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|Title:||V2O5/TiO2 catalytic xerogels raman and EPR studies|
|Author(s):||Rodella, Cristiane B.|
Franco, Roberto W. A.
Magon, Claudio J.
Donoso, Jose P.
Nunes, Luis A. O.
Saeki, Margarida J.
Aegerter, Michel A.
Florentino, Ariovaldo O.
|Year of Publication:||2002|
|OPUS Source:||Journal of sol-gel science and technology. - 25. 2002, S. 83-88|
|SWD key words:||Katalysator|
|DDC notations:||620 Engineering and machine engineering|
|Publikation type:||Journal Article|
|Abstract:||Raman spectroscopy and electron paramagnetic resonance (EPR) studies were performed on a series of V2O5/TiO2 catalysts prepared by a modified sol-gel method in order to identify the vanadium species. Two species of surface vanadium were identified by Raman measurements, monomeric vanadyls and polymeric vanadates. Monomeric vanadyls are characterized by a narrow Raman band at 1030 cm-1 and polymeric vanadates by two broad bands in the region from 900 to 960 cm-1. The Raman spectra do not exhibit characteristic peaks of crystalline V2O5. These results are in agreement with those of X-ray diffractometry (XRD) and Fourier Transform Infrared (FT-IR) previously reported (C.B. Rodella et al., J. Sol-Ge. Sci. Techn., submitted). at least tree families of V4+ ions were identified by EPR investigations. The analysis of the EPR spectra suggests that isolated V4+ ions are located in sites with octahedral symmetry substituting for Ti4+ ions in the rutile structure. Magnetically interacting V4+ ions are also present as pairs of clusters giving rise to a broad and structureless EPR line. At higher concentration of V2O5, a partial oxidation of V4+ to V5+ is apparent from the EPR results.|
|Link to this record:||urn:nbn:de:bsz:291-scidok-25172|
|Date of registration:||15-Dec-2009|
|Faculty:||SE - Sonstige Einrichtungen|
|Department:||SE - INM Leibniz-Institut für Neue Materialien|
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