Unexpected Low Temperature Activity with Low N₂O Emission of Stabilized Al-rich Zeolite Beta for Selective Catalytic Reduction of NO_x

The low temperature activity of Fe-loaded zeolites as selective catalytic reduction of NOx by NH3 (NH3-SCR) catalysts is a critical drawback for practical application. Here, we found unexpected improvement of low temperature activity by our proposed post-synthetic treatment. An Al-rich zeolite beta (Si/Al=5) is employed as the catalyst support, and the parent sample is dealuminated for higher hydrothermal stability, followed by the liquid-mediated stabilization treatment and impregnation. It is found that stabilized samples feature excellent low temperature activity and high N-2 selectivity even for a long-term operation, along with the ability to maintain high NOx conversion after aging. The improved SCR activity should be attributed to abundant acid sites in Al-rich framework and better stabilization of monomeric iron species after the stabilization treatment. Furthermore, the low yield of side product N2O is probably due to the absence of the generation of NH4NO3 during NH3-SCR catalyzed by Fe-loaded zeolites.