Highly Efficient Depolymerization of Polycarbonate Enabled by Dispersions of Ultrasmall ZnO Nanoparticles

In the pursuit of circular economies aimed at achieving sustainable development, chemical recycling emerges as a promising method for transforming polycarbonate (PC) plastic into a value-added monomer. Herein, methanol dispersions of ultrasmall ZnO nanoparticles (∼4 nm) are firstly utilized for the catalytic methanolysis of PC. Under mild reaction conditions (120 °C, 1 h) with a low catalyst amount (0.8 wt %), a complete conversion of PC and a 97.8% yield of BPA could be achieved. The above conditions are also capable of depolymerizing representative real PC plastic wastes (DVD disks, CD disks, and PC sheets) into BPA with a yield of at least 96%, exhibiting excellent prospects for industrial application. Furthermore, the possible mechanism of PC methanolysis was proposed, and the kinetics of reaction was investigated with an activation energy of 122.39 kJ/mol. More importantly, the activity can reach as high as 125 g PC h–1 (g ZnO)−1, the highest reported to date.