Combination of Low-Polar and Polar Binding Sites in Aliphatic MOFs for the Efficient C 2 H 6 /C 2 H 4 Separation.

The selective capture of CH from CH/CH mixtures is of critical importance to realize the efficient one-step purification of CH but remains challenging due to their similar properties and smaller quadrupole moment of CH that usually result in CH-preferring adsorption. Herein, we reported two isostructural pillared-layer metal-organic frameworks, ZUL-C3 and ZUL-C4, which were constructed by mixed polycycloalkane-type ligands. Their low-polar pore environment along with more accessible low-polar C-H binding sites on the pore surface are conducive to generate more van der Waals interactions with CH while the carboxylic groups distributed at four corners of pores form stronger and more dipolar interactions with CH, cooperatively resulting in a good CH/CH uptake ratio of 1.50 for ZUL-C3 and 1.72 for ZUL-C4 in static adsorption experiments and a high CH (>99.99% purity) productivity of 10.1 L/kg for ZUL-C3 and 14.6 L/kg for ZUL-C4 from an equimolar CH/CH mixture in breakthrough experiments.