INS9-0277
An Integrated, Zero-Waste Strategy for High-Efficiency Chemical Recycling of PET and Glycol-Modified Polyesters via Closed-Loop Valorization
Topic
S9. Polymer Technology for Sustainability
When and Where
Sep 29, 2026
15:50 - 16:15
Room 313
Session Chairs
Jeyoung PARK
Presenter(s)
Hyun Min JUNG (Kumoh National Institute of Technology)
Co-Author(s)
Abstract
The chemical recycling of poly(ethylene terephthalate) (PET) and its glycol-modified derivatives via glycolysis offers a practical route to recover monomers and oligomers, yet it is limited by the low reactivity of crystalline and sterically hindered polyesters, undesirable side reactions, and the large energy and water demands of purification and solvent recovery. This work presents an integrated strategy spanning pretreatment, reactivity analysis, catalyst design, product valorization, and process sustainability. Dissolving PET in dimethyl sulfoxide and recrystallizing it into micro-sized porous powders enlarged the contact area between solid PET and ethylene glycol (EG), accelerating glycolysis roughly fivefold and achieving full conversion below 180 °C while suppressing diethylene-glycol-containing byproducts. Using model compounds (BHET, BHCHT, BHDIT) for PET, PCT, and PIT, substituting the EG unit with 1,4-cyclohexanedimethanol or D-isosorbide lowered reactivity to about one-third and one-fifth or less, respectively, revealing how alcohol nucleophilicity and steric hindrance govern transesterification. A zinc-alkoxide catalytic system (Zn(OAc)₂/NaOEt or Zn(OMe)₂) was therefore developed, enhancing the rates of hindered substrates four- to fivefold and enabling efficient depolymerization of both PET and PCT. Beyond BHET, recovered streams were directly converted into value-added products: an EDTA chelating strategy deactivated the Zn catalyst during diol removal to yield low-viscosity liquid polyols for thermally stable polyurethanes, while byproduct oligomers were transformed into high-purity dimethyl terephthalate by mild methanolysis. Finally, an ethyl acetate cosolvent enabled ambient-temperature isolation of BHET at 97.8% purity and full recovery and reuse of EG, EtOAc, and catalyst, realizing a near zero-waste closed-loop process with a markedly reduced carbon footprint (3.07 versus 7.34 kg CO₂-eq per kg PET).
