Process for preparing purified terephthalic acid

摘要

The present invention relates to a process for preparing purified terephthalic acid (PTA), comprising the steps: i) dissolving crude terephthalic acid (CTA) in an aqueous medium in a reactor; ii) hydrogenating CTA at a temperature of about 260 - 320°C and a pressure of about 1100 - 1300 psig using an hydrogenation catalyst; iii) crystallizing terephthalic acid in the reactor by lowering the temperature of the solution to about 160°C without evaporation cooling; iv) transferring the content of the reactor to a filtration unit; v) filtrating the content at a temperature of about 140 - 160°C and a pressure of about 40 - 100 psig, preferably 80 - 100 psig to obtain a filter cake; vi) washing the filter cake obtained with water having a temperature of about 140 - 160°C in the filtration unit; and vii) drying the filter cake.