Distinct effect of preparation methods on reaction efficiency of Mn-Ce/Al2O3 catalysts in low-temperature NH3-SCR

In this study, a series of Mn-Ce/Al2O3 catalysts was prepared by different methods of deposition-precipitation (MnCeAl-DP), impregnation (MnCeAl-IM) and citric acid (MnCeAl-CA), and the distinct effect of preparation methods on NOx removal performance at low temperature was explored. Results show that MnCeAl-DP exhibits not only the best activity but also the highest resistance against SO2/H2O. With the assistance of comprehensive characterizations from scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET), X-ray diffraction (XRD), H2-temperature programmed reduction (H2-TPR), NH3-temperature programmed desorption (NH3-TPD), and X-ray photoelectron spectroscopy (XPS), it is revealed that the MnCeAl-DP sample owns admired features of large surface area and pore volume, enriched Mn4+ and chemisorbed oxygen species originating from enhanced interaction between MnOx and CeO2, as well as improved adsorption capacity to NH3 and NO. All these factors contribute to activity enhancement. Further in-situ DRIFTS studies reveal that the improvement of NH3-SCR performance over MnCeAl-DP is related to the formation of abundant nitrate species, which is beneficial to the “NH4NO3” reaction pathway and thus enhances low-temperature activity.