Abstract: Two ex situ presulfided MoNiP/γ-Al2O3 catalysts have been prepared, and their hydrodesulfurization performance has been evaluated using dibenzothiophene as the model compound. A conventional in situ presulfided MoNiP/γ-Al2O3 catalyst was selected as the competitor. The differences in the hydrogenation active phases of the two types of presulfided catalysts have been studied by X-ray diffraction (XRD), high-resolution transmission electron icroscopy (HRTEM), and X-ray photoelectron spectroscopy (XPS). The ex situ presulfided catalysts had a similar sulfur removal rate (99%) to the in situ presulfided one, but showed a lower hydrogenation activity. Morphology studies using XRD and HRTEM showed that the ex situ presulfided catalysts had a lower stacking number of MoS2 slabs. The XPS results showed that both the sulphidity of Mo and the content of MoS2 active phase of the ex situ presulfided catalyst were lower than those of the in situ presulfided one. The difference in active phase of the two types of presulfided catalysts led to their different hydrogenation activity.

Key words: ex situ presulfiding, dibenzothiophene, hydrodesulfurization, molybdenum, nickel, phosphorus, alumina, supported catalyst