Scalable Room-Temperature Synthesis of the Ultramicroporous Metal–Organic Framework for Separation of the C ₂ H ₆ / C ₂ H ₄ Mixture

Ethylene (C₂H₄) is a vital industrial chemical with a growing market, similarly produced through the steam cracking of hydrocarbons, such as ethane (C₂H₆). However, separating C₂H₄ from a C₂H₆ and C₂H₄ mixture remains challenging due to their similar molecular sizes and boiling points, necessitating highly energy-intensive processes such as cryogenic distillation. This study introduces two ultramicroporous metal-organic frameworks (MOFs), NKMOF-17-Co and NKMOF-17-Cu, synthesized rapidly under ambient conditions as efficient materials for C₂H₆/C₂H₄ separation via physical adsorption. Gas adsorption experiments reveal that NKMOF-17-Co and -Cu exhibit a preference for adsorbing C₂H₆ over C₂H₄. Determined by these single crystal structures of loading gases into NKMOF-17-Co and -Cu, stronger hydrogen bonding and C-H···π interactions between C₂H₆ and MOFs were confirmed clearly. Verified by breakthrough tests of a C₂H₆ and C₂H₄ mixture for NKMOF-17-Co and -Cu, C₂H₄ was obtained in high purity (>99.96%). NKMOF-17-Co and -Cu were regenerated with low energy requirements and showed stable performance under repeated cycling tests. These findings suggest that NKMOF-17-Co and -Cu hold great promise for energy-efficient separation processes in the industrial separation of C₂H₆ and C₂H₄.