Upcycling polyethylene into diesel-range hydrocarbons over Ru catalysts confined in thermally stable mesoporous N-doped carbon

Abstract

Plastic waste management is a critical sustainability challenge, but it also offers an opportunity to produce clean fuels from carbon-rich materials. In this study, we report a ruthenium catalyst supported on thermally stable mesoporous nitrogen-doped carbon (Ru/NAC) for the solvent-free hydrogenolysis of polyethylene into diesel-range hydrocarbons. The catalyst features ultrasmall Ru nanoparticles (∼1.48 nm), uniformly dispersed and stabilized by Ru–N coordination within an ordered mesoporous carbon framework. This architecture enhances polymer–catalyst interactions and enables controlled C–C bond cleavage. Under mild conditions (300 °C, 3 MPa H₂), Ru/NAC achieves a high liquid yield (86.5%) with 90.4% selectivity toward C₈–C₂₂ alkanes and a productivity of 391.1 g_p g_Ru⁻¹ h⁻¹. Mechanistic studies, including ¹³C solid-state NMR and in situ Diffuse Reflectance Infrared Fourier Transform spectroscopy, reveal that mesopore confinement and homogeneous metal dispersion synergistically promote selective depolymerization pathways. This strategy offers a practical and scalable route for transforming polyolefin waste into sustainable fuel-range hydrocarbons, advancing circular energy systems.