Unlocking High-Concentration PET Upcycling via Site-Decoupled Copper Catalysis

Upcycling polyethylene terephthalate (PET) plastic waste on islands into valuable fuels represents a promising strategy for carbon resource utilization and circular economy development; however, this approach faces critical challenges, including low processing concentrations (currently C_PET < 1.5 wt%) and fast catalyst deactivation under high-temperature redox conditions. Herein, we report a site-decoupled copper catalyst (Cu/MgAlGaZnO_x) that unlocks quantitative conversion of PET to p-xylene (PX) at unprecedented concentrations (15.1 wt%), achieving a record PX formation rate of 10.1 $\mathrm{mmo}{l}_{\mathrm{PX}}{g}_{\mathrm{Cu}}^{-1}{h}^{-1}$ -7.8-fold higher than prior CuNa/SiO₂ systems. In situ spectroscopy reveals that ethylene glycol (EG) fragment oxidation during depolymerization reduces Cu⁺ species in conventional catalysts, triggering rapid deactivation. By contrast, oxygen vacancies (O_v) in the GaZnO_x support adsorb methanolysis intermediates, spatially segregating depolymerization (GaZnO_x) from hydrodeoxygenation (Cu/MgAlO_x). This decoupling stabilizes active Cu⁺/Cu⁰─O_v sites, enabling sustained operation at high PET concentrations. Our work establishes site decoupling as a general strategy for stabilizing redox catalysts in polymer upcycling under demanding environments.