Abstract

The increasing accumulation of plastic waste presents significant environmental and economic challenges, with millions of tonnes of plastic waste contaminating landfills, oceans, and ecosystems. Conventional plastic waste disposal methods, such as landfilling and incineration, contribute to environmental degradation, greenhouse gas emissions, and resource depletion. Meanwhile, mechanical recycling faces limitations due to contamination and the heterogeneity of plastic waste. To address these challenges, this study evaluates the pyrolysis process as a viable method for converting mixed plastic wastes into valuable energy products, specifically fuel and hydrogen. Through thermochemical conversion, pyrolysis presents a promising chemical recycling approach that mitigates plastic pollution while simultaneously advancing the circular economy and sustainable energy solutions.

A process simulation model was developed using Aspen Plus software to optimise product yields from both standalone pyrolysis and pyrolysis integrated with in-line steam reforming. Key process parameters, including temperature, pressure, and steam-to-plastic ratio, were analysed to determine their impact on product composition and yield. The optimum conditions for fuel production were 460oC and 1 bar, whereas, for hydrogen production via pyrolysis and in-line steam reforming were 700oC, Steam-to-plastic ratio of 2 and 1 bar. To enhance energy efficiency, an energy analysis was performed, followed by heat integration using Aspen Energy Analyzer to minimise external energy consumption. The result demonstrated that efficient heat recovery reduced external energy consumption, boosting process sustainability. An economic assessment was carried out using the Aspen Process Economic Analyzer integrated with Aspen Plus. The results indicate that economic viability is closely tied to optimising the feedstock rate, as it directly impacts product revenue. This study advances knowledge by optimising process parameters for mixed plastic waste pyrolysis to enhance fuel and hydrogen yields. Additionally, it integrates heat recovery to improve energy efficiency and evaluates the economic feasibility of the process. These contributions support the development of sustainable waste-to-energy technologies and provide a foundation for future large-scale applications.