Low-temperature selective catalytic reduction of nitrogen oxides (NO x) with NH3 (NH3-SCR) has been identified as a promising strategy to mitigate the pollution of NO x. The fine control of synergistic effect and the suppression of aggregation of the active component, however, are still the challenge because of the weak interaction between the active component and matrix. In this work, a series of Ce-promoted Mn-based heterogeneous catalysts supported on mesoporous silica (SBA-15) with different Mn contents were prepared by two separated impregnation processes. Low-temperature NH3-SCR activity demonstrates that the Mn content in the catalyst has a great influence on the activity of the NH3-SCR reaction. The 20% MnO x-CeO x/SBA-15 catalyst exhibited the best catalytic performance in a broad temperature window. Moreover, it exhibits enhanced resistance to SO2 and H2O and long-term durability during 72 h reaction. The highly dispersive active phase, the formation of solid solution, the high ratio of Ce3+, and the spatial confinement effect largely contribute to the outstanding activity and durability of the 20% MnO x-CeO x/SBA-15 catalyst. Finally, a monolithic catalyst fabricated by the 20% MnO x-CeO x/SBA-15 catalyst powder and cordierite substrate show promising industrial application.
Keywords: confined growth; mesoporous materials; metal oxide composites; selective catalytic reduction.