New insights of the interaction of H2S with mackinawite FeS in a wet environment: An ab initio molecular dynamics study

Abstract

Mackinawite FeS is the most common corrosion product in the early stage of steel in H2S environment and also has an effective catalysis for hydrodesulfurization, hydrogen release reactions and heavy metal ion removal since its high specific surface area and reactive surface like other van der Waals materials. In this paper, ab initio molecular dynamics (AIMD) is used to study the interactions between small molecules (H2S, H2O and H) and FeS at 300 K. The calculation results show that the primary dissociation of H2S only occurs on the FeS(111) surface and H2S is chemically adsorbed on the (011) and (100) surfaces but physically adsorbed on the (001) surface. It will dissociate and generate H atoms when different amounts H2S or H2O molecules appear in the interlayer of FeS, in which H2S is more prone to dissociation. The dissociated H atoms will be “captured” by Fe/S atoms in mackinawite FeS, leading to the shrink of layer. Moreover, H atoms could combine into H2, which suggests that layered FeS has great potential for hydrogen generation. The diffusion coefficient of H atoms in mackinawite FeS layer is estimated about 1.67 × 10−8 m2/s. These findings have significant meaning for application of mackinawite FeS in corrosion science, hydrogen generation, hydrogen storage and other fields.