Catalytic wet air oxidation of ammonia over supported noble metals

Highly active and selective supported noble metal catalysts were studied in the catalytic wet air oxidation of ammonia. Under the applied reaction conditions (200 C, 50 bar total pressure) only nitrites and molecular nitrogen were detected as primary products. Nitrates formed upon oxidation of nitrites. Platinum-based catalysts were shown to be the most active and among the most selective toward molecular nitrogen. The control of the oxygen coverage at the catalyst surface (metal-oxygen bond energy) was evidenced to have a key impact on both the activity and the selectivity. The retro-disproportionation and nitrous acid decomposition reactions appeared to impact the selectivity upon the conversion of nitrites to nitrates. (C) 2014 Elsevier B.V. All rights reserved.