Thermal and catalytic decomposition of mixed plastics. III¹ PVC-containing mixed plastics

Thermal and catalytic degradation over an orthophosphoric acid-modified zeolite catalyst (P-ZSM-5) of two polymer mixtures with the composition close to that of the municipal plastic waste and containing or not PVC has been studied. The condensed pyrolysis products were characterised by standard methods used in petrochemical laboratories and by gas Chromatographic methods. It has been established that P-ZSM-5 catalyst turns the waxy products of the uncatalytic pyrolysis into oil containing light compounds and significant amount of aromatic hydrocarbons, having stronger effect with increasing temperature. PVC destabilises at degrades the other polymers of the mixture forming supplementary light pyrolysis compounds, unfortunately most of them being chlorinated hydrocarbons. Therefore a preliminary dechlorination step is necessary to obtain good quality decomposition products from mixed plastic pyrolysis. P-ZSM-5 catalyst was found to be stable in the decomposition conditions used.