A robust perylene diimide-based zirconium metal–organic framework for preferential adsorption of ethane over ethylene

Adsorptive separation of ethane (C2H6)/ ethylene (C2H4) mixtures based on C2H6-selective adsorbents through one-step separation unit has attracted great attention in view of its enormous potential to reduce energy consumption in the petrochemical industry. To achieve this, it is highly demanded to develop C2H6-selective adsorbents. However, it is challenging to construct C2H6-selective adsorbents due to the difficulty in building suitable interaction between C2H6 molecules and adsorption active sites. Here, we constructed a robust perylene diimide-based zirconium metal-organic framework (MOF, denoted as Zr-Me-PDI) of superior stability under aqueous solution of different pH values (1.0 ∼10.0), for effectively separation of C2H6 from C2H4. Zr-Me-PDI displayed C2H6-selective adsorption behavior at both 298 and 273 K. High C2H6 adsorption capacity 3.9 mmol·g-1 and C2H6/C2H4 selectivity (1.5) was achieved for Zr-Me-PDI at 1 bar and 298 K, comparable to most of the high-performance C2H6-selective MOFs. Calculation results of Grand Canonical Monte Carlo (GCMC) simulation show that the interpenetrated structure of Zr-Me-PDI exhibit multiple C-H···Cl and C-H···O interactions with C2H6 and preferentially binds to C2H6 over C2H4. Therefore, the results demonstrated in this project may provide valuable guidance for the design and synthesis of C2H6-selective adsorbents.