Mesoporous silicas of MCM-41 type modified by transition metal oxides, such as molybdenum, vanadium, and tungsten, were synthesized. These materials were characterized by low-temperature nitrogen adsorption/desorption, Fourier transform infrared spectroscopy, X-ray spectral fluorescence analysis, and transmission electron microscopy techniques and applied for the removal of sulfur compounds in model and real fuels by oxidative desulfurization. The catalysts obtained were tested under optimal conditions. Dibenzothiophene was removed completely, and sulfur removal in gasoline and diesel fractions could reach 91 and 63%, respectively. These catalysts retain their activity in gasoline fraction desulfurization for 5 cycles.

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Porous aromatic frameworks modified by sulfonic groups were synthesized and, for the first time, applied for the oxidative desulfurization of a model and a real fuel. The main factors affecting the process including the catalyst dosage, temperature, reaction time, oxidant dosage, and hydrogen peroxide concentration were investigated in detail. Under optimal conditions, dibenzothiophene (DBT) was removed completely. It was shown that the synthesized catalysts reduced the sulfur content in the straight-run gasoline fraction up to ultra-low values (7 ppm). Fuel fractions and their oxidation products were analyzed by two-dimensional gas chromatography with time-of-flight mass spectrometry detection. No byproducts of hydrocarbon oxidation were found, which confirms the high selectivity of oxidation in the presence of synthesized catalysts. These catalysts retain their activity in DBT oxidation for at least five cycles.

Acidic SBA-15 modified by molybdenum oxide has been synthesized. These materials were characterized by low nitrogen adsorption/desorption, Fourier transform infrared spectroscopy, transmission electron microscopy, NH3 temperature-programmed desorption, NMR, and XRD techniques. In this work, the activity of acidic Al-SBA-15 modified with molybdenum oxide in the oxidation of sulfur-containing compounds was investigated for the first time. It was shown that the SBA-15 support containing aluminum allows to significantly increase the catalytic activity of molybdenum oxide. The main factors affecting the process consisting of catalyst dosage, temperature, reaction time, oxidant dosage were investigated in detail. In the presence of synthesized catalysts, dibenzothiophene can be completely oxidized in 30 min. These catalysts retain their activity in DBT oxidation for 10 cycles.

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Polyoxometalate-based ionic liquid hybrid materials with a pyridinium cation, containing Brönsted acid sites, were synthesized and used as catalysts for the oxidation of model and real diesel fuels. Keggin-type polyoxometalates with the formulae [PMo12O40]3−, [PVMo11O40]4−, [PV2Mo10O40]4−, [PW12O40]3− were used as anions. It was shown that increasing the acid site strength leads to an increase of dibenzothiophene conversion to the corresponding sulfone. The best results were obtained in the presence of a catalyst, containing a nicotinic acid derivative as cation and phosphomolybdate as anion. The main factors affecting the process consisting of catalyst dosage, temperature, reaction time, oxidant dosage were investigated in detail. Under optimal conditions full oxidation of dibenzothiophene and more than a 90% desulfurization degree of real diesel fuel (initial sulfur content of 2050 ppm) were obtained (the oxidation conditions: NK-1 catalyst, molar ratio H2O2:S 10:1, molar ratio S:Mo 8:1, 1 mL MeCN, 70 °C, 1 h). The synthesized catalysts could be used five times with a slight decrease in activity.