Effect of niobium on the surface properties of Nb2O5-SiO2-supported Mo catalysts

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Title: Effect of niobium on the surface properties of Nb2O5-SiO2-supported Mo catalysts
Authors: Damyanova, S.1 soniad@satline.net, Dimitrov, L.1, Petrov, L.1, Grange, P.2
Source: Applied Surface Science. May2003, Vol. 214 Issue 1-4, p68. 7p.
Subjects: Niobium, Catalysts
Abstract: Nb2O5–SiO2 oxides with different Nb content (0.8–4.4 wt.%) were prepared by impregnation of silica with ethanol solution of niobium ethoxide, Nb(OC2H5)5. Mo catalysts supported on the Nb2O5-SiO2 carriers were prepared by wetness impregnation method of the supports with an aqueous solution of ammonium heptamolybdate, (NH4)6Mo7O24. The samples were characterized by X-ray photoelectron spectroscopy (XPS) and diffuse reflectance spectroscopy (DRS). The chemical state and dispersion of metal components (Nb and Mo) were studied in the oxides and Mo-containing catalysts. It was shown a good correlation between the amount of Nb and XPS intensity Nb/Si ratios in oxide supports. Generation of new acid sites (Lewis and Bro¨nsted) in Nb2O5-SiO2 samples was easily understood when considering the change in the binding energies of Nb 3d and O 1s photoelectrons, due to a strong interaction between Nb atoms and silica. It was found that addition of niobium improves the dispersion of molybdenum on silica. [Copyright &y& Elsevier]
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Abstract:Nb2O5–SiO2 oxides with different Nb content (0.8–4.4 wt.%) were prepared by impregnation of silica with ethanol solution of niobium ethoxide, Nb(OC2H5)5. Mo catalysts supported on the Nb2O5-SiO2 carriers were prepared by wetness impregnation method of the supports with an aqueous solution of ammonium heptamolybdate, (NH4)6Mo7O24. The samples were characterized by X-ray photoelectron spectroscopy (XPS) and diffuse reflectance spectroscopy (DRS). The chemical state and dispersion of metal components (Nb and Mo) were studied in the oxides and Mo-containing catalysts. It was shown a good correlation between the amount of Nb and XPS intensity Nb/Si ratios in oxide supports. Generation of new acid sites (Lewis and Bro¨nsted) in Nb2O5-SiO2 samples was easily understood when considering the change in the binding energies of Nb 3d and O 1s photoelectrons, due to a strong interaction between Nb atoms and silica. It was found that addition of niobium improves the dispersion of molybdenum on silica. [Copyright &y& Elsevier]
ISSN:01694332
DOI:10.1016/S0169-4332(03)00347-7