Experimental and Theoretical Comparative Study of Methane Adsorption on Activated Carbons and MOF-Basolite

摘要

In this paper, results of experimental and theoretical study of methane adsorption on activated carbons and MOF-basolite are presented. Five different activated carbons (named as AC1, AC2, AC3, AC4, AC5) and MOF-basolite were used in the study. The adsorbed amount of methane based on v/v, the critical factor in selecting materials for adsorptive storage, increases in the order of Basolite < AC4 < AC2 < AC1 < AC3 < AC5, which is not the same as the order of BET surface area – Basolite (867 m~2 /g) < AC4 (999 m~2 /g) < AC1 (1235 m~2 /g) < AC3 (1426 m~2 /g) < AC5 (1510 m~2 /g) < AC2 (1589 m~2 /g).. This reflects that fact that the synergistic effect of BET surface area, micropore volume, packing density and pore size distribution decides the adsorbed amount based on v/v. One of the key design parameters for an adsorber, isosteric heat of adsorption is obtained at different fractional loading at 21?C. The initial isosteric heat of adsorption for methane-Basolite system is higher than that for methane-AC5 system, but it decreases faster as fractional loading increases. This indicates the higher degree of heterogeneity and could explain the close-to-rectangular isotherm shape of the methane-Basolite system. The degree of heterogeneity of an adsorbent-adsorbate system is expressed mathematically by using the slope of the isosteric heat of adsorption.