Study on the pyrolysis behaviors of mixed waste plastics

Pyrolysis is considered as a promising technology to recover valuable hydrocarbons from waste streams. Even though some studies exist on waste plastics pyrolysis, it still lacks of in-depth knowledge on multiple components plastics pyrolysis. This study explores three types of waste plastics and their mixed forms to obtain thermal cracking features, products distribution, and kinetic features. TG-FTIR was used to observe the decomposition characteristics and functional groups in the volatile fractions of products. The interaction effects of the plastics components during the co-pyrolysis process were compared, analyzed, and reported. For a more precise knowledge of the reaction procedure, a thermodynamic study was conducted. Results showed that TG and DTG curves of PS and PE were similar to each other but different from those of PVC. The main products of PE and PS pyrolysis were alkanes and alkenes, while the major products of PVC pyrolysis were HCl, alkenes, and a small number of aromatic compounds. During the co-pyrolysis process of PS with PVC and PE with PVC, the thermal decomposition rates of PVC were accelerated due to synergistic effect. Implied by the kinetic parameters, pyrolysis of PS, PE, and PVC exhibited one-order reaction from pure component to multiple component mixtures. (c) 2021 Published by Elsevier Ltd.