Precise Pore Engineering of fcu-Type Y-MOFs for One-Step C₂ H₄ Purification from Ternary C₂ H₆ /C₂ H₄ /C₂ H₂ Mixtures

The purification of C₂ H₄ from C₂ H₆ /C₂ H₄ /C₂ H₂ mixtures is of great significance in the chemical industry for C₂ H₄ production but remains a daunting task. Guided by powerful reticular chemistry principles, herein a systematic study is carried out to engineer pore dimensions and pore functionality of fcu-type Y-based metal-organic frameworks (Y-MOFs) through the construction of a series of eight new structures using linear dicarboxylate linkers with different length and functional groups. This study illustrates how delicate changes in pore size and pore surface chemistry can effectively influence the adsorption preference of C₂ H₆ , C₂ H₄ , and C₂ H₂ by the MOFs. Importantly, clear relations between pore size/pore surface polarity and C₂ adsorption selectivities of this series of MOFs are established. In particular, HIAM-326 built on a linker decorated with trifluoromethoxy group shows notably preferential adsorption of C₂ H₆ and C₂ H₂ over C₂ H₄ , with balanced C₂ H₂ /C₂ H₄ and C₂ H₆ /C₂ H₄ selectivities. This endows the compound with the capability of one-step purification of C₂ H₄ from C₂ H₆ /C₂ H₄ /C₂ H₂ ternary mixtures, which is validated by breakthrough measurements where high purity C₂ H₄ (99.9%+) can be obtained directly from the separation column. Its adsorption thermodynamics and underlying selective adsorption mechanisms are further revealed by ab initio calculations.