Chemical Recycling of Polyethylene Terephthalate Waste
Summary
Chemical recycling of polyethylene terephthalate (PET) waste encompasses a suite of processes that depolymerise the polyester into its constituent monomers or chemically transform it into value-added products. Unlike mechanical recycling, which often degrades polymer properties, chemical methods can deliver monomers of near-virgin purity, enabling closed-loop recovery. Core approaches include hydrolysis, glycolysis and methanolysis, each exploiting water, glycols or alcohols under catalytic conditions to cleave ester bonds. Recent advances have broadened compatibility with coloured and multilayer PET, improved energy efficiency through novel reactor designs such as microwave-assisted systems, and explored solvent-based strategies to isolate high-purity terephthalic acid and ethylene glycol. Life-cycle assessments increasingly guide process optimisation, underscoring the imperative to balance carbon footprints, economic costs and scalability. Beyond monomer recovery, upcycling pathways now aim to convert PET waste into fuels, antifreeze components or speciality chemicals, reflecting a shift towards integrated circular-economy solutions that valorise complex waste streams and support global sustainability goals.
Research from Nature Portfolio
One study reports an acetolysis method in which waste PET is dissolved in glacial acetic acid, yielding high-purity terephthalic acid crystals and ethylene glycol diacetate. The process tolerates coloured, blended or dyed feedstocks and allows direct repolymerisation to PET, achieving a closed-loop cycle with a lower carbon profile than commercial alternatives. Life-cycle analysis highlights significant reductions in greenhouse-gas emissions compared with conventional glycolysis. Another investigation details a one-pot methanolysis coupled with catalytic hydrodeoxygenation over Cu/SiO₂, converting PET to p-xylene and ethylene glycol under mild, hydrogen-free conditions. The approach employs in situ H₂ generation from methanol and delivers gasoline-range hydrocarbons alongside monomer recovery, offering a route to automotive fuels and antifreeze precursors from post-consumer PET.
Chemical Recycling of Polyethylene Terephthalate Waste publication trend
The graph below shows the total number of articles in chemical recycling of polyethylene terephthalate waste across all publications each year (not limited to Nature Index journals).
Technical terms
Depolymerisation: Chemical cleavage of polymer chains into monomers or oligomers.
Hydrolysis: Bond scission by reaction with water under acidic or alkaline conditions.
Glycolysis: Transesterification of PET using glycols to yield bis(hydroxyethyl) terephthalate.
Acetolysis: Ester-cleavage in acetic acid producing terephthalic acid and diacetate derivatives.
Methanolysis: Reaction of PET with methanol to form dimethyl terephthalate and ethylene glycol.
Upcycling: Conversion of waste into products of equal or higher value than the original material.
Circular economy: Economic model promoting resource reuse, recycling and waste minimisation.
References
- Depolymerization within a Circular Plastics System. Chemical Reviews (2024).
- Acetolysis of waste polyethylene terephthalate for upcycling and life-cycle assessment study. Nature Communications (2023).
- Converting waste PET plastics into automobile fuels and antifreeze components. Nature Communications (2022).
- Towards closed-loop recycling of multilayer and coloured PET plastic waste by alkaline hydrolysis. Green Chemistry (2020).
- Recent advances in chemical recycling of polyethylene terephthalate waste into value added products for sustainable coating solutions – hope vs . hype. Materials Advances (2022).
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