FTIR and UV–Vis characterization of Fe-Silicalite

Spoto, G.; Zecchina, Adriano; Berlier, Gloria; Bordiga, Silvia; Clerici, Mario G.; Basini, L.

doi:10.1016/s1381-1169(00)00049-2

Cited by 62 publications

(60 citation statements)

References 25 publications

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“…This explains the lively discussion about the Fe-nitrosyl bands assignment found in literature [12]. The assignment of the different nitrosyl components could be possible only by performing experiments with 1:1 14 NO/ 15 NO mixtures [17,30]. These experiments definitely confirmed the assignment to Fe 2+ (NO) 2 and Fe 2+ (NO) 3 complexes of the two couples of bands reported in figure 2 (vide infra for a more detailed assignment).…”

Section: Ftir Spectroscopy Of Fe Nitrosyl Complexessupporting

confidence: 64%

“…FTIR spectroscopy of adsorbed NO is a well-established method to explore iron sites dispersed in inorganic matrices, as testified by the rich literature reporting IR spectra of Fe nitrosyl complexes in zeolites [12,16,17,19]. From the literature on iron nitrosyl complexes in different organic and inorganic matrices, it appears that the nitrosyl frequency (m NO ) is strongly influenced by the iron oxidation state.…”

Section: Ftir Spectroscopy Of Fe Nitrosyl Complexesmentioning

confidence: 99%

“…This technique was successfully used by several groups [12,[15][16][17][18][19] to characterize the exposed sites of different iron containing molecular sieves, and it is based on the capability of grafted and coordinatively unsaturated Fe 2+ and Fe 3+ ions to form stable NO adducts (Fe(NO) n , n=1, 2, 3) at room temperature. The maximum number of NO ligands adsorbed by each Fe 2+ and Fe 3+ centre represents a direct indication of their coordinative unsaturation and allows to differentiate the exposed Fe species, i.e.…”

Section: Introductionmentioning

confidence: 99%

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New precursor for the post-synthesis preparation of Fe-ZSM-5 zeolites with low iron content

et al. 2005

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A new method for preparing ZSM-5 catalysts containing highly dispersed iron species is presented. Iron(III) oxalate was used as the iron precursor in an aerobic aqueous exchange process. The presence of different iron species inside the zeolite pores was investigated by IR spectroscopy of adsorbed NO, which revealed an excellent iron dispersion. The results were compared with those obtained on a Fe-ZSM-5 catalysts prepared by iron(II) chloride sublimation and on samples prepared by controlled migration of framework iron in isomorphously substituted samples.

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Section: Ftir Spectroscopy Of Fe Nitrosyl Complexessupporting

confidence: 64%

Section: Ftir Spectroscopy Of Fe Nitrosyl Complexesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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New precursor for the post-synthesis preparation of Fe-ZSM-5 zeolites with low iron content

et al. 2005

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“…For the adsorptive properties of divalent transition metal ions in zeolites (including Co 2C , Ni 2C , Cu 2C and Fe 2C , the latter obtained by migration and subsequent reduction of Fe 3C from framework to extra-framework position), we only briefly mention that this is representing a growing field of study and that in some cases (Fe 2C ) the interaction with diatomic molecules like NO gives well defined Fe 2C (NO) n (n D 1, 2, 3) complexes 112 as illustrated in Figure 21. In this figure the reversible transformation of Fe 2C (NO) 2 (responsible for the doublet at 1840 and 1766 cm 1 ) into Fe 2C (NO) 3 (responsible for the doublet at 1916 and 1808 cm 1 ) species upon increasing the NO pressure is clearly illustrated.…”

Section: The Vibrational Spectra Of Molecules Adsorbed On Charge Balamentioning

confidence: 99%

Vibrational Spectroscopy of Zeolites

Zecchina¹,

Spoto²,

Bordiga³

2001

Handbook of Vibrational Spectroscopy

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The sections in this article are The Structure of Zeolites and Zeotype Materials The Vibrational Spectra of Zeolites and of Zeolitic Materials: General Considerations Framework Modes IR Modes Associated with the B rØnsted Groups and their Modifications upon Interaction with Adsorbates The Spectrum of Free B rønsted Groups Modifications Induced by Adsorbates The Vibrational Spectra of Molecules Adsorbed on Charge Balancing Cations Cation and Cation‐Sensitive Modes: Perturbations Induced by Adsorption Vibrational Spectra of Molecules Adsorbed on Strong Lewis Centers Vibrational Spectroscopies in Reaction Dynamics Studies on Zeolites

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“…This shift is small for all components (2 ± 3 cm Figure 3 illustrates the effect of decreasing P NO on the nitrosyl bands obtained on aluminium-free Fe-silicalite samples activated at 773 and 1073 K and on a Fe-ZSM-5 sample activated at 1073 K. The spectra obtained for Fe-silicalite activated at 773 K were extensively discussed and assigned in previous works. [10,11,15] The bands observed are due to extraframework Fe 2 species generated from framework Fe 3 (ÀOÀSi) 4 by thermal treatment. Apart from minor features (see ref.…”

mentioning

confidence: 99%

Anchoring Fe Ions to Amorphous and Crystalline Oxides: A Means To Tune the Degree of Fe Coordination

Berlier¹,

Bonino²,

Zecchina³

et al. 2003

ChemPhysChem

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We report on an IR spectroscopic study on the room-temperature adsorption of NO on different iron(II)-containing siliceous matrices. Fe2+ hosted inside the channels of MFI-type zeolites (Fe-ZSM-5 and Al-free Fe-silicalite) exhibits pronounced coordinative unsaturation, as witnessed by the capability to form, at 300 K, [Fe2-(NO)], [Fe2+(NO)2] and [Fe2+(NO)3] complexes with increasing NO equilibrium pressure. Fe2+ hosted on amorphous supports (high surface area SiO2 and MCM-41) sinks more deeply into the surface of the siliceous support and thus exhibits less pronounced coordinative unsaturation: only [Fe2+(NO)2] complexes were observed, even at the highest investigated NO equilibrium pressures. Activation at higher temperature (1073 K) of the Al-free Fe-silicalite sample resulted in the appearance of Fe2+ species similar to those observed on SiO2 and MCM-41, and this suggests that local (since not detectable by X-ray diffraction) amorphisation of the environment around Fe2+ anchoring sites occurs. The fact that this behaviour is not observed on the Fe-ZSM-5 sample activated at the same temperature suggests that framework Al species (and their negatively charged oxygen environment) have an important role in anchoring extraframework Fe2+ species. Such an anchoring phenomenon will prevent a random migration of iron species, with subsequent aggregation and loss of coordinative unsaturation. These observations can thus explain the higher catalytic activity of the Fe-ZSM-5 system in one-step benzene to phenol conversion when compared with the parent, Al-free, Fe-silicalite system with similar Fe content. The nature of the support and the activation temperature can therefore be used as effective means to tune the degree of Fe coordination.

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FTIR and UV–Vis characterization of Fe-Silicalite

Cited by 62 publications

References 25 publications

New precursor for the post-synthesis preparation of Fe-ZSM-5 zeolites with low iron content

New precursor for the post-synthesis preparation of Fe-ZSM-5 zeolites with low iron content

Vibrational Spectroscopy of Zeolites

Anchoring Fe Ions to Amorphous and Crystalline Oxides: A Means To Tune the Degree of Fe Coordination

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