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

Abstract

Separation of acetylene (C₂H₂) from ethylene (C₂H₄) and carbon dioxide (CO₂) 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 C₂H₂/C₂H₄ or C₂H₂/CO₂ 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)SiF₆]_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 C₂H₂ molecules, affording high C₂H₂ capture capacity and simultaneously high C₂H₂/CO₂ (18.1) and C₂H₂/C₂H₄ (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 C₂H₂ but also enable the dense packing of C₂H₂ molecules within the framework. Actual breakthrough experiments demonstrate that ZJU-280a can efficiently separate C₂H₂ from C₂H₂/CO₂ (50/50, v/v) and C₂H₂/C₂H₄ (1/99 and 50/50) mixtures, respectively.