Abstract: Nanosized MnO_x-CeO₂ catalysts with a high-surface area were prepared by a template precipitation method, with Ce(NO₃)₃ and Mn(NO₃)₂ as the precursors and surfactant CTAB as the templating agent. Their catalytic activities for CO oxidation were examined. The catalysts were characterized by XRD, Raman spectroscopy, H₂-TPR and N₂ adsorption techniques. BET specific surface areas of the catalysts were between 160 and 170 m²/g when the Mn mass fraction was lower than 34.3%. However, surface area decreased with further increasing Mn mass fraction. XRD results show that there was only CeO₂ phase when the Mn mass fraction was lower than 34.3%, while Raman spectra indicate the existance of α-Mn₂O₃. The high specific surface area was benefical to CO oxidation activity. TOF of the catalysts decreased with increasing Mn content, indicating that the highly dispersed Mn species with a small crystallite size were the active species. H₂-TPR results suggest that the activitiy was related to the high-valance Mn species. High calcination temperature caused growth of the catalyst crystallite size and decrease of surface areas, as well as decline of avarage valance of Mn species, which led to decline in the catalytic activity.

Key words: MnO_x-CeO₂, CTAB, Highly-specific surface area, CO oxidation