N2O catalytic reduction by NH3 over Fe-zeolites: Effective removal and active site
A series of Fe exchanged zeolites (MOR, USY, BEA and ZSM-5) were prepared by wet ion exchange and tested for N2O catalytic reduction by NH3. Fe-MOR exhibits the highest activity and this is attributed to its highest content of isolated Fe3+ ions and little Fe(III)xOy clusters, since isolated Fe3+ ions are the active species for N2O reduction while Fe(III)xOy clusters inhibit N2O dissociation due to strong NH3 adsorption. Moreover, Fe-MOR not only achieved N2O and NO simultaneously reduction at a very low temperature (700 K) but also showed good durability under simulated conditions at a typical nitric acid plant.
Graphical abstractFig. S1. Schematic representation of N2O decomposition over oligonuclear Fe(III)xOy clusters of Fe-USY (A) and isolated Fe ions of Fe-MOR (B); schematic representation of N2O reduction by NH3 over oligonuclear Fe(III)xOy clusters of Fe-USY (C) and isolated Fe ions of Fe-MOR (D).Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Fe-zeolites with different structure are investigated for NH3-SCR of N2O. ► Relationship between Fe species and activities for N2O reduction is illustrated. ► MOR is a more efficient host for iron ions than BEA in the reduction of N2O by NH3. ► Fe-MOR with highest isolated Fe3+ ions exhibits the highest activity. ► Simultaneous removal of N2O and NO over Fe-MOR proceeds at a very low temperature.
Journal: Catalysis Communications - Volume 18, 10 February 2012, Pages 151–155