The structure of a VOx/TiO2(anatase) powder catalyst under reduction and oxidation at 623 K

The structure of a TiO2(anatase)-supported vanadium oxide powder catalyst was determined during a reduction-oxidation cycle at 623 K. A similar treatment was given to a pure V2O5 powder as reference system. The structural changes due to the reduction and oxidation on the supported and unsupported vanadium oxide were compared. A V2O5-like structure is present on the supported vanadium oxide after an initial oxidation at 623 K. The EXAFS fits point towards V2O5-clusters on the TiO2 support. A reduction with H-2 at 623 K reduced the supported vanadium oxide to the V4+ valence state and had the same structural effect as on the V2O5. The successive re-oxidation restored the V2O5-structure on both systems