Preparation of nickel phosphide/mesoporous-TiO₂ catalyst and its hydrodesulfurization performance

Using mesoporous TiO₂ (m-TiO₂) as the support, novel nickel phosphide/m-TiO₂ catalysts (Ni₂P/m-TiO₂) were prepared by a temperature-programmed reduction method. The influence of the Ni/P molar ratio and the amount of active component on the catalyst structure and the hydrodesulfurization (HDS) performance was investigated. The results indicated that the reduction of precursor with Ni/P = 1.25 yielded mainly Ni₂P, and the optimum loading of Ni was 10. The influence of m-TiO₂ on the preparation and HDS performance of nickel phosphide catalysts was also evaluated by X-ray diffraction, N₂ physisorption, field-emission scanning electron microscopy, and temperature-programmed reduction. The results showed that m-TiO₂ with high crystallinity could dramatically decrease the reduction temperatures of Ni and P species. When the reduction temperatures were between 450 and 600°C, the textures of the Ni₂P/m-TiO₂ catalysts were very similar and the specific surface areas were about 90 m²/g. The effects of the support on the dibenzothiophene HDS performance of the nickel phosphide catalysts were also investigated. The results showed that the order of dibenzothiophene conversion was Ni₂P/m-TiO₂ > Ni₂P/SiO₂ > Ni₂P/P25.