Assessment of PET Depolymerization Processes for Circular Economy. 2. Process Design Options and Process Modeling Evaluation for Methanolysis, Glycolysis, and Hydrolysis

Poly(ethylene terephthalate) (PET) is the most widely produced thermoplastic used in many applications, such as 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 process modeling of the three primary routes to depolymerize PET: methanolysis, glycolysis, and hydrolysis. We combine industrial patent literature and process design knowledge to simulate complete depolymerization processes and demonstrate how different configurations and process variables impact the process. We find glycolysis to be the simplest and least energy-intensive process when purification is simple, methanolysis to be attractive when purification is more challenging, and hydrolysis to be fundamentally the most complex and energy-intensive process. We reasonably expect a PET depolymerization process to be able to convert PET into monomers with an energy demand between 6000 and 10,000 kJ/kg of PET.