Depolymerization Reaction Types & Products
A four-reaction reference table for depolymerisation — glycolysis, hydrolysis, methanolysis, and aminolysis — showing the primary solvent, target polymer, and main monomer product for each reaction type.
Reaction Type | Primary Solvent | Target Plastic | Main Product |
Glycolysis | Ethylene Glycol | PET / Polyester | BHET (Monomer) |
Hydrolysis | Water / Steam | Nylon / PET | PTA / MEG / Caprolactam |
Methanolysis | Methanol | PET | DMT (Monomer) |
Aminolysis | Ammonia / Amines | Nylon 6 / PU | Monomers / Polyols |
Beyond definitions
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How to read this table
- Each row is one reaction type — these are chemically distinct processes, not variants of the same reaction.
- Primary Solvent is the chemical reagent that drives the depolymerisation — it reacts with the polymer bonds to break the chains.
- Main Product is the commercially saleable monomer output after purification.
About this table
Depolymerisation is not a single reaction — it is a family of chemical processes, each using a different solvent to break a different type of polymer bond. Selecting the right reaction type for a given feedstock polymer is one of the first design decisions for a depolymerisation plant. This table covers the four commercially relevant reaction pathways and their outputs.
Glycolysis uses Ethylene Glycol as the reacting solvent to attack ester bonds in PET and polyester. The reaction produces BHET (Bis-HydroxyEthyl Terephthalate) — a monomer that can be re-polymerised into new PET or further refined into PTA and MEG. Glycolysis operates at 200–280°C with a zinc acetate or similar catalyst and is the most widely commercialised depolymerisation pathway globally for PET recycling. Hydrolysis uses water or steam to break ester bonds (in PET) and amide bonds (in Nylon). PET hydrolysis produces Purified Terephthalic Acid (PTA) and Monoethylene Glycol (MEG) — the exact monomers used to make virgin PET. Nylon 6 hydrolysis produces Caprolactam. Hydrolysis requires high pressure (especially for Nylon) and is more energy-intensive than glycolysis.
Methanolysis uses methanol as the solvent to depolymerise PET, producing Dimethyl Terephthalate (DMT) — a different intermediate from glycolysis that is used in polyester fibre and film manufacturing. DMT must be purified before use, and methanol recovery and recycling within the plant is essential for economic viability. Aminolysis uses ammonia or amines to break amide bonds in Nylon 6 and urethane bonds in Polyurethane (PU), producing monomers and Polyols respectively. Aminolysis for PU is commercially attractive because Polyols are high-value chemicals used in foam manufacturing — but the process requires careful handling of ammonia or amine reagents, which are corrosive and hazardous.
Key insights
- Glycolysis is the most commercially mature depolymerisation pathway for PET — multiple commercial plants operate globally, making it the lowest-risk technology choice for first-time investors.
- Hydrolysis produces PTA and MEG — the exact monomers that virgin PET is made from — enabling certified 'chemically recycled' claims for food-grade packaging.
- Methanolysis requires on-site methanol recovery and recycling to be economically viable — the solvent is expensive and loss in the process directly erodes margins.
- Aminolysis for Polyurethane produces high-value Polyols but requires handling ammonia or amines — corrosive, hazardous reagents that add safety and regulatory complexity.
Methodology & sources
Reaction types described are based on established chemical recycling literature and commercial plant operating data as of 2024. Temperature, pressure, and catalyst requirements vary between process variants within each reaction type. Actual process selection requires technology due diligence with a licensor who has commercial reference plants for the specific polymer and reaction type planned.
Related data tables
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