Ultramicroporous Metal‐Organic Frameworks Functionalized With Acyclic Ether Oxygen Bonds for Efficient C 2 H 2 /CO 2
Xinhui Chen, Zerui Wang, Jie Song, Hongke Dong, Chunyu Lu, Mingzhen Shao, Shubin Wang, Xiaoqing Lu, Ben Xu, Fangna DaiABSTRACT
Designing and tailoring porous materials to realize the precise separation of C 2 H 2 , C 2 H 4 and CO 2 with nearly identical kinetic diameters is an extremely challenging research task. In this study, a novel microporous metal‐organic framework (MOF) designated UPC‐523 (Zn 3 (H 4 edda) 2 ·DMF) has been synthesized by employing 5,5'‐(ethane‐1,2‐diylbis(oxy))diisophthalic acid (H 4 edda), which is constructed with ethylene ether linkages (‐O‐CH 2 ‐CH 2 ‐O‐). This rational design strategy employs ethylene ether moieties to construct a highly electronegative pore microenvironment within the framework. UPC‐523 is endowed with abundant electronegative sites, the uncoordinated oxygen atoms in the confined pores selectively capture C 2 H 2 from CO 2 and C 2 H 4 through hydrogen‐bonding interactions, enabling it to achieve selective adsorption of C 2 H 2 . At 298 K and 100 kPa, this MOF exhibits a C 2 H 2 adsorption capacity of 44.9 cm 3 /g, coupled with a moderate isosteric heat of C 2 H 2 adsorption ( Q st ) of 33.7 kJ/mol, a property conducive to the direct desorption and regeneration of UPC‐523. The IAST selectivities of C 2 H 2 /C 2 H 4 (v/v = 50/50) and C 2 H 2 /CO 2 (v/v = 50/50) are 2.1 and 3.4, respectively, comparable to the majority of reported MOFs under identical conditions. Dynamic breakthrough experiments reveal that UPC‐523 can efficiently separate C 2 H 2 from C 2 H 2 /CO 2 or C 2 H 2 /C 2 H 4 mixtures.