Hydrolytic degradation of poly(ethylene terephthalate) in a pyrolytic two step process to obtain benzene rich oil

Poly(ethylene terephthalate) (PET) was degraded in a two step process to obtain a valuable oil, consisting mainly of benzene. First, PET was hydrolyzed in a steam atmosphere at 450°C, and the resulting terephthalic acid was decarboxylized in the presence of CaO. By separating the two fundamental reactions of this degradation process, the hydrolysis reaction and decarboxylation, the amount of residue was reduced, and the amount of benzene obtained increased. It was found that the best results were obtained at a decarboxylation temperature of 700°C, with a yield of 48% benzene. At lower temperatures, the terephthalic acid was adsorbed at the catalyst without decarboxylation; at higher temperatures, large amounts of char were formed due to pyrolytic reactions. Unlike solvolysis processes, no solvent is used in this process; in effect eliminating the expense of processing waste liquids.