Hierarchically Porous Mg-MOF-74/Sodium Alginate Composite Aerogel for CO2 Capture.

One of the most promising methods for capturing carbon dioxide (CO₂) is solid physical adsorption, which is an efficient and simple technique. The key to effective CO₂ capture is the development of high-performance solid adsorbents with excellent CO₂ adsorption capacity, CO₂/N₂ selectivity, and rapid adsorption/desorption kinetics. In this paper, a Mg-MOF-74/sodium alginate composite aerogel was prepared by loading Mg-MOF-74 on sodium alginate sheets followed by directional freeze-drying. The composite aerogel exhibited a hierarchical porous structure, in which sodium alginate provided an open mesoporous/macroporous structure that promoted diffusion and contact with the active center of CO₂. The Mg-MOF-74 micropores/mesopores promoted the strong interaction between CO₂ and the adsorbent in the micropore and rapid mass transfer of CO₂ to the adsorbent through the mesopores. The experimental data showed that MSA-6 achieved CO₂ adsorption of 2.461 mmol·g^–1 at 298 K. Furthermore, the CO₂/N₂ adsorption selectivity of MSA-6 reached 35.108, indicating its strong CO₂ selective adsorption potential. [ABSTRACT FROM AUTHOR]