Production of unsaturated nitriles

Claim 1

In the process for the ammoxidation of propylene or isobutylene by contacting propylene, isobutylene or mixtures thereof with molecular oxygen and ammonia in the vapor phase in the presence of a catalyst, the improvement comprising using as the catalyst a catalyst wherein the ratio of the elements is described by the empirical formula A.sub.a C.sub.b D.sub.c Fe.sub.d Bi.sub.e Mo.sub.12 O.sub.x wherein A is thorium, zirconium, yttrium or mixture thereof; C is an alkali metal, thallium, indium, silver, copper, a rare earth metal, boron, phosphorus, arsenic or mixture thereof; and D is nickel, cobalt, magnesium, cadmium, calcium, zinc, beryllium or mixture thereof; and wherein a is greater than zero to about 4; b is 0 to 4; c is 0.1 to about 20; d and e are independently about 0.1 to about 10; and x is the number of oxygens required satisfy the valence requirements of the other elements present.