Assessment of PET Depolymerization Processes for Circular Economy. 1. Thermodynamics, Chemistry, Purification, and Process Design

Poly(ethylene terephthalate) (PET) is the most widely produced thermoplastic and is used in drink bottles, packaging, and textiles. Chemical depolymerization represents a way to recycle PET that is robust to the low purity and quality of some waste PET sources. This work investigates the three primary routes to depolymerize PET into feedstocks used to produce the PET polymer: methanolysis, glycolysis, and hydrolysis. This work is unique in providing a thorough review of the depolymerization thermodynamics, chemistry, purification strategies, and design of PET depolymerization processes from an industrial perspective. This work provides detailed descriptions of different variants of PET depolymerization processes. We summarize available data necessary to design a PET depolymerization process and indicate where gaps in data exist. We demonstrate the importance of separation and purification sections of the process, which are rarely addressed in academic literature. We also demonstrate different designs and strategies that industrial technologies employ to address challenges.