Synergistic recycling of polycarbonate: efficient BPA recovery integrated with CO2 utilization to produce valuable chemicals

Abstract

The chemical recycling of polycarbonate (PC) plastics offers a sustainable solution to address resource depletion and environmental pollution caused by bisphenol A (BPA) release. While hydrolysis is a promising method, it is hindered by significant CO₂ emissions resulting from the breakdown of carbonate groups in the PC structure, limiting its carbon utilization efficiency and practical application. To address this challenge, we developed a synergistic strategy that integrates PC hydrolysis with the high-value utilization of by-product CO₂. Using a [Bmim][Br]/ZnBr₂/K₂CO₃ catalytic system and styrene oxide (SO) as a CO₂ capture reagent, this one-pot process achieved complete PC conversion, with BPA and 4-phenyl-1,3-dioxolan-2-one (PDO) yields of 99.6% and 99.0%, respectively. The method also demonstrated excellent substrate versatility, achieving BPA yields ≥91.1% and cyclic carbonate yields ≥76.1% across various epoxides and real-world waste plastic systems. Mechanistic studies revealed that trace water and in situ formed N-heterocyclic carbenes (NHCs) are the key factors for PC depolymerization. Furthermore, kinetic studies demonstrated that the SO-triggered cycloaddition further promotes the depolymerization of PC. This work establishes a sustainable and efficient pathway for PC recycling, eliminating CO₂ emissions, maximizing carbon utilization, and offering a promising solution for managing waste PC plastics.