Structural characterization of vanadium oxide catalysts supported on nanostructured silica SBA-15 using X-ray absorption spectroscopy

• Published in: BMC chemistry Vol. 4; no. 1; p. 3
• Main Authors: Walter, Anke, Herbert, Rita, Hess, Christian, Ressler, Thorsten
• Format: Journal Article
• Language: English
• Published: Cham Springer International Publishing 11.02.2010; Springer Nature B.V; BioMed Central Ltd; BioMed Central; BMC
• Subjects: Absorption spectroscopy; Analytical Chemistry; Chemistry; Chemistry and Materials Science; Chemistry/Food Science; Data processing; Fittings; Nanostructure; Oxides; Research Article; Silicon dioxide; Spectrum analysis; Studies; Vanadium oxides; X-rays; NH4VO3; Selective Propene Oxidation; XANES Spectrum; Vanadium Loading; Vanadium Oxide
• ISSN: 1752-153X; 1752-153X; 2661-801X
• DOI: 10.1186/1752-153X-4-3

The local structure of vanadium oxide supported on nanostructured SiO 2 (V x O y /SBA-15) was investigated by in situ X-ray absorption spectroscopy (XAS). Because the number of potential parameters in XAS data analysis often exceeds the number of "independent" parameters, evaluating the reliability and significance of a particular fitting procedure is mandatory. The number of independent parameters (Nyquist) may not be sufficient. Hence, in addition to the number of independent parameters, a novel approach to evaluate the significance of structural fitting parameters in XAS data analysis is introduced. Three samples with different V loadings (i.e. 2.7 wt %, 5.4 wt %, and 10.8 wt %) were employed. Thermal treatment in air at 623 K resulted in characteristic structural changes of the V oxide species. Independent of the V loading, the local structure around V centers in dehydrated V x O y /SBA-15 corresponded to an ordered arrangement of adjacent V 2 O 7 units. Moreover, the V 2 O 7 units were found to persist under selective oxidation reaction conditions.