Process for the preparation of acrylonitrile

A process for the preparation of acrylonitrile by the gaseous phase reaction of propylene with ammonia and molecular oxygen in the presence of a catalyst, characterized in that the sole catalyst is:

• a catalyst composition represented by the following general formula
• A.sub.a MoBi.sub.b Fe.sub.f Na.sub.n P.sub.p O.sub.q
• wherein
• A is at least one element selected from potassium, rubidium and cesium;
• a, b, f, n, p and q are numbers respectively representing atomic ratios of A, bismuth, iron, sodium, phosphorus and oxygen relative to one atom of molybdenum, provided that;
• a is a number of 0.002 to 0.2;
• p is a number of 0 to 0.2;
• q is the number of oxygens required to satisfy the valence requirements of the other elements present;
• and
• b, f and n are numbers respectively defined by the following formulae ##EQU4## wherein X and Y are respectively numbers falling within the area defined by a quadrilateral formed by lines connecting points (0.45, 0.35), (0.45, 0.65), (0.85, 0.50) and (0.85, 0.65) on an XY diagrammatic system of coordinates;
• and
• Z is a number of 0 to 0.6;
• said catalyst composition being supported on 30 to 70% by weight, based on said catalyst, of silica.