Pyrolysis of poly(ethylene terephthalate) in a fluidised bed plant

Abstract

Chemical recycling of poly(ethylene terephthalate) (PET) materials was carried out by pyrolysis with a fluidised bed reactor between 510 and 730 °C. Several PET materials, with and without fillers, were successfully decomposed. Almost all products were gases and solids. The yield of gases was between 38 and 49 wt%. Pyrolysis gas consisted chiefly of CO 2 and CO. Other gases like methane, ethane and hydrogen occurred in small yields. The other major fraction was formed by solid products. Above all, the organic residues in the reactor increased strongly with temperature. Just 5 wt% of organic residues were found in the reactor at a temperature of 510 °C, but 40 wt% at 730 °C. The amount of oxygen containing compounds decreased with increasing temperature due to the decomposition of terephthalic acid and benzoic acid. The amount of liquid products was small. The aliphatic hydrocarbons in oil fraction were slight, but aromatic hydrocarbons were found between 2 and 5 wt% of all organic products due to formation of benzene, benzene derivatives and naphthalene derivatives, respectively.