Morphology tuned MnO_x loaded carbonaceous catalyst for depolymerization of PET plastic waste into valuable monomer

The selective chemical recycling of polyethylene terephthalate (PET) from plastic waste streams remains a critical challenge in advancing circular polymer economies. Herein current study, we synthesized morphology tuned carbonaceous catalysts loaded with MnO_x and performed catalytic evaluation of heterogenous catalyst for glycolytic depolymerization of PET plastic waste to bis(2-hydroxyethyl) terephthalate (BHET) monomer with high selectivity. The systematic optimization of reaction parameters like EG(ethylene glycol)/PET mass ratio, catalyst loading, temperature, and reaction time-yielded complete PET conversion (>99%) and a BHET yield exceeding (>90%) under mild conditions (180 °C, 4 h, 1 wt% catalyst). The Mn²⁺/Mn³⁺ redox couple provides synergistic Lewis acid activation of PET ester carbonyl bonds, facilitating nucleophilic attack by ethylene glycol through a concerted polarization-nucleophilic mechanism. Catalyst characterization via XRD, XPS, FTIR, Raman Spectroscopy, BET, FE-SEM and TEM confirm the presence of strong Lewis acid sites, with a high surface area and the redox-active Mn²⁺/Mn³⁺ surface speciation responsible for catalytic turnover. The catalyst exhibited stable performance and maximum monomer yield among existing catalysts, Across consecutive recycling cycles of catalyst with less activity loss. Comparative benchmarking against reported catalytic systems underscores the competitive performance, operational simplicity, easy recovery, and sustainability of the MnO_x system, positioning it as a viable platform for scalable, solvent-efficient chemical recycling of PET.