Experimental Study on Microwave-Assisted Co-Pyrolysis of Plastic Waste and Biomass

Non-recyclable plastic waste (PSW) and residual lignocellulosic biomass (WP) represent abundant yet underused resources whose conversion can generate renewable fuels with synergistic benefits. While conventional pyrolysis remains limited by slow heat transfer and poor adaptability to heterogeneous feeds, microwave-assisted pyrolysis (MAP) offers faster volumetric heating and improved syngas quality, though it is still largely confined to the laboratory scale due to limited understanding of feedstock interactions and process behaviour. In this context, the present work provides a laboratory-scale experimental investigation of the MAP co-pyrolysis of PSW/WP blends, focusing on gas yield and syngas quality, and complements the experimental analysis with a preliminary scale-up assessment for a continuous microwave reactor. The results reveal clear synergistic effects, with gas yields exceeding those predicted by linear mixing. A 70/30 wt% PSW/WP blend produced a hydrogen-rich syngas with H2 concentrations of approximately 42 vol% and an H2/CO ratio of 2–3. Compared to conventional pyrolysis under analogous conditions, MAP increased hydrogen content by around 35% and reduced CO2 concentrations by up to 40%, resulting in a cleaner and more energy-dense gas. Overall, the findings highlight the strong potential of MAP for the valorization of mixed plastic–biomass wastes.