Identification of active sites and adsorption complexes in Fe/MFI catalysts for NOx reduction

Chen, Hai-Ying; El-Malki, El-M; Wang, X; Santen, Rutger A. van; Sachtler, W. M. H.

doi:10.1016/s1381-1169(00)00287-9

Cited by 133 publications

(118 citation statements)

References 40 publications

Supporting

Mentioning

101

Contrasting

Order By: Relevance

“…As already pointed out by Marturano et al [21], washing was proved to be the key step for the formation of the binuclear Fe complexes, proposed as the catalytically active phase in Fe/ZSM5 [1,2,12,18]. It can be concluded from our work that during this step dramatic changes occur to the local environment of the Fe atoms.…”

Section: Washingsupporting

confidence: 79%

“…Several characterization studies have been performed in order to unravel the nature of the active phase [1,2,11,12,[18][19][20][21][22][23]. Binuclear iron oxo-hydroxo clusters at the ion exchange positions of the ZSM5 lattice have been proposed earlier as the active phase for both the HC-SCR of NO [1,2,18] and the catalytic decomposition of N 2 O [12].…”

Section: Introductionmentioning

confidence: 99%

“…In addition to binuclear Fe-oxocations, EPR has revealed the presence of oxo/hydroxo ions, such as (Fe(OH) 2 ) + or (Fe=O) + . Also the presence of a minor amount of iron oxide particles has been suggested [12,18,22].…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Evolution of Fe species during the synthesis of over-exchanged Fe/ZSM5 obtained by chemical vapor deposition of FeCl3

Battiston

Bitter

Groot

et al. 2003

Journal of Catalysis

165

View full text Add to dashboard Cite

The evolution of iron in over-exchanged Fe/ZSM5 prepared via chemical vapor deposition of FeCl 3 was studied at each stage of the synthesis. Different characterization techniques (EXAFS, HR-XANES, 57 Fe Mössbauer spectroscopy, 27 Al NMR, EELS, HR-TEM, XRD, N 2 physisorption, and FTIR spectroscopy) were applied in order to correlate the changes occurring in the local environment of the Fe atoms with migration and aggregation phenomena of iron at micro-and macroscopic scale. Mononuclear isolated Fe-species are formed upon FeCl 3 sublimation, which are transformed into binuclear Fe-complexes during washing. During calcination, iron detached from the Brønsted sites migrates to the external surface of the zeolite, finally leading to significant agglomeration. Nevertheless, agglomeration of Fe can be strongly suppressed by adequately tuning the conditions of the calcination.  2002 Elsevier Science (USA). All rights reserved.

show abstract

Section: Washingsupporting

confidence: 79%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Evolution of Fe species during the synthesis of over-exchanged Fe/ZSM5 obtained by chemical vapor deposition of FeCl3

Battiston

Bitter

Groot

et al. 2003

Journal of Catalysis

165

View full text Add to dashboard Cite

show abstract

“…The formation and high activity of oxygen-bridged binuclear species were suggested by numerous experimental studies, [25][26][27][28][29] but only few theoretical approaches have been reported in the literature. Investigations of binuclear iron sites in the ZSM-5 extra-framework position have considered the reactivity of a In contrast with these theoretical results, Kiwi-Minsker and co-workers 5 have reported a different N 2 O kinetic behavior "suggesting that the high activity of HZSM-5 with a high Si/ Al ratio and low iron content could be explained by the presence of binuclear iron sites".…”

mentioning

confidence: 99%

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

2008

View full text Add to dashboard Cite

The reaction mechanism for nitrous oxide (N 2 O) direct decomposition into molecular nitrogen and oxygen was studied on binuclear iron sites in Fe-ZSM-5 zeolite using the density functional theory (DFT + complex for the N 2 O decomposition. The first step of the catalytic reaction corresponds to a spontaneous adsorption of N 2 O over Fe II sites, followed by the surface atomic oxygen loading and the release of molecular nitrogen. The formation of molecular O 2 occurs through the migration of the atomic oxygen from one iron site to another one followed by the recombination of two oxygen atoms and the desorption of molecular oxygen. The computed reactivity over the binuclear iron core complex [Fe+ is consistent with experimental data reported in the literature. Although the dissociation steps of the N 2 O molecules, calculated with respect to adsorbed N 2 O intermediates, are highly energetic, the energy barrier associated with the atomic oxygen migration is the highest one. Up to 700 K, the oxygen migration step has the highest free energy barrier, suggesting that it is the rate-limiting step of the overall kinetics. This result explains the absence of O 2 formation in experimental study of N 2 O decomposition at temperatures below 623 K.

show abstract

“…Under industrial operating conditions (presence of water, sulphur oxides and an excess of oxygen), Fe-ZSM-5 zeolites have shown adequate levels of conversion and selectivity for N 2 (Centi and Vazzana, 1999), which are highly dependent on the method used in the preparation of this type of catalyst (Chen and Sachtler, 1998). In spite of the published data on the identification and nature of Fe species formed during preparation, no method enabling their quantification has been reported (Chen et al, 2000). In this context, the aim of this work was to identify and quantify Fe species in Fe-ZSM-5 catalysts prepared by ion exchange in aqueous solution and in the solid state.…”

Section: Introductionmentioning

confidence: 99%

Species active in the selective catalytic reduction of no with iso-butane on iron-exchanged ZSM-5 zeolites

Batista

Wallau

Urquieta‐González

2005

Braz. J. Chem. Eng.

View full text Add to dashboard Cite

-Fe-ZSM-5 catalysts were prepared by ion exchange in aqueous medium or in the solid state and tested in the catalytic reduction of NO with iso-butane. X-ray powder diffraction (XRD), atomic absorption spectroscopy (AAS), electron paramagnetic resonance spectroscopy (EPR), X-ray absorption spectroscopy (XANES, EXAFS), temperature-programmed reduction by H 2 (H 2 -TPR) and Mössbauer spectroscopy (MÖS-S) were used for sample characterisation. Irrespective of the method used in catalyst preparation, EPR, XANES and MÖS-S showed Fe atoms in the oxidation state of 3+. MÖS-S and H 2 -TPR data on Fe-ZSM-5 prepared by ion exchange in the solid state allowed quantification of a lower hematite (Fe 2 O 3 ) concentration and a higher proportion of Fe cations than samples prepared in an aqueous medium. In all the catalysts studied these Fe cations were the active sites in the reduction of NO to N 2 and in the oxidation of iso-butane. It is further suggested that coordination of Fe species is another important aspect to be considered in their behaviour.

show abstract

Identification of active sites and adsorption complexes in Fe/MFI catalysts for NOx reduction

Cited by 133 publications

References 40 publications

Evolution of Fe species during the synthesis of over-exchanged Fe/ZSM5 obtained by chemical vapor deposition of FeCl3

Evolution of Fe species during the synthesis of over-exchanged Fe/ZSM5 obtained by chemical vapor deposition of FeCl3

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

Species active in the selective catalytic reduction of no with iso-butane on iron-exchanged ZSM-5 zeolites

Contact Info

Product

Resources

About

Identification of active sites and adsorption complexes in Fe/MFI catalysts for NOx reduction

Cited by 133 publications

References 40 publications

Evolution of Fe species during the synthesis of over-exchanged Fe/ZSM5 obtained by chemical vapor deposition of FeCl3

Evolution of Fe species during the synthesis of over-exchanged Fe/ZSM5 obtained by chemical vapor deposition of FeCl3

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

Species active in the selective catalytic reduction of no with iso-butane on iron-exchanged ZSM-5 zeolites

Contact Info

Product

Resources

About

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