Kinetic Analysis of Ammonia Production on Ru Catalyst Under High Pressure Conditions

Abstract

To promote deployment of ammonia production system using hydrogen generated by renewable energy, it is necessary for operation of catalytic reactor to vary process parameters, such as temperature, pressure, space velocity and ratio for flow rate of hydrogen to nitrogen, according to the situation of hydrogen supply and forecast of renewable energy supply. Therefore, development of kinetic model that can be applied to various operating conditions is important for design of the ammonia production system. In this chapter, kinetic analysis of ammonia synthesis on ruthenium-based catalysts under high pressure conditions for simulating the reactor situation under varying hydrogen supply is discussed. Various kinetic analysis on iron-based catalysts is considered, and then the reaction rate equation for ruthenium-based catalysts is estimated. In analysis of kinetics of ammonia synthesis over Ru/Cs/MgO catalyst, ammonia production on this catalyst is well explained by the Langmuir–Hinshelwood model. In kinetic analysis for Ru/CeO₂, an optimized kinetic model on the catalyst is showed to be different from that on the above-mentioned Ru/Cs/MgO catalyst. And it could be estimated that Ru/CeO₂ performs favorable activity as an ammonia synthesis catalyst under high pressure conditions. Additionally, the intermediate surface species (NH_x) on Ru/CeO₂ is suggested to be contribute to the total rate of ammonia synthesis under high pressure conditions.