A kinetic study on the low temperature oxidation of CO over Ag-contaminated Au fine powder

摘要

The mechanism of CO oxidation with O_2 on Ag-contaminated Au fine powder (Ag/Au) was studied by kinetic measurements combined with the determination of the amount of CO_2 produced. The kinetic behavior of "Ag/Au having the steady state surfaces" indicated that the oxidation proceeds through co-adsorption of CO and O_2 to form (CO3)~* succeeded by its decomposition enhanced by the interaction with CO and O_2 to produce CO_2 at the contact interface between surface silver and gold support. The kinetics measurements performed on "Ag/Au having the oxidized surfaces" indicated that only the reduction of reactive adsorbed oxygen with CO in the reaction mixture to produce CO_2 proceeds at first without incorporation of O_2 in the gas phase and that the participation of O_2 in the CO_2 production process as well as its incorporation into the catalyst surface starts gradually as the reduction of reactive adsorbed oxygen on Ag proceeds.