TRANSITION-METAL OXIDE PILLARED CLAY .1. A COMPARATIVE-STUDY OF TEXTURAL AND ACIDIC PROPERTIES OF FE(III) PILLARED MONTMORILLONITE AND PILLARED ACID-ACTIVATED MONTMORILLONITE

Fe(III) pillared montmorillonite samples have been prepared by interca lating trinuclear acetato hydroxy-iron (III) nitrate [Fe(COOCH3)(7)OH 2H(2)O](+) NO3- between the layers of both Na-exchanged and acid-activ ated montmorillonite, followed by calcination and characterized by var ious techniques. The multistep ion exchange process gave better comple x loading than the single step process. FTIR and Mossbauer spectral an alysis showed the presence of the complex inside the silicate layers. Materials prepared from the two starting materials are thermally stabl e up to 500 degrees C, having basal spacings of 18.0 and 17.6 Angstrom and high surface areas of 284 and 276 m(2)/g, respectively. The acid- activated pillared montmorillonite shows somewhat low complex intake, but has high acidity in comparison to the Na-exchanged material. (C) 1 996 Academic Press, Inc.