Adsorption of hydrogen sulfide as initial step of H2S removal: A DFT study on metal exchanged ZSM-12 clusters

•H2S was theoretically adsorbed on (Fe, Co, Ni, Cu and Zn)–ZSM-12 zeolite clusters.•Cu–ZSM-12 has the lowest chemical potential with minimum adsorption energy.•Cu–ZSM-12 is softer than other clusters because of its lower chemical hardness.•Cu–ZSM-12 is a promising candidate for removal of hydrogen sulfide.

The molecular adsorption of hydrogen sulfide has been theoretically studied via DFT on additional framework with cations of metals (Fe, Co, Ni, Cu and Zn) in 14T-channel ZSM-12 zeolite cluster model. The method employed in this study is B3LYP functional with LanL2DZ and 6–31 G(d,p) basis sets. Cu–ZSM-12 cluster has the lowest chemical potential with minimum adsorption energy value with negative ΔG, highest electronegativity and lowest energy gap between HOMO and LUMO with respect to other clusters. It is softer than other clusters because of its lower chemical hardness value. Accordingly, based on these data it can be mentioned that Cu–ZSM-12 is a promising candidate catalyst as for removal of hydrogen sulfide via activation of S–H bond than other metal ZSM-12 zeolites.