One ethane-selective metal–organic framework with customized pore size and specific binding sites for efficient purification of ethylene

Abstract

Removing small amount of ethane (C2H6) from ethylene (C2H4) to obtain high-purity C2H4 is of great significance in the industries. However, the construction of C2H6-selective metal–organic frameworks (MOFs) remains challenging, mainly because that C2H4 has smaller kinetic diameter and larger quadrupole moment. Herein, an ultra-microporous MOF (PCP-bdc) with customized pore size and specific binding sites is reported to efficiently purify C2H4 from C2H6/C2H4 mixture. The channel size of PCP-bdc is comparable to the size of C2H6 molecule, which can provide more accessible channel surfaces for C2H6. The channel surface of PCP-bdc is rich of low-polar aromatic groups and the uncoordinated O atoms can interact with C2H6 molecules strongly. Thus, PCP-bdc exhibits a remarkable C2H6/C2H4 (50/50) selectivity (2.82) and C2H6 uptake (53.8 cm3 g−1) at 298 K and 1 bar, which outperform those of many C2H6-selective adsorbents. Density functional theory calculations further reveal the formation of multiple synergies between this MOF and C2H6 enables the efficient separation for C2H6/C2H4 mixture. Breakthrough experiments demonstrate that PCP-bdc can purify C2H4 from C2H6/C2H4 mixture through one-step operation. These results indicate PCP-bdc is a promising adsorbent for C2H6/C2H4 separation.