Catalytic co-pyrolysis of woody biomass with waste plastics: Effects of HZSM-5 and pyrolysis temperature on producing high-value pyrolytic products and reducing wax formation

In this study, using an analytical pyrolysis-GC/MS system, pine sawdust was pyrolyzed with polyethylene (PE) and polyethylene terephthalate (PET) in the presence of HZSM-5 to investigate the effect of plastic. Pyrolysis was performed at 500 degrees C, 600 degrees C, and 700 degrees C after 3.0 mg feedstock loading. Chemical com-pounds were identified and classified into six groups: Monomeric Aromatic Hydrocarbon (MAH), Poly -cyclic Aromatic Hydrocarbon (PAH), Phenols, Furfurals, Alkenes, and Alkanes. Results showed that pine and PE co-pyrolysis significantly decreased oxygen content from 23.4% (pine only) to 0.3% (pine + PE/ HZSM-5), which increased products' HHV from 25.9 MJ/kg to 34.4 MJ/kg. It also revealed that the pine and PE ratio did not heavily influence the petrochemical concentration (aromatic hydrocarbons + alkenes (C < 15) + alkanes (C < 13)). However, a higher plastic ratio led to a higher wax production, which is the reason for poor condensation performance in condenser bio-oil capture. A pinewood sawdust to PE ratio of 3:1 showed the most higher-level petrochemicals and least amount of wax formation. Pine and PET co-pyrolysis produced significantly less wax and similar aromatic hydro-carbons to pine and PE co-pyrolysis. It also made as many acids as PET depolymerization and is a problem for pyrolysis oil use. (c) 2021 Elsevier Ltd. All rights reserved.

Automated summary

The study found that co-pyrolysis of pine and PE significantly reduced oxygen content and increased product HHV. A higher plastic ratio resulted in more wax production, affecting condensation performance in bio-oil capture. A pinewood sawdust to PE ratio of 3:1 yielded the highest petrochemicals and least wax formation.