Vanadium oxidative dehydrogenation

Marchal-Roch, C. Bayer, R. Moisan, J.F. Teze, A. Herve, G. Oxidative dehydrogenation of isobu-tyric acid Characterization and modeling of vanadium containing polyoxometalate catalysts. Top. Catal. 1996, 5,407-419. 

Watling, T.C. Deo, G. Seshan, K. Wachs, I.E. Lercher, J.A. Oxidative dehydrogenation of propane over niobia supported vanadium oxide catalysts. Catal. Today 1996, 28, 139-145. 

Nature of Vanadium Species in Vanadium-Containing Silicalite and Their Behavior in Oxidative Dehydrogenation of Propane... 

The good catalytic behavior of V-containing silicalite may be associated with the presence of the tetrahedral V species stabilized by the interaction with the zeolite framework as regards both redox and coordination changes. In fact, ESR and TPR data indicate the lower rate of reduction of this species as compared to that of supported vanadium-oxide, and V-NMR data indicate the stability against changes in the coordination environment. Catalytic data (Fig.s 2 and 3) indicate the better catalytic performances of this species in propane oxidative dehydrogenation as compared to supported polynuclear vanadium-oxide which can be removed by treatment with an ammonium acetate solution. 

It has been shown that the activity of niobia for the oxidative dehydrogenation of propane can be increased by adding vanadium or chromium, while maintaining a high selectivity towards propylene. 

This paper summarized our current understanding of the factors that determine selectivity for dehydrogenation versus formation of oxygen-containing products in the oxidation of light alkanes. From the patterns of product distribution in the oxidation of C2 to C6 alkanes obtained with supported vanadium oxide, orthovanadates of cations of different reduction potentials, and vanadates of different bonding units of VO in the active sites, it was shown that the selectivities can be explained by the probability of the surface alkyl species (or the... 

Vanadium species in V-containing silicalite in propane oxidative dehydrogenation— Continued... 

A reaction of particular relevance with respect to applied catalysis is the oxidative dehydrogenation (ODH) of hydrocarbon by VmOn ions according to reaction 2, which involves a two-electron reduction of the cluster. By means of a systematic study of the reactions of various YmOn ions as well as the related oxo-vanadium hydroxides VmO H+ ions with a set of C4-hydrocarbons, it was demonstrated recently that the ODH activity of the cluster ions shows a clear correlation with the formal valence of vanadium in the cluster ions with a maximum reactivity for formal vanadium (V) (Fig. 3) [84]. In such a kind of reactivity screening, it is essential to include more than a single reagent as a probe for the reactivity of the different ions in order to reduce interferences by kinetic barriers of one particular combination of neutral and ionic reactants [85]. Accordingly, the sums of the relative rate constants for the ODH reactions of the four different butenes are considered and normalized to the most reactive ion studied, which turns out to be the formally pure vanadium (V) compoimd In addition to isomeric... 

Oxidative Dehydrogenation. Specific reviews deal with oxidative dehydro-genation of lower alkanes, particularly over vanadium oxide-based cata-... 

The catalysts based on vanadium oxide are one of the better studied systems. A V-Mg oxide in which Mg orthovanadate (Mg2(V04)2) and MgO were the only identifiable phases was a rather selective catalyst (27). Since MgO was relatively inactive in alkane activation, Mg orthovanadate was assumed to be the active component. Indeed, Mg orthovanadate prepared as a stoichiometric compound showed high selectivities for the oxidative dehydrogenation of propane (29). In this latter study, it was shown interestingly that Mg orthovanadate was the only alkali or alkali earth orthovanadate that... 

The multifunctionality is achieved through either the combination of two different compounds (phase-cooperation) or the presence of different elements inside a single crystalline structure. In antimonates-based systems, cooperation between the metal antimonate (having a rutile crystalline structure), employed for propane oxidative dehydrogenation and propene activation, and the dispersed antimony oxide, active in allylic ammoxidation, is made more efficient through the dispersion of the latter compound over the former. In metal molybdates, one single crystalline structure contains both the element active in the oxidative dehydrogenation of the hydrocarbon (vanadium) and those active in the transformation of the olefin and in the allylic insertion of the N H2 species (tellurium and molybdenum). 

Cortez, G.G. Banares, M.A. A Raman Spectroscopy Study of Alumina-Supported Vanadium Oxide Catalyst During Propane Oxidative Dehydrogenation with Online Activity Measurement /. Catal. 2002, 209, 197-201. 

Oxidative dehydrogenation of alcohols is a new approach in the development of industrial processes for the synthesis of aldehydes and ketones [103-105], In this regard, the technologically most suitable is the method of acetaldehyde synthesis in the presence of melted vanadium oxide, alkaline metals with promoting additives, alkaline metal sulfates or chlorides as catalysts [105], The target product yield equals 65.9% per used alcohol at 69.2% conversion. The disadvantage of the method is the relatively low yield of the target product... 

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