Ultrasonic-assisted synthesis of highly active catalyst Au/MnOx-CeO2 used for the preferential oxidation of CO in H2-rich stream

A series of nano-gold catalysts supported on binary oxides MOx-CeO2 (atomic ratio W Ce = 1:1, M = Mn, Fe, Co, Ni) are prepared by deposition-precipitation (DP). An innovative and rather convenient ultrasonic pretreatment of the support is employed for AU/MnOx-CeO2 preparation. It is found that for preferential CO oxidation Au/MnOx-CeO2 is more active than Au/CeO2. Ultrasonic pretreatment of MnOk-CeO2 further promotes the performance of Au/MnOx-CeO2, with CO conversion increased by 24 % at 120 degrees C. Meanwhile, the selectivity of oxygen to CO2 is promoted in the whole temperature range, especially in 80-120 degrees C, the selectivity is increased by 15-21%. HR-TEM and XRD results indicate that ultrasonic pretreatment is favorable to the formation of much smaller gold nanoparticles (<5 nm). The characterization of XPS, UV-vis DRS, H-2-TPR and CO-TPR confirms that the strong interaction between Au and the support effectively inhibits the dissociation and oxidation of H-2 over the ultrasonically pretreated catalyst Au/MnOx-CeO2, making it highly selective to CO oxidation. (C) 2009 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.