Benchmark C<sub>2</sub>H<sub>2</sub>/CO<sub>2</sub>Separation in an Ultra‐Microporous Metal–Organic Framework via Copper(I)‐Alkynyl Chemistry
Ling Zhang, Ke Jiang, Lifeng Yang, Libo Li, Enlai Hu, Ling Yang, Kai Shao, Huabin Xing, Yuanjing Cui, Yu Yang, Bin Li, Banglin Chen, Guodong Qian
Abstract
Abstract Separation of acetylene from carbon dioxide remains a daunting challenge because of their very similar molecular sizes and physical properties. We herein report the first example of using copper(I)‐alkynyl chemistry within an ultra‐microporous MOF (Cu I @UiO‐66‐(COOH) 2 ) to achieve ultrahigh C 2 H 2 /CO 2 separation selectivity. The anchored Cu I ions on the pore surfaces can specifically and strongly interact with C 2 H 2 molecule through copper(I)‐alkynyl π‐complexation and thus rapidly adsorb large amount of C 2 H 2 at low‐pressure region, while effectively reduce CO 2 uptake due to the small pore sizes. This material thus exhibits the record high C 2 H 2 /CO 2 selectivity of 185 at ambient conditions, significantly higher than the previous benchmark ZJU‐74a (36.5) and ATC‐Cu (53.6). Theoretical calculations reveal that the unique π‐complexation between Cu I and C 2 H 2 mainly contributes to the ultra‐strong C 2 H 2 binding affinity and record selectivity. The exceptional separation performance was evidenced by breakthrough experiments for C 2 H 2 /CO 2 gas mixtures. This work suggests a new perspective to functionalizing MOFs with copper(I)‐alkynyl chemistry for highly selective separation of C 2 H 2 over CO 2 .