A quad-core Zn (II) cluster-based microporous metal-organic framework with nonpolar cages for efficient removal of ethane from ethane/ethylene mixtures

Abstract

Ethane (C2H6) and ethylene (C2H4) have similar physical and chemical properties, which are critical and difficult for the separation of C2H6/C2H4 mixtures in the petrochemical process. Traditional C2H4-selective adsorbents can separate the C2H6/C2H4 mixtures, but need further desorption treatment to obtain pure C2H4 production. On the contrary, high-pure C2H4 can be prepared in one step by C2H6-selective porous material. Herein, we present a caged metal-organic framework (GNU-2) based on Zn (II) clusters, which has advantageous adsorption sites and cavity pockets for the reverse capture of C2H6 from C2H6/C2H4 mixtures. At 298 K and 1 bar, high C2H6 uptake (5.10 mmol g−1) and C2H6/C2H4 selectivity (1.849) were attained based on the activated GNU-2 (GNU-2a), exceeding a number of top C2H6-selective adsorbents. Grand canonical Monte Carlo (GCMC) simulations exhibit that the appropriate chemical environment of nonpolar cage in GNU-2a allows it to continuously maintain closer van der Waals contacts between C2H6 molecule, saturated Zn cluster and nonpolar pore surface through multiple CH···O hydrogen interactions and CH···π hydrogen interactions. Moreover, dynamic breakthrough studies also show that GNU-2a displays the actual separation performances of C2H6.