Catalytic Oxidation of Hydrogen Sulfide to Sulfur on Vanadium Antimonate

The catalytic oxidation of hydrogen sulfide to sulfur on three vanadium antimonate catalysts (with bulk V/Sb atomic ratio at 5/1, 1/1, and 1/5) was studied with a flow reactor in the temperature range of 180−280 °C. Strong synergistic phenomena in catalytic activity and selectivity were observed for the vanadium antimonate catalysts. The catalyst with equal vanadium atoms and antimony atoms (abbreviated as VSB11 catalyst) was found to be the most effective, and the X-ray diffractometric data showed that the major phase present in the VSB11 catalyst was rutile VSbO 4 which contained antimony in the oxidized state (Sb 5+ ) and vanadium in the reduced state. X-ray photoelectron spectroscopic data suggested that both surface vanadium sites and surface antimony sites were in the reduced state after the oxidation of hydrogen sulfide. Under the condition of dilute H 2 S and O 2 /H 2 S molar ratio ≥1, the oxidation rate on the VSB11 catalyst was determined to be first order in hydrogen sulfide and zero order in oxygen, which suggested that the reaction followed the redox mechanism and the rate-limiting step was the reduction of the oxidized catalyst (probably VSbO 4 ) by hydrogen sulfide.