How was the research progress of synthesized ammonia catalysts in foreign countries in 1990s

The first iron-free catalyst for ammonia synthesis was applied by Kellogg (now KBR) in its KAAP (Kellogg Ammonia Assembly Production Process) process in 1992. This ruthenium catalyst used a graphitized carbon as a carrier and was claimed to be 10.20 times more active than conventional molten iron catalysts. In the reaction, this catalyst has a different kinetic profile, and the inner pieces can be operated at lower than stoichiometric hydrogen-to-nitrogen ratios and at pressures of about 9 MPa.

Researchers at the Haldor Topsoe Research Laboratory have succeeded in developing a series of products that can replace conventional iron catalysts. The ternary nitrides (Fe3Mo3N, Co3Mo3N, and Ni2Mo3N) are highly active and thermally stable when used as ammonia catalysts under the operating conditions of industrial plants. If cesium is added to the Co-Mo-N catalyst, the activity will be higher than that of the currently used iron catalyst.

It has also been reported that under the same operating conditions, the activity of Co-Mo-N with cesium as co-catalyst is twice as high as that of conventional iron catalysts if the temperature is 400°C, the pressure is 20 MPa, and the hydrogen to nitrogen ratio is 3:1.

Ruhr (Ruhr) University has investigated a catalyst consisting of barium metal, ruthenium metal and magnesium oxide, which produces more ammonia and has a longer lifetime than existing ammonia catalysts. The barium-ruthenium catalyst is reportedly 2,4 times more active than conventional iron-based catalysts or other types of ruthenium-based catalysts, and the developed barium-ruthenium catalyst can produce double the ammonia yield compared to cerium-ruthenium catalysts. If the ratio of barium to ruthenium is optimized, the ammonia yield can be further increased.