Ti-Si composite glycol salts: depolymerization and repolymerization studies of PET.

In this study, a Ti-Si-ethylene glycol salt (Ti/Si-EG) was synthesized and used as a catalyst for the depolymerization of PET-ethylene glycol to produce bis(hydroxyethyl)terephthalate (BHET), and the optimum conditions for the depolymerization were determined by response surface analysis: (EG) : (PET) was 4 : 1, the catalyst mass dosage was 0.56% (in terms of the mass of PET), the depolymerization temperature was 203 °C, the depolymerization time was 3.8 h, and the highest yield of the product (BHET) was 90.