(558m) Ammoxidation of Toulene By Using V2O5/Al2O3 As Catalyst to Synthesize Benzonitrile

A series of V₂O₅/Al₂O₃ catalysts were prepared by a wet impregnation method and employed for a onestep synthesis of benzonitrile from toluene via ammoxidation in a fixed bed reactor at atmospheric pressure. The catalysts were characterized by BET-SA, XRD, FT-IR, TPR, UV-Vis DRS and NH3-TPD to identify the molecular structural changes of the catalysts. The characterization results revealed that the addition of V₂O₅ to Al₂O₃ amplified the crystallinity of alumina and also resulted in the formation of an interactive species i.e. AlVO4. Most of the V₂O₅ existed in the form of isolated surface and polymeric tetrahedral vanadia species in a highly dispersed state and/or having a strong interaction with the support. The formation of different kinds of vanadia species was entirely dependent on the content of vanadia present in the catalyst. A 10 wt% V₂O₅/Al₂O₃ catalyst was found to be the best and the high selectivity for benzonitrile was presumably due to the formation of the isolated surface and polymeric tetrahedral vanadia species along with aluminum vanadate species.