Hydrodesulfurization of methanethiol over Co-promoted MoS₂ model catalysts

The process of hydrodesulfurization is one of the most important heterogeneous catalytic reactions in industry as it helps with reducing global SO_x emissions by selectively removing the sulfur contaminants from commercial fuel. In this work, we successfully combine high-pressure scanning tunneling microscopy and reaction modeling using density functional theory to observe the hydrodesulfurization of methanethiol (CH₃SH) on the Co-substituted S edges of a Co-promoted MoS₂ model catalyst in situ at near-industrial conditions and investigate the plausible reaction pathways. The active sites on the Co-substituted S edges show a time-varying atomic structure influenced by the hydrodesulfurization reaction rate. The involvement of the edge Co site allows for the C-S bond scission to occur at appreciable rates, and is the critical step in the hydrodesulfurization of CH₃SH. The atomic structures of the S-edge active sites from our reaction models match excellently with those observed in situ in the experiments.