Microwave Accelerated Methanolysis of Poly(ethylene terephthalate)

Abstract

Poly(ethylene terephthalate) (PET) is an important commodity polymer that has the potential to be 100% recycled, but this is currently not economically viable as the costs of recovering the starting materials are greater than virgin materials. As well as PET, there are a number of other interesting poly(terephthalate)s which have higher economic value. However, for many of these, virgin material is necessary to avoid contamination with ET units. This can be avoided by chemically deconstructing the PET to simple terephthalates. In this work, we show that dimethyl terephthalate (DMT) can be easily obtained from PET, in high purity (> 99.5% for the crude) with a relatively low energy use (ca. 0.3 Mj.g-1), by using a microwave reactor. In a microwave reactor the methanolysis proceeds an order of magnitude faster than in a conventional reactor. This is apparently due to cavitation caused by hot-spots, which break up the PET, increasing the active surface, and an increased population of PET particles above the Ea in the hot zones.