(326b) Thermal-Electro-Synthesis of Ammonia over Molybdenum Oxynitride at 250°C
AIChE Annual Meeting
2023
2023 AIChE Annual Meeting
Engineering Sciences and Fundamentals
Electrochemical Fundamentals: Faculty Candidate Session I
Monday, November 6, 2023 - 3:54pm to 4:06pm
NH3 is a critical global resource for fertilizers and chemical intermediates and can also serve as an easily transported hydrogen vector in support of a hydrogen economy. An electrochemically driven process generates high chemical potential of reactant species allowing us to circumvent pressurization of the system. Thus, electrochemical NH3 synthesis would reduce capital costs, decrease energy consumption, and enable NH3 synthesis at smaller scales than the incumbent high-pressure process (Haber-Bosch). In this work, we electrochemically synthesized ammonia (NH3) using protons, steam (H2O), and N2 as reactants over molybdenum oxynitride using cesium dihydrogen phosphate (CsH2PO4) solid acid electrolytes (Cathode conditions of 38% H2O, 62% N2, anode conditions of 38% H2O, 62% H2, both at 1 atm total pressure, 250°C and -0.7 VOCV). We first discuss the challenge of eliminating false positives and protocols to confidently detect and quantify NH3 using NMR. Molybdenum oxynitrides were synthesized from molybdenum trioxide (MoO3) precursors and utilized in the cathode. We find that the NH3 synthesis rate is only marginally lower when the system is starved of N2 reactant, indicating that the majority, if not all, of the N in NH3 originates from N in the oxynitride.