X-ray Photoelectron Spectroscopy Study of Mo-Ni/γ-Al₂O₃ Catalysts for Hydroconversion of Fatty Oil Derivatives

The chemical states of Mo and Ni supported on γ-Al₂O₃ prepared under various conditions were investigated using X-ray photoelectron spectroscopy. The Mo species interacted with the Ni species interacting weakly with the support by co-impregnation of both the metal species to form Ni-Mo-O binary oxides. Increasing hydrogen pressure during pretreatment of the catalysts led to the formation of Ni-Mo-O binary oxides consisting of the metal species with a lower oxidation number, while the interaction between the two metal species was retained. By contrast, the strong Ni interaction with the support remained independent of the hydrogen pressure. In the hydroconversion of methyl laurate on Mo-Ni/γ-Al₂O₃, the Mo species with a higher oxidation number in the binary oxide contributed to the formation of C₁₂ hydrocarbons, while the reduced Ni species and the Mo species with the lower oxidation number in the binary oxide promoted the formation of C₁₁ hydrocarbons. The strong interaction of the Mo species with the Ni species suppressed catalytic activity derived from the Ni species; however, that played an important role in the selective production of hydrocarbons with jet fuel fractions.