XAFS study of niobium oxide on alumina

• Published in: Catalysis today Vol. 28; no. 1; pp. 71 - 78
• Main Authors: Tanaka, Tsunehiro, Yoshida, Tomoko, Yoshida, Hisao, Aritani, Hirofumi, Funabiki, Takuzo, Yoshida, Satohiro, Jehng, Jih-Mirn, Wachs, Israel E.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Amsterdam Elsevier B.V 01.04.1996; Elsevier Science
• Subjects: Alumina; Catalysis; Catalysts: preparations and properties; Chemistry; Exact sciences and technology; General and physical chemistry; Niobium oxide; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry; X-ray absorption fine structure; Niobium oxide; Alumina; X-ray absorption fine structure; Niobium Oxides; XANES spectrometry; Experimental study; Supported catalyst; EXAFS spectrometry
• ISSN: 0920-5861; 1873-4308
• DOI: 10.1016/0920-5861(95)00231-6

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 x /Al 2O 3. The XANES spectra of 5 wt.-% NbO x /Al 2O 3 suggests that NbO 4tetrahedra with two NbO bonds are present and one or two water molecules are adsorbed onto the species. On 5 wt.-% NbO x /Al 2O 3, the presence of a mixture of the monomer NbO 4 and the dimer Nb 2O 7 are concluded from the EXAFS analysis.