Jungwon Woo and Vadim V. Guliants
Chemical Engineering, University of Cincinnati, Cincinnati OH 45221
Selective (amm)oxidation of propane over the bulk mixed MoVTeNbO catalysts containing so-called M1 and M2 phases has attracted significant attention of the catalysis community in recent years. Although the M1 phase alone is capable of activating propane to acrylic acid and acrylonitrile, the presence of the M2 phase was proposed to improve the selectivity to these products because it could efficiently convert the propylene intermediate desorbed from the M1 surface. While this phase cooperation effect was proposed for the MoVTeNbO system, other compositional variants in the M1/M2 catalytic system have not been systematically investigated.
In this study, the M1 and M2 phases of MoV(Te, Sb)(Nb, Ta)O catalytic system were synthesized by the slurry evaporation and hydrothermal synthesis methods. The M1 and M2 phases of the MoVSbTaO composition were synthesized for the very first time. The M1/M2 phase mixtures and pure M1 and M2 phases were systematically investigated in propane and propylene ammoxidation. The results obtained indicated that the enhanced selectivity to acrylonitrile observed for the M1/M2 phase mixtures may be explained by grinding the M1 phase crystals that resulted in preferential exposure of the ab planes of this phase proposed to contained the active and selective sites for propane (amm)oxidation.
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