Fine regulation of Ru species improved the polyethylene hydrogenolysis performance over Ru/Al 2 O 3 catalyst

Abstract Thermocatalytic technologies are the most promising approach for converting plastic waste into valuable chemicals. The Ru-based catalysts are the most active catalysts reported, which are highly efficient for C–C bond breaking during thermocatalytic plastic degradation. Still, significant challenges remain in controlling the selectivity of the valuable liquid product. A trade-off relationship between the activity and selectivity is commonly found during thermocatalytic plastic degradation. Herein, we demonstrated that a Ru/γ-Al2O3-Ar catalyst, prepared from commercial γ-Al2O3 pre-calcined under an Ar atmosphere, achieved 100% conversion over low-density polyethylene (LDPE) hydrogenolysis and an 85.9% selectivity for fuel-range and wax hydrocarbons at 250 °C for 4 h. In contrast, Ru loaded on the synthesized γ-Al2O3 showed only a 17.9% selectivity toward fuel range and wax hydrocarbons, with methane being the predominant product. Comprehensive characterizations revealed a strong metal-support interaction (MSI) at the interface between Ru and γ-Al2O3-Ar, leading to the abundance of Run+ species at the Ru-Al2O3 interface. Combined experimental and density functional theory (DFT) computational studies reveal that the incorporation of Run+ effectively suppresses excessive dehydrogenation into methane intermediates. Simultaneously, it promotes the hydrogenation of hydrocarbon intermediates through a synergistic hydrogen spillover effect, driven by high H* coverage, which ultimately boosts catalytic efficiency.