Synergy effects in the catalytic properties of bismuth molybdates

Abstract

Different phases (α, β and γ) and intimate equimolar mixtures of the α and γ phases of bismuth molybdate have been investigated for the mild oxidation of propene into acrolein. The mixtures were prepared either as a coprecipitate or as intimately compressed and ground mixtures. A synergy effect between the α and γ phases was observed with an enhancement in activity and selectivity for an intimate equimolar mixture. A study by X-ray diffraction, X-ray photoelectron spectroscopy and infrared spectroscopy allowed us to follow the effect of mixing on the different phases in the bulk or at the outer layers. Changes in elemental composition in either Mo or Bi because of mixing or preparation conditions were not detected.