XPS characterization of zirconium-promoted CoMo hydrodesulfurization catalysts

CoMo hydrodesulfurization catalysts (HDS) supported on mixed ZrO2-Al2O3 and ZrO2-SiO2 oxides have been prepared via a two-step impregnation using the incipient wetness method. The S-BET method, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) were used for characterization of the samples. Increasing the ZrO2 content decreases the surface areas and the pore volumes of supported CoMo catalysts. The effect of Zr content on the dispersion of Mo and Co species is more pronounced in the case of CoMo/ZrO2-SiO2 samples; a higher dispersion corresponds to a higher ZrO2 content. The sulfidation of molybdenum forms MoS2. A higher degree of sulfidation of molybdenum is observed for CoMo catalysts supported on ZrO2-Al2O3. A comparison between surface properties and catalytic activity behaviors of CoMo catalysts in HDS of thiophene is presented. (C) 2002 Elsevier Science B.V. All rights reserved.