Abstract: Ni/Mo/N catalysts made to have an interstitial structure gave high catalytic activity and sulfur tolerance in the hydrotreating of coal liquid fuel to produce high performance jet fuel. The dissolving of N atoms into the metal lattices to make the interstitial structure is difficult to control, and the preparation conditions of the precursor synthesis and the crystallinity of the precursors were changed to monitor how N atoms were inserted into the metal lattice. Ni/Mo/N catalysts were prepared by a one pot synthesis using ammonium molybdate [(NH₄)₆Mo₇O₂₄?4H₂O] and nickel acetate [Ni(CH₃COO)₂?4H₂O] and the decomposition of hexamine under an argon atmosphere at 650 °C. Benzene hydrogenation was used as a model reaction to evaluate catalytic activity. Benzene was hydrogenated over the Ni/Mo/N catalyst at 250 °C and 3 MPa in a fixed bed reactor in the absence and presence of thiophene to also test the Ni/Mo/N catalysts for sulfur tolerance. X-ray diffraction analysis showed that the formation of different precursors and use of different aging times affected the composition of the Ni/Mo/N catalysts, and also determined the crystal phases in the Ni/Mo/N catalysts. Ni₂Mo₃N, Mo₂C, and Ni metal phases were present in the most active Ni/Mo/N catalyst which gave a conversion of benzene of 93% and selectivity to cyclohexane of almost 100%. The atomic ratio of Ni/Mo in the most active Ni/Mo/N catalyst was 5/4 as determined by energy dispersive X-ray spectroscopy. Benzene hydrogenation over the Ni/Mo/N catalyst in the presence of thiophene led to a decline in benzene conversion from 72% to 50% due to the formation of MoS₂.

Key words: Ni/Mo/N catalyst, Benzene, Hydrogenation, Thiophene, X-ray diffraction