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

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 an ammoxidation catalyst comprising a compound oxide and a silica carrier having supported thereon said compound oxide,

• wherein said catalyst has an alkali metal content of 0.01 or less in terms of the atomic ratio of an alkali metal, relative to molybdenum,
• wherein said catalyst is produced by a method comprising:
• providing an aqueous mixture of a silica sol and compounds of molybdenum, vanadium, niobium, at least one element selected from the group consisting of tellurium and antimony, and optionally at least one element selected from the group consisting of ytterbium, dysprosium, erbium, cerium, neodymium, samarium, lanthanum, praseodymium, europium, gadolinium, terbium, holmium, thulium, lutetium, scandium, tungsten, chromium, tantalum, titanium, zirconium, hafnium, manganese, rhenium, iron, ruthenium, cobalt, rhodium, nickel, palladium, platinum, copper, silver, zinc, boron, aluminum, gallium, indium, germanium, tin, lead, phosphorus, bismuth and alkaline earth metals;
• drying said aqueous mixture, to thereby obtain a catalyst precursor;
• and
• calcining the catalyst precursor in an atmosphere of inert gas which is substantially free of molecular oxygen,
• said silica sol having an alkali metal content of 0.007 or less in terms of the atomic ratio of an alkali metal, relative to silicon.