Mechanism of thiophene hydrodesulfurization on clean/sulfided β-Mo2C(0 0 1) based on density functional theory—cis- and trans-2-Butene formation at the initial stage Original Research Article

The mechanism of thiophene hydrodesulfurization (HDS) on clean/sulfided β-Mo2C(0 0 1) slabs was studied based on density functional theory (DFT) calculations with different thiophene configurations. Self-consistent, gradient-corrected, periodic DFT calculations were performed. The η5-configuration of thiophene on the Mo atom of Mo carbide preferred the η1-configuration of the adsorption of the thiophene sulfur atom and induced the subsequent scission of the C–S bonds. The addition of hydrogen atoms to the adsorbed C4 species led to the formation of trans-2-butene and S–Mo bonding on the clean β-Mo2C(0 0 1) slab, while cis-2-butene was formed as a result of hydrogen addition on the sulfided β-Mo2C(0 0 1) slab. The difference between the formation of trans-2-butene for the β-Mo2C(0 0 1) slab and cis-2-butene for the sulfided β-Mo2C(0 0 1) was discussed.