Designing Al-SiO2 nanospheres with co-doped Ce/Cd for the removal of 4,6-dimethyldibenzothiophene of fuel oil

Abstract

Catalytic oxidative coupled in-situ hydrodesulfurization technology as an emerging desulfurization process is applied to the removal of organic sulfides from fuels. In this study, Al-SiO2@Ce/Cd core-shell nanosphere catalysts were prepared by a sol-gel method and a co-impregnation method using silica as the carrier, and were in turn applied for the ultra-deep desulfurization of highly resilient 4,6-DMDBT from diesel oil under visible light irradiation. The prepared photocatalyst were characterized by transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and Brauner-Emmette-Teller (BET). Characterization results revealed that Al-SiO2@Ce/Cd had a nanosphere structure, and Ce/Cd were successfully loaded on the surface of Al-SiO2. Bimetallic loading helped increase the specific surface area of the SiO2 material, which could anchor more effective metal active sites. The effects of metal doping amount, doping ratio, catalyst dosage, and reaction temperature on 4,6-DMDBT desulfurization were studied. The results showed that 20% Al-SiO2@Ce/Cd achieved 100% desulfurization performance within 30 min at 60 ℃, thus surpassing many state of the art catalysts reported in literature. Al-SiO2@Ce/Cd remained highly active after 10 times successive reuses with rapid recovery by washing and filtering. Organic nitride had a strong inhibitory effect on diesel desulfurization, which was derived from the competitive adsorption of nitride and sulfide on the effective active site of the catalyst. Based on characterization results and desulfurization results, the appropriate reaction mechanism of the catalytic oxidative coupling in-situ hydrodesulfurization of Al-SiO2@Ce/Cd catalysts was speculated.