Coordination and oxidation changes undergone by iron species in Fe-MCM-22 upon template removal, activation and red–ox treatments: an in situ IR, EXAFS and XANES study

Berlier, Gloria; Pourny, Manuel; Bordiga, Silvia; Spoto, G.; Zecchina, Adriano; Lamberti, Carlo

doi:10.1016/j.jcat.2004.10.007

Cited by 39 publications

(58 citation statements)

References 56 publications

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“…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 Complexesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

et al. 2005

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“…The adsorption of NO or NO 2 on acid-and metal-exchanged zeolites followed by infrared spectroscopy is a well-known method for the characterization of exposed ions, through the formation of adsorbed complexes with characteristic vibrational fingerprints. Moreover, indirect indications about the Brønsted or metal ions' reactivity can be inferred by observing the formation of adsorbed NO/NO 2 reaction products, such as nitrosonium ions NO + , nitrates NO 3 − , nitrites NO 2 − , and/or water [40][41][42][43][44].…”

Section: No Adsorption Studies Followed By Ftirmentioning

confidence: 99%

Fe Speciation in Iron Modified Natural Zeolites as Sustainable Environmental Catalysts

et al. 2019

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Natural purified mordenite from Palmarito de Cauto (ZP) deposit, Cuba, was subjected to a hydrothermal ion exchange process in acid medium with Fe2+ or Fe3+ salts (Fe2+ZP and Fe3+ZP). The set of samples was characterized regarding their textural properties, morphology, and crystallinity, and tested in the NO reduction with CO/C3H6. Infrared spectroscopy coupled with NO as a probe molecule was used to give a qualitative description of the Fe species’ nature and distribution. The exchange process caused an increase in the iron loading of the samples and a redistribution, resulting in more dispersed Fe2+ and Fe3+ species. When contacted with the NO probe, Fe2+ZP showed the highest intensity of nitrosyl bands, assigned to NO adducts on isolated/highly dispersed Fe2+/Fe3+ extra-framework sites and FexOy clusters. This sample is also characterized by the highest NO sorption capacity and activity in NO reduction. Fe3+ZP showed a higher intensity of nitrosonium (NO+) species, without a correlation to NO storage and conversion, pointing to the reactivity of small FexOy aggregates in providing oxygen atoms for the NO to NO+ reaction. The same sites are proposed to be responsible for the higher production of CO2 observed on this sample, and thus to be detrimental to the activity in NO SCR.

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“…The MCM-22 zeolite was originally synthesized by Mobil researchers in 1990 [42]. From a structural point of view, MCM-22 is characterized by a complex porosity, containing both medium and large pores [43]. The structure of the MCM-22 zeolite (IZA structure, code MWW) consists of two independent pores systems [44], one of which is defined by two-dimensional sinusoidal 10-membered-ring (MR) channels (0.40x0.50 nm).…”

Section: Introductionmentioning

confidence: 99%

Influence of the methodology on the formation of zeolite membranes MCM-22 for the oil/water emulsion separation

Barbosa

Rodrigues

2019

Cerâmica

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This work aimed to produce zeolite membranes MCM-22 using two methods of synthesis, dip coating (DC) and vapor phase transport (VPT), to be evaluated in the oil/water emulsion separation process. The membranes were prepared at 150 °C for 10 days and characterized by X-ray diffraction and scanning electron microscopy. They were evaluated in tests of pure water permeation and oil/water emulsion separation system of a synthetic effluent, using a stainless-steel module under the conditions of the initial concentration of the emulsion of 100 mg/L, temperature of 25 °C and pressure of 2.0 bar. The results showed that the MCM-22 zeolite membrane by DC had the final value of the permeate concentration of 3.2 mg/L and the membrane prepared by VPT presented a final value of 3.9 mg/L which were within the standards required by Resolution No. 392 of CONAMA which is up to 20 mg/L of mineral oils.

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Coordination and oxidation changes undergone by iron species in Fe-MCM-22 upon template removal, activation and red–ox treatments: an in situ IR, EXAFS and XANES study

Cited by 39 publications

References 56 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

Fe Speciation in Iron Modified Natural Zeolites as Sustainable Environmental Catalysts

Influence of the methodology on the formation of zeolite membranes MCM-22 for the oil/water emulsion separation

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