A theoretical investigation on the influence of anatase support and vanadia dispersion on the oxidative dehydrogenation of propane to propene

• ODP reaction on four VOx/TiO2 catalysts has been studied by DFT methods.
• Key factors affecting activity: support surface, vanadia loading and active sites.
• Activity is controlled by the oxidizability and bonding ability of active sites.
• The coexistence of OV= and OV–Ti sites enhances the catalytic activity.

The oxidative dehydrogenation of propane (ODP) on the anatase supported vanadia catalysts (VOx/TiO2) have been investigated using periodic DFT calculations. Free energy profiles indicate that the first C–H activation step is the rate-determining (RD) step and the transition state (TS) of the propene formation step is the RD–TS. ODP activity can be tuned by vanadia dispersion and support surface via the modification of the electronic structure of the active oxygen sites. For the RD step, on both dimer VOx/TiO2 catalysts terminal sites have higher activity. On monomer VOx/TiO2 (1 0 0) terminal and interface sites exhibit similar activity, while on monomer VOx/TiO2 (0 0 1) interface sites have higher activity. With increasing vanadia loading, the formation of propene changes from propyl radical mechanism to a concerted propoxide one. The results suggest that TiO2 (1 0 0) is a better support surface. Terminal and interface oxygen sites act cooperatively as the first and second C–H bond activation centers, respectively.

First principle calculations on the ODP reaction catalyzed by VOx/TiO2 indicate that the catalytic activity is related with support surface, vanadia loading and active sites by affecting the oxidizability and bonding ability of active sites. The coexistence of OV= and OV–Ti sites enhances the catalytic activity.Figure optionsDownload high-quality image (197 K)Download as PowerPoint slide