Customizing Metal-Organic Frameworks by Lego-Brick Strategy for One-Step Purification of Ethylene from a Quaternary Gas Mixture.

One-step purification of ethylene (C 2 H 4 ) from a quaternary gas mixture of C 2 H 6 /C 2 H 4 /C 2 H 2 /CO 2 by adsorption is a promising separation process, yet developing adsorbents that synergistically capture various gas impurities remains challenging. Herein, a Lego-brick strategy is proposed to customize pore chemistry in a unified framework material. The ethane-selective MOF platform is further modified with customized binding sites to specifically adsorb acetylene and carbon dioxide, thus one-step purification of C 2 H 4 with high productivity of polymer-grade product (134 mol kg -1 ) is achieved on the assembly of porous coordination polymer-2,5-furandicarboxylic acid (PCP-FDCA) and PCP-5-aminoisophthalic acid (IPA-NH 2 ). Computational studies verify that the low-polarity surface of this MOFs-based platform provides a delicate environment for C 2 H 6 recognition, and the specific binding sites (FDCA and IPA-NH 2 ) exhibit favorable trapping of C 2 H 2 and CO 2 via CH δ+ ···O δ- and C δ+ ···N δ- electrostatic interactions, respectively. The proposed Lego-brick strategy to customize binding sites within the MOFs structure provides new ideas for the design of adsorbents for compounded separation tasks.