Nature of active sites in a Fe-Beta catalyst for NOx selective catalytic reduction by NH3

Nature of Active Sites of Fe-Beta Catalyst for NOx-SCR by NH3

“…2) similar to that observed in [6,11] for Fe-ZSM-5 catalysts. This correlation for zeolites with different Si/Al ratio was discussed by us earlier [7] and it was concluded that active species of Fe-Beta and Fe-ZSM-5 catalysts in NH 3 -deNO x are isolated mononuclear tetrahedrally coordinated Fe complexes represented by the ESR signal at g & 4.3 and presumably located in zeolite cationic positions.…”

“…The task of the present paper is to verify the assumption made in our previous paper [7] that only isolated tetrahedrally-coordinated Fe 3? represented by an ESR signal at g & 4.3 cations are active in NH 3 -deNO x . To reach this goal we prepared and studied samples with ultralow Fe content (e.g., 0-0.1 wt% Fe) which is one of the novel distinctive features of this study.…”

Fe-doped Beta zeolite from organotemplate-free synthesis for NH3-SCR of NOx

“…A variety of Fe species are identified, including isolated Fe species, oligomers of varying nuclearity and α-Fe 2 O 3 particles that coexisted. [15][16][17][18] However, their catalytic functions during the SCR reaction are still under discussion. As pointed out by Brandenberger et al, 19 the SCR activity was observed to be primarily caused by monomeric iron sites at temperatures below 300 °C; at T > 300 °C, the contributions are from dimeric iron species, oligomeric species, and partially uncoordinated iron sites in the outermost layer of iron oxide particles; while Sachtler et al 17,18 suggested that not all monomer sites were equally active in the SCR reaction.…”

Alkali Resistant Fe-Zeolite Catalysts for SCR of NO with NH3 in Flue Gases

“…However, shortcomes such as environmental hazardous vanadium, rapid catalyst deactivation by alkali containing flue gas, moderate thermal stability and narrow operational window (350-400°C) motivates the development of novel NO SCR catalysts [5].…”