A microporous chromium-organic framework fabricated via solvent-assisted metal metathesis for C 2 H 2 /CO 2 separation.

Removal of CO 2 or C 2 H 4 from C 2 H 2 is still a challenging task due to their similar physical-chemical properties. Here, a bifunctional ligand decorated with amino and sulfoxide groups, 5',5''''-sulfonylbis (2'-amino-[1,1':3',1''-terphenyl]-4,4''-dicarboxylic acid) (H 4 L), was employed to construct a new microporous iron-organic framework (Fe-MOF) with the formula [(Fe 3 O)(L) 1.5 (H 2 O) 3 ] n . This MOF can serve as a parent structure to obtain the isostructural Cr-MOF by solvent-assisted metal metathesis. Furthermore, the gas adsorption and separation performance of these two MOFs were systematically investigated. Compared to Fe-MOF, Cr-MOF shows a moderately higher CO 2 , C 2 H 2 and C 2 H 4 uptake capacity. Additionally, Cr-MOF can selectively adsorb C 2 H 2 over CO 2 and C 2 H 4 . The separation potential towards C 2 H 2 /C 2 H 4 and C 2 H 2 /CO 2 was further established via IAST calculations of mixture adsorption equilibrium. IAST selectivity values of Cr-MOF are 3.4 for C 2 H 2 /C 2 H 4 and 6.9 for C 2 H 2 /CO 2 at 298 K and initial pressure, indicating its potential C 2 H 2 separation ability.