Interlayer Symmetry Control in Flexible-Robust Layered Metal-Organic Frameworks for Highly Efficient C 2 H 2 /CO 2 Separation.

Removal of the CO 2 impurities from C 2 H 2 /CO 2 mixtures is an essential process to produce high-purity C 2 H 2 . 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 C 2 H 2 /CO 2 separation. This indicates that interlayer symmetrical control can achieve more efficient packing of C 2 H 2 into Ni(4-DPDS) 2 CrO 4 , with a high C 2 H 2 capacity of 45.7 cm 3 ·g -1 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) 2 MO 4 (M = Mo, W). Crystallographic studies and DFT-D calculations reveal that such a C 2 H 2 -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 C 2 H 2 /CO 2 separation performance of this unique material.