Molecular simulation on hydrodesulfurization of thiophenic compounds over MoS 2 using ZINDO

Abstract

In order to develop a fundamental understanding of the HDS mechanism of thiophenic compounds over molybdenum disulfide (MoS 2), a molecular simulation of the hydrodesulfurization (HDS) of thiophenic compounds over MoS 2 has been performed using Zerner's Intermediate Neglect of Differential Overlap (ZINDO) program. On the basis of the calculated edge structure, stoichiometry of MoS 2, shape of the crystal, and the size corresponding to real MoS 2 particles, a single-slab cluster, Mo 27S 54, has been proposed for modeling the highly dispersed MoS 2. The proposed cluster is a regular hexagon with (1̄010) and (303̄0) edge planes only. According to the calculated electronic properties of the surface, the coordinately unsaturated Mo IV in the (303̄0) 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 η 5-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 (303̄0) plane of MoS 2 is discussed according to quantum chemical insights in combination with experimental results from the literature.