A Kinetic and Modeling\nStudy of Bis(2-hydroxyethyl)\nterephthalate (BHET) Hydrolysis Reaction Network

This study investigates the kinetics of bis(2-hydroxyethyl)\nterephthalate\n(BHET) hydrolysis catalyzed by Sb<sub>2</sub>O<sub>3</sub>, aiming\nto optimize the chemical recycling process of polyethylene terephthalate\n(PET) since BHET can be obtained from glycolysis of PET. The hydrolysis\nof BHET leads to a network of reactions, including hydrolysis, esterification,\ncondensation, transesterification, and dimerization. The reactions\nwere conducted at different temperatures (160–200 °C)\nand initial water concentrations (2.5–12.5 wt %). Results demonstrated\nthat higher temperatures and water concentrations significantly enhance\nhydrolysis efficiency, as indicated by increased carboxyl end groups\n(CEG) values. The study employed mass balance equations and nonlinear\nregression analysis to estimate kinetic and thermodynamic parameters.\nThe kinetic model was tested via experimental data, showing deviations\nwithin ±20%. This comprehensive kinetic analysis provides insights\ninto optimizing hydrolysis conditions to maximize the yield of hydrolyzed\nBHET, facilitating the subsequent polycondensation process to produce\nhigh-quality recycled PET (r-PET).