Flexible-robust interlayer space in a 2D metal–organic framework for light hydrocarbons separation

The separation of light hydrocarbons is industrially important and scientifically challenging due to their high similarity in physicochemical properties. Two-dimensional metal-organic frameworks (2D MOFs) assembled by weak supramolecular interactions are more likely to induce structural flexibility and exhibit guest-dependent gate-opening behavior than 3D MOFs, opening new horizons for LHs storage and separation. Here, a 2D MOF (Cu-APC, APC = 2-aminopyrimidine-5-carboxylic acid) with flexible-robust interlayer space was effectively used as an adsorbent to realize C2 and C3 hydrocarbons separation. Evidenced by gas adsorption isotherms and the ideal adsorbed solution theory (IAST) calculations, Cu-APC exhibits moderate C2H2/CO2 selectivity (2.87), high C2H6/C2H4 selectivity (2.27) and unique multistep adsorption behavior toward C3H4/C3H6 at ambient conditions. Moreover, theoretical calculations revealed that C-H···N, C=O···H-C, and C-H···π interactions are formed with C2H2, CO2, C2H4, and C2H6 in the suitable pockets within Cu-APC. The separation performances of Cu-APC for C2H2/CO2, C2H6/C2H4, and C3H4/C3H6 mixtures were also confirmed by column breakthrough experiments.