Comparison between γ-Bi2MoO6 and Bi2WO6 catalysts in the CO oxidation

Bismuth molybdate (gamma-Bi2MoO6) and bismuth tungstate (Bi2WO6) catalysts were prepared by solid-state reaction and their catalytic properties evaluated in the CO oxidation reaction. We characterize their structure by X-ray diffraction, scanning electron microscopy, Auger electron spectroscopy, and BET nitrogen absorption. X-ray diffraction analysis shows that both gamma-Bi2MoO6 and Bi2WO6 are structural analogs (SG P2(1)ab). Auger analysis shows that Bi2WO6 catalysts have more bismuth on the surface than gamma-Bi2MoO6, although both samples are bismuth deficient as compared to the stoichiometric compound. The results regarding catalytic activity show that Bi2WO6 prepared at 1073 K reaches total conversion of CO (100%) at a lower temperature when compared to gamma-Bi2MoO6. It indicates that Bi2WO6 is a potential candidate to be used as catalyst in the CO to CO2 oxidation.