Abstract: Ru/MgO-CeO₂ catalysts were prepared by co-precipitation with different precursors, including K₂RuO₄, Ru(Ac)₃, and RuCl₃, the obtained catalysts were characterized by X-ray diffraction, X-ray fluorescence, N₂ physisorption, temperature-programmed reduction, and CO chemisorption. The results showed that the ammonia synthesis activity of the Ru/MgO-CeO₂ catalyst prepared with K₂RuO₄ was 16.0% at 10 MPa, 450 °C, and 10 000 h^-1, which was higher than those obtained with the other two precursors. The turnover frequency (TOF) of the Ru/MgO-CeO₂ catalyst prepared with K₂RuO₄ was higher than those obtained with the other precursors under the same reaction conditions. The influence of precursors and preparation methods on the structure and performance of the catalysts was studied. The ratio of Ru/MgO-CeO₂ catalysts prepared with K₂RuO₄, Ru(Ac)₃, and RuCl₃ as precursors for ammonia synthesis turnover frequency is 1.33:1.05:1 under 10 MPa, 425 °C, and 10 000 h^-1.

Key words: precursor, ammonia synthesis, magnesium oxide, cerium dioxide, ruthenium