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1H, 51V and 15N nuclear magnetic resonance studies of structure and properties of vanadia supported on TiOxSiO2

✍ Scribed by V.M. Mastikhin; V.V. Terskikh; O.B. Lapina; S.V. Filimonova; M. Seidl; H. Knözinger

Publisher
Elsevier Science
Year
1995
Tongue
English
Weight
958 KB
Volume
4
Category
Article
ISSN
0926-2040

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✦ Synopsis

1H magic-angle spinning nuclear magnetic resonance (MAS NMR) spectra of TiO chi/SiO2 catalysts suggest the interaction of surface TiO chi species with Si-OH groups of the silica. Simultaneously, Ti-OH groups from surface titania species appear. The distribution of TiO chi species over SiO2 is non-uniform, since a considerable part of surface OH groups remains unreacted with supported titania. Supported vanadia species interact both with Si-OH and Ti-OH groups. 51V NMR spectra suggest the interaction of vanadia with supported titania species and show the non-uniform distribution of titania over the SiO2 surface. Deposition of titania as well as vanadia produces strong electron-accepting (Lewis) sites which interact with the terminal N atom of adsorbed N2O molecules, resulting in a downfield shift of the resonance in 15N NMR spectra. The acid strength of electron-accepting sites is similar in both cases. Only about 10% of the total amount of supported titania and vanadia create Lewis sites.

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