Abstract
In order to investigate the formation mechanism of hydrogen sulfide corrosion products in petroleum and petrochemical facilities, the interaction mechanism between iron oxides and H(2)S was studied by density functional theory (DFT). First, the adsorption of H(2)S on Fe(2)O(3) clusters and Fe(3)O(4) clusters was studied. The results indicated that H(2)S was more inclined to adsorb on the Fe site. After adsorption, the S-H bond changed from 1.356 to 1.360 Å in the gas phase, which was the main reason for the decomposition of H(2)S. On this basis, the reaction paths of Fe(2)O(3) clusters and Fe(3)O(4) clusters with H(2)S and the rate-determining steps of different reaction paths were calculated. The thermodynamic parameters and kinetic parameters of the rate-determining step of each path are analyzed. The results indicated that reaction path 1 of H(2)S and Fe(2)O(3) clusters is the best reaction channel. The reaction will gradually form products such as S, H(2)O, and Fe(2)S(2), which can release a total of 622.23 kJ/mol heat. The reaction path 2 of H(2)S and Fe(3)O(4) clusters is the best reaction channel. The reaction will gradually form products such as S, H(2)O, and Fe(3)S(2), which can release a total of 260.40 kJ/mol heat. Finally, the reaction paths of Fe(2)S(2), Fe(3)S(2), and S(2) were further calculated, and it was observed that the products formed by hydrogen sulfide corrosion were easy to react with S(2) to form sulfur-iron compounds with different iron-sulfur ratios. This is consistent with the corrosion products including FeS, FeS(2), and Fe(3)S(4) observed in the experiment. It lays a theoretical foundation for the subsequent study of the effect of associated elemental sulfur on the spontaneous combustion of sulfur-iron compounds.