Effect of antimony oxide on magnesium vanadates for the selective oxidation of hydrogen sulfide to sulfur

The effect of antimony oxide addition to MgV2O6 and Mg3V2O8 was studied in the selective oxidation of hydrogen sulfide to sulfur. Significant improvements in sulfur selectivity and yield were observed for the uncalcined mechanical mixtures of magnesium vanadates with α-Sb2O4. Calcination of the mechanical mixtures resulted in the much stronger synergy in catalytic activity and sulfur selectivity. For the uncalcined samples, XRD, TPR and XPS studies indicated that antimony reduction behaviors in the mechanical mixtures differed very much from those in α-Sb2O4 alone, suggested that their selectivity improvements might be due to the interactions (probably oxygen transfer) between α-Sb2O4 and magnesium vanadates. For the calcined samples, XRD results indicated that their better catalytic performances in H2S oxidation were primarily attributed to the formation of VSbO4 compound from antimony oxide and magnesium vanadates.