(139d) Theoretical Study of Propane Activation Over Cluster Models of the Surface Ab Planes of Mo-V-Te-Nb-O M1 Phase

The mixed metal oxide Mo-V-Te-Nb-O catalysts containing so-called M1 phase have gained much recent interest due to their unique ability to transform propane directly into acrylonitrile. Despite a great deal of research on this catalytic system, the fundamental understanding of this catalyst is still rudimentary. To optimize the selectivity required of this catalyst for practical applications, it is essential to determine the mechanism of selective propane transformation reactions.

In this paper, we perform density functional theory (DFT) calculations to investigate the ab plane of the Mo-V-Te-Nb-O M1 phase that contains vanadyl (V=O), the proposed active center for propane activation, using several cluster models. We found that the energy and charge of the surface atomic layer, as well as the charge of the individual metal centers in the surface, require ca. three atomic layers to converge, suggesting that at least three ab layers are needed in a cluster model to accurately reflect the electronic properties of the surface vanadyl center of the M1 phase. We also investigated the proposed mechanism for propane activation.