Partial oxidation of H2S to sulfur on V-Cu-O mixed oxides bronzes

Abstract

The present paper shows the influence of Cu-content in Cu-promoted V2O5 catalysts on both the physicochemical characteristics of catalysts and their catalytic performance in the partial oxidation of hydrogen sulfide. Both, the catalytic activity for H2S conversion and the selectivity to sulfur increased when increasing the Cu/V ratio of catalysts. The best catalyst gives a selectivity to sulfur at ca. 98% at total conversion of H2S. According to the characterization results (XRD, FTIR), V2O5 is partially transformed into vanadium oxide bronze, i.e. β-Cu0.261V2O5, up to Cu/V ratios of 0.25. For higher Cu/V ratios, CuV2O6 and β-Cu0.261V2O5 are observed. In the same way, the reducibility of V-species increased when increasing the Cu/V ratio of catalysts. On the other hand, the characterization of used catalysts indicates the transformation of V2O5 into V4O9, whereas the vanadium oxide bronze is stable under the studied reaction. The catalytic results are explained on the basis of the nature of crystalline phases and the presence of V5+-O-V4+ pairs in the more selective catalysts.