Ag/Ce1‐xMnxO2 Catalysts for Soot Oxidation in the Presence of NOx and NOx─CO: Role of Ce/Mn Molar Ratio

This study investigates the effectiveness in soot oxidation under tight and loose contact of Ag/CeO2, Ag/MnOx, and Ag/CeMnOx catalysts with different Ce:Mn molar ratios prepared by the citrate sol-gel method. The sol-gel method promoted the formation of a nanodomain structure in the CeMnOx composite. The interaction between cerium and manganese oxides and the Ce/Mn ratio were the key factors to form such a nanodomain structure. A 1:1 Ce/Mn ratio provided high activity and stability by preventing CeO2 nanoparticle sintering, while at different Ce/Mn ratios deactivation eventually occurred. The presence of NO in the reaction mixture inhibited soot oxidation, while the CO presence in the NO + O-2 mixture limited such effect. The most promising Ag/CeMnOx catalyst with 1:1 Ce/Mn ratio was successfully applied to a cordierite monolith. Both powder and the monolithic catalysts selectively oxidized soot to CO2 below 500 and 600 degrees C, respectively, demonstrating to be promising for practical applications in efficient soot oxidation.