Are metal dopant and ligands efficient to optimize the adsorption rate of CH4, H2 and H2S on IRMOFs? Insights from factorial design

Adsorption-based gas storage can be more efficient when porous structures such as MOFs are used as adsorbent material, while structural modifications of these materials can further maximize the application. It is known that MOF organic ligands are generally deficient adsorption sites. Thus, improvements in these ligands can increase the adsorption rate. In this work, modifications were made to the organic ligands of IRMOF-1 and IRMOF-6, generating new structures following a full factorial design 23. These modifications consist in decorating the aromatic ring with Al and substituting ligand hydrogen atoms bonded to the ring by donor and acceptor groups. As a result, the factorial design provided effects with 95% of confidence for the adsorption of CH4, H-2, and H2S gases. It was found that the inclusion of electron donor groups promotes increment in the CH4 and H-2 adsorption. The H2S molecules preferentially interact with electron acceptor groups, and the inclusion of Al atom increased the adsorption significantly, where these interactions have an electrostatic character.