Enhancement of Ammonia Synthesis on a Co₃Mo₃N-Ag Electrocatalyst in a K-βAl₂O₃ Solid Electrolyte Cell

Abstract

The electrochemical promotion of ammonia synthesis by potassium ions (K+) on a Co3Mo3N-Ag electrocatalyst was studied in a K-β″-Al2O3 solid electrolyte cell. The effect of temperature (400–550 °C), PH2/PN2 feed composition (1.0, 3.0 and 6.0) and applied voltage was explored in detail. The catalyst was prepared by ammonolysis of the mixed oxide and was characterized by XRD and SEM. A volcano-type behavior was found, i.e., around 1% of potassium per total moles of Co3Mo3N improved the ammonia formation rate by as much as 48%. However, high percentages of potassium act as poison for the reaction, possibly due to the formation of K–N–H compounds that block the active sites. Faradaic efficiency (Λ) values close to 300 are for the first time reported in NH3 synthesis.