Catalytic Reduction of N₂O by NH₃ over Fe-zeolite Catalysts with Different Topologies

To reveal the effect of zeolite topology on the status of iron species, a series of Fe-zeolite catalysts (Fe-Beta, Fe-ZSM-5, Fe-Y, Fe-ZSM-35, Fe-MCM-22, Fe-SSZ-13) were synthesized using the wet ion-exchange technique. The catalytic reduction of N₂O by NH₃ with Fe-zeolites was carried out, and the corresponding activities followed the order Fe-Beta > Fe-ZSM-5 > Fe-Y > Fe-ZSM-35 > Fe-MCM-22 > Fe-SSZ-13. The Fe-Beta catalyst shows the best activity, which achieving more than 98% N₂O conversion at 350 ℃. The prepared catalysts were subjected to physicochemical characterization. It shows that the structure of Fe-Beta and Fe-ZSM-5 zeolite facilitated the loading of Fe ions upon the framework of zeolites through the pores and the sequent formation of active centers (Fe³⁺) on the ion exchange sites. In addition, the larger pore sizes in Fe-zeolites are more favorable for the diffusion of N₂O within the pores and channels of the zeolite, so the catalytic reduction of N₂O by ammonia is promoted.