Kilogram-Scale Fabrication of a Robust Olefin-Linked Covalent Organic Framework for Separating Ethylene from a Ternary C Hydrocarbon Mixture.

One-step adsorptive purification of ethylene (CH) from a ternary mixture of acetylene (CH), CH, and ethane (CH) by a single material is of great importance but challenging in the petrochemical industry. Herein, a chemically robust olefin-linked covalent organic framework (COF), NKCOF-62, is designed and synthesized by a melt polymerization method employing tetramethylpyrazine and terephthalaldehyde as cheap monomers. This method avoids most of the disadvantages of classical solvothermal methods, which enable the cost-effective kilogram fabrication of olefin-linked COFs in one pot. Furthermore, NKCOF-62 shows remarkably selective adsorption of CH and CH over CH thanks to its unique pore environments and suitable pore size. Breakthrough experiments demonstrate that polymer-grade CH can be directly obtained from CH/CH/CH (1/1/1) ternary mixtures through a single separation process. Notably, NKCOF-62 is the first demonstration of the potential to use COFs for CH/CH/CH separation, which provides a blueprint for the design and construction of robust COFs for industrial gas separations.