Efficient and Sustainable Closed‐Loop Recycling of Broad Range Polyester Plastic Wastes over In Situ Grown Bifunctional ZnO–SiO 2 Catalysts

Abstract The growing accumulation of plastic waste presents serious environmental and health concerns, necessitating efficient recycling technologies to support a circular economy. Here, a cost‐effective and efficient catalyst is reported for depolymerizing polyethylene terephthalate (PET) and various polyesters into their respective monomers. This closed‐loop recycling strategy is inspired by solvolysis and enabled by a bifunctional acid–base ZnO–SiO 2 catalyst. An in situ growth method enhances metal–support interactions at the Zn─O─Si interface, leading to the formation of Zn─O─Si species and well‐dispersed small ZnO nanoclusters (≈3.5 nm), which generate abundant acid–base active sites. The optimized catalyst achieved a 94% yield of bis(2‐hydroxyethyl) terephthalate (BHET) from PET glycolysis at 180 °C in 1.5 h under co‐solvent‐free conditions. It further exhibits high catalytic efficiency in the methanolysis of PET and other polyesters (polybutylene terephthalate (PBT), polybutylene succinate (PBS), and polylactic acid (PLA)), with monomer yields above 90%. A scale‐up experiment with 10 g PET delivers ≈90% BHET yield, confirming the catalyst's practical applicability. Green chemistry metrics are used to validate the efficiency and sustainability of the process. The high monomer productivity (40–50 g monomer ·g catalyst −1 ·h −1 ) and reduced environmental footprint highlight the promise of this system for sustainable plastic upcycling.