Influence of reducing power on selective oxidation of H2S over V2O5 catalyst in IGCC system

Abstract

Among the transition metal oxides tested for the selective oxidation of H2S in this study, V2O5 showed the highest conversion of H2S and the selectivity of elemental sulfur. Conversion of H2S on V2O5 in the presence of water vapor was 75%, which was 17% lower than that under the water-free condition, at 200 °C due to the degraded reduction of V2O5, caused by the decrease of reducing power. The degraded reduction of V2O5 could be lessened by physically mixing with zeolite-NaX. Conversion of H2S on a physically mixed V2O5/zeolite-NaX was about 83%, which was 7% higher than that on an unmixed V2O5 under the same condition. On the other hand, conversion of H2S on a chemically mixed V2O5/zeolite-NaX was about 20%. It could be concluded that the selective oxidation of H2S could be improved by the alleviated reduction of V2O5 as it was physically mixed with zeolite-NaX. However, the conversion of H2S on V2O5 in presence of coal derived synthesis gas was 30%. It could be enhanced by the increase of oxygen or water content. From these results, it could be concluded that the reducing power of reactants was the most important factor in the selective oxidation of H2S and the selective oxidation of H2S can be applied to the hot gas cleanup in IGCC system.