A Carbon-Neutral Approach to Solar-Thermochemical Ammonia Production via Metal Nitride Synthesis

The Haber-Bosch process revolutionized ammonia production in 1909, yet its reliance on fossil fuels and high energy consumption poses environmental challenges. This paper explores a sustainable alternative: a solar-thermochemical looping process utilizing metal nitrides. The study investigates the synthesis and characteristics of tertiary nitrides as potential catalysts for ammonia production. Through a down-selection process based on formation energies, 18 elements are identified, paving the way for the synthesis of metal oxides and subsequent nitridation. The modified Pechini synthesis method is employed, followed by calcination and nitridation processes. Through x-ray diffraction analysis, the successful synthesis of crystalline manganese- nickel oxide compounds is confirmed, with varying compositions corresponding to manganese oxide and nickel oxide phases. Calcination at different temperatures influences crystallinity and phase composition, yet its impact on nitridation outcomes remains inconclusive. Despite challenges, revised nitridation conditions yield the first successful formation of Mn3N2 from Mn0.5Ni0.5N, marking a significant advancement. However, further optimization through re- nitridation is necessary for complete crystal formation. These findings contribute to understanding transition metal oxide synthesis and nitridation, paving the way for future research in ammonia production and technological innovation. This research contributes to the development of a carbon- neutral approach to ammonia production, reducing reliance on fossil fuels and mitigating carbon emissions.