Heat of adsorption of pure sulfur hexafluoride on micro-mesoporous adsorbents

The isotherms and the isosteric heats of adsorption of pure SF6 were measured on two microporous zeolites (NaX and Silicalite), one mesoporous alumina, and two activated carbons (BPL and PCB) at 305 K. The adsorption isotherms were Type I by Brunauer classification. The PCB carbon adsorbed SF6 most strongly and the alumina adsorbed SF6 most weakly. The adsorption of SF6 on the other three materials were comparable in the low pressure region despite their drastic differences in the physicochemical properties. The heat of adsorption of SF6 on the silicalite and the alumina remained practically constant over a large range of coverage. The heat of adsorption of SF6 increased with increasing adsorbate loading on the NaX zeolite in the high coverage region. The heat of adsorption of SF6 on the activated carbons decreased with increasing adsorbate loading before leveling off in the high coverage region.