Selective gas adsorption by metal exchanged amorphous kaolinite derivatives

Metal exchanged amorphous kaolinite derivates are studied for their gas adsorption properties. The kaolinite derivatives were prepared by aqueous reaction of the clay with concentrated KF solution at 80–110°C. The K+ ions were then exchanged by Cs+, Sr2+, La3+, Fe3+ or Cu2+. Fe(II)- and Cu(I)-containing derivatives were prepared by reduction under H2. The gases tested were N2, O2, CH4, CO, CO2, and C2H2. Correlations between gas retention and various physical and chemical variables are investigated. Gas retention levels normalised against BET surface show that level of adsorption is at least partly determined by surface chemical composition. The highest gas retention levels per unit area are achieved for alkali metal exchanged derivatives or alternately for exchange cations with the largest ionic radius.