On the nature of active sites in Fe/ZSM-5 catalysts for NOx abatement

Direct decomposition of NO by microwave heating over Fe/NaZSM-5

“…The addition of H 2 O to the reactant gas mixture often produce the negative effects on NO conversion over many catalysts in the conventional reaction mode, except for an FeZSM-5 catalyst prepared by a special method [21,22]. We have also investigated the effect of H 2 O addition on NO conversion over the Fe (20%)/NaZSM-5 catalyst.…”

Theoretical Studies of the Coordination and Stability of Divalent Cations in ZSM-5

“…It has been proposed that metal cations can form µ-bridged metal-oxo dimers, [M-O-M] 2+ . 21,22,[24][25][26][27][28]37,[30][31][32][33]36 To assess the stability of such dimers, calculations were performed for the following reaction (see Figure 5): …”

“…There is also a growing body of evidence suggesting the presence of dimer cations in which two M 2+ cations are bridged by an O atom or two M 3+ cations are bridged by two O atoms. [21][22][23][24][25][26][27][28][29][30][31][32][33][34][35] Such structures can be represented by Z -[M(O)M] 2+ Z -and Z -[M-(O) 2 M] 2+ Z -. The experimental evidence also indicates that M 2+ cations can be reduced to form small metal particles or can react with oxygen and water to form metal oxide particles.…”

Nitrous Oxide Decomposition on the Binuclear [FeII(μ-O)(μ-OH)FeII] Center in Fe-ZSM-5 Zeolite

“…According to numerous experimental studies on the nature of iron sites in Fe-ZSM-5 regarding the zeolite preparation/ activation steps, 25,29,41 it has been concluded that iron first exists as isolated Fe species with tetrahedral coordination, which upon subsequent steaming and calcination are transformed into hydroxylated binuclear complexes. 25,33 In this structure, iron cations are in the oxidation state Fe III and are completely inactive for the N 2 O decomposition.…”