Adsorption study of CO 2 , CH 4 , N 2 , and H 2 O on an interwoven copper carboxylate metal–organic framework (MOF-14)

Metal–organic frameworks (MOFs) are attractive microporous materials for adsorption separations due to their extraordinary structures and impressive high surface areas. Catenation, or framework interpenetration, can significantly impact the crystal stability and improve the adsorption interactions. This interesting approach was used to obtain {[Cu3(BTB)2(H2O)3]⋅(DMF)9(H2O)2} (MOF-14) as a microporous material with a high surface area and large pore volume, which are desirable parameters for adsorption applications. Here, we report a detailed study of this catenated material with its gas adsorption properties. The potential for adsorption separations is evaluated by measuring pure-component adsorption isotherms for carbon dioxide, methane, and nitrogen. The Ideal Adsorbed Solution Theory (IAST) was used to evaluate adsorption selectivities of MOF-14 for CO2/CH4 and CO2/N2 equimolar mixtures. In addition, water adsorption and the impact of exposure on structural degradation are reported. Compared to other open-metal site MOFs, MOF-14 adsorbs significantly less water. This interwoven MOF is a promising competitor to other MOF materials in the gas separation field due to low interactions with water and high selectivity for CO2 over N2.