Efficient low-temperature depolymerization of polycarbonate catalyzed by lanthanum β-diketonate complexes

Abstract

The chemical recycling of polycarbonate is crucial for addressing plastic waste and promoting sustainability. Conventional methods often require high temperatures and harsh conditions, leading to energy consumption and potential degradation of the recovered monomers. In this study, we present a high-yielding depolymerization of BPA-based powdered polycarbonate, prepared through a pretreatment with toluene as the substrate using a series of lanthanum β-diketonate complexes as catalysts. Among the complexes investigated, lanthanum 3,4-dimethoxybenzoylacetonate exhibited the highest catalytic activity. This method enables depolymerization at significantly lower temperatures (e.g., 60 °C) compared to conventional approaches without using co-solvent. Under optimized conditions, we achieved a high depolymerization rate to give monomers in 96% and 93% yield within 8 h. This mild and high-yielding depolymerization process offers a promising approach to sustainable polycarbonate recycling and contributes to the development of a circular economy.