A MOF-based Ultra-Strong Acetylene Nano-trap for Highly Efficient C2H2/CO2 Separation.

Porous materials with open metal sites have been extensively investigated to separate various gas mixtures in the last decades. However, compared with the multiple binding sites, the current open metal sites show the limitation in the separation of some challenging gas mixtures, such as C 2 H 2 /CO 2 , which have very similar physical properties. Herein, we propose a new type of ultra-strong C 2 H 2 nano-trap based on multiple binding interactions to efficiently capture C 2 H 2 molecules and separate C 2 H 2 /CO 2 mixture. The ultra-strong acetylene nano-trap shows a benchmark Q st of 79.1 kJ mol -1 for C 2 H 2 , a record high pure C 2 H 2 uptake of 2.54 mmol g -1 at 1×10 -2 bar, and the highest C 2 H 2 /CO 2 selectivity (53.6), making it as a new benchmark material for the capture of C 2 H 2 and the separation of C 2 H 2 /CO 2 . The locations of C 2 H 2 molecules within the MOF-based nanotrap have been visualized by the in-situ single-crystal X-ray diffraction studies, which also identify the multiple binding sites accountable for the strong interactions with C 2 H 2 . Our work not only provides a record C 2 H 2 adsorbent but also suggests a new approach to construct efficient separation materials based on synergistic effect.