The development of an energy efficient process for production of ammonia, which is one of the most widely produced chemicals worldwide and consumes 1-2% of the world energy supply, will be one of the ultimate achievements of the present century [1,2]. Recent studies have focused on development of new catalysts that operate at lower temperatures and pressures, and alternative processes. One of the most promising processes is electrocatalytically-assisted ammonia production using solid oxide electrolytes since this process can utilize H2O as a H+ source instead of using H2 [3, 4]. In this process, N2 reacts with H2O to form NH3, H2 and O2- at the cathode side. Oxide ions are conducted through the solid oxide electrolyte and reach anode side where they recombine and form O2. In order to achieve high activity, the cathode material should possess high electrical and ionic conductivity and high selectivity towards nitrogen activation and ammonia production. Although perovskite-type mixed oxide materials are promising cathode catalysts due to their tunable electrical/ionic conductivity, they do not provide high activity for ammonia production. Metal nitrides are considered promising ammonia production catalysts due to the presence of lattice nitrogen in their structure which, in presence of H2, can be converted to NH3 and N vacancies [3] but they do not have any ionic/electrical conductivity. In the present study, the activity of doped lanthanum ferrite-type perovskite was enhanced by incorporation of iron nitride-type active phase and the activity of this complex cathode was tested in a single-chamber solid oxide electrolyte cell (SOEC)-type reactor. The perovskite and metal nitride-type cathode materials were synthesized and characterized using different ex-situ/in-situ spectroscopy techniques. The electrocatalytic activity experiments were performed using both perovskite cathodes and metal nitride incorporated perovskite cathodes. The electrocatalytic activity experiments showed that metal nitride incorporation significantly enhances the NH3 production rate.

Metal nitride incorporated perovskite-type novel cathode catalysts for electrocatalytic ammonia production at atmospheric pressure

2019 Fall National Meeting

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