A density functional theory study of the hydrodesulfurization reaction of dibenzothiophene to biphenyl on a single-layer NiMoS cluster

The hydrodesulfurization of dibenzothiophene on a NiMoS cluster consisting of 1 Ni and 18 Mo atoms was investigated by means of density functional theory. The calculations focus on the direct desulfurization pathway where dibenzothiophene reacts with H2 to biphenyl and H2S. Critical steps with high activation energies are breaking of the two C–S bonds of the DBT molecule (ca. 32 kcal/mol), the activation of H2 by heterolytic dissociation and the removal of the formed biphenyl molecule from the catalyst surface (17 kcal/mol, respectively). All other reaction steps have activation energies of ≤10 kcal/mol.