Effect of preparation method and reaction parameters on catalytic activity for ammonia synthesis

MgO-CeO2 support was prepared by three different methods and impregnated by 1% Ru. These mixed oxides supported Ru catalysts were applied to ammonia (NH3) synthesis. NH3 synthesis activity was highly dependent on the H-2/N-2 ratio, temperature, pressure condi-tions, and physical characteristics of the catalysts. NH3 synthesis increased using a higher H-2 concentration in reactant stream at a relatively higher temperature and pressure con-ditions, while lower H-2 concentration was suitable at lower temperatures. Likewise, the effect of increasing pressure was more dominant at a higher temperature for higher H-2 concentration. Physical characteristics of the catalysts strongly influenced NH3 synthesis activity, which varied for different methods. Increased surface area, high dispersion of Ru and CeO2, and preferential deposition of Ru on CeO2 were responsible for higher NH3 synthesis activity of the catalyst prepared from the co-precipitation method. (c) 2021 Published by Elsevier Ltd on behalf of Hydrogen Energy Publications LLC.