Upcycling of waste polyester for the development of circular economy

Abstract

The rapid increasing production and widespread application of plastic bring convenience to our lives, but it has consumed a huge nonrenewable fossil energy, brought additional CO2 emission and generated enormous amount of plastic waste (also called as white pollution). Chemical recycling and upcycling of waste plastic products (also called as waste plastic refinery) into recycled monomers and/or valuable chemicals can decrease the dependence of fossil energy and/or reduce the emission of CO2, which can fully utilize carbon resources for the development of circular economy. Polyester, a vital species of plastics, is an ideal feedstock for chemical recycling due to the easily depolymerizable ester bonds compared to polyolefins. Among them, polyethylene terephthalate (PET) is the most widely used product, making its chemical recycling to circular carbon resource a hot topic with significant concerns. In this review, recent progresses of waste polyester (PET and/or PET-containing materials) depolymerization and the subsequent upgrading of depolymerized monomer (or intermediates) to valuable chemicals were introduced and prospected. Those newly reported technologies, such as thermal catalysis, photocatalysis, electrocatalysis, and biocatalysis were discussed. The achievements, challenge, and potential of industrial applications in chemical recycling of polyester were addressed.