THE MUTUAL PROMOTION EFFECT OF MOLYBDATES IN MULTICOMPONENT MOLYBDATECATALYSTS

Multicomponent molybdate catalysts (e.g. of the composition Bi2Fe1,5Co 7Cr10Mo19Oy) are produced by coprecipitation, drying and calcination. These catalysts exhibit high activity and selectivity in the ammoxidat ion of propene to acrylonitrile. The individual molybdates (Co-, Fe- a nd Cr-molybdate) exhibit no selectivity in the ammoxidation of propene . Therefore a mutual promotion effect of these molybdates exists. The cause of the promotion effect is the formation of the active and selec tive phase from the beta-phase of Co-molybdate by exchange of protons with ions of Fe3+ and Cr3+ from the molybdates of Fe and Cr. The struc ture of this catalytic active and selective phase is similar to the st ructure of the beta-phase of Co-molybdate.