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This article is devoted to scientific and technical aspects of the direct catalytic oxidation of hydrogen sulfide for the production of elemental sulfur. It includes a detailed description of the Claus process as the main reference technology for hydrogen sulfide processing methods. An overview of modern catalytic systems for direct catalytic oxidation technology and known processes is presented. Descriptions of the scientific results of the Institute of Catalysis of the SB RAS in a study of the physical and chemical foundations of the process and the creation of a catalyst for it are included. The Boreskov Institute of Catalysis SB RAS technologies based on fundamental studies and their pilot and industrial testing results are described.

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The possibility of oxidative desulfurization of dibenzothiophene dissolved in toluene as a model organosulfur compound of diesel fuel in the presence of catalytic CuZnAl compositions was studied. It was shown that the CuZnAl catalysts at 350-450°C ensure sulfur removal from the model fuel to the extent of up to 40-45%. Part of the sulfur is removed as SO 2 , and some sulfur is absorbed on the catalyst surface.

<p>An effective gas-phase oxidative desulfurization (ODS) process was proposed. The process was studied in a laboratory reactor with a proprietary catalyst at 300-400 ºС and ambient pressure with model fuels represented by thiophene, dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (DMDBT) dissolved in octane, isooctane or toluene. The reactivity of different sulfur containing molecules in ODS was shown to increase in the sequence: thiophene &lt; DBT &lt; DMDBT. The main sulfur containing product of oxidation of these compounds was SO₂. During the gas-phase ODS both processes of sulfur species oxidation and processes of their adsorption were observed and studied. Based on the conducted studies, different ODS process designs comprising its integration with adsorption and regeneration processes and with conventional hydrodesulfurization (HDS) process were proposed. One scheme is based on alternating regimes of ODS and catalyst regeneration in two reactors: sulfur is removed from organic feedstock by oxidation and adsorption in one reactor while simultaneous regeneration of the catalyst that has accumulated sulfur  compounds takes place in another reactor. Two other schemes are based on joint use of ODS and HDS. The conventional HDS process is most effective for removal of low-boiling sulfur containing compounds reactive with respect to hydrogen, while removal of refractory sulfur compounds, such as DMDBT is more easily achieved by gas phase ODS. Thus the combination of these processes is expected to be most efficient for deep desulfurization of diesel fuel.</p>