Catalytic oxidation of 1-butene over bismuth molybdates : promoters for the Bi2O3.MoO3 catalyst

Effect of the promoters BiPO4, Fe2O3, and Cr2O3 on the catalytic activity of the moderately active Bi2O3.3MoO3 catalyst (2:3) were investigated for oxidn. of butene to butadiene. All compds. present in quantities equiv. to 10% (mole ratios) show a pronounced promoting effect. For these concns., 2 of the 3 promoters, BiPO4 and Fe2O3, promoter action is caused by formation of the active Bi2O3.MoO3 (Koechlinite) phase (2:1). This conclusion is consistent with observations that the 2:1 lines appear in the X-ray diagrams. The kinetics of the reaction shift to those earlier obsd. for the 2:1 phase and finally that the adsorptive properties for butene and butadiene become more similar to those earlier reported for 2:1 than for 2:3. The catalytic properties of the system Bi2O3.-3MoO3 + Fe2O3.3MoO3 were studied in the entire range from Bi to Fe