Multiscale Theoretical Study of Sulfur Dioxide (SO(2)) Adsorption in Metal–Organic Frameworks

In the present work, we used DFT in order to study the interaction of SO(2) with 41 strategically functionalized benzenes that can be incorporated in MOF linkers. The interaction energy of phenyl phosphonic acid (–PO(3)H(2)) with SO(2) was determined to be the strongest (−10.1 kcal/mol), which is about 2.5 times greater than the binding energy with unfunctionalized benzene (−4.1 kcal/mol). To better understand the nature of SO(2) interactions with functionalized benzenes, electron redistribution density maps of the relevant complexes with SO(2) were created. In addition, three of the top performing functional groups were selected (–PO(3)H(2), –CNH(2)NOH, –OSO(3)H) to modify the IRMOF-8 organic linker and calculate its SO(2) adsorption capacity with Grand Canonical Monte Carlo (GCMC) simulations. Our results showed a great increase in the absolute volumetric uptake at low pressures, indicating that the suggested functionalization technique can be used to enhance the SO(2) uptake capability not only in MOFs but in a variety of porous materials.