KINETICS AND MECHANISMS OF THE OXIDATION OF CARBON-MONOXIDE ON ALPHA-FE2O3

The catalytic oxidation of CO has been investigated in the presence of vacuum-activated α-Fe2O3 under various partial pressures of CO and O2 at temperatures from 200 to 350 °C. The oxidation rates have been correlated with 1.5-order kinetics; first order with respect to CO and 0.5 order with respect to O2. CO appears to be adsorbed essentially as an ionic species, while O2 is adsorbed as an ionic as well as a nonionic species. Two surface sites, probably an Fei2+ interstitial and an oxygen vacancy, might be required to adsorb CO and O2. The conductivity data show that the adsorption of CO exceeds the O2 adsorption and indicate that the adsorption process of CO (CO(g) ⇌ CO+(ads) + e-) is the rate-determining step. From the agreement between the kinetic data and conductivity measurements, the oxidation mechanism of CO and the defect structure of vacuum-activated α-Fe2O3 are suggested. © 1979 American Chemical Society.