Chemically induced fast solid-state transitions of omega-VOPO4 in vanadium phosphate catalysts.
Vanadium phosphates are important catalysts for the oxidation of alkanes, and commercial catalysts comprise a complex range of V4+ and V5+ phosphates. We used three complementary in situ characterization methodologies-powder x-ray diffraction and laser Raman and electron paramagnetic resonance spectroscopies-to show that the metastable phase omega-VOPO4 is very sensitive to many of the reactants and products of butane oxidation. A rapid transformation from omega-VOPO4 to delta-VOPO4 occurs on exposure to butane at the reaction temperature, and hence the metastable omega-VOPO4 may play a role in the formation of commercial catalysts.
Conte
Marco
M
School of Chemistry, Cardiff University, Main Building, Park Place, Cardiff CF10 3AT, UK.
Budroni
Gerolamo
G
Bartley
Jonathan K
JK
Taylor
Stuart H
SH
Carley
Albert F
AF
Schmidt
Andi
A
Murphy
Damien M
DM
Girgsdies
Frank
F
Ressler
Thorsten
T
Schlögl
Robert
R
Hutchings
Graham J
GJ