Valorization of Waste Polyester for 1,4-Cyclohexanedimethanol Production

Polyesters, especially polyethylene terephthalate (PET), are widely used in plastic bottles and clothing fibers because of their stability and cost-effectiveness. Upcycling waste polyesters into value-added materials not only solves the environmental crisis but also realizes significant economic interests. Here, we report a step-economic two-step catalytic process for the upcycling of waste polyester materials, specifically PET, into 1,4-cyclohexanedimethanol (CHDM), an essential monomer for functional polyesters and key feedstock for the liquid crystal industry. The combination of PET methanolysis and hydrogenation of aromatic rings significantly reduces the reaction temperature and energy consumption of the depolymerization of PET, which introduces remarkable engineering benefits. By developing the CO-resistant bifunctional Ru/MnO2 and CuZnZr mixed oxide catalyst system, PET is demonstrated to be converted completely with the final yield of CHDM up to 78%. The implementation of the two-step catalytic process for transforming PET into CHDM holds significant implications for advancing the value chain of polyesters and contributing to waste material utilization for a renewable future.