Abstract: The effect of alkaline-earth oxides as promoters on Ru/AC (AC = activated carbon) catalysts was explored. Alkaline-earth metal oxides can reduce the agglomeration of ruthenium particles at high temperatures, which increases the amount of available ruthenium. The influence of the Mg promoter on the distribution and activity of the Ru/AC catalyst were investigated by CO chemisorption, X-ray diffraction, and energy dispersive spectrometry and by an activity test for ammonia synthesis. The results show that a specific quantity of magnesium significantly promotes the uniform distribution of Ba and Ru on the surface of AC, which enhances catalytic activity. The introduction of Mg significantly improved the size of the Ru particles and increased the Ru surface area. The distribution and interaction were improved greatly for the Ba promoter and the Ru precursor on the surface of the AC because of the addition of the Mg promoter. The introduction of magnesium to Ru-Ba-K/AC significantly improved the utilization ratio of the noble metals and the performance-price ratio.

Key words: barium, activated carbon, magnesium, ruthenium, ammonia synthesis