A molecular study of CO2 adsorption performance of functionalized Mg-MOF-74 at different water vapor concentrations and pressures

This study numerically evaluates the CO2 adsorption capability of functionalized Mg-MOF-74 at different water vapor concentrations and pressures. The-O-Li- and -NO2 display the most advantageous adsorption locations for CO2 and enhance the adsorption energy for H2O within the secondary building unit region. The enhancement of CO2 adsorption at 1 bar is achieved through the incorporation of Li-O and -NO2, whereas introducing -CH3 improves the selectivity of Mg-MOF-74 towards CO2/H2O. The absorption of CO2 at 10 bar is influenced by the available void space within the pores and altering the functional groups leads to a reduced porosity, thereby hindering the CO2 adsorption. However, -CH3 can effectively improve the CO2/H2O selectivity. The increased CO2 adsorption sites by the functionalization is more advantageous for enhancing CO2 adsorption capacity in gas/vapor mixtures at low pressures. Furthermore, enhancing absorbent hydrophobicity results in an enhanced selectivity for CO2/H2O, thereby facilitating CO2 adsorption at elevated pressures.