Vanadium-containing catalysts for the selective oxidation of H2S to elemental sulfur in the presence of excess water

Various vanadium-containing catalysts were searched for the commercial application in the selective oxidation of H2S to elemental sulfur at low temperatures (less than 250 degreesC) in the presence of excess (more than 35 vol.%) water. In the test of binary oxides, it was found that TiVOx was the only catalyst that could sustain its activity without deactivation at 230 degreesC. The best catalytic activity (85-90% sulfur yield) was obtained when VOx/TiO2 was incorporated with other metals such as Fe, Cr and Mo. Reaction occurred via redox mechanism and the reoxidation of reduced vanadium was the rate-limiting step. A long-term deactivation observed during the reaction was due to slower reoxidation of reduced vanadium by oxygen than the reduction by H2S. Catalytic activities of VOx/SiO2, VOx/TiO2 and V-Fe-Cr-Mo-O-x/TiO2 were well correlated with their redox properties that were observed by TPR/TPO and XPS measurements. (C) 2000 Elsevier Science B.V. All rights reserved.