Electrochemical conversion characteristics of ammonia to nitrogen

In order to evaluate the electrolytic decomposition characteristics of ammonia to nitrogen, this work has studied several experimental variables of electrolytic ammonia decomposition. The effects of the pH and the chloride ion in the solution, kinds of anodes such as IrO2, RuO2, and Pt on the electrolytic decomposition of ammonia were compared, and the existence of a membrane equipped in the cell, the changes of the current density, the initial ammonia concentration, and so on were investigated for the decomposition. The performances of the electrode were totally in the order of RuO2 approximate to IrO2 > Pt in both the acid and alkali conditions. The ammonia decomposition was the highest at a current density of 80mA/cm(2), over which it decreased, because the adsorption of the ammonia at the electrode surface was hindered by the hydroxyl ions in the solution. The ammonia decomposition yield increased with the concentration of the chloride ion in the solution. However, the increment rate became much lesser over 10 g/l of the chloride ion. The RuO2 electrode among the tested anodes generated the most OH radicals which could oxidize the ammonium ion at pH 7. (c) 2006 Elsevier Ltd. All rights reserved.