Pyrolysis and Thermal Degradation of Plastic Waste

Plastic waste has become a global environmental challenge owing to its persistence and volume. Pyrolysis and related thermal degradation processes offer promising routes for converting end-of-life plastics into valuable fuels, chemicals and raw materials. In pyrolysis, polymer chains are thermally cleaved in an oxygen-limited environment, yielding a spectrum of gaseous products, liquid oils and solid chars. Process parameters, such as temperature, heating rate and residence time, strongly influence product distribution and quality. Thermal degradation in the presence of catalysts or sorbents can further upgrade volatile fractions, remove detrimental heteroatoms and enhance fuel properties. Recent work has also targeted co-pyrolysis of mixed or contaminated waste streams, aiming to manage chlorine content and other impurities through feedstock pre-treatment, reactor design and in-situ dehalogenation. As technologies advance, scalable reactor configurations—from fixed-bed to fluidised systems—are being evaluated alongside life-cycle assessments to ensure that thermal recycling aligns with circular-economy goals. Ultimately, integrating pyrolysis into existing waste management infrastructures holds promise for mitigating plastic pollution while recovering energy and materials at a competitive cost.

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Pyrolysis and Thermal Degradation of Plastic Waste publication trend

The graph below shows the total number of articles in pyrolysis and thermal degradation of plastic waste across all publications each year (not limited to Nature Index journals).

Technical terms

Pyrolysis: Thermal decomposition of organic materials in an oxygen-limited environment, yielding gases, liquids and solids.

Thermal degradation: Breakdown of polymer chains under elevated temperatures, often leading to volatile compound formation.

Heteroatom: Atom other than carbon or hydrogen within a polymer or pyrolysis product, commonly chlorine, sulfur or nitrogen.

Dehalogenation: Chemical removal of halogen atoms (e.g. chlorine) from organic molecules, essential for reducing toxic by-products.

Catalytic upgrading: Use of solid catalysts to convert primary pyrolysis products into more valuable or stable hydrocarbons.

Fixed-bed reactor: Reactor type where solid feedstock remains stationary while heated, enabling controlled thermal decomposition.

Pyrolysis oil: Liquid condensate from pyrolysis, containing a complex mixture of hydrocarbons suitable for fuels or further refining.

References

1. Virgin polymers via pyrolysis – A review of heteroatom removal options. Fuel Processing Technology (2024).
2. Pyrolysis of mixed plastic waste (DKR-350): Effect of washing pre-treatment and fate of chlorine. Fuel Processing Technology (2022).
3. Thermal Degradation and Organic Chlorine Removal from Mixed Plastic Wastes. Energies (2022).