Influences of different phosphorus contents on NiMoP/Al2O3 hydrotreating catalysts

NiMoP/Al2O3 hydrotreating catalysts with different phosphorus contents were prepared by impregnating NiMoP aqueous solution into γ-Al2O3. The hydrodesulfurization (HDS) and hydrodenitrogenation (HDN) performances of the catalysts were evaluated using the model compounds dibenzothiophene and quinoline in toluene. The results show that the HDS and HDN performances of the catalysts can be improved by adding appropriate quantities of phosphorus in the catalysts, and its performance can be decreased markedly when the catalysts have high phosphorus content. The catalysts were investigated by means of XRD and high-resolution transmission electron microscopy (HRTEM) to get a better understanding of the nature of active phases. The results of XRD and HRTEM characterizations indicate that the stacked layers number of active component MoS2 nanoparticles increases with the increase of the phosphorus content. Because the interaction between active component and γ-Al2O3 carrier is weakened by adding phosphorus into the catalysts, the relative content of type-II “Ni-Mo-S” phase is increased.