Interlayer Symmetry Control in Flexible-Robust Layered Metal-Organic Frameworks for Highly Efficient CH/CO Separation.

Removal of the CO impurities from CH/CO mixtures is an essential process to produce high-purity CH. Fabricating an adsorbent capable of discriminating these species, which have close kinetic diameters, is critical for developing advanced adsorption processes. Herein, we demonstrate a strategy to exploit the tunability of interlayer and intralayer spaces of two-dimensional (2D) layered metal-organic frameworks to achieve high performance for CH/CO separation. This indicates that interlayer symmetrical control can achieve more efficient packing of CH into Ni(4-DPDS)CrO, with a high CH capacity of 45.7 cm·g at 0.01 bar and a selectivity of 67.7 (298 K, 1 bar), which strikes a good balance between working capacity and separation selectivity compared to other isostructural Ni(4-DPDS)MO (M = Mo, W). Crystallographic studies and DFT-D calculations reveal that such a CH-selective adsorbent possesses strong binding interactions due to the tailored pore confinement provided by the angular anions and rich electronic environment. Experimental breakthrough results comprehensively demonstrate the efficient CH/CO separation performance of this unique material.