Novel adsorption-based upgradation of end-of-life polypropylene pyrolysis oil using carbonised rice husk

Abstract

Plastic waste management is a global issue, with end-of-life polypropylene (EoL PP) having significant contribution. Polypropylene degradation forms undesirable compounds in pyrolysis oil, reducing its quality and limiting its fuel usability. Pyrolysis offers a promising solution for converting plastic waste into valuable fuels; however, the presence of degraded materials necessitates an effective upgrading process to enhance the fuel quality. This study introduces an innovative ex-situ adsorption-based upgradation technique using carbonised rice husk (CRH), an abundantly available, sustainable and cost-effective biomass residue, to significantly improve the quality of pyrolysis oil derived from EoL PP. The upgradation process reduced sulphur content in polypropylene pyrolysis oil from 0.19 % to 0.02 %. The cetane index, a key fuel quality metric, rose from 43.83 to 55.25, enhancing combustion properties. Proton nuclear magnetic resonance showed an increase in paraffin content from 53.15 vol% to 60.81 vol%, improving energy content and combustion efficiency. Olefins and aromatics decreased, improving fuel stability and reducing emissions. GCxGC TOF-MS analysis revealed a decrease in oxygenates and an increase in diesel-range hydrocarbons, improving fuel quality and stability. This comprehensive study highlights the dual benefits of CRH in enhancing fuel quality and supporting circular economy practices, making a significant contribution to the development of sustainable fuel alternatives in the waste-to-energy conversion sector.