Developments in chemical depolymerization techniques for circular recycling of polyesters: Emphasis on hydrolysis, methanolysis, and ethanolysis
Year: 2026
Type: article
Abstract: Chemical depolymerization is emerging as a key enabler of polymer circularity as demand grows for sustainable resource use and improved management of synthetic waste. Unlike mechanical recycling, which often yields downcycled materials, depolymerization cleaves polymer chains to recover high-purity monomers and intermediates suitable for re-polymerization or upgrading into value-added chemicals. This review provides a critical, cross-route assessment of three major PET depolymerization pathways Hydrolysis, Methanolysis, and Ethanolysis highlighting reaction mechanisms, catalyst development, and process conditions. Hydrolysis, especially in hot-compressed water (HCW), tolerates mixed and contaminated feedstocks and can reduce pretreatment demands, but it remains energy intensive and faces corrosion, salt formation, and challenging aqueous separations. Methanolysis is advancing toward industrial deployment: pilot and demonstration efforts report high dimethyl terephthalate (DMT) yields and high-purity ethylene glycol (EG), while defect-engineered catalysts and bio-based co-solvents increasingly improve rates and lower environmental burden. Ethanolysis is less mature but can leverage bioethanol supply chains and enables selective depolymerization of polyester/cotton blends; however, slower kinetics and more complex separations limit productivity. Beyond chemistry, we discuss reactor innovations, process intensification, integrated flowsheets, solvent-loop closure, and control strategies relevant to scale-up. Remaining barriers include catalyst toxicity, solvent recovery and purification costs, feedstock variability, and overall techno-economic feasibility.
Source: Next Energy
Institutions: Kütahya Dumlupınar Üniversitesi, University of Kerbala
Language: English
Subfield: Polymers and Plastics
Field: Materials Science
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $1,280
OpenAlex ID: W7213985944