Adsorption, aggregation and diffusion of S8 molecules on calcite surface

Sulfur deposition is a big challenge in high-sulfur natural gas development. It is assumed in current deposition models that particles are formed by released sulfur molecules in the gas phase, before their deposition on the surface. The surface attraction to the sulfur molecules is ignored. The adsorption, aggregation and diffusion of elemental sulfur (S8) on the calcite surface are studied by density functional theory calculations and molecular dynamics simulations. Our calculations reveal that the S8-surface interaction is stronger than that between S8 molecules, indicating the important role of surface attraction in sulfur deposition. Cooperative effect is revealed in the aggregation of S8 molecules, which is attributed to the charge transfer between adsorbed molecules and the surface. Our findings suggest the necessity of including the surface attraction in the sulfur deposition models.