Catalytic Oxidation of Commodity Plastics: Advances in Polyethylene and Polystyrene Valorization

Polyethylene and polystyrene are among the most representative hard-to-degrade plastic due to their chemical inertness and massive generation, making their efficient upcycling a pressing challenge for environmental sustainability. Conventional recycling methods, such as incineration, landfilling, and mechanical processing, often cause high energy consumption, severe pollution, and product devaluation, which is unfavorable for circular utilization of plastics. In contrast, chemical recycling, particularly catalytic oxidation, has recently gained much attention for enabling plastic valorization under relatively mild conditions, with straightforward separation processes and high-value products. Despite these advantages, catalytic oxidation remains at an early stage, facing challenges such as unclear catalyst structure-activity relationships, insufficient reactivity, and limited selectivity. To address these issues, this review highlights recent advances in the catalytic oxidative conversion of polyethylene and polystyrene, focusing on catalyst design, reaction mechanism elucidation, and product selectivity control. Furthermore, perspectives are provided on future research directions, including the development of novel catalysts, optimization of mass transfer, regulation of reactive oxygen species, adaptability to mixed plastic waste, techno-economic analysis, life cycle assessment, and reaction safety evaluation.