Recovery of terephthalic acid by decomposition of PET in supercritical water

Abstract

The possibility for chemical recycling of PET via the recovery of terephthalic acid from decomposition of PET with supercritical water is investigated. PET decomposes to terephthalic acid and ethylene glycol, which are raw materials for PET, in supercritical water and the yield of terephthalic acid reaches 91% with purity of 97% under the conditions of 673 K, 40 MPa and reaction time of 12.5 min. Reaction temperature influences the decomposition rate of PET. It takes 90 min for 90% terephthalic acid recovery at 573 K. Increasing reaction pressure is effective for suppressing char formation or carbon dioxide production during decomposition.