Engineering the Microporous Environment of Flexible Metal–Organic Frameworks with Bifunctionality for Promoting the Separation of Ethylene from a Ternary Mixture

Abstract The separation of ethylene (C 2 H 4 ) from mixtures with carbon dioxide (CO 2 ) and acetylene (C 2 H 2 ) is of great industrial importance but remains a critical challenge. Here, we report that a rationally designed flexible metal–organic framework (FMOF), featuring a specifically engineered microporous environment with bifunctionality, can promote the efficient one‐step separation of C 2 H 4 from a ternary mixture. Adsorption isotherms and dynamic breakthrough tests provide experimental evidence confirming the selective adsorption of CO 2 and C 2 H 2 over C 2 H 4 on such a FMOF, as well as its ability to separate C 2 H 4 from a CO 2 /C 2 H 2 /C 2 H 4 ternary mixture. Theoretical calculations and simulations provide critical insights into the flexible adsorption process and the separation mechanism of the FMOF. The bifunctionality incorporated in FMOF provides exceptionally strong binding of CO 2 and C 2 H 2 but inhibition of C 2 H 4 , which, in turn, enables high adsorption selectivity for CO 2 /C 2 H 4 and C 2 H 2 /C 2 H 4 . This FMOF has high potential for industrial applications in the separation of C 2 H 4 from gas mixtures.