Temperature-dependent oxygen release, intercalation behaviour and catalytic properties of V2O5.xNb2O5 compounds

Graphical abstract: Temperature dependent oxygen loss and uptake of V2,38Nb10,7O32,7 in N2 (p(O2) = 4 x 10-5 bar) and IR spectra of gas mixtures after the reactor with V2,38Nb10,7O32,7 (A = 16.1 m2/g) and propane. Highlights: → V2O5.xNb2O5 complex oxide compounds as catalysts. → The (V, Nb)2O5 phases are able to a reversible release and uptake of oxygen without a structural variation. → Metastable (V, Nb)2O5 phases are able to catalyse the oxidative dehydrogenation of propane and propene. → Thermodynamically stable VNb9O25 phase shows no measurable catalytic activity. -- Abstract: In order to investigate the catalytic properties, V2,38Nb10,7O32,7, VNb9O25 and solid solutions of V2O5 in TT-Nb2O5 were prepared by thermal decomposition of freeze-dried oxalate precursors. The samples were characterised by X-ray diffraction and surface area determination. The crystalline samples are capable of the intercalation of sodium and lithium ions from solution. Above a temperature of about 500 oC, in dependence on the oxygen partial pressure a reversible release and uptake of oxygen without a structural variation takes place. The catalytic properties have been evaluated for the oxidative dehydrogenation (ODH) of propane and propene. There are only small differences in the catalytic activity of the different crystalline samples. Because of the relative high starting temperature, a selective catalytic oxidation of propane to propene is hardly observed.