Preparation of Ni₂P/TiO₂-Al₂O₃ and the catalytic performance for hydrodesulfurization of 3-methylthiophene

Composite TiO₂-Al₂O₃ supports were prepared by the sol-gel technique using tetra-n-butyl-titanate and γ-Al₂O₃ as raw materials, and the Ni ₂P/TiO₂-Al₂O₃ catalysts were obtained by incipient wetness impregnation of aqueous metal phosphate precursors, followed by temperature-programmed reduction of inflowing H ₂. The supports and catalysts were characterized by X-ray diffraction, infrared spectroscopy, transmission electron microscopy, and N ₂ adsorption. The hydrodesulfurization (HDS) activity was examined in a fixedbed reactor. Experimental results indicate that the composite support can effectively prevent the formation of aluminumphosphates based on the strong interaction between P and γ-Al₂O₃, overcome the disadvantage of low surface titania, and improve metal support interaction, which significantly increase catalyst activity and selectivity. The Ni ₂P/TiO₂-Al₂O₃ catalyst exhibits good activity for the HDS of 3-methylthiophene (3-MT), used as a model compound. The activity and stability of t e Ni₂P/TiO₂-Al ₂O₃ catalyst are affected by the phosphorus content, both achieving a maximum with an initial Ni/P molar ratio of 1:2. The reaction temperature and the weight hourly space velocity (WHSV) show significant influence, but the reaction pressure and the volume ratio of hydrogen/oil have little effect on the HDS performance of the Ni₂P/TiO ₂-Al₂O₃ catalyst. The conversion of 3-MT is close to 100% when the reaction temperature reaches 603 K, reaction pressure reaches 2.0 MPa, WHSV reaches 1.275 h^-1, and volume ratio of hydrogen/oil reaches 400.