Structural Model of Al13-Pillared Montmorillonite

Virgil I. Dimov, Albena V. Ilieva, Nelly G. Khaltakova and Liudmila D. Filizova
Central Laboratory of Mineralogy and Crystallography, Bulgarian Academy of Sciences, 1000 Sofia, Bulgaria
E-mail of corresponding author: mincryst@bas.bg

Abstract: Alumina-pillared montmorillonite is prepared by intercalation of polyoxyhydroxy aluminum cations (Al137+) of a natural montmorillonite from Dimitrovgrad, Bulgaria. Transmission electron microscopy, powder X-ray diffraction, energy dispersive X-ray spectroscopy, and surface area (BET) methods are used to study the untreated and pillared forms of the montmorillonite. A structural model involving deformed Al13 pillars is proposed. Four pillar types are derived and these pillars are uniformly distributed over the interlayer-cation positions of montmorillonite. Calculated electron diffraction patterns were simulated using the multi-slice method. The structural model explains the increased ordering along the c axis of the pillared form compared with the untreated montmorillonite. The model explains the structure of a pillared montmorillonite with different distributions of the pillars in the interlayer. The proposed model is consistent with the observed data.

Key Words: Alumina Pillaring • Computer Simulation • Keggin Pillaring • Montmorillonite • Structural Model • Transmission Electron Microscopy

Clays and Clay Minerals; February 2000 v. 48; no. 1; p. 1-9; DOI: 10.1346/CCMN.2000.0480101
© 2000, The Clay Minerals Society
Clay Minerals Society (www.clays.org)