Transition states energies for catalytic hydrodesulfurization reaction in Co9S8/MoS2 theoretical interface using computer-assisted simulations

Transition state computational studies of the sulfur removal from dibenzothiophene (DBT) molecule have herein been performed considering the Co9S8/MoS2 interface existing on unsupported Co/MoS2 catalysts. The linear synchronous transit (LST) and quadratic synchronous transit (QST) methods integrated in a density functional theory (DFT) program such as Dmol(3) were used for the calculations of energy barriers of the transition states. Three different configurations present on the Co9S8/MoS2 interface have been envisaged as possible catalytic sites: sulfur-sulfur (S,S) sites, and molybdenum-sulfur (Mo,S) and molybdenum-molybdenum (Mo, Mo) edge sites. This study revealed that the (Mo, Mo) edge site is the most catalytically active site for the hydrodesulfurization (HDS) reaction followed by the (Mo, S) edge site while the (S, S) site shows almost inertness for the HDS reaction. This information allows us to propose clues to design new catalysts based on bulk Co9S8/MoS2 phases with higher efficiency by increasing the proportion of (Mo, Mo) edge sites. (C) 2016 Elsevier B.V. All rights reserved.