Ultramicroporous Metal-Organic Framework with Inert Pore Surfaces for Inversed Separation of Ethylene from C 2 Hydrocarbons Mixtures.

The achievement of direct C 2 H 4 separation from C 2 hydrocarbons is very challenging in the petrochemical industry due to their similar molecular sizes, boiling points, and physicochemical properties. In this work, a nonpolar/inert ultramicroporous metal-organic framework (MOF), [Co 3 (μ 3 -OH)(tipa)(bpy) 1.5 ]·3DMF·6H 2 O ( 1 ), with stand-alone one-dimensional square tubular channels was successfully constructed, its pore enriched with plenty of aromatic rings causing nonpolar/inert pore surfaces. The MOF shows preferential adsorption of C 2 H 6 compared to C 2 H 4 and C 2 H 2 in the low-pressure region, which is further verified by adsorption heats and selectivities. The C 2 H 4 separation potential in one step for binary C 2 H 6 /C 2 H 4 (50/50 and 10/90) and ternary C 2 H 4 /C 2 H 6 /C 2 H 2 (89/10/1) is also examined by transient breakthrough simulations. Moreover, grand canonical Monte Carlo simulations demonstrate that the unique reversed adsorption mechanism is due to the shortest and most number of C-H···π interactions between C 2 H 6 and the framework.