Pore Space Partitioning MIL-88(Co): Developing Robust Adsorbents for CO/CH Separation Featured with High CO Adsorption and Rapid Desorption.

Metal-organic frameworks (MOFs) have attracted significant attention as sorbents for gas separation and purification. Ideally, an industrially potential adsorbent should combine exceptional gas uptake, excellent stability, and a lower regeneration energy; however, it remains a great challenge. Here, by utilizing the pore space partition (PSP) strategy, we develop three isostructural MOF materials (, , and ) based on pristine MIL-88(Co). The three pore-space-partitioned crystalline microporous MOFs have triangular bipyramid cages and segmented one-dimensional channels, and among them, exhibits the highest CO uptake capacity (4.35 mmol g) and good CO/N (29.7) and CO/CH (6.2) selectivity. The selectivity-capacity synergy endows it with excellent CO/N and CO/CH separation performance. Moreover, can complete desorption within 10 min. The satisfactory CO adsorption ability can be attributed to both microporous aperture arising from PSP and modification of the pore surface by the polar hydroxy group, which enhances the interaction between and CO molecules significantly. The exceptional regeneration property may be due to its lower CO isosteric heat of adsorption (23.6 kJ/mol). The developed pore-space-partitioned MIL-88(Co) material may have potential application to flue gas and natural gas purification.