← Back to Publications

Advancements in Chemical Recycling of Plastic Waste: A Sustainable Path Forward

Author: Dr. Ahmad Saylam

Document type: Open technical preprint

Version: v1

Publication date:

Technical status: Structured narrative review and technology overview. It supports orientation and early-stage comparison of chemical-recycling routes, but it is not a systematic review, a validated process model, a certified life-cycle assessment, a final plant design or an industrial performance guarantee.

DOI: 10.5281/zenodo.19438550

Zenodo record: https://zenodo.org/records/19438551

Abstract

Plastic waste presents major management challenges because of material heterogeneity, contamination, degradation, additive content and losses to the environment. Mechanical recycling can be effective for suitable, sufficiently clean streams but becomes more difficult when polymer mixtures, contamination or degradation limit product quality. Chemical-recycling routes are therefore considered as complementary options for selected feedstocks rather than automatic replacements for mechanical recycling.

This paper provides a structured overview of chemical-recycling technologies for plastic-waste management. Key processes—including pyrolysis, gasification and depolymerization—are examined in terms of operating principles, treatment conditions, feedstock suitability, product quality and downstream requirements. These routes produce different outputs and should not be grouped as equivalent forms of recycling: pyrolysis generally yields hydrocarbon products requiring upgrading, gasification produces synthesis gas for further use, while depolymerization can recover monomers or oligomers from suitable polymers under route-specific conditions.

The analysis highlights potential routes for recovering useful products from selected waste streams. It also identifies major limitations related to energy demand, process efficiency, sorting and pretreatment, additives and fillers, halogens and other contaminants, catalyst or reagent requirements, product upgrading and purification, residue management, economic scalability and integration with existing waste-management systems.

Chemical recycling is therefore best considered as one component of an integrated waste-management strategy rather than a universal substitute for prevention, reuse or mechanical recycling. Its value depends on feedstock suitability, recovered-product quality, displacement of virgin production, process energy, emissions, residues, solvent or catalyst recovery where applicable, and downstream use. Environmental and economic viability must be established for the specific route, feedstock and product system.

Principal routes covered

Pyrolysis

Thermal conversion in the absence of oxygen can produce hydrocarbon vapours, liquids, gases and solid residues. Product distribution and quality depend strongly on polymer composition, additives, contamination, temperature, residence time, heat and mass transfer, reactor configuration and downstream upgrading. Chlorine-, bromine-, nitrogen- or oxygen-containing components may require specific pretreatment, corrosion control, contaminant removal or product cleanup.

Gasification

Partial oxidation at elevated temperature can convert carbonaceous plastic waste into a synthesis-gas mixture. Practical deployment requires control of oxidant ratio and temperature, gas cleaning, contaminant and particulate management, heat integration and a defined downstream use for the gas. Gasification should therefore be evaluated as a feedstock-to-syngas route rather than as direct closed-loop polymer recycling unless subsequent chemistry and product substitution justify that interpretation.

Depolymerization

Chemical, catalytic or solvent-assisted cleavage can recover monomers or oligomers from suitable polymers, particularly when the polymer chemistry permits selective bond cleavage. Performance is feedstock-specific and depends on polymer purity, additives, solvent or reagent use, catalyst choice, reaction selectivity, solvent and catalyst recovery, separation requirements and recovered-product specifications.

Scope and evidence boundary

The review supports technology orientation, preliminary pathway comparison, identification of feedstock and product questions and definition of focused laboratory, modelling or pilot work. It does not establish a ranked recommendation among chemical-recycling technologies for a specific waste stream.

Application to a specific plastic-waste stream requires verified polymer composition, additives and contamination data, experimentally supported yields and product quality, kinetic and transport analysis, closed mass and energy balances, emissions and residue characterization, catalyst, reagent or solvent recovery where applicable, separation and upgrading design, process-safety assessment and representative pilot validation.

Environmental benefit should be evaluated against a clearly defined reference system, functional basis and complete process or life-cycle boundary. Chemical conversion alone does not establish circularity, closed-loop recycling, lower greenhouse-gas impact or economic feasibility. Claims of circularity should distinguish material recycling from fuel production, energy recovery and downcycling.

Industrial interpretation

Laboratory conversion or high product yield is not sufficient to establish an industrial recycling route. Product purification, contaminant control, catalyst or solvent recovery, residue handling, heat integration, equipment durability, process safety and stable operation under variable feed composition can determine whether a technically feasible reaction becomes a viable process.

The appropriate comparison also depends on the intended product. Recovering polymer-grade monomer, producing cracker-compatible hydrocarbon feed, generating synthesis gas and producing fuel are different technical and circularity outcomes and should not be treated as equivalent.

Full text

License

The deposited paper identifies the work as available under the Creative Commons Attribution 4.0 International licence .

Recommended citation

Saylam, A. (2024). Advancements in Chemical Recycling of Plastic Waste: A Sustainable Path Forward. Version v1. Zenodo. https://doi.org/10.5281/zenodo.19438550