Glycolysis of Poly(ethylene terephthalate) Catalyzed by the Lewis Base Ionic Liquid [Bmim][OAc]

The glycolysis of poly(ethylene terephthalate) (PET) was studied using 1-butyl-3-methylimidazolium acetate ([Bmim][OAc]) as a catalyst. The effects of temperature, time, ethylene glycol dosage, PET amount, and [Bmim][OAc] dosage on the glycolysis reaction were examined. The results revealed that [Bmim][OAc] has a PET conversion of 100% and a bis(2-hydroxyethyl)terephthalate (BHET) yield of 58.2% under the optimum conditions of 1.0 g of [Bmim][OAc] with 20 g of ethylene glycol in the presence of 3.0 g of PET at 190 °C after 3 h of glycolysis. The ionic liquid could be reused up to six times with no apparent decrease in the conversion of PET or yield of BHET. The pH plays a major role in explaining the proposed mechanism of glycolysis using the Lewis base ionic liquid [Bmim][OAc]. The kinetics of the reaction was first-order with an activation energy of 58.53 kJ/mol.