Intercalation of Silica in Smectite1

T. Endo2, M. M. Mortland and T. J. Pinnavaia
Department of Crop and Soil Science, Michigan State University East Lansing, Michigan 48824
Department of Chemistry, Michigan Stage University East Lansing, Michigan 48824
1Published as Agricultural Experiment Station manuscript #9233.
2Present address: National Institute for Research, 1-1 Namiki, Sakura-mura, Niihari-gun Ibaraki 305, Japan.

Abstract: Silica has been intercalated in swelling clays by hydrolysis and/or oxidation of tris(acetylacetonato)silicon(IV) cations, Si(acac)3+, and polychlorosiloxanes, (-SiOCl2-)n, in the interlamellar regions of the minerals. The Si(acac)3+ ions have been placed on the interlamellar surfaces by ion exchange and by in situ reaction of the acetylacetone-solvated clays with SiCl4. The (-SiOCl2-)n polymers were formed in the interlayers by reaction of adsorbed benzaldehyde with SiCl4. The optimum (001) spacing observed after firing the clays in air at 500°C (12.6 Å) corresponds to the presence of a monolayer of siloxane chains. Nitrogen BET surface areas range from 40 to 240 m2/g, depending on the amount of internal surface covered by the intercalated silica. In some cases, highly ordered products were formed which exhibit four orders of (00ℓ) reflection. Interstratified products with d(001) values between 9.6 and 12.6 Å exhibit surface areas consistent with the presence of a random mixture of totally collapsed interlayers and interlayers containing siloxane monolayers. Attempts to achieve silica intercalation by hydrolysis of SiCl4 in the clay interlayers were not productive.

Key Words: Hectorite • Intercalation • Silica • Smectite • Vermiculite

Clays and Clay Minerals; April 1980 v. 28; no. 2; p. 105-110; DOI: 10.1346/CCMN.1980.0280205
© 1980, The Clay Minerals Society
Clay Minerals Society (www.clays.org)