(80h) Enhanced Low-Temperature Activity with Low Nitrous Oxide Emission of Stabilized Al-Rich Zeolite Beta for Selective Catalytic Reduction of NOx

For practical application, the poorer low-temperature activity is a critical drawback of Fe-loaded zeolites as NH₃-SCR catalyst of NO_x. Here, we present unexpected improvement of low temperature activity by a post-synthetic treatment proposed by us [1].

An Al-rich zeolite beta (Si/Al = 5) synthesized without OSDA [2] is employed as the catalyst, and the parent sample is dealuminated, followed by the liquid-mediated stabilization treatment and the impregnation with Fe. It is found that stabilized samples feature excellent low-temperature activity and high N₂ selectivity even for a long-term operation, along with the ability to maintain high NO_x 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, of which GHG effect is 300 times of CO₂, is probably due to the absence of the generation of NH₄NO₃ during NH₃-SCR catalyzed by Fe-loaded zeolites [3].

[1] K. Iyoki et. al., JACS, 2020, 142, 3931-3938.

[2] K. Itabashi et. al., JACS, 2012, 134, 11542-11549.

[3] J. Yu et. al., Chem European J., 2023, e202303177.