(83c) Catalytic Microwave Assisted Pyrolysis of Waste Plastics for Production of Value Added Chemicals

Microwave-assisted catalytic pyrolysis is emerging as a viable technique for converting plastic waste derived from petroleum into valuable chemicals, supporting a more sustainable circular economy. In this research, the catalytic pyrolysis of low-density polyethylene (LDPE) was performed using microwave heating, and the effects of different catalysts (HZSM-5, Ga/ZSM-5, Ga/Ni/ZSM-5, Ga/Co/ZSM-5, and Ga/Cu/ZSM-5) on product yield and composition were evaluated. Among the catalysts tested, Ga/ZSM-5 produced the highest liquid oil yield, approximately 41%. The Ga/Ni/ZSM-5 catalyst demonstrated superior performance in generating long-chain olefins, accounting for roughly 27% of the liquid output. In contrast, Ga/Co/ZSM-5 resulted in the formation of heavier pyrolysis oils, with about 25% long-chain paraffins, making it less effective for high-value chemical production. On the other hand, Ga/Cu/ZSM-5 yielded an oil rich in aromatic compounds, with benzene derivatives comprising about 90% of the liquid fraction, indicating its suitability for the desired application. The liquid products were analyzed using SimDist, showing that the HZSM-5 catalyst could produce an 86.4% naphtha fraction. Moreover, Ga/Cu/ZSM-5 was found to produce the highest levels of hydrogen and syngas, as revealed by MicroGC analysis, and exhibited the most coke deposition (1.35%) after the reaction, likely due to the high aromatic hydrocarbon content and significant hydrogen release. A comparison between fresh and spent catalysts was conducted to examine catalyst activity and the influence of metal doping on product distribution. These results highlight the promise of microwave-assisted catalytic pyrolysis, particularly with Ga/Cu/ZSM-5, for efficiently converting plastic waste into valuable chemicals, promoting sustainable resource use and environmental protection.