Process for producing unsaturated aldehydes, and unsaturated fatty acids

In a process for the gas phase catalytic oxidation of at least one olefinic hydrocarbon of 3 to 4 carbon atoms in the presence of molecular oxygen at 200.degree. to 450.degree. C. to produce mixtures of the corresponding aldehyde and acid, the improvement comprising:

• oxidizing said compound over a calcined catalyst consisting essentially of Mo.sub.a Sb.sub.b Bi.sub.c Fe.sub.d Ni.sub.e Sn.sub.f X.sub.g Y.sub.h O.sub.i wherein X is at least one alkali metal selected from the group consisting of potassium, rubidium and cesium;
• Y is at least one metal selected from the group consisting of cobalt, uranium, germanium, tungsten and titanium;
• a to h are atomic ratios wherein a=12, b=0.2 to 20, c=0.2 to 12, d=0.2 to 12, e=0.2 to 12, f=0 to 20, g=0.01 to 4 and h=0 to 6;
• and i is determined according to the oxidation states of the metal atoms in the catalyst.