DEGRADATION OF WASTE POLY(ETHYLENE-TEREPHTHALATE) IN A STEAM ATMOSPHERE TO RECOVER TEREPHTHALIC ACID AND TO MINIMIZE CARBONACEOUS RESIDUE

Poly(ethylene terephthalate) (PET) waste was successfully decomposed i n a steam atmosphere, yielding an amount of terephthalic acid predicte d from the chemical formula of PET. It was found that steam accelerate d the hydrolysis of PET, yielding terephthalic acid and oxygen-contain ing compounds such as aldehyde and ester with less than 1% carbonaceou s residue. The amount of carbonaceous residue decreased with an increa se in the fraction of steam in the carrier gas and was about 16% in ni trogen steam and below 1% in steam. The amount of terephthalic acid pr edicted from the chemical formula of PET (about 87%) was recovered at about 723 K in a carrier gas containing 70% steam and 30% nitrogen. Ki netic equations are proposed by considering both the hydrolysis and th ermal pyrolysis of PET. (C) 1997 Elsevier Science Limited.