Ammonia (NH3) synthesis has attracted a lot of research attention in the last decade due to the need for more sustainable production pathways. The demand for NH3 is expected to almost quadruple by 2050 since it is not only an important base chemical mainly used for the production of fertilizers, but also discussed as prospective carbon-free hydrogen (H2) carrier. The-state-of-the-art method for NH3 production today is the Haber-Bosch process with natural gas as the main H2 source. Since NH3 synthesis (eq. ( )) is an exothermic reaction but also exhibits a high energy barrier for breaking the N≡N triple bond, its industrial synthesis requires a catalyst as well as sufficiently high temperatures (> 400 °C) to ensure suitable reaction rates. Mainly iron (Fe) oxide-based, but also ruthenium-(Ru) based catalysts are used in industrial NH3 synthesis. As high temperatures shift the equilibrium towards the reactant side, high pressures of 100 -400 bar are applied to counteract, but the NH3 molar fraction in the product gas is still limited thermodynamically to 20 -25 %. Depending on the applied space velocity (SV), which typically ranges from 12000 h -1 to 35000 h -1 , the NH3 content in the reactor outlet can be even smaller. N + 3 H ⇌ 2 NH