Zeolite sorbents. Modification by impregnation with salts

Abstract

A study has been made of the effect of salt inclusion in certain zeolites upon the kinetics of sorption of, and the molecule sieving behaviour shown towards, n-hexane, 2- and 3-methyl pentanes, 2,2- and 2,3-dimethyl butanes, cyclohexane and benzene. The zeolites selected provided three typical one dimensional channel systems. They were zeolite L, offretite and H-mordenite. The salts used to impregnate the channels were KCl, KBr, K₂SO₄ and K₂CrO₄, all comparatively stable to heating. The effects of salt concentration and salt type were investigated in each zeolite and also of washing and extraction of salt-impregnated sorbents. Among the above salts K₂CrO₄ gave the largest effects. Access to the channels could be selectively controlled and changed by salt imbibition giving rise to various separation possibilities based on differences in size and shape of sorbate molecules.