Molecular simulation on hydrodesulfurization of thiophenic compounds over MoS2 using ZINDO

In order to develop a fundamental understanding of the HDS mechanism of thiophenic compounds over molybdenum disulfide (MoS₂), a molecular simulation of the hydrodesulfurization (HDS) of thiophenic compounds over MoS₂ has been performed using Zerner's Intermediate Neglect of Differential Overlap (ZINDO) program. On the basis of the calculated edge structure, stoichiometry of MoS₂, shape of the crystal, and the size corresponding to real MoS₂ particles, a single-slab cluster, Mo₂₇S₅₄, has been proposed for modeling the highly dispersed MoS₂. The proposed cluster is a regular hexagon with (010) and (300) edge planes only. According to the calculated electronic properties of the surface, the coordinately unsaturated Mo_IV in the (300) plane is expected to be the active site for hydrogenation of thiophenic and aromatic compounds. The most stable adsorption configuration of thiophene on the Mo_IV is a flat adsorption configuration via the η⁵-bound coordination, whereas the most stable adsorption configuration of tetrahydrothiophene (THT) on the Mo_IV is a tilted adsorption configuration via the S-bound coordination. HDS mechanism of thiophene through the hydrogenation pathway over the (300) plane of MoS₂ is discussed according to quantum chemical insights in combination with experimental results from the literature.