Structural and Redox Properties of Vanadium Complexes in Molten Salts of Interest for the Catalytic Oxidation of Sulfur Dioxide
Publication: Research - peer-review › Article in proceedings – Annual report year: 2000
Electronic absorption (UV/VIS) spectra have been obtained at 450 degrees C from V2O5-K2S2O7 molten mixtures in SO2 ( P-SO2 = 0 - 1.2 atm) gas atmospheres. The data are in agreement with the V-V reversible arrow V-IV equilibrium: (VO)(2)O(SO4)(4)(4-)(l) + SO2(g) - 2VO(SO4)(2)(2-)(l) + SO3(g). Sulfur dioxide does not coordinate to the V-V complex but starts significantly to coordinate to V-IV for P-SO2 > 0 4 atm in accordance with the equilibrium: VO(SO4)(2)(2-)(l) + SO2(g) reversible arrow VO(SO4)(2)SO22-(l). Furthermore, high temperature Raman spectroscopy has been used to establish the structural and vibrational properties of the vanadium complexes formed in the molten salt-gas system V2O5-M2S2O7-M2SO4/SO2-O-2 (M = K or Cs). The spectral features and the exploitation of the relative Raman intensities indicate that the (VO)(2)O(SO4)(4)(+) dimeric complex unit which possesses a V-O-V bridge is formed in the V2O5-M2S2O7 molten mixtures. Interaction with SO2 or addition of sulfate leads to cleavage of the V-O-V bridge and formation of the (VO)-O-IV(SO4)(2)(2-) or (VO2)-O-V(SO4)(2)(3-) complex units respectively. The most prominent Raman bands due to the V-V and V-IV complexes formed are assigned and the spectral data are discussed in terms of possible structural models.
|Title||Twelfth International Symposium on Molten Salts|
|Editors||P. Trulove, et al.|
|Place of publication||Pennington, N.J., USA|
|Publisher||The Electrochemical Society|
|Conference||Twelfth International Symposium on Molten Salts|
|Period||17-10-99 → 22-10-99|
|Name||Electrochemical Society Series|
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