Enhancing Hydrogen Spillover via Crystalline-Phase Engineering of Ru/ZrO ₂ for Selective Liquid Alkane Production in Polyethylene Hydrogenolysis

The efficient conversion of polyethylene (PE) plastic waste into high-value liquid fuels is critical for mitigating environmental pollution and increasing economic benefits. However, the hydrogenolysis of PE typically produces low-value alkanes, and an effective catalyst for selectively producing liquid alkanes via this route remains lacking. Herein, we present a crystalline-phase engineering strategy to optimize Ru/ZrO2 catalysts, achieving 64.2% selectivity toward C7–C40 liquid products under mild conditions (250 °C, 3 MPa of H2, 4 h). Systematic characterizations reveal that the Ru/ZrO2-600 catalyst exhibits the highest tetragonal phase content (33.2%) and the highest oxygen vacancy concentration (37.8%), which facilitates hydrogen spillover from Ru to the ZrO2 support, thereby increasing the surface hydrogen coverage. This effect weakens the adsorption of alkane intermediates and accelerates hydrogenation kinetics, thus suppressing further cracking into light hydrocarbons (C1–C6) and promoting the formation of long-chain liquid products. Ru/ZrO2-600 achieves 62.3 and 61.5% selectivity toward C7–C40 liquid hydrocarbons during the hydrogenolysis of commercial PE gloves and PE film, respectively. This work provides a promising strategy for the sustainable and economically viable recycling of waste PE plastics.