How were ruthenium-based ammonia catalysts developed and applied?

In spite of the many advantages of ferrous catalysts, efforts have been made to develop new types of catalysts and there has been a great deal of interest in iron-free catalysts. In the 1970s and 1980s, Japan actively sought to develop ruthenium-based catalysts. After the introduction of iron-cobalt catalysts in the ICI AMV and LCA processes, the development of ruthenium catalysts for ammonia synthesis was boosted by the use of carbon-based ruthenium catalysts in the KAAP process. The activity of completely iron-free and ruthenium-free catalysts (e.g., Cs/Co3Mo3 N catalysts) is intermediate between ferrous and ruthenium catalysts and lower than that of ruthenium catalysts, as can be seen from the comparison of the Cs/Co3Mo3N catalysts, KM1R catalysts (Topsoe's ferrous catalysts), and carbon-based catalysts with 6% barium and 6.7% ruthenium under the process conditions of 3 B1 and 1 B1 H/N ratios. A comparison of the Cs/Co3Mo3 N catalysts at hydrogen/nitrogen ratios of 3B1 and 1B1 shows that the kinetics of the Cs/Co3Mo3 N catalysts are intermediate between those of the ferrous iron and ruthenium-based catalysts, but that it regenerates oxidising particles when burnt in air at 600 e.

Ruthenium is a precious metal, even rarer than platinum, and was first refined by Klaus in Russia in 1844. After the early discovery of ruthenium catalysts by Mittasch, no progress was made in the development of ruthenium catalysts until 1970, when the kinetics of ruthenium catalysts based on diatomaceous earth was introduced to Japan for ammonia synthesis. Japanese researchers continued to study the activity of a large number of potassium-promoted metals (Co, Ni, Re, Mo, Fe, Ru, Os) over carbon carriers and found that ruthenium was more active than conventional bimetallic iron catalysts. The first application of a graphite-based ruthenium catalyst for ammonia synthesis was reported in Japan in 1972, and it was actually brought into production by BP in 1979. Afterwards, Kellogg accepted the transfer of catalyst technology from BP and co-developed and applied this catalyst to the KAAP process. 1992 was the first year that Ocelot Ammonia Producers in Canada loaded its industrial plant with a ruthenium catalyst, followed by two other plant modifications. The first two plants using the KAAP process were commissioned in 1998 in the Point Lisas and Trinidad areas, with a production capacity of 1.85 kt/d. The first two plants using the KAAP process were commissioned in 1998 in the Point Lisas and Trinidad areas.