Towards enhanced understanding of synergistic effects in co-pyrolysis of pinewood and polycarbonate

Utilization of biomass and plastic wastes has drawn growing attention in recent years as it offers promising pathway for simultaneous energy production and waste disposal. In this paper, the co-pyrolysis of pinewood and polycarbonate was performed in a fixed bed reactor with focus on determining the extent of synergistic effects and unraveling the underlying synergistic mechanism. The extent of synergistic effects was quantified via direct comparison of the results from co-pyrolysis of pinewood-polycarbonate mixture with the weighted average values from individual components pyrolysis. The observed synergistic effects were further deconvolved into different component interactions (such as volatiles-volatiles interactions, volatiles-feedstocks interaction, and catalytic effects of chars) using tailored feedstock configurations to gain more insights into the synergistic mechanism. The results showed that co-pyrolysis enhancedH2 by 33%, CO by 26%, and total syngas yields by 19% as compared to their weighted values from individual pyrolysis. Co-pyrolysis also exhibited superiority in energy recovery as the overall energy efficiency was noticeably promoted from 42.9% to 48.6%. Deconvolution of synergistic effects revealed that volatiles-volatiles interactions were the primary contributor for the enhancement of H2 and CO. Examination of volatiles-feedstock interactions indicated that the highly reactive pinewood volatiles facilitated polycarbonate degradation, while polycarbonate volatiles were relatively stable and unable to promote pinewood decomposition. Furthermore, pinewood char catalytically enhanced polycarbonate degradation. This paper provides a deconvolved understanding of synergistic effects in co-pyrolysis of lignocellulosic biomass and polycarbonate wastes, which is very helpful in designing clean and efficient energy recovery systems from these waste resources.