Investigate the potential synergistic interactions for co-pyrolysis of olive stone and polyolefinic plastic to increase the quality of pyrolysis oils

The development of sustainable, clean modern energy carriers has swept across the energy sector in line with the goals of moving towards low carbon economies. This has resulted in the increased utilisation of previously neglected solid organic waste resources as alternative carbon feedstocks for fuels and petrochemicals, as evidenced by more research towards valorisation of lignocellulosic and plastic waste resources. Co-pyrolysis has been identified as a potential pathway to benefit from this readily available stream of residual carbon providing a platform to produce valuable products that may fit into the different energy vector streams. Despite a lot of work being done at microscale pyrolysis to determine the synergistical potential of co-feeding, less work has been done on large scale reactors with potential for commercialisation on the impact of co-pyrolysis to improve the quality of pyrolysis oils. In this study, our focus is identifying potential synergy between devolatilization and condensation products that may occur in the presence of an inert and catalytic bed under bench scale fluidised bed conditions. The product distribution from non-catalytic pyrolysis of olive stone and polyethylene was comprised of derivatives indicative of a combination of the individual pyrolysis products i.e., oxygenated biomass derivatives plus olefinic monomers plastic derivatives. This could suggest that condensation synergy as suggested by Gunasee, et al. [1] may be the dominant process, requiring changes in operating procedure to allow for secondary reactions. For the catalytic experiments, the product distribution was shifted due to secondary reactions, however there was no conclusive information to distinguish the type of synergy that may have occurred, i.e., devolatilization/condensation synergy. There is still ongoing work on this project to try to optimise the process parameters towards increasing the interactive devolatilization synergy towards improving the quality of pyrolysis oils.