Sieving Effect for the Separation of C2H2/C2H4 in an Ultrastable Ultramicroporous Zinc-Organic Framework

The separation of C2H2 from C2H4 is one of the most challenging tasks due to the similarity of their physical properties. In addition, green synthetic protocol and adsorbent's stability are also the major concerns during the separation. Herein, under hydrothermal green synthesis conditions, an ultrastable ultramicroporous Zn-MOF was designed and synthesized with a high yield. The pore diameter of the Zn-MOF is 3.6 angstrom, which lies in between the diameters of C2H2 (3.3 angstrom) and C2H4 (4.2 angstrom) molecules, leading to an efficient separation of the C2H2/C2H4 mixtures by the sieving effect. The practical separation performance of C2H2/C2H4 was confirmed by the dynamic breakthrough experiments. Moreover, the high stability enables the adsorption capacity of the Zn-MOF to C2H2, which can be maintained under a wide range of pH (1-13). Molecular simulations were also performed to identify the different C2H2- and C2H4-binding sites in Zn-MOF.