2025 AIChE Annual Meeting

(584dh) Stabilizing Calcium Nitride for Efficient Ammonia Synthesis

Authors

Meenesh R Singh, University of Illinois Chicago
Calcium-mediated electrochemical ammonia synthesis presents a sustainable alternative to the Haber–Bosch process, though its advancement is limited by gas–liquid mass transport inefficiencies, slow hydrogen oxidation kinetics, and solvent degradation. In this work, we address these challenges by (i) implementing high-activity anodes to enhance hydrogen oxidation and suppress solvent breakdown, (ii) replacing tetrahydrofuran (THF) with a more chemically stable ether-based solvent, dimethoxyethane (DME), and (iii) designing a custom polyetheretherketone (PEEK) flow cell to improve gas–liquid interfacial stability. These system-level improvements support stable calcium nitride formation, confirmed by in-situ Raman and post-electrolysis XPS, and highlight the role of interfacial engineering in maintaining reactivity and selectivity. Isotope-labeling with ¹⁵N₂ confirms N₂ as the nitrogen source, and kinetic studies reveal the influence of anode material on hydrogen oxidation and overall cell performance. This work establishes critical mechanistic understanding and design principles for reliable and efficient calcium-mediated nitrogen fixation under continuous operation.