Catalysis of Sodium Alloys for Ammonia Synthesis around Atmospheric Pressure

In this work, catalysis for ammonia production of sodium alloys is systematically investigated. Sodium alloys are synthesized from sodium and group 14 elements and characterized by X-ray diffraction, thermal desorption mass spectroscopy, and nuclear magnetic resonance experiments. The catalytic properties of Na alloys are evaluated by heating alloys under flow conditions of mixed gases of hydrogen and nitrogen. As a result, ammonia can be synthesized on sodium alloys below 400 °C under atmospheric pressure, and catalysis is preserved for more than 100 h. From the above experimental results, it is clarified that the ammonia synthesis temperature and catalysis are related to the thermal stability and metallic feature of sodium atoms in the alloys, respectively. Although the sodium alloys are partially decomposed during the ammonia synthesis process, the higher partial pressure of hydrogen would suppress the decomposition. The obtained results indicate that Na alloys are potential ammonia synthesis catalysts.