Observation of Sublattice Disordering of the Catalytic Sites in a Complex Mo-V-Nb-Te-O Oxidation Catalyst Using High Temperature STEM Imaging

Douglas A. Blom, Thomas Vogt, Larry F. Allard, Douglas J. Buttrey

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    29 Scopus citations

    Abstract

    A Mo-V-Nb-Te-O oxidation catalyst has been imaged using scanning transmission electron microscopy at 780 K, which is slightly above its operating temperature. We observe a sublattice disordering of the corner-sharing octahedra forming the catalytic sites containing V5+ while the edge-sharing pentagonal bipyramidal {Nb(Mo5)} sublattice remains structurally more rigid and thereby maintains the overall structural integrity of the catalyst. Imaging the termination of the edges of the [001] basal zones at room temperature reveal a preference for presence of a closed network of secondary structural {Nb(Mo)5} units providing further evidence of the stability of this sublattice structure. We propose that sublattice disordering of catalytic sites enables structural flexibility to accommodate different oxidation states during multistep chemical reactions within a more rigid superstructure and presents a new paradigm for compositionally and structurally complex catalysts.

    Original languageEnglish
    Pages (from-to)1138-1144
    Number of pages7
    JournalTopics in Catalysis
    Volume57
    Issue number14-16
    DOIs
    StatePublished - Sep 1 2014

    Funding

    Acknowledgments We thank the USC NanoCenter for financial support for beam time on the JEOL 2100 F and travel support to ORNL. We also thank A. F. Volpe Jr., C. G. Lugmair, and R. K. Grasselli for providing the M1 specimen used in this study. Microscopy research at the Oak Ridge National Laboratory was sponsored by the U. S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Vehicle Technologies Program, as part of the Propulsion Materials Program.

    Keywords

    • Active site
    • Ammoxidation
    • M1 phase
    • MoVNbTeO catalyst
    • STEM imaging
    • Selective oxidation
    • Sublattice disorder

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