Co-pyrolysis mechanism of waste vehicle seats derived artificial leather and foam

Abstract

Co-pyrolysis is an important means to realize the clean disposal of organic wastes and generate some value-added chemicals. In the present study, the co-pyrolysis behavior of polyvinyl chloride (PVC) artificial leather (LE) and polyurethane foam (PU), the main components of waste vehicle seats, was systematically investigated to uncover the existing synergistic interaction effects. The pyrolysis experiments and kinetic analysis were carried out using TG/MS and Py-GC/MS, wherein the key parameters such as temperature and LE-to-PU mass ratio were examined. The co-pyrolysis of LE and PU at 650 °C remarkably accelerated the formation of aromatic compounds such as styrene. The relative content of aromatics from co-pyrolysis achieved 43.8%, which was much higher than that of 20.4% and 5.2% in the case of individual pyrolysis. The kinetic results further verified that the synergistic effect of LE and PU greatly lowered the reaction energy barriers of key steps in the co-pyrolysis, especially for the cases of LE-to-PU mass ratios of 3:2 and 2:3. The competing reactions such as intermolecular cross-linking of conjugated polyolefin intermediates and C–C cleavage, as well as the thermal conversion of methyl diphenyl diisocyanate in PU, favored the selective production of aromatics. In addition, the plausible pathways and synergistic mechanisms for the co-pyrolysis of LE and PU were discussed in detail. The present research significantly contributes to the selective upgrading of PVC artificial leather and polyurethane foam into high-quality pyrolysis oils rich in aromatics, thus achieving the clean disposal and resource utilization of waste vehicle seats.