The ammoxidation of propane directly into acrylonitrile catalyzed by the Mo-V-Te-Nb mixed metal oxides has received considerable attention for being more environmentally benign than the propylene ammoxidation process.  However, limited understanding of the reaction mechanism has hindered the progress to improve the activity and selectivity of the catalyst required for commercialization.  We present a density functional theory based investigation for propane ammoxidation on the active center in the M1 ab plane of the oxide.  The cations exhibit distinctly different affinities for C3, CN, OHx, and NHx intermediates.  The activation barriers for propane dehydrogenation to allyl have been calculated.  V5+=O is much more active than V4+=O for propane activation with Ea=1.2 eV, consistent with V5+ being the active site on vanadium oxides for alkane activation.  Factors controlling activity and selectivity will be discussed in the context of a microkinetic model consisting of propane activation, C-N bond formation, and acrylonitrile decomposition steps.

Theoretical investigation of propane ammoxidation on Mo-V-Te-Nb-O M1 catalyst

245th National Meeting (2013)

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