Recovery of oil from waste poly(ethylene terephthalate) without producing any sublimate materials

When household waste plastics are thermally decomposed, sublimate materials such as terephthalic acid and benzoic acid are produced, which cause serious pipe blocking in plants built for the degradation of the waste. The sublimate materials produced have been successfully decomposed using FeOOH catalyst. The main products were acetophenone, phenol, benzene and carbon dioxide. Ni(OH)(2) and NiO showed low activity, and Fe2O3 was inactive. A reaction mechanism is proposed and kinetic equations derived. These model equations were found to represent the experimental data well. FeOOH catalyst was transformed into porous Fe2O3 with pores of about 50-10nm in diameter after steam treatment above 773 K. Many active sites are thought to be generated on the surface of the pores. As expected from this result, an iron ore containing a large amount of FeOOH was found to show high activity for the decomposition of terephthalic acid, whereas the activity of an iron ore containing Fe2O3 was negligible. This suggests that an iron ore with a large amount of FeOOH can be used as a cheap catalyst with high mechanical strength for the degradation of poly(ethylene terephthalate) without producing any sublimate. (C) 1998 Elsevier Science Limited. All rights reserved.