Gas Chromatographic Separation of Linear Hydrocarbons on Microporous Organo-Smectites

Hongbai Lao and Christian Detellier
Ottawa-Carleton Chemistry Institute, Department of Chemistry University of Ottawa, Ottawa, Ontario, Canada K1N 6N5

Abstract: A series of organo-montmorillonites and organo-hectorites was prepared by complete ion-exchange from the pure sodium form of the parent smectites. The organic cations were tetramethylammonium, trimethylated quaternary ammonium derivatives of the lysine and of the ornithine methyl esters, quaternarized polyammonium cations, or tetraphenylphosphonium (TPP). These organo-smectites were used as packing material for gas chromatography columns. Mixtures of light hydrocarbons (methane to n-butane; “C1” to “C4”) could be separated. The degree of separation depends on the presence of micropores or of organophilic mesopores. The BET surface area, the micropore and mesopore volumes, as well as the size distribution of micropores and mesopores were measured for several systems. As a general trend, the retention times of the light hydrocarbons decrease with an increase of the micropore volume. In the case of TPP-montmorillonite, characterized by a large mesopore volume but for which no microporosity could be detected, separation of longer linear hydrocarbons (n-pentane to n-octane) could also be achieved.

Key Words: Gas chromatography • Gas separation • Hectorite • Hydrocarbons • Mesoporosity • Microporosity • Montmorillonite • Organo-clays • Smectites

Clays and Clay Minerals; August 1994 v. 42; no. 4; p. 477-481; DOI: 10.1346/CCMN.1994.0420415
© 1994, The Clay Minerals Society
Clay Minerals Society (www.clays.org)