12033-07-7

Manganese nitride (Mn₃N₂) is a greyish-black powder that reacts with water at elevated temperatures to produce ammonia. It is employed in the preparation of high-purity nitride ceramics and hydrogen storage materials.​

Manganese nitride has good electrical and thermal conductivity as well as excellent chemical stability and corrosion resistance. It is mainly used for the production of special steel and non-ferrous metal alloys. In addition, manganese nitride is used in fields such as metal manufacturing, the electronics industry, and the chemical industry. Its nitrogen content can be controlled within the range of 6-10%.

Developing advanced catalytic materials for mild-condition ammonia (NH3) synthesis is essential for improving the energy efficiency of the industrial Haber-Bosch process. Here, we report a ζ-phase manganese nitride (MnN0.43) catalyst for low-temperature NH3 synthesis. The as-synthesized MnN0.43 catalyst is protected by a carbon shell, allowing for the storage and processing of the air-sensitive metal nitride under ambient conditions. After activation in situ, the MnN0.43 catalyst exhibits high activity for NH3 synthesis at 250–350 °C, surpassing the conventional noble metal based Ru/MgO catalyst. A combination of kinetic, chemisorption, isotope labeling and computational studies indicate that a nitrogen vacancy-mediated associative mechanism accounts for the catalytic enhancements. Our work highlights the great potential of earth-abundant transition metal nitrides for catalyzing mild-condition NH3 synthesis.

The nitride is prepared from very reactive sublimed manganese. The metal is heated in an apparatus which permits the continuous measurement of the amount of N3 used in the reaction. A completely O3-free nitrogen is used, under a pressure of ~ 100 mm.and a temperature of 690°C. The reaction is continued until aconstant final pressure is obtained (12-24 hours).

[1] QU W, ROY P, WANG C, et al. Earth-Abundant Manganese Nitride Catalysts for Mild-Condition Ammonia Synthesis[J]. ACS Catalysis , 2025, 23 1. DOI:10.1021/acscatal.5c00899.