Selective Recycling of Mixed Polyesters via Heterogeneous Photothermal Catalysis

Abstract

The selective recycling of mixed plastic wastes with similar structural units is challenging. While heterogeneous catalysis shows potential for selective recycling, challenges such as complex mass transfer at multiphase interfaces and unclear catalytic mechanisms have slowed progress. In this study, a breakthrough in recycling mixed polyester wastes is introduced using heterogeneous photothermal catalysis. By adding co-solvents, the difficulties associated with multiphase interfacial mass transfer are overcome. Grain boundary (GB)-rich CeO₂ photothermal catalysts are used to selectively glycolyze mixed poly(ethylene terephthalate) (PET) and poly(bisphenol A carbonate) (PC) plastics into bisphenol A (BPA) and bis(2-hydroxyethyl) terephthalate (BHET), achieving yields of 97.8% and 93.4%, respectively. The high concentration of oxygen vacancies in GB-rich CeO₂ catalysts adjusts the adsorption energy of intermediates, leading to more selective and efficient depolymerization compared to GB-poor CeO₂ catalysts. The economic and environmental analysis demonstrates that this process, which utilizes heterogeneous photothermal catalysis, provides significant energy savings and carbon reduction, representing a major advancement in mixed plastic waste recycling.