A novel C2H2-selective microporous Cd-MOF for C2H2/C2H4 and C2H2/CO2 separation

A novel Cd-MOF with accessible O atoms adsorption sites was synthesized, showing high adsorption uptake for C 2 H 2 and selectivity for C 2 H 2 over CO 2 , C 2 H 4 , and CH 4 as well as C 2 H 2 separation potential over CH 4 , C 2 H 4 , and CO 2 under ambient condition. • The MOF based on the unique pyridylcarboxylate ligands forms three-dimensional framework decorated by carboxylic acid oxygen atoms. • The carboxylic acid oxygen atoms of MOF provide best contact with C 2 H 2 compared to C 2 H 4 and CO 2 , affording ultrahigh C 2 H 2 adsorption uptake of 124.4 cm 3 g -1 at 298 K. • Breakthrough experiments revealed that the MOF performs effective separation of C 2 H 2 from C 2 H 2 /C 2 H 4 , C 2 H 2 /CH 4 and C 2 H 2 /CO 2 mixtures. • The simulated transient breakthroughs for 1/99 C 2 H 2 /C 2 H 4 mixtures demonstrate that MOF can yield high-purity (>99.996%) C 2 H 4 with high productivities. Separation of acetylene (C 2 H 2 ) from ethylene (C 2 H 4 ) or carbon dioxide (CO 2 ) is a vital and difficult task in petrochemical industry. Owing to the similar physical properties, it is very challenging to synthesize porous target materials with standout separation performance. Herein, we report the utilization of an isophthalic acid linker substituted with pyridine groups to construct a novel microporous Cd-MOF [Cd 2 (dpip) 2 (DMF)(H 2 O)]·DMF·H 2 O ( 1 ). The Cd-MOF features suitable pore surfaces modified by carboxyl oxygen atoms to contact closely with C 2 H 2 molecules, which leads to considerable C 2 H 2 adsorption ability of 124.4 cm 3 g -1 at 100 kPa and 298 K, significantly higher compared to C 2 H 4 and CO 2 . Experimental breakthroughs indicate the Cd-MOF can efficiently separate C 2 H 2 from C 2 H 2 /CO 2 , C 2 H 2 /CH 4 , and C 2 H 2 /C 2 H 4 mixtures. The productivities of ≥99.996% C 2 H 4 purity calculated on the basis of simulated transient breakthroughs for 1/99 C 2 H 2 /C 2 H 4 were determined to be 27.72 and 60.77 L kg -1 at 298 and 273 K, respectively. Molecular simulation demonstrates the pivotal role of the multiple interactions in the framework for C 2 H 2 .