Study of porous structure of pillared clays: 1. Montmorillonite fixed by chromium (III) oxide

The porous structure of montmorillonite fixed by chromium oxide was studied by nitrogen, water vapor, and benzene adsorption.The adsorption data obtained were analyzed in detail by the cr"-method and the theory of volume fllling of micropores. The fixation of acid-treated montmorillonite K 10 by hydroxochromium cations resulted in the formation of the pillared clay with considerable mesoporosity. Additional micropores appeared, and new polar adsorption sites were formed. The role of new absorption sites belongs to hydroxochromium cations or chromium oxide clusters localized in the interlayer space of the pillared clay. A microporous material was found to be formed mostly by the fixation of Oglanli bentonite. Thecalcination of the synthesized pillared clays at 673 K resulted in an increase in the average width of their micropores and mesoporosity. The porous montmorillonite structure fixed by chromium oxide can be purposefully formed using clays of different chemical composition and physical and chemical properties