A 3D Microporous MOF with mab Topology for Selective CO 2 Adsorption and Separation

Abstract A three dimensional MOF, {[Zn(OBA)(L) 0.5 ].DMA} n ( IITKGP‐7 , IITKGP stands for Indian Institute of Technology Kharagpur), has been synthesized by the combination of a V‐shaped organic acid linker (H 2 OBA=4, 4′‐oxybisbenzoic acid) with flexible N,N‐donor spacer ( L =2,5‐bis(3‐pyridyl)‐3,4 – diaza‐2,4‐hexadiene), forming a network with mab topology (DMA=N, N‐dimethylacetamide). This MOF is characterized by Fourier‐transform infrared spectroscopy (FTIR), elemental analysis (EA), powder X‐ray diffraction (PXRD), thermo gravimetric analysis (TGA) and single crystal X‐ray diffraction. The framework exhibits rhombus‐shaped channels of approximate size of 5.3 Å x 6.4 Å along crystallographic b axis with a potential solvent accessible volume of 31.8%. Gas sorption measurements of the evacuated framework shows preferential uptake of CO 2 at 273 and 295 K under 1 bar over N 2 and CH 4 . Calculations based on ideal adsorbed solution theory (IAST) show that the selectivity values of CO 2 /N 2 (15:85) are 57 at 273 K and 121.4 at 295 K, whereas CO 2 /CH 4 (50:50) selectivity values are 8.4 at 273 K and 8.8 at 295 K under 1 bar. The high CO 2 separation selectivity over N 2 and CH 4 makes this MOF a potential candidate for CO 2 separation from flue gas mixture and landfill gas mixture.