Valorization of plastic waste into drop-in fuels: Economic and environmental perspectives

Plastic waste presents a major sustainability challenge due to its environmental persistence and low recycling rates. Bifunctional depolymerization has emerged as a promising catalytic strategy for converting waste polyolefins into valuable liquid fuels, leveraging the synergistic action of metal and acid sites to enhance product selectivity and conversion. However, its economic and environmental viability remains underexplored. Here, we assess the catalytic depolymerization of low-density polyethylene (LDPE) using Ru/zeolite-Y under six reaction configurations, varying water addition, Ru loading, and temperature. Coupling experimental data with techno-economic analysis and life cycle assessment, we quantitatively identify how these parameters influence conversion, product distribution, cost, and greenhouse-gas (GHG) intensity. Particularly, water co-feeding promotes the bifunctional pathway, increasing conversion and shifting product distribution toward heavier hydrocarbons, thereby lowering the minimum fuel-selling price. Depolymerization at 250 °C with 0.2 wt% Ru loading in the presence of water emerged as an optimal “sweet spot”, reducing GHG emissions by an estimated 17.7×10³ CO₂-eq yr⁻¹ while delivering drop-in fuels at prices competitive with conventional gasoline. This study provides a scalable, economically attractive route for converting waste plastics into transportation fuels and advancing a circular carbon economy through process-informed technological development.