The oxidation of methanol over highly dispersed vanadia supported on TiO2 (anatase) has been investigated using in situ Fourier transform infrared spectroscopy (FTIR), near ambient pressure X-ray photoelectron spectroscopy (NAP XPS), X-ray absorption near-edge structure (XANES), and a temperature-programmed reaction technique. The data were complemented by kinetic measurements collected in a fl...

A series of vanadia catalysts supported on SBA-15 (V/SBA) with a vanadia (V) content ranging from 1% to 11% were prepared by an incipient wetness method. Their catalytic behavior in the dehydrogenation of isobutane to isobutene with CO2 was examined. The catalysts were characterized by N2 adsorption, X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectroscopy, and temperatur...

Nanostructured vanadia model catalysts, i.e. highly dispersed vanadium oxide supported on mesoporous silica SBA-15 (VOx/SBA-15), were prepared. The mechanism for the synthesis of VOx/SBA-15 was elucidated by detailed characterization of the individual synthesis steps using XPS and vibrational spectrocopy. The resulting surface vanadium oxide species (0 – 2.3 V/nm), grafted on the inner pores of...

Two types of vanadia are present in fresh V20JIi02(anatase) catalysts calcined at 450°C: surface vanadia coordinated to the TiOz support and small crystallites of V205 (1, 2). The surface vanadia is the active site for the oxidation of o-xylene to phthalic anhydride (I, 3, 4). The surface vanadia is more active and selective than the VZOfi crystallites for the o-xylene oxidation reaction (I). T...

The surface chemistry of adsorbed isopropoxy groups on supported vanadia–alumina and vanadia–silica catalysts was investigated with multiple in situ spectroscopic techniques. The in situ FT-IR, Raman and UV–vis spectroscopic measurements provided molecular level information about the surface intermediates and the surface vanadium oxide species as a function of different conditions. The spectros...

The behavior of lithium ion diffusion from an electrolyte into a polycrystalline layered cathode has been studied using molecular dynamics computer simulations. Lithium silicate glass was the model solid electrolyte while the cathode was a nanocrystalline vanadia with amorphous V2O5 intergranular films ~IGF! between the crystals. Nanosized V2O5 crystals were aligned with their ~001! planes para...

The interactions between surface sulfate and surface vanadate species present on sulfated supported vanadia catalysts under dehydrated conditions have been investigated with infrared and Raman spectroscopies. The surface sulfate species present on sulfated TiO2, ZrO2, and Al2O3 supports and V2O5/TiO2, V2O5/ZrO2, and V2O5/Al2O3 catalysts have identical molecular structures, i.e., (M-O)3SdO, wher...

A series of supported V2O5/Al2O3 catalysts were synthesized by incipient wetness impregnation with vanadium isopropoxide in isopropanol solutions and subsequent calcination. The vanadium surface density was varied from 0.3 to 11.4 V atoms/nm2 spanning the sub-monolayer and above-monolayer regions. The resulting supported vanadium oxide catalysts were physically characterized with in situ Raman ...

The growth, and reactivity of monolayer V2O5 films supported on TiO2(110) produced via the oxidation of vapor-deposited vanadium were studied using X-ray photoelectron spectroscopy (XPS) and temperature programmed desorption (TPD). Oxidation of vapor-deposited vanadium in 10-7 Torr of O2 at 600 K produced vanadia films that contained primarily V+3, while oxidation in 10-3 Torr at 400 K produced...

A quantitative method based on UV-vis diffuse reflectance spectroscopy (DRS) was developed that allows determination of the fraction of monomeric and polymeric VO(x) species that are present in vanadate materials. This new quantitative method allows determination of the distribution of monomeric and polymeric surface VO(x) species present in dehydrated supported V(2)O(5)/SiO(2), V(2)O(5)/Al(2)O...