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

The catalytic oxidation of hydrogen sulfide to elemental sulfur was investi gated on four rare earth orthovanadates REVO4 (R-E was Ce, Y, La or Sm) and three magnesium vanadates (MgV2O6, Mg2V2O7, and Mg3V2O8). These catalysts were prepared with the citrate method. Catalytic performances of REVO4 were found to be superior to those of magnesium vanadates. Among the rare earth orthovanadates, the sulfur yield decreased in the order CeVO4>YVO4>SmVO4>L aVO4. The sulfur yields of REVO4 and MgV2O6 were much better than those of the corresponding single-oxide catalysts, which might be due to the reducib ility difference between vanadium cation and R-E(3+) (or Mg2+). H-2-tempera ture programmed reduction (TPR) results showed that the reduction of vanadi um cations in REVO4 was more difficult than that in vanadium oxide alone. X -ray diffraction (XRD) measurements indicated that the bulk structures of r are earth orthovanadates and magnesium vanadates were much more stable than that of single vanadium oxide; this result suggests that these binary oxid es exhibited better resistance to sulfidation or sulfation. (C) 2001 Elsevi er Science B.V. All rights reserved.