Monomer recycling of polyethylene terephthalate, polycarbonate and polyethers: Scalable processes to achieve high carbon circularity

Abstract

This review presents a comprehensive description of the current pathways used in the chemical recycling of oxygenated plastics, with a specific focus on poly(ethylene terephthalate) (PET), poly(bisphenol-A carbonate) (PC), and polyethers including anhydride-cured epoxies. For PC and PET, the emphasis is on processes that achieve high depolymerization efficiencies as well as monomer selectivity and the potential to simplify downstream processing for the recovery of pure monomers. In the case of epoxies, this work focuses on depolymerization processes that produce curable molecules, as studies on epoxy depolymerization are scarce. To assess scalability, different depolymerization pathways are compared for each polymer based on the process conditions and monomer yields. The review concludes with the discussion on potentials and challenges of the distinct depolymerization pathways that have been developed for oxygenated plastics, such as hydrolysis, alcoholysis, and reductive depolymerization.