The low-temperature catalytic oxidation of CO with N 2O by molybdenum oxide supported on silica gel

Abstract

On the surface of partially reduced molybdenum oxide supported on silica gel the O − ion was formed from adsorbed N 2O and reacted with CO to give the CO 2 − ion. The latter ion was thermally stable to temperatures in excess of 100 °C. Preadsorption of CO inhibited the formation of the O − and CO 2 − ions, but the preadsorption of CO 2 had no effect on the formation of the two species. The supported molybdenum oxide was active for the oxidation of CO to CO 2 at temperatures as low as 0 °C. At all pressures and temperatures studied, the reaction rate was zero order in the partial pressure of CO and CO 2; whereas, the rate was zero or first order with respect to the N 2O partial pressure, depending upon the pressure and temperature. Apparent activation energies of 14.9 and 10.8 kcal/mole were determined for the zero and first order reactions, respectively. In view of the thermal stability of CO 2 − and the inhibiting effect of CO, it is concluded that the O − ion is not an intermediate in the low-temperature reaction. Rather, the reaction appears to involve molecular complexes of N 2O and CO on clusters of metal ions.