Adsorption mechanism of H2S and CH3SH on Fe(110) surface: A density functional theory study

Abstract

Based on the first-principles method of density functional theory (DFT), the adsorption properties, bond strength and electronic structure of two sulfur-containing compounds (H 2 S and CH 3 SH) in oil and natural gas were analyzed by means of adsorption energy, partial density of states (PDOS) and charge difference density. The adsorption energy of H 2 S and CH 3 SH molecules on the LB site of Fe (110) surface is the lowest. Their adsorption energies are −2.88 eV and −3.13 eV, respectively. When the H 2 S symmetry axis is perpendicular to the surface, the S–H bond is easy to break. The generated S atom is firmly adsorbed on the hollow site. The results of partial density of states show that the hybrid conjugation peaks of the three adsorbed species appear on the substrate surface, and new bonds are formed between the surface molecules and the iron substrate. The charge around the three adsorbates is redistributed, and the order of interaction size between these molecules and the Fe (110) surface is S > CH 3 SH > H 2 S. This also shows that in oil and gas, H 2 S, CH 3 SH and S atoms generated after dissociation are very easy to adsorb on the surface of iron pipes, which directly affects the accuracy of the determination of sulfide gas in oil and natural gas. • The adsorption of H 2 S and CH 3 SH on four highly symmetric sites of Fe (110) surface is calculated. • The adsorption configurations of hydrogen sulfide and methyl mercaptan on Fe (110) surface were constructed. • The adsorption structure, adsorption energy, bonding and the change of electronic structure were discussed in detail. • The H 2 S molecules adsorbed horizontally are easy to dissociate.