Ammonia Synthesis and Decomposition with Ru Supported Catalysts

Abstract

An analytical equation for the rate of formation/consumption of nitrogen in the reversible reaction N2 + + 3H2 ↔ 2NH3 was obtained on the base of the analysis of the catalytic properties of 4%Ru–13.6%Cs/Sibunit and 4%Ru–5.4%Ba–7.9%Cs/Sibunit in the processes of ammonia decomposition (105 Pa; 350–470°C) and synthesis ammonia (6×105–5×106 Pa; 400–430°C). This equation allows one to describe correctly the dependence of the chemical reaction rate on the partial pressures of the components of the reaction mixtures for both forward and reverse reactions. The approach used to obtain the kinetic equation is based on the assumption that the adsorption sites on the ruthenium surface are initially filled with hydrogen and then replaced by nitrogen during competitive interaction. The values of the equilibrium constants and apparent activation energies for the synthesis and decomposition of ammonia on the 4%Ru–13.6%Cs/Sibunit and 4%Ru–5.4%Ba–7.9%Cs/Sibunit was found by using the proposed kinetic equation. The data are in good agreement with the ones presented in the literature.