As regulation of sulfur emission levels become more stringent, there is an urgent need for improved hydrodesulfurization (HDS) catalysts. Molybdenum sulfide and alumina supported cobalt-molybdenum sulfides have been the industrial standard for HDS. To improve such catalysts, better dispersion of MoS2 edge sites, which are the active HDS phase, must be achieved. Using Ultrasonic Spray Pyrolysis (USP) as the preparatory method, an unsupported molybdenum sulfide catalyst of submicron particles was synthesized; these particles are nanostructured and have a porous architecture similar to aerogels. Using a 1.7 MHz ultrasonic humidifier, an aqueous ammonium tetrathiolmolybdate solution containing colloidal silica was atomized in an inert atmosphere; the aerosol droplets were carried into a heated furnace where precursor decomposition occurred. The material was then collected in bubblers and treated with HF to remove the template silica. The etched material was precipitated from solution by centrifugation and characterized by elemental analysis, SEM, TEM, STEM, EDX, XRD, and BET. The porous, high surface area MoS2 so produced was also tested for thiophene HDS and found to be a highly active catalyst compared to other unsupported MoS2 sources. Additionally, the as-produced MoS2 network can be subsequently modified to produce promoted catalysts by using the metal salt impregnation technique. Using cobalt nitrate hexahydrate as the impregnation salt, Co-promoted MoS2 was synthesized, characterized, and tested for thiophene HDS activity; promotion effects were observed.
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