A novel anion-pillared metal-organic framework for highly efficient separation of acetylene from ethylene and carbon dioxide

Separation of acetylene (C 2 H 2 ) from ethylene (C 2 H 4 ) and carbon dioxide (CO 2 ) is of great importance in the petrochemical industry but remains a daunting challenge due to their very similar sizes and physical properties. Although a number of porous materials have been developed as promising adsorbents for either C 2 H 2 /C 2 H 4 or C 2 H 2 /CO 2 separation, few materials exhibit simultaneously high selectivities for both gas mixtures. Herein, we report the use of a four-connected N-donor organic linker to construct a novel water-stable SIFSIX-type material, [Cu(TPB)SiF 6 ] n (termed ZJU-280, TPB = 1,2,4,5-tetra(pyridin-4-yl)benzene). This material features suitable rhombic pores and functional surfaces to interact optimally with C 2 H 2 molecules, affording high C 2 H 2 capture capacity and simultaneously high C 2 H 2 /CO 2 (18.1) and C 2 H 2 /C 2 H 4 (44.5) selectivities under ambient conditions. Theoretical calculations indicate that the suitable rhombic pores and functional sites can provide a multipoint binding environment to not only preferentially interact with C 2 H 2 but also enable the dense packing of C 2 H 2 molecules within the framework. Actual breakthrough experiments demonstrate that ZJU-280a can efficiently separate C 2 H 2 from C 2 H 2 /CO 2 (50/50, v/v) and C 2 H 2 /C 2 H 4 (1/99 and 50/50) mixtures, respectively. A novel water-stable anion-pillared MOF material with suitable rhombic pores and functional surfaces exhibits high C 2 H 2 capture capacity and simultaneously high C 2 H 2 /CO 2 and C 2 H 2 /C 2 H 4 selectivities under ambient conditions.