Vanadium oxide monolayer catalysts. 3. A Raman spectroscopic and temperature-programmed reduction study of monolayer and crystal-type vanadia on various supports
Fred Roozeboom,MC Mittelmeijer-Hazeleger,Jacob A. Moulijn,J Medema,de Vhj Vincent Beer,P.J. Gellings +5 more
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TLDR
In this article, a combination of Raman spectroscopy and temperature-programmed reduction (TPR) was used for qualitative and quantitative structural analysis of vanadium(V) oxide supported on 7-A1203, GO2, Cr2O3, Si02, Ti02, and Zr02.Abstract:
Vanadium(V) oxide supported on 7-A1203, GO2, Cr2O3, Si02, Ti02, and Zr02 was studied by X-ray fluorescence, by X-ray diffraction, and especially by the combination of Raman spectroscopy and temperature-programmed reduction (TPR) for qualitative and quantitative structural analysis, respectively. Catalysts were prepared via ion-exchange and wet-impregnation methods. The V contents ranged from - 1 to 40 wt % V. At low surface concentrations only surface vanadate phases of two-dimensional character are observed for all carriers. According to Raman and TPR data the structure of these surface vanadate species is independent of the preparation technique. At medium and high surface concentrations, the webimpregnated samples already contain crystalline V20b At equal surface concentrations the ion-exchanged catalysts contain no V205 crystallites. An exception is Si02 on which also crystalline V206 is formed in both preparation techniques. Monolayer stability toward thermal treatment decreases in the order AZO>3 Ti02> Ce02,w hereas on heating ion-exchanged V/Si02 the crystalline V206 spreads out over the silica surface. The reducibilities of the ion-exchanged catalyats, as measured by TPR, can be used as a measure for the contact interaction between vanadia and the carrier oxides. At temperatures of 500-800 K, this interaction ranges from strong with titania to weak with silica as a carrier.read more
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Catalytic Properties of Ceria and CeO2-Containing Materials
TL;DR: A survey of the use of cerium oxide and CeO2-containing materials as oxidation and reduction catalysts is presented in this paper, with a special focus on catalytic interaction with small molecules such as hydrogen, carbon monoxide, oxygen, and nitric oxide.
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Chemistry, spectroscopy and the role of supported vanadium oxides in heterogeneous catalysis
TL;DR: In this paper, an overview of the current knowledge available about vanadium oxide-based catalysts is given, including the molecular structure of supported vanadium oxides under hydrated, dehydrated and reduced conditions, including parameters which influence the molecular structures formed at the surface of the support oxide.
Journal ArticleDOI
Structure and reactivity of surface vanadium oxide species on oxide supports
TL;DR: In this article, a comparison of the molecular structure and reactivity information of supported vanadium oxide catalysts is presented, which provides new fundamental insights into the catalytic properties of surface vanadia species during hydrocarbon oxidation reactions.
Journal ArticleDOI
Oxidative dyhydrogenation of short chain alkanes on supported vanadium oxide catalysts
T. Blasco,J.M. López Nieto +1 more
TL;DR: In this article, the main data appeared in the last years on the oxidative dehydrogenation (ODH) of short chain alkanes on supported vanadium oxide catalysts, and it was concluded that tetrahedral V5+-species are active and selective sites in the ODH of C2-C4 alkanes.
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Vanadium oxide monolayer catalysts Preparation, characterization and catalytic activity
TL;DR: A review of vanadium oxide monolayer catalysts can be found in this article, where the authors provide a guide to the recent literature on the preparation, structure and catalytic properties.
References
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Oxidations carried out by means of vanadium oxide catalysts
P. Mars,D. W. van Krevelen +1 more
TL;DR: In this paper, it was shown that the partial pressures of the reacting substances appeared to influence the reaction rate, and a formula depicting this influence was derived, which may be interpreted by assuming two successive reactions, namely the reaction between the aromatic and the oxygen on the surface, and the re-oxidation of the partly reduced surface by means of oxygen.