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Elsevier, Journal of Catalysis, (305), p. 46-55

DOI: 10.1016/j.jcat.2013.04.020

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Mononuclear pseudo-tetrahedral V species of VSiBEA zeolite as the active sites of the selective oxidative dehydrogenation of propane

This paper was not found in any repository, but could be made available legally by the author.
This paper was not found in any repository, but could be made available legally by the author.

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Abstract

This work reports on the investigation of the influence of the nature of the V species in the ODH of propane. For this purpose, VSiBEA catalysts, including framework and/or extra-framework V species, were synthesized via the two-step method by controlling the speciation of the V species of the aqueous NH4VO3 solutions (via the pH of the corresponding solutions) to which the SiBEA zeolite was contacted with. The samples were characterized by N2 physisorption, XRD, FT-IR, 27Al, 29Si and 57V NMR, DR UV-vis and EPR. The TOF of the C3H8 ODH reaction of the samples exhibiting framework V species were found to be in good agreement with those reported in earlier works for which V species were highly dispersed on various silica supports and one order of magnitude higher than those of the samples exhibiting extra-framework V species, suggesting that isolated pseudo-tetrahedral framework V species would be the active sites of the C3H8 ODH catalytic reaction. EPR measurements of the spent catalysts indicated that these pseudo-tetrahedral framework V species were stable under the C3H8 ODH reaction conditions and were much more abundant in the V0.70SiBEA sample (for which incorporation of V in the SiBEA framework was targeted) than in the V1.00SiBEA sample (for which deposition of V occurred both in framework and extra-framework positions of SiBEA).