Substituting Fe for Al in the Al13O407+ Keggin ion was attempted and the incorporation of the resulted moieties in Na-montmorillonite was performed. The Keggin ion sulfates, the pillared structures as well as the Fe ion-exchanged clay materials were scrutinized by X-ray diffractometry, X-ray fluorescence, 57Fe Mössbauer, mid and far FT-IR spectroscopies. The pillared and the ion-exchanged materials were also studied by BET surface measurements and thermogravimetry. The acidity of the solids was investigated by pyridine adsorption followed by IR spectroscopy and various acid-catalyzed reactions. It was found that aluminium was not substituted by iron, however, above a certain concentration polynuclear iron (II, III) hydrous oxides crystallized together with the Keggin ion sulfate. Iron could be incorporated in the ion-exchanged and the pillared materials also in the form of polynuclear hydrous oxide species. The main effect of this incorporation was the considerable increase in the acidity of the resulting substances.
ASJC Scopus subject areas
- Condensed Matter Physics
- Physical and Theoretical Chemistry
- Surfaces, Coatings and Films
- Materials Chemistry