In order to research into the influence of MnOx-CeO2 composite oxides on catalytic oxidation of NO from diesel engine

a series of xMn10Ce/γ-Al2O3（x=5

6

7

8) catalysts with different Mn/Ce mole ratio were prepared by the solgel method. A combination of characterization techniques

namely X-ray diffraction(XRD)

X-ray Photoelectron Spectroscopy（XPS) and H2 Temperature Programmed Reduction（H2-TPR)

was adopted to analysis its phase structure

element valence and reducibility

respectively. Results illustrate that the grain size of ceria gradually increases with the rise in Mn content

and the addition of appropriate amount of Mn is also beneficial to the increase of the number of Mn4+ in the catalyst

so as to promote the oxidation of NO. When x is equal to 6

the catalyst has the best redox properties. Finally

the impact of different Mn/Ce mole ratio on NO oxidation performance of xMn10Ce/γ-Al2O3 catalysts was investigated based on a simulated gas bench test. Test results show that at a temperature of 350 ℃

the time required for NO concentration to reach saturation and the reaction rate are nonlinear with the amount of Mn added when the temperature is between 250 ℃ and 450 ℃

the NO oxidation properties of 6Mn10Ce/γ-Al2O3 are the best. At this time

the timing required for NO concentration to reach stability is only 4 min

but it is extended to 6 min at 450 ℃

which is mainly the result of a combination of the thermodynamic equilibrium as well as the amount of active oxygen and the gradual saturation of oxygen vacancy during the reaction.