Internal Dimethyl Carbonate Circulation-Promoted Synergistic Co-Recycling of Polycarbonates and Polyesters in Methanol

Abstract Co-recycling of mixed plastic streams offers a viable opportunity to manage spent plastic mixtures and realize a circular economy. Herein, we present an internal dimethyl carbonate (DMC) circulation-promoted co-recycling of polycarbonate (PC) and polyester mixture into their monomers in methanol under mild conditions (e.g., 120 °C). In this protocol, PC is first methanolized to generate DMC and diol under the catalysis of ionic liquids (e.g., 1-butyl-3-methylimidazolium chloride ([BMIm][Cl])), and the resultant DMC participates in the subsequent degradation of polyester over the same catalyst, yielding dimethyl ester and carbonate. Furthermore, the generated carbonate is quickly converted into DMC under the experimental conditions, thus forming an internal DMC circulation. This strategy can be employed in handling mixtures of PC and polyester with various ratios using methanol, affording corresponding monomers in high yields. It provides an innovative perspective that accelerates the development of co-recycling technology for mixed plastic wastes.