Development of vanadium-based mixed oxide catalysts for selective oxidation of H2S to sulfur

Various vanadium-based binary and multi-metallic oxides were prepared and their catalytic activities for the selective oxidation of H2S to elemental sulfur were tested. Because the deactivation of vanadium-based catalysts originated from a relatively slow rate of reoxidation of the reduced vanadium oxide [PhD thesis, Pohang University of Science and Technology, 2000], the focus was given to increase the redox ability, especially in the reoxidation step. Stable and improved activity was observed in BiVOx, TiVOx, and ZrV2O7 at 250°C, but TiVOx was the only catalyst that could maintain its activity below 250°C. Much higher activity was observed when VOx/TiO2 became multi-metallic by the incorporation of Fe, Cr, and Mo. TPR–TPO, microbalance, and XPS techniques were used to explain the redox properties of VOx/SiO2, VOx/TiO2, and V-Fe-Cr-Mo-Ox/TiO2 catalysts in the reoxidation step.