Clays and Clay Minerals, Vol. 55, No. 2, 165–176, 2007.
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Authors
Grygar, T.
Hradil, D.
Bezdicˇka, P.
Dousˇova´, B.
Cˇapek, L.
Schneeweiss, O.
Issue Date
2007
Type
Article
Language
Keywords
Periodicals , Geology , As sorption , Fe-montmorillonite , Fe-bentonite , Oxidative Dehydrogenation of Propane , Pillaring , Speciation of Fe
Alternative Title
Fe(iii)-modified Montmorillonite And Bentonite: Synthesis, Chemical And Uv-vis Spectral Characterization, Arsenic Sorption, And Catalysis Of Oxidative Dehydrogenation Of Propane
Abstract
Two major species were identified in Fe-treated montmorillonite: monomeric or dimeric hydroxoaqua cations Fe(OH)x (3-x)+ (form I), and polymeric structures with edge-shared Fe(O,OH)6 (form II). These species have different electron spectra (absorption maximum is 29,600 cm-1 in form I, and 26,000 and 28,000 cm-1 in form II), chemical and thermal stability, and electrochemical behavior. Form I behaves as a partly exchangeable cation in interaction with Cu2+ from Cu-trien solution and Ni2+ from Ni-EDTA, that can be used for selective quantitative analysis. On heating above the dehydration temperature (~100-150ºC) montmorillonite with Fe3+ in form I is converted to a mica-like structure and Fe3+ ions are fixed more strongly in the montmorillonite structure. Form II behaves similarly to hydrous ferric oxides, but its thermal crystallization to hematite is postponed to ~500-600ºC. The Fe3+ cations in the interlayer space are much less thermally stable than Al pillars in pillared interlayered clays (PILCs). Form I is more active in oxidative dehydrogenation of propane, while form II is the active species in sorption of As and the non-specific combustion of propane. To produce only form II by the treatment of montmorillonite with Fe3+, its load must be kept below ~20 wt.%; otherwise the usual hydrous ferric oxides are formed.
Description
Clays and Clay Minerals, Vol. 55, No. 2, 165–176, 2007. Fe(iii)-modified Montmorillonite And Bentonite: Synthesis, Chemical And Uv-vis Spectral Characterization, Arsenic Sorption, And Catalysis Of Oxidative Dehydrogenation Of Propane. T. Grygar; D. Hradil; P. Bezdicˇka; B. Dousˇova´; L. Cˇapek; O. Schneeweiss. DOI: 10.1346/CCMN.2007.0550206. Copyright © 2007, The Clay Minerals Society.
Citation
Clays and Clay Minerals, Vol. 55, No. 2, 165–176, 2007.
Publisher
The Clay Minerals Society
License
Copyright © 2006-2018, The Clay Minerals Society