Selective Oxidation of Hydrogen Sulfide to Sulfur over LaVO4 Catalyst: Promotional Effect of Antimony Oxide Addition

The promoting effect of antimony oxide addition on the catalytic performances of LaVO4 catalyst for catalyzing the selective oxidation of hydrogen sulfide to sulfur was studied. The multiphase La-V-Sb catalysts were characterized by temperature programmed reduction, X-ray diffraction, and Brunauer-Emmett-Teller techniques. A synergistic effect between the mixed metal oxides was observed which strongly increased the catalyst selectivity and the sulfur yield (the maximum yield increased from 88.5% for LaVO4 to 100% for La-V-Sb when weight hourly space velocity was 0.0244 mol of H2S/((g of catalyst)/h)). The best activity was observed for the La-V-Sb catalyst with V/Sb atomic ratio = 1.0. The improvements of catalytic performances were partly ascribed to the formation of SbVO4 species. The La-V-Sb catalysts showed a much wider temperature window for obtaining 100% sulfur yield than V-Sb and Mg-V-Sb catalysts. This was explained in terms of the better isolation of the active sites (caused by the large La3+ size) and the easier desorption of the elemental sulfur (caused by the lanthanum basicity).