Involvement of Redox Sites in Propane Ammoxidation on V-Sb-Oxide Catalysts.

Abstract

V-Sb-Oxide catalysts were prepared by SS (solid solution) and CP (co-precipitation) methods, and the involvement of redox sites and acid sites in the ammoxidation of propane were investigated by BET, XRD, XPS, NARP (Nitric oxide-Ammonia Rectangular Pulse) and NH3-TPD methods. Both series of catalysts mainly consisted of the SbVO4 phase with minor components of V2O5 and α-Sb2O4 phases. The reaction rate of propane ammoxidation increased linearly with the increase in the number of redox sites measured by NARP technique. There was no significant effect of strength and amount of acid sites on the activity of propane ammoxidation at low conversion levels. The number of redox sites is the determining factor for ammoxidation activity. V-Sb-Oxide catalysts with excess α-Sb2O4 phase exhibited higher turnover frequency.