Preparation of composite TiO2–Al2O3 supported nickel phosphide hydrotreating catalysts and catalytic activity for hydrodesulfurization of dibenzothiophene

Composite TiO2–Al2O3 supports were prepared by the sol–gel methods, and a series of Ni–P hydrotreating catalysts supported on TiO2–Al2O3 supports were prepared by impregnation of nickel phosphate precursors followed by reduction in hydrogen at 973 K. The catalysts were characterized by X-ray diffraction (XRD), N2-adsorption specific surface area measurements (BET), transmission electron microscope (TEM), infrared spectroscopy (IR), X-ray photoelectron spectroscopy (XPS) and thermogravimetry differential thermal analysis (TG-DTA). The effect of Ti/Al molar ratio and initial Ni/P molar ratio on catalyst structure as well as HDS performance was studied. The results indicated that the TiO2 can inhibit the formation of AlPO4, and act as an electronic promoter for the Ni–P catalyst. When the initial Ni/P molar ratio is lower than 1/1, the main phase obtained is Ni2P. The Ni2P/TiO2–Al2O3 catalyst prepared with initial Ni/P ratios of 1/1 and Ti/Al molar ratio of 1/1.6 exhibited the highest activity. At a reaction temperature of 606 K, a pressure of 3.0 MPa, a H2/oil ratio of 500 (V/V), and a weight hourly space velocity (WHSV) of 2.0 h− 1, the HDS conversion reached 96.00%.