support has been explained by the formation of highly High surface area titania-supported materials prepared from dispersed vanadia species. As the interaction between va-V(IV) precursors and calcined at high temperatures have been nadium oxide and titania support takes place essentially characterized by Vis-UV diffuse reflectance, FT Raman, elecby anchoring V(IV) species on titania support, the use of tron spin resonance, and X-ray photoelectron spectroscopies V(IV) precursors is expected to result in better dispersion and tested in the partial oxidation of methane. Vanadium oxide of vanadium oxide species. Simultaneously, a better interloading and calcination temperature determine the structure action of vanadium oxide species with titania support apof V 2 O 5 /TiO 2 materials. Below theoretical surface monolayer pears to promote anatase to rutile transformation at lower coverage, V(IV) species closely interacting with the support temperatures than for a vanadium oxide free titania (anaare observed. Vanadiam oxide species anchor by reaction with tase) (15). The metal oxide-support interaction is weaker titanium oxide surface hydroxyl groups. The V(IV) species on titania (rutile) than on titania (anatase) as evidenced are stabilized by interaction with titania support and further by the smaller monolayer dispersion capacity of titania stabilization occurs at high calcination temperatures by their location in titania (rutile) lattice. Larger loadings of vanadium (rutile) vs titania (anatase). The lower dispersion capacity decrease the temperatures required for conversion of titania appears to be essentially related to the lower amount of (anatase) to titania (rutile). At higher vanadium loading segresurface hydroxyl groups present on titania (rutile) phase.
gation into bulk V 2 O 5 oxide takes place, thus decreasing interac-Partial oxidation of methane on supported metal oxides tion with titania support. This enables a larger population of is quite a challenging field . Few oxides have proved V(V) species than samples with surface dispersed vanadium to be active for converting methane into C 1 -oxygenates, oxide species. Although partial oxidation of methane is nonsehowever only silica support appears to be appropriate for lective on titania (anatase), partial oxidation products are obthe selective conversion of methane. The use of other supserved on titania (rutile)-supported vanadium oxide catalysts. ports promote, in general, nonselective oxidation reactions
The higher selectivity to partial oxidation product formaldeof methane . The effect of the support on the hyde appears to be related to the high stability of V(IV) cations catalytic performance in the case of methanol oxidation located on rutile lattice and the absence of V(V) sites.