Kinetics of dibenzothiophene hydrodesulfurization over MoS2 supported catalysts: modelization of the H2S partial pressure effect

The influence of H₂S partial pressure over the catalytic activity of MoS₂, supported on three different oxides: Al₂O₃, TiO₂ and ZrO₂, was studied in the hydrodesulfurization of dibenzothiophene (DBT). A complex inhibiting effect is observed and two orders of reaction relative to H₂S were determined: −1/2 and 0, as a function of H₂S partial pressure. The experimental results are in good agreement with the kinetic models whereby the DBT transformation takes place through a dihydrogenated intermediate (DH-DBT). The associated mechanism considers that the heterolytic dissociative adsorption of H₂ and H₂S occurs over an unsaturated Mo ion and over a stable sulfur ion.