Preparation And Characterization Of Ni₂P/TiO₂-Al₂O₃ Catalysts And Their Hydrodesulfurization Performances Evaluation

In recent years, the awareness of environmental protection continues to increase all over the world with the increasingly serious problem of air pollution. Countries around the world have also formulated strict laws and regulations to reduce the man-made environmental pollution. Harsh limit standards were founded for the production and emission of fuel oil such as gasoline and diesel, with the decreasing discharge requirements for the sulfur and nitrogen compounds year after year. Transition metal phosphide Ni2 P is a novel catalytic material, not only has high thermal stability, chemical stability and catalytic activity, but also possesses many advantages like the corrosion resistance and high melting point, which was most commonly used in the hydrodesulfurization reaction of the crude oil. However, the catalytic activity of Ni2 P was influenced to some degree due to the small specific surface area of Ni2 P, which need to be loaded to higher specific surface area carriers to improve the reaction activity. TiO₂-Al₂O₃ was the first choice supporter to carry Ni2 P, which possess the highly catalytic activity of TiO₂ and high specific surface area of Al2O3 at the same time. Therefore, there was very important significance to research and develop high activity Ni₂P/TiO₂-Al₂O₃ hydrodesulfurization catalyst.In this thesis, TiO₂-Al₂O₃ composite carriers were prepared by the sol-gel method and then Ni₂P/TiO₂-Al₂O₃ hydrodesulfurization catalysts were obtained with the aid of Impregnation method. By means of X-ray diffraction, scanning electron microscopy, infrared spectrum and other characterization methods, the effect of different preparation methods, loading amount, sintering temperature and molar ratio on the performances of the Ni₂P/TiO₂-Al₂O₃ hydrodesulfurization catalyst were explored. The catalyst was evaluated with the dibenzothiophene as target compound to select the optimization preparation condition. According to the researching results, the best catalyst activity of the composite support was achieved with a 30% TiO₂ mass fraction prepared by sol-gel method, while the 30% loading amount Ni2 P, 1/1 Ni/P molar ration and 700℃ reducing temperature were employed. Under continuous working conditions, the catalytic activity of Ni₂P/Ti O₂-Al2O3 on dibenzothiophene could be achieved more than 95%, which was much better than other kinds of catalysts.