Ammoxidation of paraffins and catalysts therefor

A process for the ammoxidation of a paraffin selected from propane and isobutane to make acrylonitrile and methacrylonitrile, respectively, by the catalytic vapor phase reaction of such a paraffin in admixture with oxygen and ammonia by contact with a complex metal oxide catalyst which is essentially free of bismuth, and has the elements and the proportions which are represented by the following empirical formula:

• VSb.sub.m A.sub.a D.sub.b C.sub.c O.sub.x,
• where
• A is one or more of W, Sn, B Mo and Ge;
• D is one or more of Fe, Co, Ni, Cr, Mn, Cu, Pb, Zn, Se, Te and As;
• C is one or more of an alkali metal, Ca, Sr, Ba, Tl and where m is greater than 1 and up to 20;
• a is 0.2-10;
• b is 0-5;
• c is 0-1;
• a is equal to or less than m;
• b is equal to or less than m;
• wherein x is determined by oxidation state of the other elements present, and wherein the antimony has an average valency higher than +3 and the vanadium has an average valency lower than +5, wherein A includes at least 0.2 atoms of W, crystalline Sb.sub.2 O.sub.4 is present in said catalyst, and wherein the foregoing catalyst is on an inorganic oxide support material selected from silica, alumina, titania, zirconia, silica-niobia, silica-zirconia, silica-titania, silica-alumina, Nb.sub.2 O.sub.5 and magnesia.