Ni(Co,P,V)WN_x/TiO₂-γ-Al₂O₃ catalysts were synthesized by nitriding with N₂-H₂ mixture in the process of temperature programmed reduction. Nitrogen adsorption, temperature-programmed desorption of ammonia (NH₃-TPD), TG-DTA and XPS techniques were employed to analyze the natures of the catalysts. The results show that the reduction-nitriding of the precursors of Ni(Co,P,V)WN_x/TiO₂-γ-Al₂O₃ catalysts can be carried out more easily than that of WN_x/TiO₂-γ-Al₂O₃ catalyst, and the BET surface areas and acid amounts of Ni(Co,P,V)WN_x/TiO₂-γ-Al₂O₃ catalysts are smaller than those of WN_x/TiO₂-γ-Al₂O₃ catalyst. Among the Ni(Co,P,V)WN_x/TiO₂-γ-Al₂O₃ catalysts, the BET surface area and acid amount of the NiWN_x/TiO₂-γ-Al₂O₃ catalyst are relatively larger, and the precursor of the NiWN_x/TiO₂-γ-Al₂O₃ catalyst is most easily reduced and nitrided. In addition, the addition of additive Ni is more conducive to the stability of active W species on the WN_x/TiO₂-γ-Al₂O₃ catalyst. At last, the activities of thiophene hydrodesulphurization (HDS) over the catalysts were evaluated. The results show that the addition of additives can promote the activities of thiophene HDS over the WN_x/TiO₂-γ-Al₂O₃ catalyst, and the NiWN_x/TiO₂-γ-Al₂O₃ catalyst has a higher activity of thiophene HDS.

Key words: nitrogenation, tungsten, additives, hydrodesulphurization, TiO₂-γ-Al₂O₃