Ammonia Synthesis and Decomposition in the Presence of Supported Ruthenium Catalysts

Abstract

Based on analysis of the catalytic properties of 4%Ru–13.6%Cs/Sibunit and 4%Ru–5.4%Ba–7.9%Cs/Sibunit in the ammonia decomposition (10⁵ Pa, 350–470°C) and ammonia synthesis processes (6 × 10⁵–5 × 10⁶ Pa, 400–430°C), an analytical expression for nitrogen formation/consumption rate in the reversible reaction N₂ + 3H₂ \( \rightleftharpoons \) 2NH₃ has been derived to correctly describe the dependence of the chemical reaction rate on the partial pressures of the reaction mixture components for both the forward and reverse reactions. The approach used to derive the kinetic equation is based on the assumption that the adsorption sites of the ruthenium surface are filled with hydrogen, which is subsequently displaced by nitrogen during competitive interaction. Using the proposed kinetic equation, the equilibrium constants and apparent activation energies for ammonia synthesis and decomposition in the presence of 4%Ru–13.6%Cs/Sibunit and 4%Ru–5.4%Ba–7.9%Cs/Sibunit catalysts have been determined; the values are in good agreement with the published data.