Adsorption of Dibenzothiophene Derivatives over a MoS2 NanoclusterA Density Functional Theory Study of Structure−Reactivity Relations

Abstract

Various adsorption configurations of dibenzothiophene, a series of one and two methyl-substituted dibenzothiophenes and their hydrogenated derivatives on a MoS2 nanocluster, were studied using self-consistent density functional theory with generalized-gradient approximation. The objective was to explore the relationship between the structure and catalytic hydrodesulfurization reactivity of these sulfur molecules. The calculated adsorption energies indicated that flat adsorption was more energetically favorable over perpendicular adsorption, due to the interactions of the sulfur atom, the thiophene, and aromatic rings of the sulfur molecule with the molybdenum atoms on the catalyst surface. The adsorption energy in the flat adsorption mode decreased when the aromatic ring was saturated, while the adsorption energy in the perpendicular mode increased with progressive saturation of the dibenzothiophenes. In the flat adsorption mode, dibenzothiophene, 4-methyldibenzothiophene, 2,8-, 3,7-, and 4,6-dimethyldibe...