Surface Structure of γ-Alumina-Supported Iron Catalysts for Ammonia Synthesis

Iron supported catalysts were prepared by impregnation of iron from a K₄[Fe(CN)₆] aqueous solution, upon several acid-modified γ-Al₂O₃ samples. Characterization of the catalysts was carried out by CO chemisorption, temperature programmed reduction (TPR), and kinetics of hydrogen reduction, resulting the particle size and dispersion of the metallic phase dependent on the previous acid modification of the γ-Al₂O₃. The catalytic activity for ammonia synthesis was followed at atmospheric pressure and 593 K (N₂/H₂ = 1/3). Correlations of the surface properties of the catalysts with their method of preparation and catalytic activities are obtained.