Synergy effects between bismuth molybdate catalyst phases (Bi/Mo from 0.57 to 2) for the selective oxidation of propylene to arcrolein

In this work, the synergy effect between different phases of bismuth molybdate catalysts was investigated systematically. The catalysts were prepared by spray drying and had a Bi/Mo atomic between 0.57 and 2. It is found that the synergy effect is only observed in mixtures containing γ-phase. A mixture with Bi/Mo ratio = 1.3 consisting of γ- and α-phase, exhibits the highest activity. Less homogeneous 'artificial mixtures' exhibit reduced synergy effects when compared to homogeneous 'in situ mixtures'.