Co-pyrolysis of various plastic waste components as an environmentally sustainable source of alternative fuels

Abstract

In this study, pyrolysis and co-pyrolysis of commonly used plastic materials (poly(ethyleneterephthalate) - PET, high density polyethylene - HDPE, and polystyrene - PS) were conducted to analyse the chemical composition of the corresponding pyrolyzates. Different ratios of plastic materials were applied to obtain a composition of aliphatic and aromatic degradation products that closely resemble those of conventional fossil fuels. The systematic chemical variations can act as base for evaluating this approach as a sustainable source of alternative fuels. HDPE revealed an aliphatic composition of degradation products, while PS and PET produced only aromatic compounds. Quantitative analysis of the obtained pyrolyzates revealed a clear correlation of initial proportion with the resulting quantitative product composition. The generation of individual pyrolysis products revealed a high reproducibility. However, it became evident that the decomposition products of PS consistently emerged as the most prominent among all tested HDPE/PS mixtures. The ratio of HDPE : PS=1:3 revealed 96 % of the aromatic compounds as PS decomposition products. PET revealed a oxygen containing structure of the products, contributing to 83 % of the HDPE : PET=1:3 mixture. These results gain insights into the potential of plastic waste as a sustainable source for alternative fuels and valuable chemicals.