A Manganese–Cerium Composite Oxide Catalyst for Highly Efficient Glycolysis of Waste Polyethylene Terephthalate Plastics

The glycolysis of polyethylene terephthalate (PET) has emerged as an efficient catalytic approach for recycling monomers from plastic waste, with reaction efficiency and product selectivity critically governed by catalyst design. Herein, we report a readily available and efficient manganese–cerium composite oxide (MnCeOx) for PET glycolysis to the monomers, i.e., bis(2-hydroxyethyl) terephthalate (BHET) and ethylene glycol. A series of MnCeOx catalysts with different Mn/Ce ratios and calcination temperatures were prepared, characterized, and evaluated in PET glycolysis, among which Mn0.33CeOx-550 exhibited optimal performance, achieving a 95.6% BHET yield at 200 °C within 150 min. The catalytic system demonstrated broad applicability in the conversion of various PET-based waste plastics, including PET bottles, PET woven tapes, and PET transparent films, to the target monomers with high yields. Mechanistic investigation revealed that the strong acid–base sites and the oxygen vacancies created through the incorporation of Mn into CeO2 greatly affected the catalyst’s reactivity. This work not only establishes a facile and efficient method for PET waste recycling but also advances the field toward greener industrial practices while expanding the catalyst library for sustainable plastic upcycling.