Adsorption of H 2 S and SO 2 in IRMOF-1: a computational study using DFT and GCMC simulations

H $_2^{}$ S and SO $_2^{}$ are harmful gases found in nature and from industrial production. This study investigated their adsorption within IRMOF-1 cavities by means of periodic density functional theory. QTAIM-based IGMH isosurface and adsorption energy analyses provided insight into the SO $_2^{}$ $_{}^{...}$ H $_2^{}$ S interactions, where SO $_2^{}$ is directed to the inorganic moiety. The mixed gases show significant interactions between SO $_2^{}$ and H $_2^{}$ S. Regardless of the density functional approximation chosen, SO $_2^{}$ exhibited a stronger adsorption preference over H $_2^{}$ S. B3LYP BSSE and dispersion-corrected interaction energies were consistently stronger than HSE06, whereas the B3LYP band gap presents larger values than HSE06. Grand Canonical Monte Carlo (GCMC) simulations further confirmed that SO $_2^{}$ preferentially occupies the IRMOF-1 pores, with higher pressures enhancing adsorption.

Periodic optimizations were performed using the density functional approximations (DFAs) with B3LYP and HSE06 hybrid functionals, incorporating D3 dispersion and BSSE counterpoise corrections. Two basis sets were employed to analyze the B3LYP and HSE06 electronic and adsorption results: the pob-TZVP basis set and the modified m-6-311G(d) basis set. GCMC simulations were conducted to evaluate adsorption isotherms, while QTAIM and IGMH were used to account for the interaction behavior.