracting useful components contained in the PTA mother liquor remaining after the separation of the terephthalic acid with an azeotrope forming agent; using the agent in a distillation tower for discharging the water formed from the mother liquor; and treating the resultant extract containing the agent by using the distillation tower. The above process can greatly reduce the effluent water treatment load and enhance the yield of the objective terephthalic acid in addition to the recovery of the useful ingredients.