Catalyst Principles and Mechanism

Most efficient in the ammoxidation of propene are catalysts containing simultaneously 

In the presence of ammonia, some oxidic molybdenum sites (Mo=0) are likely to be replaced by imino (Mo=NH) or diimino functions (Mo(=NH)2) which then couple with the allyl group. The final product, acrylonitrile, is obtained after dehydrogenation and the catalyst is reoxidized with air. 

At the same time, degradation and side reactions should be suppressed (see above). 

---