Efficient C 2 H 2 /CO 2 Separation in Ultramicroporous Metal–Organic Frameworks with Record C 2 H 2 Storage Density

作者：Wei Gong, Hui Cui, Yi Xie, Yingguo Li, Xianhui Tang, Yan Liu, Yong Cui, Banglin Chen · 发表于：Journal of the American Chemical Society · 年份：2021 · DOI：10.1021/jacs.1c07191 · 被引用次数：192 · 研究领域：Metal-Organic Frameworks: Synthesis and Applications、Covalent Organic Framework Applications、Crystallography and molecular interactions

Physical separation of C 2 H 2 from CO 2 on metal–organic frameworks (MOFs) has received substantial research interest due to the advantages of simplicity, security, and energy efficiency. However, that C 2 H 2 and CO 2 exhibit very close physical properties makes their separation exceptionally challenging. Previous work appeared to mostly focused on introducing open metal sites that aims to enhance the C 2 H 2 affinity at desired sites, whereas the reticular manipulation of organic components has rarely been investigated. In this work, by reticulating preselected amino and hydroxy functionalities into isostructural ultramicroporous chiral MOFs—Ni 2 ( l -asp) 2 (bpy) ( MOF-NH 2 ) and Ni 2 ( l -mal) 2 (bpy) ( MOF-OH )—we targeted efficient C 2 H 2 uptake and C 2 H 2 /CO 2 separation, which outperforms most benchmark materials. Explicitly, MOF-OH adsorbs substantial amount of C 2 H 2 with record storage density of 0.81 g mL –1 at ambient conditions, which even exceeds the solid density of C 2 H 2 at 189 K. In addition, MOF-OH gave IAST selectivity of 25 toward equimolar mixture of C 2 H 2 /CO 2, which is nearly twice higher than that of MOF-NH 2 . Notably, the adsorption enthalpies for C 2 H 2 at zero converge in both MOFs are remarkably low (17.5 kJ mol –1 for MOF-OH and 16.7 kJ mol –1 for MOF-NH 2 ), which to our knowledge are the lowest among efficient rigid C 2 H 2 sorbents. The efficiencies of both MOFs for the separation of C 2 H 2 /CO 2 are validated by multicycle breakt...