Selective oxidation of H2S to elemental sulfur over Ce–V mixed oxide and CeO2 catalysts prepared by the complexation technique

Selective oxidation of H2S to elemental sulfur was investigated in a fixed bed reactor using Ce–V mixed oxides and cerium oxide (CeO2) catalytic materials prepared by the complexation technique. The Ce–V mixed oxide with a V/Ce atomic ratio of one and with the CeVO4 crystal structure gave very high sulfur selectivity values (close to one) at almost complete conversion of H2S, for O2/H2S mole ratios close to 0.5. Best operation temperature was found as 250 °C with this catalyst. CeO2 gave lower selectivities, causing the formation of some SO2, even at sub-stoichiometric O2/H2S feed ratios. It also showed a fast deactivation due to the partial sulfidation of the catalyst surface during the reaction. XPS analysis of the fresh and the used catalysts containing different V/Ce ratios strongly indicated that the selective oxidation of H2S to elemental sulfur over the Ce–V mixed oxides involved a redox cycle of cerium, rather than a redox cycle of vanadium.