Copper manganese mixed oxides were prepared by a hydrolysis-coprecipitation method using tetramethyl ammonium hydroxide and calcined at 573–873Â K. The effect of aging treatment after the coprecipitation process on the catalytic properties of the calcined mixed oxides for CO oxidation was investigated. XRD and EXAFS studies showed that spinel phases were mainly formed in the aged catalysts and the degree of disorder in the Cu–Mn spinel oxide phases increased. The aging treatment suppressed the formation of crystallites of mixed oxides, but the treatment promoted the crystallization of impurity CuO phase. The aged catalyst exhibited higher activity for CO oxidation than the unaged catalysts. The optimum calcination temperature for obtaining the highest activity was changed by aging treatment. Refluxing during the aging treatment led to the detrimental effect on the CO oxidation activities.
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