IRMOF‐8: Theoretical evaluation of aluminum doping on hydrogen, methane, and hydrogen sulfide adsorption

The use of porous materials, aimed at increasing gas storage capacity at lower pressures, exploits physical adsorption and is an emerging strategy that is being widely investigated. In this scope, porous materials such as metal organic frameworks (MOFs) are a viable alternative, where structural modifications can enhance the properties of these materials and improve the degree of adsorption for a given gas. In this work, we evaluated the adsorption of methane, hydrogen, and hydrogen sulfide gases on pure isoreticular MOF (IRMOF)‐8 and aluminum‐doped IRMOF‐8 using density functional theory Perdew‐Burke‐Ernzerhof/DZVP and semiempirical AM1, PM3, PM6, PM6‐DH+, PM6‐DH2, PM6‐D3, and PM7 methods. Adsorption isotherms were calculated by means of Grand Canonical Monte Carlo simulations. It was found that doping did not provide a significant increase in the amount of adsorbed methane and hydrogen gases. Conversely, doping led to a considerable increase for hydrogen sulfide capture. Based on results obtained from theoretical calculations, it was demonstrated that the doping of the IRMOF‐8 aromatic rings promotes a slight increase in physical adsorption of hydrogen and methane gases when compared to pure IRMOF‐8, focusing on the use of this structure in gas storage. It has also been shown that the doped structure has promoted a considerable increase in the hydrogen sulfide side capture, and noncovalent interaction calculation indicates that the interaction has electrostatic character.