Enhancing CO2 solubility for efficient carbon capture via self-assembly deep eutectic solvents on MOF-808

The capture of CO 2 from flue gas has emerged as the most effective technology for carbon reduction. The relatively low partial pressure of CO 2 in flue gas necessitates the development of CO 2 -selective adsorbents, which provide a direct pathway to obtaining pure CO 2 in one-step, thereby reducing energy consumption. Herein, an amino-rich deep eutectic solution (DES) is dispersed on the surface of formate ligand-removed MOF-808 using a self-assembly approach for post-combustion carbon capture. The high solubility of DES towards CO 2 enables the composite to effectively capture CO 2 , with MOF-808 serving as a porous gas storage tank. Material characterization confirms the loading of DES on the surface of MOF support while retaining its microporous structure. Owing to their unique CO 2 solution-diffusion mechanism, DES-modified adsorbents exhibit promising performance on CO 2 capacity, kinetics, CO 2 /N 2 selectivity, and isosteric heat. The optimized sample DES-2@MOF-808-FR demonstrates a notable CO 2 adsorption capacity of 4.16 mmol/g at 298 K and 1 bar. When tested with simulated flue gas (15 vol% CO 2 ), it maintains a working capacity of 2.86 mmol/g and a CO 2 /N 2 selectivity of 1184, surpassing most of existed materials. DES-2@MOF-808-FR can also retain its capacities after 10 adsorption/desorption cycles in simulated flue gas. This solution-based modification approach circumvents the challenges associated with precise structural control of the adsorbent, thereby facilitating potential industrial applications.