Title: Chemical Recycling of Poly(ethylene terephthalate) (PET) for High-Purity Bis(2-hydroxyethyl) terephthalate (BHET) Recovery and Closed-loop Systems
This study optimizes the chemical recycling of PET to address low reactivity caused by high crystallinity and the economic challenges of recovering bis(2-hydroxyethyl) terephthalate (BHET). A stepwise process from pretreatment to purification was developed. First, dimethyl sulfoxide (DMSO) pretreatment transformed PET flakes into micro-sized powders, maximizing surface area and reducing glycolysis time fivefold. This low-temperature approach also suppressed the byproduct diethylene glycol terephthalate (DCTC), ensuring BHET quality. Second, an ethyl acetate (EtOAc)-based non-aqueous purification system was implemented, achieving 97.8% BHET purity at 25°C. A closed-loop system was established by recovering solvents, unreacted ethylene glycol (EG), and catalysts via distillation. The recovered resources maintained consistent BHET yields across multiple cycles. In conclusion, This work provides a practical roadmap for the economic recovery of high-purity BHET from waste PET.