2024 AIChE Annual Meeting

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

Authors

Tatsuya Okubo - Presenter, The University Of Tokyo
Jingyun Yu, The University of Tokyo
Kenta Iyoki, The University of Tokyo
Shanmugam P. Elangovan, The University of Tokyo
Haruko Fujinuma, The University of Tokyo
Toru Wakihara, The University of Tokyo
For practical application, the poorer low-temperature activity is a critical drawback of Fe-loaded zeolites as NH3-SCR catalyst of NOx. 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 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, 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.