2008 Volume 41 Issue 9 Pages 923-928
In this study, we propose a new hybrid process consisting of glycolysis/methanolysis and then a vapor methanolysis process to obtain dimethyl terephthalate (DMT) and ethylene glycol (EG) in the depolymerization of waste poly(ethylene terephthalate) (PET). Zinc acetate was used to catalyze the reactions. We found that the depolymerization rate increased remarkably when glycolysis and methanolysis reactions were simultaneously carried out than when the glycolysis reaction was performed alone. We explored the possibility of the hybrid process and examined optimal weighting between glycolysis and methanolysis in the glycolysis/methanolysis step to increase the DMT yield and production rate. We also investigated the effect of major process variables such as reaction pressure, reaction temperature, reaction time, amount of EG, and methanol feed rate on process performance. We found that methanolysis has a greater role than glycolysis in the glycolysis/methanolysis step and the DMT yield has a maximum at a reaction temperature of 513.15 K and EG/PET mole ratio of 0.52, and increases with reaction pressure.