Novel activated carbon modified magnesium-MOF-74 composites with enhanced CO2 adsorption separation efficiency

Metal-organic frameworks (MOFs) are interesting materials for carbon dioxide (CO2) adsorption. Herein, novel nanocomposite materials comprising activated carbon (AC) and Magnesium-MOF-74 were synthesized by impregnating different loading ratios of activated carbon into synthesized Magnesium-MOF-74 to yield Magnesium-MOF-74@AC-X (where X represents the Magnesium/AC ratio set to 1:2, 1:1, and 2:1). Compared to Magnesium-MOF-74 alone, Magnesium-MOF-74@AC-X exhibited higher specific surface area, superior thermal stability, elevated CO2 adsorption capacity, and better adsorption selectivity. At 273 K, the adsorption of CO2 by Magnesium-MOF-74@AC sample containing Magnesium to AC ratio of 1:2 reached 40.31 cm3/g, while that of pristine Magnesium-MOF-74 was only 21.01 cm3/g. At 298 K, the adsorption capacity reached 29.45 cm3/g, while that of pristine Magnesium-MOF-74 was 1.91-fold lower. The linear fitting of the adsorption isotherms of composite in the Henry adsorption region using Henry's law yielded a CO2/N2 selectivity adsorption capacity of 32.19, a value 4.55-fold higher than pristine Magnesium-MOF-74.