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CATALYTIC ACTIVITY OF VOX-SBA-15 PREPARED BY DIRECT SYNTHESIS

Autoři: Švadlák Daniel | Setnička Michal | Bulánek Roman | Pastva Jakub | Zukal Arnošt

Rok: 2013

Druh publikace: ostatní - přednáška nebo poster

Strana od-do: nestránkováno

Tituly:

Jazyk	Název	Abstrakt	Klíčová slova
eng	CATALYTIC ACTIVITY OF VOX-SBA-15 PREPARED BY DIRECT SYNTHESIS	Direct hydrothermal synthesis of mesoporous vanado-silicate with SBA-15 structure is an alternative method for incorporation of VOx species on the silica surface or to the silica wall 1,2. This method leads to catalysts with better dispersion and coordination of VOx units on the surface and with higher performance in ODH reactions in comparison with catalysts prepared by conventional wet impregnation method. In this contribution, we report successful preparation of the mesoporous vanado silicate with SBA-15 structure by direct synthesis according procedure reported by Gao at al.3. We used triblock copolymer Pluronic P123 as a structure directing agent and the tetraethyl orthosilicate and ammonium metavanadate were used as sources of silicon and vanadium, respectively. Textural properties of catalysts were characterized by nitrogen adsorption-desorption isotherm, the concentration of vanadium was determined by X-ray fluorescence and vanadium complex speciation was investigated by diffuse reflectance UV?vis spectroscopy and hydrogen temperature programmed reduction (H2 TPR). The catalytic activities in oxidative dehydrogenation of propane (C3-ODH) were tested in plug-flow fixed-bed micro-reactor at 540 °C under different contact times. It was found out that catalyst exhibit well developed mesoporous structure with high surface area and volume of mesopores. Mainly monomeric and low oligomeric vanadium species with tetrahedral coordination were present in the catalysts. Catalytic performance of the catalysts was better than the best VOx-SBA-15 catalyst prepared by wet impregnation method which was used as a reference catalyst. Effects of the acidity and vanadium content in the synthesis gel on vanadium speciation, effectiveness of vanadium incorporation and catalytic activity and propene selectivity of the catalysts in the C3-ODH were investigated in this study. The whole set of experimental results will be shown and discussed in a broader context.	CATALYTIC ACTIVITY; VOX-SBA-15; DIRECT SYNTHESIS

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