Selective oxidation of hydrogen sulfide on rare earth orthovanadates and magnesium vanadates

Abstract

The catalytic oxidation of hydrogen sulfide to elemental sulfur was investigated on four rare earth orthovanadates R EVO 4 (R E was Ce, Y, La or Sm) and three magnesium vanadates (MgV 2O 6, Mg 2V 2O 7, and Mg 3V 2O 8). These catalysts were prepared with the citrate method. Catalytic performances of R EVO 4 were found to be superior to those of magnesium vanadates. Among the rare earth orthovanadates, the sulfur yield decreased in the order CeVO 4>YVO 4>SmVO 4>LaVO 4. The sulfur yields of R EVO 4 and MgV 2O 6 were much better than those of the corresponding single-oxide catalysts, which might be due to the reducibility difference between vanadium cation and R E 3+ (or Mg 2+). H 2-temperature programmed reduction (TPR) results showed that the reduction of vanadium cations in R EVO 4 was more difficult than that in vanadium oxide alone. X-ray diffraction (XRD) measurements indicated that the bulk structures of rare earth orthovanadates and magnesium vanadates were much more stable than that of single vanadium oxide; this result suggests that these binary oxides exhibited better resistance to sulfidation or sulfation.