From waste to wealth: Glycolysis of PET for high-value resource utilization

The extensive application of plastic products has led to the accumulation of substantial quantities of polyethylene terephthalate (PET) waste. How to recycle the increasing PET waste is becoming a global challenge. The chemical recycling of PET, which employs a depolymerization-repolymerization approach to maximize resource value, has garnered growing attention from the scientific community. Of the numerous PET recycling methods proposed, glycolysis is especially promising because of its mild reaction conditions and the ease of separating the products. This paper explores the progress and obstacles in the glycolytic transformation of PET into bis(2-hydroxyethyl) terephthalate (BHET), covering aspects such as the glycolysis mechanism, process flow, catalyst development, optimization of reaction strategies, and reaction kinetics. Notably, the primary challenges in PET glycolysis are slow reaction rates and poor product selectivity. Various effective strategies have been proposed to address these issues, and their advantages and disadvantages are discussed. Furthermore, the potential applications of the BHET monomers are explored. Finally, the challenges and future prospects of glycolysis are presented. This review aims to offer valuable insights into glycolysis and act as a helpful reference for developing high-performance catalysts and advancing industrial applications.