Chemical recycling

Chemical recycling uses chemical reactions to convert polymer waste into chemical feedstocks or fuels. Its methods include breaking polymers into monomers, smaller molecules, or synthesis gas.

Depolymerization: The breakdown of polymers into monomers or smaller molecules through chemical or biological processes. It reverses polymer formation to recover monomers that can become new polymers.
Polyethylene terephthalate: A polyester used in beverage bottles, food packaging, and textile fibers. Its ester bonds enable chemical routes that recover monomers such as terephthalic acid and ethylene glycol.
Mechanical recycling: Processing waste plastics into new materials through physical operations such as sorting, washing, and melting. Unlike chemical recycling, it generally preserves polymer chains rather than converting them into molecules.
Life-cycle assessment: A method for evaluating environmental impacts across a product or process’s life cycle. It compares chemical recycling’s energy use and emissions with alternative waste and feedstock pathways.
Plastic-to-fuel: Conversion of plastic waste into fuels that are burned for energy. Fuel production raises the question of whether a route counts as recycling when its output is combusted.
Pyrolysis: Thermal decomposition of materials in the absence of oxygen. It converts mixed plastic waste into hydrocarbon liquids, gases, and char.
Polyurethane: A polymer family formed from reactions involving isocyanates and polyols. Its varied formulations can be broken down to recover polyols or other chemical products.
Energy recovery: The use of waste as a source of usable heat or electricity through combustion or other processes. It recovers energy from waste rather than producing chemical feedstocks for material production.
Plastic pollution: The accumulation of plastic materials in the environment, where they can persist and cause harm. Chemical recycling is proposed as one response to plastic waste, but does not by itself prevent leakage.
Plastic pyrolysis oil: A liquid product of plastic pyrolysis containing a mixture of hydrocarbons and other compounds. Its contaminants and variable composition can limit direct use as petrochemical feedstock.

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