Fe–ZSM-5 Catalysts for the Selective Reduction of NO by Isobutane—The Problem of the Active Sites

Heinrich, Frank; Schmidt, Carmen; Löffler, Elke; Menzel, M.; Grünert, Wolfgang

doi:10.1006/jcat.2002.3775

Cited by 142 publications

(93 citation statements)

References 21 publications

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“…2 together with the parent ZSM-5 zeolite used in ion exchange. All samples exhibited the typical diffractograms of the MFI framework (2u = 7-98 and 23-258) which emphasized high dispersion of Cu and Fe ions in compensating positions inside zeolites [24][25][26][27][28][29][30][31][32]. The course of the baseline indicated that no-impurity phase was observed.…”

Section: X-ray Diffraction Studiesmentioning

confidence: 99%

Characterization and catalytic activity of CuFeZSM-5 catalysts for oxidative degradation of Rhodamine 6G in aqueous solutions

Dükkancı

Gündüz

Yılmaz

et al. 2010

Applied Catalysis B: Environmental

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This study presents an evaluation of the catalytic performances of Fe and Cu containing ZSM-5 zeolites for oxidation of Rhodamine 6G. Fe and Cu were loaded by ion exchange or through hydrothermal synthesis. The catalytic process was carried out in an aqueous solution using H2O2 as an oxidant. The catalyst prepared by hydrothermal synthesis showed the highest activity (100% decolorization, 59.1% aromatic degradation and 51.8% TOC removal at initial pH of 3.5). This catalyst was stable against leaching even at low pH. The change in activity of the catalysts prepared was attributed to incorporation of the Fe and Cu species with ZSM-5. Fe and Cu were in structural locations - in the framework - in the catalyst prepared by hydrothermal synthesis while there were extraframework cations or species in catalysts prepared by ion exchange. Incoporation of Cu into FeZSM-5 increased its catalytic activity. © 2010 Elsevier B.V. All rights reserved.TÜBİTAK and NASU project number 107M62

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Section: X-ray Diffraction Studiesmentioning

confidence: 99%

Characterization and catalytic activity of CuFeZSM-5 catalysts for oxidative degradation of Rhodamine 6G in aqueous solutions

Dükkancı

Gündüz

Yılmaz

et al. 2010

Applied Catalysis B: Environmental

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“…Lately, several groups have used XANES to study the local coordination of iron in over-exchanged Fe/ZSM-5. 9,[13][14][15][16] Lamberti and co-workers reported on the characterization of aluminum-free Fe-silicalite, which has a similar MFI zeolite structure as ZSM-5. [17][18][19][20][21] Using Fe K-edge XANES they investigated the influence of template removal and calcination on the coordination and oxidation state of iron initially incorporated in Fe-silicalite.…”

Section: Introductionmentioning

confidence: 99%

Kβ-Detected XANES of Framework-Substituted FeZSM-5 Zeolites

et al. 2004

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The valence and local symmetry of iron in framework-substituted FeZSM-5 with a high Fe dilution (Si/Fe ) 360) was studied by means of K -detected X-ray absorption spectroscopy. This technique combines highresolution (∆E ∼1 eV) fluorescence detection of the 3p to 1s (K ) transition with the X-ray absorption near-edge structure (XANES) at the Fe K-edge. An absorption-like spectrum is recorded by detecting the K fluorescence intensity as a function of the incident energy that is scanned through the K absorption edge. K -detected XANES spectra allow for a more precise separation of the weak K pre-edge structure from the main edge as compared to conventional absorption spectroscopy. Subsequent analysis and interpretation of the pre-edge spectral features therefore is more accurate. The pre-edge is sensitive to changes in the local coordination and oxidation state of Fe. Using this technique we were able to quantitatively determine the degree of iron extraction out of a zeolite framework upon steaming. With the use of appropriate reference compounds, the pre-edge analysis was used to monitor the activation of low-loaded, framework-substituted FeZSM-5 (0.3 wt % Fe). Template removal and calcination distort the zeolite framework and induce a deviation from T d symmetry for incorporated iron. The (deliberate) presence of water at high temperature (T > 500°C) facilitates the hydrolysis of the Si-O-Fe bonds and increases the formation of extraframework iron species. The amount of Fe III occupying tetrahedral sites in the MFI-type zeolite decreases to 32% and 19%, respectively, for mild-and hard-steamed samples.

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“…Iron loaded zeolites have recently attracted renewed attention due to their outstanding catalytic properties [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. In particular, over-exchanged Fe/ZSM5 (Fe/Al molar ratio > 0.5) obtained through the chemical vapor deposition (CVD) of anhydrous iron trichloride has been reported to be very efficient in the selective catalytic reduction of nitrogen oxides using HydroCarbons (HC-SCR).…”

Section: Introductionmentioning

confidence: 99%

“…These include aqueous ion exchange from ferrous oxalate, performed under exclusion of air [8], and solid-state ion exchange using Fe(II)chloride [9,10], Fe(III)chloride [11][12][13][14] or FeSO 4 · 7H 2 O [15]. The synthesis in aqueous solution with ferrous oxalate as precursor has led to results comparable to those obtained through the CVD of FeCl 3 , with respect to both the iron loading and the catalytic activity towards HC-SCR with isobutane.…”

Section: Introductionmentioning

confidence: 99%

“…Via solid-state ion exchange the amount of iron loaded on the ZSM5 can easily be tuned during the synthesis. The solidstate ion exchanged Fe/ZSM5 has shown high activity in the catalytic decomposition of N 2 O [12] and in the HC-SCR of NO with isobutane [13]. However, the use of FeCl 3 in its gaseous form has a clear advantage: by avoiding the contact between the ZSM5 support and the moisture always present in the precursor, it prevents the formation of large iron hydroxide and oxide clusters [11].…”

Section: Introductionmentioning

confidence: 99%

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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

163

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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.

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Fe–ZSM-5 Catalysts for the Selective Reduction of NO by Isobutane—The Problem of the Active Sites

Cited by 142 publications

References 21 publications

Characterization and catalytic activity of CuFeZSM-5 catalysts for oxidative degradation of Rhodamine 6G in aqueous solutions

Characterization and catalytic activity of CuFeZSM-5 catalysts for oxidative degradation of Rhodamine 6G in aqueous solutions

Kβ-Detected XANES of Framework-Substituted FeZSM-5 Zeolites

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

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