METHOD FOR REMOVING SOLID FOREIGN MATTER FROM AQUEOUS SOLUTION OF TEREPHTHALIC ACID

摘要

PURPOSE:To stably and efficiently remove fine solid foreign matters from an aqueous solution of crude terephthalic acid over a long period and improve the quality of a polymer derived from terephthalic acid by contacting an aqueous solution of crude terephthalic acid with a catalyst containing a noble metal and filtering the product with a specific filter. CONSTITUTION:An aqueous solution of crude terephthalic acid obtained by the liquid-phase oxidation of p-xylene with molecular oxygen is subjected to the contact treatment with a catalyst containing a noble metal such as palladium. Solid foreign matters are removed from the treated aqueous solution of terephthalic acid by using a filter produced by winding a twisted yarn of a carbon multifilament around a bobbin provided with holes 5 and having at least one opened end and covering the side face of the bobbin 1 with the wound carbon multifilament yarn.