Abstract: The Ru/CeO₂ catalyst was prepared by precipitation methods, including normal precipitation, reverse precipitation, parallel flow precipitation, and deposition-precipitation. The obtained catalysts were characterized by N₂ adsorption-desorption, X-ray diffraction, H₂ temperature-programmed reduction, CO chemisorption, and X-ray fluorescence spectroscopy. The results showed that the ammonia synthesis activity of the Ru/CeO₂ catalyst prepared by normal precipitation was 11.9% at 10 MPa, 10000 h^-1,?and 450 ^oC, which was higher than those obtained by other methods. The residual chloride content in this catalyst was much lower and its cerium was easier to be reduced. Thus the activity of the catalyst prepared using normal precipitation was high.

Key words: precipitation method, ammonia synthesis, cerium dioxide, ruthenium, co-precipitation, deposition-precipitation