AMMOXIDATION OF 3-PICOLINE TO NICOTINONITRILE OVER VANADIUM PHOSPHORUS OXIDE-BASED CATALYSTS

Ammoxidation of 3-picoline to nicotinonitrile was investigated on vana dium phosphorus oxide (VPO), VPO/SiO2 and additive atom (Cu, Zr, Mn an d Co) incorporated VPO catalysts under atmospheric pressure and at 673 K. For the purpose of comparison a conventional V2O5-MoO3/Al2O3 catal yst was also studied under identical conditions. These catalysts were characterized by means of X-ray diffraction, electron spin resonance, infrared, ammonia chemisorption and BET surface area methods. The VPO- based catalysts show better performance than the V2O5-MoO3/Al2O3 catal yst. Further, the VPO/SiO2 and VPO catalysts exhibit better conversion and product selectivities than the additive-containing VPO catalysts. Better activity of VPO and VPO/SiO, catalysts was related to their hi gh active surface area, higher surface acidity and lower oxidation sta te of vanadium. The redox couple between (VO)(2)P2O7 (V4+) and alpha(1 )-VOPO4 (V5+) phases appears to be responsible for the ammoxidation ac tivity of VPO catalysts. (C) 1998 SCI.