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This study explains a co-promoting interaction of cerium and barium additives in a cobalt catalyst used for ammonia synthesis. The results show that a synergistic effect of Ce and Ba promoters in the catalyst is associated with an emergence of a third promoter—BaCeO3—which forms in situ from its individual components during catalyst activation. The influence of perovskite-type barium cerate is substantial due to its strong basic properties, i.e. high electron-donating ability and a tendency to stabilize the Co hcp cobalt phase (more active in ammonia synthesis than the Co fcc phase). BaCeO3 diversifies the structure of adsorption sites on the cobalt surface by contributing to the exposure of facets with more favourable adsorption and binding energies with regards to rate-limiting reactions steps. It allows to a more fluent formation and transfer of species unrestricted by the hydrogen or product poisoning consequently accelerating the entire ammonia synthesis process.

The reduction of cobalt molybdenum oxide under an ammonia atmosphere resulting in the formation of ternary interstitial nitride CoMoN was studied. Intermediate phases were identified by an in situ powder X-ray diffraction using a reaction chamber. It was supplemented by a thermogravimetric analysis of the process. The presence of intermediate phases, CoMoO, CoMoO, MoN, metallic cobalt, and CoMoN, was observed. A synthesis route of CoMoN by an ammonolysis method was proposed.

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The formation and stability of an ammonia synthesis catalyst, based on cobalt molybdenum nitrides, were studied. The activation process of the catalyst was examined by in situ X-ray diffractometry. The thermal stability of obtained active phase of the catalyst was tested at 700 °C under ammonia atmosphere, N 2 /H 2 mixture and under pure hydrogen. The presence of Co 2 Mo 3 N and Co 3 Mo 3 N phases in the catalyst was confirmed. The phase composition was stable in a long-term test performed under nitrogen/hydrogen atmosphere. Co 3 Mo 3 N phase decomposed into Co 6 Mo 6 N after exposure to pure hydrogen.