Taming structure and modulating carbon dioxide (CO2) adsorption isosteric heat of nickel-based metal organic framework (MOF-74(Ni)) for remarkable CO2 capture

Though the highest CO2 capture capacity belongs to liquid amine-solutions, solid matters capable of CO2 capture are also highly sought, providing that, they offer at least analogous CO2 adsorption capacity and CO2/N2 selectivity. Herein, a surprisingly high-performance Ni-based metal-organic framework for CO2 adsorption, namely MOF-74(Ni), was synthesized by a facile condensation reflux approach. It was found that the structure and CO2 adsorption isosteric heat of MOF-74(Ni) could tune upon varying the synthesis duration under various temperatures. The optimized MOF-74(Ni)-24-140 (synthesized at 140 °C for 24 h) displays outstanding CO2 adsorption capacity of 8.29/6.61 mmol/g at 273/298 K under normal pressure of 1.0 bar, several times higher than previously reported MOF-74-Ni (2.0/2.1 times), UTSA-16 (1.5/1.6 times), and DA-CMP-1 (3.6/4.9 times) under similar conditions. The excellent CO2 capture capacity is associated to the abundant adsorption sites (mainly arising from the cationic Ni2+ ions) and narrow micropore channels (mainly arising from the cage structure of Ni2+ ions coordinated with organic linkers). Offering a high CO2 selectivity (CO2/N2 = 49) and a well-tuned isosteric heat of CO2 adsorption (27-52 kJ/mol) besides its decent CO2 capture capacity, MOF-74(Ni) strongly stands out as an efficient and strong CO2 capturing material with industrial scale applicability.