Low-temperature selective catalytic reduction of NO with NH3 over monolith catalyst of MnOx/CeO2–ZrO2–Al2O3

MnOx/CeO2–ZrO2–Al2O3 (MnOx/CZA) catalysts with different amounts of manganese loading were prepared by incipient wetness impregnation method for selective catalytic reduction (SCR) of NO with NH3 at low temperature. The catalysts were characterized by N2 adsorption–desorption measurement, XRD, XPS, and H2-TPR. Catalytic activity tests reveal that the MnOx/CZA catalyst with 10% manganese loading has the best catalytic activity, almost 90% NO is translated to N2 in the temperature range of 143–300 °C. The highly dispersed MnOx species, the good oxidation activity of NO to NO2, the existent synergistic effect between the manganese and cerium oxides, and the various oxidation states of manganese oxides may be the main reasons for the best SCR activity. In addition, the SCR activity is slightly influenced in the presence of SO2 and H2O, while such effect is restorable after heating treatment.

Graphical abstractThe selective catalytic reduction of NO by NH3 over MnOx/CeO2–ZrO2–Al2O3 catalysts with different manganese loadings was studied. The NO conversion increased with the increasing of manganese content until the amount of manganese reached 10%. After this level, the SCR activity slightly decreased with the increase of manganese loading.Figure optionsDownload full-size imageDownload high-quality image (127 K)Download as PowerPoint slideHighlights► MnOx/CeO2–ZrO2–Al2O3 catalysts have excellent performance for SCR of NO by NH3 at low temperature. ► The 10% MnOx/CeO2–ZrO2–Al2O3 is resistant to H2O and SO2. ► The 10% MnOx/CeO2–ZrO2–Al2O3 has good oxidation activity of NO to NO2. ► The manganese oxide exists as highly dispersed MnOx species on the surface of 10% MnOx/CeO2–ZrO2–Al2O3. ► The manganese oxides species exist as various oxidation states in 10% MnOx/CeO2–ZrO2–Al2O3.