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

Abstract

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. In 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.