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P: Fachverband Plasmaphysik
P 16: Atmospheric Pressure Plasmas and their Applications III
P 16.4: Vortrag
Mittwoch, 28. Februar 2024, 15:00–15:15, WW 1: HS
Ammonia synthesis in an atmospheric catalytic RF plasma — •Steijn Vervloedt and Achim von Keudell — Experimental Physics II, Ruhr University Bochum, Bochum, Germany
The synthesis of ammonia is a vital part of the production of nitrogen-based artificial fertilisers. Also, in the future, it might prove a worthy candidate for energy storage, by acting as a hydrogen carrier. In this contribution, the recent results of ammonia synthesis in an atmospheric RF-plasma are presented, as well as the impact of introducing various catalysts. The plasma physics and chemistry are simplified by using helium as a buffer gas. The nitrogen and hydrogen are admixed up to ∼1%, to minimise their impact on the plasma dynamics. The products of the plasma are measured with ex-situ infrared Fourier transform (FTIR) absorption spectroscopy. The plasma dynamics are probed by observing trends in the emission of the second positive and first negative systems of nitrogen. Furthermore, a kinetic model is able to explain the experimentally observed trends. The results indicate that the synthesis is very sensitive to the plasma properties, e.g. the electron energy distribution and differences of less than 0.1 eV are sufficient to explain the results. This likely originates from the sensitivity of the NH3 production - which happens mostly at the surface - to the atomic nitrogen flux towards the surface where the rate-limiting step is the electron-induced dissociation of nitrogen molecules.
Keywords: ammonia synthesis; plasma catalysis; global model