Application of Calcium Hydride, Calcium Nitride, and Lithium Hydride Catalysts for Enhanced Ammonia Synthesis in Dielectric Barrier Discharge Plasma

Abstract

Dielectric barrier discharge plasma has been shown as an effective alternative in renewable NH₃ production, however a catalyst which enhances the process to commercial potential is still being sought. This work investigates three catalysts, CaH₂, Ca₃N₂, and LiH for NH₃ synthesis when subjected to plasma. This work found a maximum synthesis rate of 6440 µmol h^− 1 g_cat⁻¹ for CaH₂ and an efficiency of 4.0 g-NH₃ kWh^− 1 g_cat⁻¹. Varying flow ratios to determine effects on synthesis demonstrated CaH₂ and LiH preferred hydrogen rich environments while Ca₃N₂ performed best in nitrogen rich flows. These results suggest each of the tested catalysts could have different reaction pathways or dependencies. Gas chromatography was used to quantify production levels and optical emission spectroscopy was used to determine vibrational temperatures of molecular nitrogen. These findings introduce three catalysts for use in plasma-based NH₃ synthesis and characterize the potential for increased efficiency of ammonia production.