Abstract
The Au/MnO x–CeO 2 catalysts used for CO preferential oxidation were prepared by deposition–precipitation with ultrasonic assistance. The effect of calcination temperature (150–350 °C) on the structures and catalytic performance of the catalysts was systematically investigated. It is found that the catalyst Au/MnO x–CeO 2 calcined at 250 °C exhibits the best catalytic performance, giving not only the highest CO conversion of 90.9% but also the highest selectivity of oxygen to CO 2 at 120 °C. The results of XRD, TEM and XPS indicate that this catalyst possesses the smallest particle size, the highest dispersion of Au species and the largest amount of surface adsorbed oxygen species, which are favorable to CO oxidation. The H 2-TPR results reveal that the selectivity of oxygen to CO 2 is mainly determined by the reducibility of Au species in the catalysts. The strong interaction between Au species and the support in Au/MnO x–CeO 2-250 decreases its capability for H 2 dissociation and oxidation, leading to high selectivity of oxygen to CO 2.
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