Influence of method of preparation on ammonia synthesis activity of cesium promoted ruthenium catalysts supported on active carbon (AC)

Abstract

Cesium promoted ruthenium catalysts supported on active carbon (AC) with the weight ratio of Cs:Ru:AC = 51:10:100 are prepared by three different methods, (1) by depositing CsNO₃ on reduced Ru/AC, (2) by simultaneous deposition of CsNO₃ and RuCI₃ on AC and (3) by depositing RuCl₃ on reduced Cs₂O/AC through aqueous medium and evaluated for ammonia synthesis at atmospheric pressure and at 400°C. It is observed that the catalyst prepared by method (I) exhibits the highest activity which is almost equal to thermodynamic equilibrium value at 400°C and the activities follow the sequence: catalyst-1 > catalyst-2 » catalyst-3. Ruthenium dispersions of these catalysts are determined by CO chemisorption at ambient temperature. The ammonia synthesis activities of the catalysts are correlated to the dispersion characteristics of ruthenium influenced by the methods of preparation.