Designing oxygen vacancy rich mesoporous CeO2 nanorods with co-doped Cd and Ni for synergistic oxidative‑hydrogenation desulfurization of transportation fuel oils

Abstract

Photocatalytic oxidative coupled in situ hydrogenation is an emerging and alternative route to the traditional costly hydrodesulfurization strategy for the eradication of organosulfur compounds from transportation fuels under mild operating conditions. In this study, Cd/Ni-doped CeO2 catalysts were prepared by improved hydrothermal method, and were in turn applied for the ultra-deep desulfurization of highly resilient 4,6-dimethyldibenzothiophene (4,6-DMDBT) from diesel oil under visible light irradiation. The prepared photocatalyst were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman, Fourier transform infra-red (FTIR) spectroscopy, ultra-violet visible (UV–vis) spectroscopy and Brauner-Emmette-Teller (BET) analyses. Characterization results revealed that bimetallic doped CeO2 mesoporous nanorods were of uniform size (length: 100–200 nm and width: 30–40 nm) having different oxygen vacancies. Catalytic activity evaluation results revealed that under visible light irradiation, 20%Cd/Ni@CeO2 achieved 100% desulfurization performance of 4,6-DMDBT within 50 min at 60 °C, thus surpassing many state of the art catalysts reported in literature. Cd/Ni@CeO2 remained highly active after 10 successive reuses with rapid recovery by simple washing and filtration. Based on the experimental and characterization results, a suitable reaction mechanism was speculated for the photocatalytic desulfurization of 4,6-DMDBT using Cd/Ni@CeO2.