Cross-Linked Smectites. III. Synthesis and Properties of Hydroxy-Aluminum Hectorites and Fluorhectorites

J. Shabtai, Maria Rosell1 and M. Tokarz2
Department of Fuels Engineering, University of Utah, Salt Lake City, Utah 84112
1 On leave of absence from EKA AB, Surte, Sweden, 1982.
2 On leave of absence from the University of Mining and Metallurgy, Krakow, Poland, 1981–1983.

Abstract: Interaction of La3+ and Ce3+-exchanged hectorites with oligomeric hydroxy-Al cations results in the formation of cross-linked hectorites possessing moderately high surface areas (∼220–280 m2/g) and high thermal stability. The basal spacings of these products were generally in the range 17.0–18.0 Å, the exact d(001) value depending on the age of the hydroxy-Al oligomeric solution and on the pH of the starting hectorite dispersion. Interaction of Li- or Ce-fluorhectorite with hydroxy-Al oligocations produced the corresponding cross-linked fluorhectorites, which showed markedly higher basal spacings (18.2–20.0 Å for air-dried samples), surface areas (∼300–380 m2/g), and thermal stability, as compared with those of the cross-linked hectorites. The cross-linking agent applied in the synthesis of the hydroxy-Al hectorite and fluorhectorite products consisted of a solution of hydroxy-Al oligomers aged for periods of 7 to 27 days. A constant ratio of 2.0 mmole Al/g of smectite was used in all preparations. The high basal spacings and porosity of the newly synthesized products are consistent with a structure similar to that previously proposed for cross-linked hydroxy-Al montmorillonite.

Key Words: Cross-linking • Fluorhectorite • Hectorite • Hydroxyaluminum • Molecular sieve • Surface area • Synthesis • Thermal stability

Clays and Clay Minerals; April 1984 v. 32; no. 2; p. 99-107; DOI: 10.1346/CCMN.1984.0320203
© 1984, The Clay Minerals Society
Clay Minerals Society (