Unlocking circular economy potential: evaluating high-value chemical production from pyrolysis of plastics recovered from landfilled municipal solid waste

Abstract

This study evaluates the potential for producing valuable chemical products from plastics recovered from municipal solid waste (MSW) landfills and therefore contributing to waste reduction and resource recovery. Using pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS) we analysed the decomposition products of 10 plastic samples including fresh and excavated samples of different landfill periods from 4 landfill sites. The samples comprised polyethylene (PE), polypropylene (PP), two mixed excavated plastic materials containing PE, PP, polystyrene (PS), poly(ethylene terephthalate) (PET) and poly(vinyl chloride) (PVC). All samples were pyrolyzed at 350, 500, 650 and 800 °C to semi-quantitatively identify the range of compounds produced at each temperature. Hydrocarbon production was the highest at 500 °C and 650 °C whit a significant proportion of the products falling within the naphtha range (C6-C10), which is a critical feedstock in the plastic industry. Notably, naphtha can be cracked to produce 55 wt% high-value chemicals, such as ethylene and propylene. Additionally, aromatic compounds such as benzene, toluene and styrene, especially in the mixed samples demonstrate potential for use in the chemical industries for polymers, solvents and dyes. These results provide encouraging evidence that excavated landfill plastics can serve as a viable source of valuable chemical intermediates, supporting both resource recovery and the advancement of a circular plastics economy. While this study offers an important initial assessment, primarily qualitative and focused on single polymers and controlled artificial mixtures, it establishes a solid foundation for future research. Further investigations using heterogeneous and larger-scale processing are recommended to fully demonstrate the techno-economic feasibility and environmental benefits of integrating pyrolysis of aged plastics into sustainable waste management and resource recovery strategies.