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OXIDATIVE DESULFURIZATION OF PETROLEUM PRODUCTS

The modern world market makes stringent requirements for the quality of motor fuels, in particular for sulfur content in them. The main classes of sulfur-containing compounds in petroleum fractions are thiols, dialkyl and cycloalkyl sulfides, alkylaryl sulfides, as well as heteroaromatic compounds – benzothiophene, dibenzothiophene and their alkyl derivatives. They have a negative impact on the quality of petroleum products. Growing demands on the quality of oil and petroleum products have led to the search for ways to reduce the sulfur content in oils and which would not lead to deterioration of physicochemical parameters of oil, such as viscosity, density, acidity, elemental and fractional composition, etc. Among the existing methods of desulfurization of oils and their fractions, special attention is drawn to oxidation methods that allow organic sulfur compounds to be converted into sulfoxides and sulfones which are easily removed by conventional separation methods, in particular by extraction or adsorption. The prospects of the oxidation method are due to the possibility of practical use of sulfoxides and sulfones in various sectors of the economy. The most common oxidants in the processes of oxidative desulfurization of petroleum fractions are hydrogen peroxide and alkylhydroperoxides in combination with catalysts that provide high selectivity and speed of the process. Transition metal compounds (Mo, V, W,) are most often used as catalysts because they are able to form peroxocomplexes in the presence of peroxides. Heterogeneous catalytic systems consisting of various solid carriers (salts, oxides, activated carbon, zeolites) and peroxide oxidants (hydrogen peroxide or alkyl hydroperoxides) are actively developing. Molybdenum-containing catalysts are one of the most efficient heterogeneous systems for oxidative desulfurization of diesel fuel. There is proved the effectiveness of oxidative desulfurization, which is a combination of catalytic oxidation of sulfur-containing compounds in the presence of a heterogeneous catalyst and adsorption on activated carbon. Methods of oxidative desulfurization with their advantages and disadvantages can be logical addition to large-tonnage hydrotreating processes, and also potentially can be used as an independent method of deep purification of oil and petroleum products from sulfur-containing compounds.