Chemical stability of aluminium–iron- and iron-pillared montmorillonite: extraction and reduction of iron

Komadel, Peter; Doff, David H.; Stucki, Joseph W.

doi:10.1039/c39940001243

Cited by 14 publications

(4 citation statements)

References 18 publications

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“…The possibility of incorporating a large number of metal cations in the pillaring oxide particle provide the opportunity of creating multifunctional catalysts. Few metal cations form positively charged polymeric species in solution before precipitation, but the use of such mixed oligomer solutions has already permitted the insertion of a wide variety of mixed oxides, mainly into clays. − …”

Section: Preparation and Characterization Of Pillared Metal(iv) Phosp...mentioning

confidence: 99%

Nanostructured Inorganically Pillared Layered Metal(IV) Phosphates

et al. 1996

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This article reviews the synthesis, characterization and ion-exchange, ion-transport, sorptive, and catalytic properties of inorganically pillared layered metal(IV) phosphates, typified by Zr(HPO 4 ) 2 ‚H 2 O. Porous nanostructures are generally prepared from metal(IV) phosphates either by ion exchange of polynuclear species or by intercalation from solutions of condensed species obtained by the hydrolysis of organometallic precursors using sol-gel methods, followed by thermal treatment to eliminate organic moieties, condense hydroxyl groups, eliminate water, and consolidate the structure by grafting the pillar to the layer. The different strategies devised to overcome the problem presented by the high layer charge density of R-and γ-structured phosphates in obtaining porous solids, including exfoliation and local surface growth of pillaring ions, and modification of the zirconium phosphate matrix to reduce the cation-exchange capacity, are described. Structural and textural characteristics of Al, Cr, mixed Al-Cr, Fe-Cr, Ga-Al and of Si-pillared phosphates obtained from XAFS, XPS, and MAS NMR are presented, and the perspectives of nanocomposite pillared layered solids in general are discussed in the current context of mesoporous solids synthesized using templating routes.

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Section: Preparation and Characterization Of Pillared Metal(iv) Phosp...mentioning

confidence: 99%

Nanostructured Inorganically Pillared Layered Metal(IV) Phosphates

et al. 1996

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“…A drop in pH and an increase maleic acid concentration were noted during the reaction suggesting that mineralization is not advanced giving the lower TOC conversion (25% after 20h). It has been also reported [9,25] that pillared clays, in particular with the combination of Fe and Al, have a reduced potential for iron leaching. Fe lixiviation levels remained very low at the end of the reaction indicating that the active phase of this catalyst is strongly xed to its support.…”

Section: Catalytic Test Resultsmentioning

confidence: 87%

“…The low Fe lixiviation levels in all solids were obtained except the MR-Al catalyst with a rate of 15%. Indeed, according to bibliographic reports [9,25], clays pillared in particular with the combination of Fe and Al have a reduced potential for iron leaching.…”

Section: Catalytic Test Resultsmentioning

confidence: 99%

Catalytic Activity of Phenol Oxidation over Iron and Cooper-Exchanged Pillared Bentonite

Chellal,

Hamidouche,

Boudieb

et al. 2024

Chemistry Africa

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Al, mixed Al-Fe and Al-Cu pillared clays were prepared. The solids were characterized by X-ray diffraction (XRD), N 2 adsorption and H 2 -TPR. The dispersion of the cold clay suspension, before the pillaring, increases the basal spacing and the speci c surface area. CWPO of phenol under mild conditions (25 °C, 1 atm) was carried out without correction of pH. Mixed Al-Fe and Al-Cu pillared clays have comparable performances, although they showed some differences in the H 2 O 2 decomposition kinetics. A total conversion of H 2 O 2 is obtained without the complete phenol conversion over mixed Al-Fe pillared clays suggesting the presence of active species in these catalysts. In a slight excess of H 2 O 2 , the activity increased for all iron-based clays catalysts with the increase in Fe content. A total conversion of phenol is obtained after 15 h of reaction over Fe/MR-AlFe(10) and after extending the reaction time to 30 h in the presence of Fe/MR-Al. While MR-AlFe(10) only converted 57.12% under the same conditions. MR-AlFe(10) has the greater basal space (17.44 Å) and is more active for H 2 O 2 decomposition than Fe/MR-Al, which certainly allowed greater accessibility of the reactant to the iron species. Iron exchanged and postpillared clay with mixed (Al-Fe) solution containing 10% of iron expressed as molar percentage {Fe/MR-AlFe (10)} was the most e cient for this reaction combining good catalytic activity with high stability against iron leaching (0.02%). It showed a total phenol degradation, the highest H 2 O 2 decomposition (85.7%) and more than 80% of TOC removal after 15 h of reaction.

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“…Iron on montmorillonite could further be present as the clay exchange complex Choudary et al, 1994;Coyne and Banin, 1986;Diamant et al, 1982;Ebitani et al, 2002;Helsen and Goodman, 1983;Hirt et al, 1993;Johnston and Cardile, 1987;Kamei et al, 1999;Letaief et al, 2002;Thompson and Tahir, 1991). Structural iron could be occurred in either the octahedral or tetrahedral sheets by replacement of Al 3+ (Reinholdt et al, 2001) or Si 4+ , or in pillars bridging two individual clay particles as in the ''pillared clays'' (Bergaya and Barrault, 1990;Bergaya et al, 1991;Chirchi and Ghorbel, 2002;Komadel et al, 1994;Mishra and Parida, 1998;Mody et al, 1993;Pálinkó et al, 1996;Rightor et al, 1991;Wasserman et al, 1998). Charlet and Tournassat (2005) studied a 57 Fe(II)-exchanged natural montmorillonite in a chloride medium and highlighted the existence of Mössbauer distinguishable Fe 2+ and FeCl + as cation exchange species.…”

Section: Structural or Adsorbed Fe On Montmorillonitesmentioning

confidence: 97%