Tandem Methanolysis and Catalytic Transfer Hydrogenolysis of Polyethylene Terephthalate to p‐Xylene Over Cu/ZnZrO _x Catalysts

We demonstrate a novel approach of utilizing methanol (CH₃OH) in a dual role for (1) the methanolysis of polyethylene terephthalate (PET) to form dimethyl terephthalate (DMT) at near-quantitative yields (~97 %) and (2) serving as an in situ H₂ source for the catalytic transfer hydrogenolysis (CTH) of DMT to p-xylene (PX, ~63 % at 240 °C and 16 h) on a reducible ZnZrO_x supported Cu catalyst (i.e., Cu/ZnZrO_x). Pre- and post-reaction surface and bulk characterization, along with density functional theory (DFT) computations, explicate the dual role of the metal-support interface of Cu/ZnZrO_x in activating both CH₃OH and DMT and facilitating a lower free-energy pathway for both CH₃OH dehydrogenation and DMT hydrogenolysis, compared to Cu supported on a redox-neutral SiO₂ support. Loading studies and thermodynamic calculations showed that, under reaction conditions, CH₃OH in the gas phase, rather than in the liquid phase, is critical for CTH of DMT. Interestingly, the Cu/ZnZrO_x catalyst was also effective for the methanolysis and hydrogenolysis of C-C bonds (compared to C-O bonds for PET) of waste polycarbonate (PC), largely forming xylenol (~38 %) and methyl isopropyl anisole (~42 %) demonstrating the versatility of this approach toward valorizing a wide range of condensation polymers.