Solvent-Induced In(III)-MOFs with Controllable Interpenetration Degree Performing High-Efficiency Separation of...

Herein, three In(III)-based metal-organic frameworks (In-MOFs) with different degrees of interpenetration (DOI), namely In-MOF-1, In-MOF-2, and In-MOF-3, constructed by In³⁺ and Y-shaped ligands 4,4',4″-s-triazine-2,4,6-triyltribenzoate (H₃TATB), are successfully synthesized through the ionothermal/solvothermal method. Subsequently, three novel In-MOFs, including noninterpenetration polycatenation, 2-fold interpenetrated, and 4-fold interpenetrated structure, are employed as the platform for systematically investigating the separation efficiency of CO₂/N₂, CO₂/CH₄, and CO₂/CH₄/N₂ mixture gas system. Among them, In-MOF-2 shows the highest CO₂ uptake capacities at 298 K and simultaneously possesses the low adsorption enthalpy of CO₂ (26.4 kJ/mol at low coverage), a feature desirable for low-energy-cost adsorbent regeneration. The CO₂/N₂ (v: v = 15/85) selectivity of In-MOF-2 reaches 37.6 (at 298 K and 1 bar), also revealing outstanding selective separation ability from flue gases and purifying natural gas, affording a unique robust separation material as it has moderate DOI and pore size. In-MOF-2 shows exceptional stability and feasibility to achieve reproducibility. Aperture adjustment makes In-MOF-2 a versatile platform for selectively capturing CO₂ from flue gases or purifying natural gas.