Poly(ethylene terephthalate) (PET) is a kind of thermoplastic polymer resin and has been widely used in many fields because of its excellent thermodynamics and mechanics performance, such as synthetic fiber, plastic film, food packaging, water and soft-drink bottles and so on. However, with the extensive use of PET materials and their inherently hard-to-degrade characteristics, our environment is facing significant challenges in environmental protection and resource reuse. Therefore, it is very necessary to carry out research on the recycling of PET. The recycling methods for PET are mainly divided into physical and chemical methods. Since chemical methods can degrade PET into raw materials and then reuse them, these methods have received more and more attention. Alcoholysis is a relatively mild method in chemical methods with the advantages of mild reaction conditions and easy separation of products. In order to achieve rapid and gentle degradation of PET and to obtain high conversion and selectivity, ethylene glycol was chosen as a solvent and polyoxometalate (POM) as catalysts for degradation of waste PET. In this study, a kind of transition-metal-substituted POM Na12[WZnMn2(H2O)2(ZnW9O34)2] with a sandwich structure was synthesized and it was used to catalyst the alcoholysis of poly(ethylene terephthalate) (PET). The effects of reaction time, reaction temperature, and the amount of catalyst on PET degradation were researched, the conditions was optimized. The results showed that PET could be 100% degraded at 190℃ for 80 min under the conditions of catalyst amount was 1.0wt% of PET and mass ratio of PET to ethylene glycol (EG) was 1:4, the yield of bis(hydroxyethyl) terephthalate (BHET) achieved 84.42%. In addition, in order to determine the structure and properties of the degradation products, the degradation products were characterized by NMR, IR, TGA, DSC, HPLC and other instruments. The final experimental results showed that the catalyst can efficiently catalyze the alcoholysis reaction of PET and obtain high-purity BHET products.
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