Synergistic effect of acidic sites and mesoporous confinement in Ce-doped Ru/SBA-15 catalysts for efficient hydrogenolysis of low-density polyethylene to liquid fuels†

Abstract

The chemical upcycling of waste plastics into liquid fuels offers a promising approach to mitigating plastic pollution and reducing reliance on fossil resources. However, optimizing product distribution while enhancing the efficiency of hydrogenolysis remains a significant challenge. Herein, we report a multifunctional Ru-Ce/SBA-15 catalyst, which features uniformly dispersed Ru nanoparticles embedded within the mesoporous channels of SBA-15 via precise impregnation, and additional acidic sites introduced by Ce doping. Under optimized conditions (280 °C, 35 bar H₂), the catalyst achieves an exceptional low-density polyethylene (LDPE) conversion rate of 939 g_p g_Ru⁻¹ h⁻¹ and produces a narrow hydrocarbon range (C₈–C₂₅) ideal for liquid fuels. Comparative screening experiments demonstrate that the Ru-Ce/SBA-15 catalyst significantly outperforms commercial Ru, Pt, and Pd catalysts. Mechanistic investigations reveal that Ru within the mesopores facilitates hydrogen activation and C–C bond cleavage, whereas Ce doping enhances acidity, leading to controlled polymer chain scission and enhanced selectivity. The synergistic effect of acidic sites and mesoporous confinement, along with robust stability over multiple cycles, provide a solid theoretical foundation for designing next-generation catalysts for sustainable waste-to-fuel technologies.