A density functional theory study on the interaction mechanism between H2S and the α-Fe2O3(0001) surface

The interaction mechanism of H2S and the α-Fe2O3(0001) surface during the desulfurization has been investigated by the density functional theory (DFT) method within a periodic slab model. Adsorptions of H2S, SH, S and H on the α-Fe2O3(0001) surface have been initially examined. Our results show that H2S, SH and atomic S favorably adsorb on the top of Fe site, and atomic H lies on the top of O site. Potential energy profiles have been constructed for the interactions of H2S with the α-Fe2O3(0001) surface along with two channels producing H2 and H2O. The calculations show that H2S firstly adsorbs on the α-Fe2O3(0001) surface in molecular mode, followed by two dehydrogenation processes and forming surface sulfur species. Further, the processes of H-migration lead to the formation of H2 or H2O. Molecular-level calculations demonstrate that the pathways of H2-forming and H2O-forming are competitive kinetically. Two roles of the α-Fe2O3 during the interactions between H2S and the α-Fe2O3(0001) surface have also been discussed.