Adsorption equilibrium of methane and carbon dioxide on porous metal-organic framework Zn-BTB

Porous metal-organic frameworks (MOFs) have emerged over the past decade as an important new class of materials possessing permanent porosities, uniform pore structures, high surface areas, and low crystal densities. MOFs are regarded as promising solid adsorbents for gas storage and separation but have not reached an applied level yet. One impediment to MOF applications is incomplete adsorption information and lack of structure-property relationships. In this paper, we present pure-component adsorption equilibrium data for methane and carbon dioxide at different temperatures on a new three-dimensional Zn-MOF material built from the ligand 1,3,5-tris(4-carboxyphenyl)benzene (H ₃BTB) with Zn metal. The data are described by Toth's equation and Dubinin-Astakhov (D-A) equation. Thermodynamic properties including isosteric heat of adsorption are estimated based on the two models and comparisons are made with other adsorbents. The smaller pore diameters of Zn-MOF compared to related structures MOF-177 and UMCM-1 lead to greater adsorption loadings at 1 bar.