Study Of Sulfided NiMo Catalysts And Preparation Process For Diesel Hydrotreating

Depth hydrogenation was the feasible way to reduce sulfur in diesel. In this paper, NiMoS/γ-Al₂O₃ catalysts were prepared by pore volume impregnation methods step by step. The catalysts were characterized by different analysis methods, and the activity were measured in a high pressure flow micro-reactor. It was investigated that the preparation methods and surface properties of the HDS catalysts could influence the active phase and activity of NiMoS/γ-Al₂O₃ catalysts.The results showed that Ni could improve the dispersion degree of active component of the catalysts on carrier surface, and Ni content could influence structure of the MoS2 active phase for the catalyst. The slab length of MoS2 and the stacking degree of MoS2 could be affected along with the increase of Ni content.The length MoS₂ slabs would reduce and the active phase dispersion degree would increase by increasing the content of Ni. In the while, the activity and selectivity of hydrodesulfurization catalyst increased.And it were investigated that the preparation methods of catalysts could influence the activity and selectivity of catalysts to some degree. The results showed that the impregnating order could influence the activity of catalyst. It was studied that the activity of catalyst prepared by impregnating sulfide precursor ammonium tetrathiomolybdate(ATTM) aqua solution was better than the catalyst prepared by impregnating nitric solution. The activity of catalyst which was perpared by ATTM ligand solution instead of ammonium molybdate solution would increase.The results suggested that the selectivity of NiMoS/γ-Al₂O₃ catalysts were higher. HDS ratio was above 87% and the selectivity of BP was above 91% under the conditions of 300°C, 2.0MPa, hyrogen-to-oil volumetric ratio of 300:1 and LHSV of 10h-1 when the metal loading was 26%(wt()NiO+MoO₃)and Ni/(Ni+Mo) atomic ratio was 0.3. The activity and selectivity of catalyst would increase when the reaction temperature was increased. The NiMoS/γ-Al₂O₃ catalysts could be used directly, and it is not necessary to be presulfided.