Reactivity of dibenzothiophene type molecules over Pd catalysts

The reactivity of dibenzothiophene (DBT) over Pd/γ-Al2O3 catalysts and the possible nature of the Pd active phase were analyzed. DBT conversion was studied as a function of the activating agent, the temperature, and in the presence of naphthalene (NP). Pd showed a high selectivity to the hydrogenation (HYD) route of DBT hydrodesulfurization (HDS). However, activation with H2S decreased HYD selectivity. A reaction mechanism for the DBT conversion over Pd catalysts via HYD was proposed based on the mechanism usually accepted for aromatics hydrogenation. This mechanism comprises the initial saturation of one of the aromatic rings of DBT and a consecutive roll-over of the molecule onto the Pd surface. NP was found to inhibit HYD. Finally, the catalytic performance of Pd in HDS was found to agree well with the characteristics of a Pd metallic active phase.

The reactivity of DBT type molecules over Pd under HDT conditions was analyzed. High selectivity to the HYD route was interpreted considering Pd interaction with aromatic rings. A mechanism for conversion via HYD comprising saturation of one of the aromatic rings of DBT and roll-over of the molecule onto Pd surface was proposed. Catalytic trends were found to agree well with the characteristics of a Pd metallic active phase.Figure optionsDownload as PowerPoint slide