Integrated DeNO (x) -DeSoot Catalytic Systems with Improved Low-Temperature Performance

Performance of the combined catalysts [CeO2-ZrO2 + FeBETA] and [Mn/CeO2-ZrO2 + FeBETA], prepared by mechanical mixing of the component powders, was studied in soot oxidation and NH3-SCR. [CeO2-ZrO2 + FeBETA] catalyst (with component volumetric ratio of 3/1) demonstrated efficient soot oxidation at 400-450 A degrees C and DeNO (x) performance similar to that of FeBETA catalyst, despite the fact that the amount of zeolite was reduced by four times indicating a strong synergistic effect between the components. Low-temperature DeNO (x) performance of the [CeO2-ZrO2 + FeBETA] system can be additionally enhanced by doping the CeO2-ZrO2 with Mn. It was found that NO (x) conversion over [Mn/CeO2-ZrO2 + FeBETA] at 150-250 A degrees C was steadily improved by increasing the Mn loading, and [5.4 % Mn/CeO2-ZrO2 + FeBETA] attained NO (x) conversion above 90 % at T-react similar to 190 A degrees C. Comparative studies of soot oxidation and NH3-SCR over combined catalysts and individual components indicated that the soot oxidation activity is assigned to the soot oxidation over ceria-zirconia component, while enhanced low-temperature SCR performance is a result of a bi-functional SCR mechanism comprising NO oxidation to NO2 over CeO2-ZrO2 component followed by fast-SCR over FeBETA.