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Issue 7, 2012
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Topology of silica supported vanadium–titanium oxide catalysts for oxidative dehydrogenation of propane

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Abstract

Two-dimensional vanadia and titania surface clusters were hosted on the walls of the hierarchical pore system of mesoporous silica SBA-15. The topology of the catalyst surface was varied by sequential grafting of vanadium and titanium alkoxides generating an extended library of mixed (VOx)n–(TiOx)n/SBA-15 catalysts. The surface of the catalysts was analyzed by FTIR, UV-vis, Raman, and NEXAFS spectroscopy. Electron microscopy, X-ray fluorescence, X-ray diffraction, and nitrogen adsorption have been applied to characterize chemical composition, micro- and meso-structure of the materials. Segregation of nano-crystalline vanadia and titania particles was excluded by UV-vis, Raman and NEXAFS spectroscopy. Monolayer coverage of titanium oxide surface species has been achieved in the range between 17 and 19 wt% Ti loading corresponding to 6–8 Ti atoms per nmcat2 and Si/Ti ratios between 3.3 and 2.8. Up to a critical total metal loading, vanadia is grafted on both the silica surface and surface titania species yielding tetrahedrally coordinated vanadium oxo-species characterized by low nuclearity and moderate catalytic activity. A volcano-type dependency with respect to the propylene space-time yield has been observed in the oxidative dehydrogenation of propane. The maximum in productivity of propylene is attributed to a particular surface topology that is characterized by (VOx)n islands embedded in a matrix of dispersed titania species forming an almost complete combined vanadia–titania monolayer on the silica surface.

Graphical abstract: Topology of silica supported vanadium–titanium oxide catalysts for oxidative dehydrogenation of propane

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Publication details

The article was received on 23 Dec 2011, accepted on 04 Mar 2012 and first published on 06 Mar 2012


Article type: Paper
DOI: 10.1039/C2CY00541G
Citation: Catal. Sci. Technol., 2012,2, 1346-1359
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    Topology of silica supported vanadium–titanium oxide catalysts for oxidative dehydrogenation of propane

    N. Hamilton, T. Wolfram, G. Tzolova Müller, M. Hävecker, J. Kröhnert, C. Carrero, R. Schomäcker, A. Trunschke and R. Schlögl, Catal. Sci. Technol., 2012, 2, 1346
    DOI: 10.1039/C2CY00541G

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