Two series of FeOx/SBA-15 and FeOx/Zr-SBA-15 mesoporous catalysts were synthesized with ultrasound-assisted method by varying Fe content from 10 wt% to 20 and 30 wt%. The crystalline structure, textural properties, surface morphologies, surface acidity, and phase composition of the catalysts were characterized by X-ray diffraction (XRD), N2 adsorption–desorption isotherm, scanning electron microscopy (SEM), transmission electron microscopy (TEM), in situ Fourier transform infrared spectroscopy (FTIR). The XRD, Raman and Mössbauer spectroscopic characterizations showed that both γ-Fe2O3 and α-Fe2O3 nanoparticles were present in all the catalysts and Fe3+ ions were dispersed on the surface of SBA-15 with different coordination. In the oxidation desulfurization (ODS) of a model diesel, the reaction parameters (temperature, time, and catalyst mass), Fe content, zirconium doping, and surface acidity of the catalysts were all critical for the ODS in a biphasic reaction system. All catalysts chiefly contained Lewis acidity which was related to iron content and zirconium modification and could correlate well with catalytic activity. Zirconium incooperating into the SBA-15 solid increased surface acidity and promoted γ-Fe2O3 formation by inhibiting the amorphous iron oxide in the Fe/Zr-SBA-15 catalysts, thus improved the ODS efficiency. The reaction temperature 60 °C was the optimal for ODS reaction, temperature greater than 80 °C led to oxidant partial decomposition. Under the optimal reaction condition, 0.1 g of the best catalysts (30%Fe/SBA-15 and 30%Fe/Zr-SBA-15) could remove all dibenzothiophene (DBT) (300 ppm DBT in 100 ml n-hexadecane) at 60 °C within 30 min. Thus, the combination of catalysis, oxidation and extraction in our polar-nonpolar-solid reaction system was simultaneously realized in one unit, which will be promising for effectively removal of organosulfur compounds for production of ultralow sulfur fuels.
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