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.