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 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:semantics><mml:mrow><mml:mi>mmo</mml:mi> <mml:msub><mml:mi>l</mml:mi> <mml:mi>PX</mml:mi></mml:msub> <mml:msubsup><mml:mrow><mml:mspace></mml:mspace> <mml:mi>g</mml:mi></mml:mrow> <mml:mi>Cu</mml:mi> <mml:mrow><mml:mo>-</mml:mo> <mml:mn>1</mml:mn></mml:mrow> </mml:msubsup> <mml:msup><mml:mi>h</mml:mi> <mml:mrow><mml:mo>-</mml:mo> <mml:mn>1</mml:mn></mml:mrow> </mml:msup> </mml:mrow> <mml:annotation>${\mathrm{mmo}}{{\mathrm{l}}_{{\mathrm{PX}}}}{\mathrm{\;g}}_{{\mathrm{Cu}}}^{-1} {{\mathrm{h}}^{-1}}$</mml:annotation></mml:semantics> </mml:math> -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.