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

Separation of acetylene (C₂H₂) from ethylene (C₂H₄) or carbon dioxide (CO₂) is a vital and difficult task in petrochemical industry. Owing to the similar physical properties, it is very challenging to synthesize target porous 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 [Cd₂(dpip)₂(DMF)(H₂O)]·DMF·H₂O (1). The Cd-MOF features suitable pore surfaces modified by carboxyl oxygen atoms to contact closely with C₂H₂ molecules, which leads to considerable C₂H₂ adsorption ability of 124.4 cm³ g⁻¹ at 100 kPa and 298 K, significantly higher than C₂H₄ and CO₂. Experimental breakthroughs indicate the Cd-MOF can efficiently separate C₂H₂ from C₂H₂/CO₂, C₂H₂/CH₄, and C₂H₂/C₂H₄ mixtures. The productivities of ≥ 99.996% C₂H₄ purity calculated on the basis of simulated transient breakthroughs for 1/99 C₂H₂/C₂H₄ 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 C₂H₂.