Precise Pore Engineering of fcu-Type Y-MOFs for One-Step C2H4 Purification from Ternary C2H6/C2H4/C2H2 Mixtures

The purification of C2H4 from C2H6/C2H4/C2H2 mixtures is of great significance in the chemical industry for C2H4 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 C2H6, C2H4, and C2H2 by the MOFs. Importantly, clear relations between pore size/pore surface polarity and C-2 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 C2H6 and C2H2 over C2H4, with balanced C2H2/C2H4 and C2H6/C2H4 selectivities. This endows the compound with the capability of one-step purification of C2H4 from C2H6/C2H4/C2H2 ternary mixtures, which is validated by breakthrough measurements where high purity C2H4 (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.