Patent ID: 6075163
Filing Date: 2000-06-13
Classification: C07C

Abstract:
A process for manufacturing terephthalic acid wherein polyethylene terephthalate is hydrolyzed and crystallized to give terephthalic acid in accordance with the practice of this invention comprising the following processes:(a) a process in which PET scrap is hydrolyzed by alkali metal/earth metal hydroxide in the presence of solvent and a wetting agent, to prepare terephthalic acid alkali metal/earth metal salt;(b) a process in which an aqueous solution of terephthalic acid alkali metal/earth metal salt dissolved in water was separated as solids and liquids; the solids are fed back to said (a) step hydrolysis process or discharged, while the liquids are transferred to the next adsorption process;(c) a process in which an aqueous solution of terephthalic acid alkali metal/earth metal salt is adsorbed and neutralized with acid to give terephthalic acid;(d) a crystallization process to enlarge the particle of terephthalic acid;(e) and, a process in which the enlarged partide of terephthalic acid is cooled under reduced pressure, filtered and dried.