Ni/Nb₂O₅ as a noble-metal-free catalyst for the chemical upcycling of waste polyolefin plastics

The resource utilization of waste polyolefin plastics is expected to be achieved through upgrading and reconstruction processes, but the primary scientific challenge lies in the development of efficient and cost-effective catalysts. In this paper, we present Ni nanoparticles supported on Nb₂O₅ with tunable acid sites (Ni/Nb₂O₅-T) as noble-metal-free catalysts for the upcycling of waste plastics. These catalysts efficiently facilitate a one-pot, solvent-free catalytic hydrogenolysis of waste plastics, converting them into aromatic-free, highly branched alkane aviation fuels under mild conditions. Notably, the bifunctional Ni/Nb₂O₅-400 catalyst, characterized by highly dispersed metallic Ni sites and strong Brønsted acid sites, promotes key reactions such as hydrogenation/dehydrogenation, skeletal rearrangements, and β-scission of linear low-density polyethylene. This process achieves 100 % conversion with a yield of over 80 % for liquid products at 250 °C and 3 MPa H₂ for 4 h. The carbon distribution of the resulting liquid fuels primarily ranges from C₆ to C₁₈, with 71 % composed of isoparaffins, highlighting them as promising candidates for aviation fuels. Additionally, the Ni/Nb₂O₅-400 catalyst exhibits versatile activity, delivering high yields of highly branched alkane aviation fuels through the chemical upcycling of various types of waste polyolefin plastics. A techno-economic analysis further confirms that this Ni-catalyzed plastic-to-fuel process offers significant economic advantages, underscoring its potential for industrial-scale implementation. © 2025 Elsevier B.V.