Covalent organic frameworks (COFs) are an emerging class of organic porous crystalline materials based on light elements interconnected through covalent bonds. Attributed to their predictable structures, high porosity, tunable pore sizes and high chemical stability, COFs have shown unique properties and great potential in gas storage and separation applications. Many experiments have been devoted to purity C 2 H 4 from C 2 -gases mixtures. In 2018, Zhu and co-workers used imide-linked COFs (PAF-110) to purity C 2 H 4 from binary C 2 H 2 /C 2 H 4 mixtures. Recently, our group reported that three-dimensional (3D) COFs with bcu topology could efficiently remove C 2 H 6 from binary C 2 H 2 /C 2 H 4 mixtures to produce polymer-grade C 2 H 4 . (Figure ). olefin-linked COFs with nearly irreversible C=C linkage, as a rising star, is one of the promising candidates for gas separations at an industrial scale owing to their superb chemical stability, scalable synthesis and low production cost. Significantly, recent investigations also demonstrate that the melt polymerization method without adding organic solvent, pioneered by our group, can access a wide range of COFs, and enables the large-scale and low-cost fabrication of olefin-linked COFs, hence making olefin-linked COFs promising candidates to solve the formidable challenge of C 2 H 2 /C 2 H 4 /C 2 H 6 separation. To address the above challenges, we discovered a new commercially available D 2h -symmetric monomer (tetramethylpyrazine), which has been widely used as an intermediate in flavoring agents, fragrances, pharmaceuticals and pesticides, showing great industrial application potential due to its extremely low cost (<$90/kg). Herein, we constructed a new olefin-linked COF (denoted as NKCOF-62, NKCOF = Nankai covalent organic framework) with orthorhombic reticular topology from two cheap building blocks, tetramethylpyrazine (TMPZ) and terephthalaldehyde (TPA) ($30/kg) through melt polymerization method. Notably, the melt polymerization strategy avoids using organic solvents and high operation pressure, making COFs easily scaled up to the hectogram level. Attributed to its relatively small pore size and unique pore