Ammoxidation catalyst for use in producing acrylonitrile or methacrylonitrile from propane or isobutane by ammoxidation

A process for producing acrylonitrile or methacrylonitrile, which comprises reacting propane or isobutane with ammonia and molecular oxygen in the gaseous phase in the presence of a catalyst, which comprises:

• a compound oxide represented by the following formula (1):
• Mo.sub.1.0 V.sub.p X.sub.q Nb.sub.r Z.sub.s O.sub.n ( 1)
• wherein:
• X is at least one element selected from the group consisting of tellurium and antimony;
• Z is at least one element selected from the group consisting of tantalum, tungsten, chromium, titanium, zirconium, bismuth, tin, hafnium, manganese, rhenium, iron, ruthenium, cobalt, rhodium, nickel, palladium, platinum, silver, zinc, boron, aluminum, gallium, indium, germanium, lead, phosphorus, rare earth elements and alkaline earth metals;
• and p, q, r, s and n are, respectively, the atomic ratios of vanadium, X, niobium, Z and oxygen, relative to molybdenum,
• wherein
• 0.1.ltoreq.p.ltoreq.0.6;
• 0.01.ltoreq.q.ltoreq.0.6;
• 0.01.ltoreq.r.ltoreq.0.6;
• 0.ltoreq.s.ltoreq.1;
• and
• n is a number determined by the valence requirements of the other elements present,
• said compound oxide exhibiting an X-ray diffraction pattern satisfying the following relationship (2):
• 0.40.ltoreq.R.ltoreq.0.75 (2)
• wherein R represents the intensity ratio defined by the following formula (3):
• R=P.sub.1 /(P.sub.1 +P.sub.2) (3)
• wherein P.sub.1 and P.sub.2 represent the intensities of peak 1 and peak 2 appearing at diffraction angles (2.theta.) of 27.3.+-.0.3.degree. and 28.2.+-.0.3.degree., respectively.