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

Abstract

One-step purification of ethylene (C2 H4 ) from a quaternary gas mixture of C2 H6 /C2 H4 /C2 H2 /CO2 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 C2 H4 with high productivity of polymer-grade product (134mol kg-1 ) is achieved on the assembly of porous coordination polymer-2,5-furandicarboxylic acid (PCP-FDCA) and PCP-5-aminoisophthalic acid (IPA-NH2 ). Computational studies verify that the low-polarity surface of this MOFs-based platform provides a delicate environment for C2 H6 recognition, and the specific binding sites (FDCA and IPA-NH2 ) exhibit favorable trapping of C2 H2 and CO2 via CHδ+ ···Oδ- and Cδ+ ···Nδ- 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.