Insight into interface chemistry of metal oxides anchored on biowaste-derived support for highly selective glycolysis of waste polyethylene terephthalate

Abstract

The unprecedented rise of polyethylene terephthalate (PET) waste demands sustainable solutions like catalytic glycolysis, a promising recycling technology that mitigates environmental harm. Herein, we synthesized a series of novel Mo-Zn@SiO2 catalysts for PET glycolysis, derived from readily available rice husk ash via the wetness impregnation method. The optimum Mo-Zn@SiO2 exhibits exceptional activity, achieving complete PET conversion and a 90.4 % yield of bis(2-hydroxyethyl) terephthalate (BHET) – one of the highest performances reported for heterogeneous catalysts. Density functional theory (DFT) calculations suggest that the formation of the ZnMoO4 phase optimizes reactant and product adsorption energies, enhancing Lewis acidity and facilitating depolymerization. Kinetic studies reveal a low apparent activation energy (139.27 kJ/mol) for BHET production at 175–190 °C. Additionally, the catalyst demonstrates excellent recyclability, maintaining activity after five cycles. This work presents a viable and efficient strategy for PET waste valorization using a low-cost, readily available, and easily synthesized catalyst.