Two vanadium phosphorus oxide precursors doped by Co and Fe have been prepared by a new route consisting of a reduction of VOPO4, 2H2O by isobutanol which is known to give a particular morphology of VOHPO4, 0.5H2O, developing crystallites in the [110] direction. Their activation undern-butane/air catalytic atmosphere (1.5%) has been compared to the corresponding undoped precursor prepared under the same conditions and used as a reference. The modification of the structure of the VPO materials has been followed on-line byin situlaser Raman spectroscopy. In a first period of the activation, the nucleation of αI-VOPO4is favoured for the undoped VPO precursor, while (VO)2P2O7appears in a second period. For the Co-doped VPO precursor, αI- and αII-VOPO4first appear, and then (VO)2P2O7appears. At variance, the Fe-doped VPO precursor promotes the only nucleation of αI-VOPO4. When comparing with the classical organic route, catalytic performances are markedly improved when the VOHPO4, 0.5H2O precursor is prepared via this new route both for the undoped and the Co-doped VPO catalysts. At variance, the Fe-doped catalyst gives poorer performances which have been explained by a high oxidation state for this catalyst (almost (V5+) as αI-VOPO4). This is confirmed by an analysis of the bulk and surface composition of the final catalysts by XRD and XPS spectroscopy. The role of the two dopants on this new morphology of VOHPO4, 0.5H2O is then quite different at variance with what was observed on the same precursor prepared by the classical route of reduction of V2O5by isobutanol (see B. Abdelouahabet al., 1995,J. Catal.,157, 687. The present study demonstrates that the preparative route for the formation of doped VPO precursors is most important in controlling the VOPO4/(VO)2P2O7dispersion and catalytic performance of the final catalyst.

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{{Explor lien
   |wiki=    Wicri/Terre
   |area=    CobaltMaghrebV1
   |flux=    France
   |étape=   Analysis
   |type=    RBID
   |clé=     ISTEX:66DA8E4FB964503759F079A2260B5F8068DBACA3
   |texte=   On the Role of Fe and Co Dopants during the Activation of the VO(HPO4), 0.5 H2O Precursor of the Vanadium Phosphorus Catalyst as Studied by in Situ Laser Raman Spectroscopy
}}