Low temperature NH3–SCR over Zr and Ce pillared clay based catalysts

Abstract

A series of Zr and Ce pillared clay loaded with manganese oxide were prepared by wet-impregnation for the low temperature selective catalytic reduction (SCR) of NO. Various preparation methods for the MnOx/Zr–Ce–PILCs catalysts were studied with respect to the effects on NOx conversions. The MnOx(12%)/Zr–Ce–PILC(30) catalyst prepared by the simultaneous Zr–Ce pillaring with a Zr:Ce molar ratio of 5:5 was demonstrated to be optimal in NH3–SCR reaction at low temperature, reaching 96% of NOx conversion at 200°C. Various techniques were used to characterize these catalysts. N2 physisorption results suggested that the simultaneous Zr–Ce pillaring enlarged the specific surface area and pore volume. The XRD and XPS results illustrated that MnO2, Mn2O3 and Mn3O4 all existed on the surfaces of the catalysts. The results of H2–TPR NH3–TPD for the catalysts demonstrated that the MnOx(12%)/Zr–Ce–PILC(30) catalyst had high redox characteristic and surface acidity. The shift of Mn and O elements to lower binding energies indicated more active for these elements in MnOx(12%)/Zr–Ce–PILC(30). This demonstrated that Zr–Ce–PILC was a kind of potential support, which contributed to the high SCR activity of MnOx(12%)/Zr–Ce–PILC(30).