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

• Published in: Separation and purification technology 2024-04, Vol.334, p.125972, Article 125972
• Main Authors: Li, Shi-Ming, Jiang, Hong-Chan, Ni, Qing-Ling, Gui, Liu-Cheng, Wang, Xiu-Jian
• Format: Article
• Language: English
• Subjects: Adsorption mechanism research; C2H6/C2H4 separation; Ethane-selective MOF; Metal-organic framework (MOF); Nonpolar cages
• ISSN: 1383-5866
• DOI: 10.1016/j.seppur.2023.125972

A new 3D MOF [Zn4O(tda)]·(Guest) (GNU-2) having advantageous adsorption sites and cavity pockets, which made it having a high adsorption capacity and selectivity for C2H6 and C2H4. [Display omitted] •A kind of novel MOF with high stability was designed and constructed based on hexacarboxylic acid ligand.•The elaborate pore size/confinement made the MOF has high adsorption capacities and strong affinities for C2H6/ C2H4.•The MOF represents high selectivities for C2H6/C2H4 mixtures.•One-step C2H4 purification from a highly complex two-component C2H6/ C2H4 mixture was realized using the MOF. 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.