XAFS study of niobium oxide on alumina
نویسندگان
چکیده
The structure of the niobium oxide on alumina surface was investigated for low loading (5 wt.-%) and high loading (19 wt.-%) samples. The TPD profile of water molecules showed the appearance of water adsorption sites other than those on alumina. The XANES and EXAFS spectra clearly showed that niobic acid-like species are formed on the surface of 19 wt.-% NbO,/Al,O,. The XANES spectra of 5 wt.-% NbO,/Al,O, suggests that NbO, tetrahedra with two Nb=O bonds are present and one or two water molecules are adsorbed onto the species. On 5 wt.-% NbO,/AI,O,, the presence of a mixture of the monomer NbO, and the dimer Nb,O, are concluded from the EXAFS analysis.
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