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.

The influence of chromium compounds on the properties of cobalt molybdenum nitrides was studied. CoMoO4 obtained by precipitation from cobalt and molybdenum salts was modified by the addition of chromium(III) nitrate. A mixture of cobalt-molybdenum nitrides, Co2Mo3N and Co3Mo3N, was formed by ammonolysis of modified CoMoO4. The concentration of Co2Mo3N decreases with increasing chromium content. The specific surface area of cobalt molybdenum nitrides consisting of 2 wt% of Cr atoms increased by 50% in comparison to pure cobalt molybdenum nitrides. The catalytic activity of obtained catalysts in ammonia synthesis process decreases with rising of chromium concentration.

Co supported on mixed MgO–La2O3 oxides as efficient and stable catalysts for ammonia synthesis.