Limitations of V-Sb-W and Mo-V-Nb-Te mixed oxides in catalyzing propane ammoxidation

Testing of several catalysts proposed in the literature revealed that the activity and selectivity of Mo-V-Nb-Te mixed oxides for the ammoxidation of propane compares favourably with the activity and selectivity of V-Sb, Bi-Mo, and VPO mixed oxides under oxidizing reaction conditions. Ln addition to a higher acrylonitrile yield, the required reaction temperature is also lower. Reactor temperature, feed composition, and catalyst composition were optimized. Acrylonitrile yields of >50% were obtained with Mo-V-Nb-Te mixed oxide catalysts using a feed consisting of propane, ammonia, and oxygen in a ratio of 1 : 1.2 : 3. Data on the decomposition of ammonia and the combustion of propane over Mo-V-Nb-Te, V-Sb, and Bi-Mo mixed oxides revealed that the ammoxidation of propane is limited by propane activation for Bi-Mo mixed oxide and by ammonia activation for V-Sb mixed oxide. The high activity and selectivity of Mo-V-Nb-Te mixed oxides was attributed to its ability to activate both, propane and ammonia at low temperatures. (C) 1998 Elsevier Science B.V. All rights reserved.