The control of catalytic performance of rutile-type Sn/V/Nb/Sb mixed oxides, catalysts for propane ammoxidation to acrylonitrile

摘要

This paper describes the effect of the composition of rutile-type Sn/V/Nb/Sb mixed oxides catalysts on theudcatalytic performance in the gas-phase ammoxidation of propane to acrylonitrile. The variation in theudatomic ratio between components in catalysts is the key for the control of activity and selectivity. Inudsamples with atomic composition Sn/V/Nb/Sb 1/0.2/1/x (0 x 5) and 1/0.2/y/3 (0 y 3) severaludcompounds formed, i.e., SnO2, Sb/Nbmixed oxide, Sb6O13 and non-stoichiometric rutile-type V/Nb/Sb/O;udthe latter segregated preferentially at the surface of the catalyst. Tin oxide provided the rutile matrix forudthe dispersion of the mixed oxides. The main role of Sb was shown to generate mixed oxides containingudspecific sites for the allylic ammoxidation of propylene intermediately formed. The presence of Nbudenhanced the activity and selectivity of these sites.