Calcined sodium silicate as solid base catalyst for alcoholysis of poly(ethylene terephthalate)

Abstract BACKGROUND Chemical recycling of waste poly(ethylene terephthalate) (PET) is an effective way to save energy and protect the environment. In this work, calcined sodium silicate was adopted as a novel solid base catalyst for methanolysis of PET for the first time. The effects of various parameters on the conversion of PET and the yield of dimethyl terephthalate (DMT) in the methanolysis process of PET were investigated. RESULTS The results showed that the conversion of PET could reach about 100% and the yield of DMT could reach about 95% under the following conditions: calcined sodium silicate, 5 wt%; molar ratio of methanol to PET, 5:1; reaction time, 30 min; reaction temperature, 200 °C. The higher the mass ratio of methanol to PET and the higher the temperature, the higher were the conversion of PET and the yield of DMT. In addition, the catalyst can be reused more than five times and has good catalytic activity. CONCLUSIONS Calcined sodium silicate has the advantages of low cost, simple fabrication method, high catalytic activity and environmental friendliness. The use of this solid base catalyst is a promising strategy for realizing the recycling of waste polyester. © 2022 Society of Chemical Industry (SCI).