Work

Targeted conversion of waste PET into dimethyl terephthalate and ethylene carbonate under metal-free conditions

Year: 2025

Type: article

Abstract: Ionic liquid-catalyzed methanolysis emerges as an efficient technique for transforming PET into premium-grade dimethyl terephthalate (DMT). However, incomplete depolymerization remains a major obstacle to the further industrial application of IL-catalyzed PET methanolysis. The proposed method utilized dimethyl carbonate (DMC) as the solvent for the complete methanolysis of waste PET under mild conditions, resulting in pure DMT and ethylene carbonate (EC) within 2.5 h. The use of 1-ethyl-3-methylimidazolium acetate ([EMIm][OAc]) as the IL catalyst significantly enhanced the reaction efficiency. Spectroscopic analyses using 1 H NMR and FT-IR confirmed the pivotal role of [EMIm][OAc] in establishing multiple hydrogen bonds with the reactants (PET, DMC, and MeOH) and the intermediate [ethylene glycol (EG)] during the catalytic process. This catalytic system exhibited remarkable performance, achieving complete conversion of PET, which resulted in the production of DMT and EC with yields of 99% and 91%, respectively. Moreover, this versatile approach is applicable to the upcycling of a wide variety of commercial polyesters and polycarbonates, underscoring its potential as a comprehensive solution for plastic waste management. • A comprehensive strategy for converting waste PET into dimethyl terephthalate and cyclic ethylene carbonate is proposed. • This strategy features minimal methanol dosage and wide substrate scope harvesting various waste polyesters and polycarbonates. • This upcycling method is highly efficient and selective, and the products can be easily separated and purified. • Multiple H-bond intermediates during the reaction process plays a pivotal role in the catalytic process. • The [EMIm][OAc] catalyst is efficient and environmentally friendly.

Source: Eco-Environment & Health

DOI: 10.1016/j.eehl.2025.100139