Abstract: In this work, NiMo catalysts with various contents of MoO₃ were prepared through incipient wetness impregnation by a two-step method (NM-xA) and one-pot method (NM-xB). The catalysts were then characterized by XRD, XPS, NH₃-TPD, H₂-TPR, HR-TEM, and N₂ adsorption-desorption technologies. The performance of the NiMo/Al₂O₃ catalysts was investigated by hydrocracking low-temperature coal tar. When the MoO₃ content was 15 wt%, the interaction between Ni species and Al₂O₃ on the NM-15B catalyst was stronger than that on the NM-15A catalyst, resulting in the poor performance of the former. When the MoO₃ content was 20 wt%, MoO₃ agglomerated on the surface of the NM-20A catalyst, leading to decreased number of active sites and specific surface area and reduced catalytic performance. The increase in the number of MoS₂ stack layers strengthened the interaction between Ni and Mo species of the NM-20B catalyst and consequently improved its catalytic performance. When the MoO₃ content reached 25 wt%, the active metals agglomerated on the surface of the NiMo catalysts, thereby directly decreasing the number of active sites. In conclusion, the two-step method is suitable for preparing catalysts with large pore diameter and low MoO₃ content loading, and the one-pot method is more appropriate for preparing catalysts with large specific surface area and high MoO₃ content. Moreover, the NM-xA catalysts had larger average pore diameter than the NM-xB catalysts and exhibited improved desulfurization performance.

Key words: Preparation methods, Hydrocracking performance, The NiMo catalysts, MoO₃ content

摘要： In this work, NiMo catalysts with various contents of MoO₃ were prepared through incipient wetness impregnation by a two-step method (NM-xA) and one-pot method (NM-xB). The catalysts were then characterized by XRD, XPS, NH₃-TPD, H₂-TPR, HR-TEM, and N₂ adsorption-desorption technologies. The performance of the NiMo/Al₂O₃ catalysts was investigated by hydrocracking low-temperature coal tar. When the MoO₃ content was 15 wt%, the interaction between Ni species and Al₂O₃ on the NM-15B catalyst was stronger than that on the NM-15A catalyst, resulting in the poor performance of the former. When the MoO₃ content was 20 wt%, MoO₃ agglomerated on the surface of the NM-20A catalyst, leading to decreased number of active sites and specific surface area and reduced catalytic performance. The increase in the number of MoS₂ stack layers strengthened the interaction between Ni and Mo species of the NM-20B catalyst and consequently improved its catalytic performance. When the MoO₃ content reached 25 wt%, the active metals agglomerated on the surface of the NiMo catalysts, thereby directly decreasing the number of active sites. In conclusion, the two-step method is suitable for preparing catalysts with large pore diameter and low MoO₃ content loading, and the one-pot method is more appropriate for preparing catalysts with large specific surface area and high MoO₃ content. Moreover, the NM-xA catalysts had larger average pore diameter than the NM-xB catalysts and exhibited improved desulfurization performance.

关键词: Preparation methods, Hydrocracking performance, The NiMo catalysts, MoO₃ content