Preparation of Nickel Phosphide/Mesoporous-TiO2 Catalyst and Its Hydrodesulfurization Performance

Abstract

Using mesoporous TiO 2 (m-TiO 2 ) as the support, novel nickel phosphide/m-TiO 2 catalysts (Ni 2 P/m-TiO 2 ) 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 Ni 2 P, and the optimum loading of Ni was 10%. The influence of m-TiO 2 on the preparation and HDS performance of nickel phosphide catalysts was also evaluated by X-ray diffraction, N 2 physisorption, field-emission scanning electron microscopy, and temperature-programmed reduction. The results showed that m-TiO 2 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 Ni 2 P/m-TiO 2 catalysts were very similar and the specific surface areas were about 90 m 2 /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 Ni 2 P/m-TiO 2 > Ni 2 P/SiO 2 > Ni 2 P/P25. 以介孔 TiO 2 (m-TiO 2 ) 为载体, 采用程序升温还原法制备了 Ni 2 P/m-TiO 2 催化剂, 考察了不同起始 Ni/P 摩尔比及活性组分负载量对该催化剂结构及其催化加氢脱硫 (HDS) 性能的影响. 结果表明, 当 Ni/P 摩尔比为 1.25 时, 活性组分以 Ni 2 P 为主, 催化剂的最佳 Ni 负载量为 10%. 采用 X 射线衍射、低温 N 2 吸附-脱附、场发射扫描电镜和程序升温还原等技术表征了 m-TiO 2 及其它不同载体负载的 Ni 2 P 催化剂. 结果表明, 高结晶度 m-TiO 2 载体使 Ni 和 P 物种的还原温度大幅度降低, 在 450–600 o C 还原制得的 Ni 2 P/m-TiO 2 催化剂的结构参数基本一致, 比表面积均为 90 m 2 /g 左右, 具有很高的热稳定性和对二苯并噻吩的 HDS 催化性能. 在相同的反应条件下, m-TiO 2 负载的 Ni 2 P 催化剂 HDS 性能最好, 各载体负载的 Ni 2 P 催化剂活性大小顺序为 Ni 2 P/m-TiO 2 > Ni 2 P/SiO 2 > Ni 2 P/P25. The use of highly crystalline mesoporous TiO 2 as the support could dramatically decrease the reduction temperatures of Ni and P precursor species, and produce catalysts with higher dibenzothiophene (DBT) conversion than those obtained using SiO 2 and P25 supports.