A review of recent advances in thermal-catalytic cracking of plastic waste

Abstract

The extensive use of plastics has resulted in severe environmental pollution, making the valorization of plastic waste not only a strategy for value recovery but also an effective approach to mitigate its environmental impact. Consequently, this topic has become a focal point of research in industry and academia. Pyrolysis is a key step in the carbon resource conversion of plastic waste, facilitating the degradation of complex polymeric materials into high value products such as alkanes, olefins, and BTX. This review summarizes recent advancements in plastic pyrolysis technologies, as a focus on scientific challenges and technological breakthroughs in this domain. Through a systematic analysis, the study examines the pyrolysis mechanisms and current research status of the most widely used plastics, exploring the critical factors influencing the pyrolysis process including reaction conditions, such as temperature, residence time, and catalyst dosage, and the reactor design which has a significant role in improving the pyrolysis efficiency and product selection. This review provides a summary of commonly used catalyst types, with emphasis on the exceptional performance of zeolite based catalysts and their metal modified productions. Research indicates that zeolite catalysts, owing to their strong acidity and stable pore structures, markedly enhance the activity and selectivity of pyrolysis reactions. Other catalysts such as FCC catalysts, clay catalysts and metal oxides have shown promising catalytic performance under certain conditions, offering potential for the industrial applicability of plastic pyrolysis technologies. However, plastic waste pyrolysis research remains a challenge, including regulation of reaction pathways for co-pyrolysis of multi-component plastics, reducing catalyst deactivation, and optimization of energy efficiency. These challenges not only limit further promotion of pyrolysis technologies but also demand more fundamental scientific research and engineering advances. Finally, we conclude with future research directions, with suggestions for theoretical guidance and technology support for plastic waste pyrolysis development and industrial applications.