Chemical recycle of polyester waste using novel zwitterionic catalysts

The influence ofreaction temperature, glycolysis time, ethylene glycol:PET ratios, and theamount of the zwitterionic imidazolium-2-carboxylate catalysts used on theconversion of PET, isolated yield of BHET, and the selectivity of BHET in theglycolysis of PET were investigated.<br><br> The results demonstrate that 1,3-dimethylimidazolium-2-carboxylate can bean effective basic catalyst for PET glycolysis, with PET depolymerization of upto 100% observed.

BHET was isolated from the reaction mixture with yields ofup to 61.0% under the optimum reaction conditions using 0.15 g catalyst to 1.0g PET in the presence of 10.0 g ethylene glycol (0.15:1:10 mass ratio) at 185oCin 1 h. This is the first time that 1,3-dialkyl-imidazolium-2-carboxylates havebeen reported to be catalysts for glycolysis of PET and, compared to 1,3-dialkylimidazolium acetate ionic liquids, were more effective as catalyst in theglycolysis.