Catalytic wet oxidation of ammonia: why is N2 formed preferentially against NO3 -?
The role of catalyst and the reason for the preferential formation of N(2) in the catalytic oxidation reaction of ammonia in water over a Ru (3wt.%)/TiO(2) catalyst were elucidated. It was verified that the catalyst in the reaction had no direct relevance to the selective formation of N(2), but was responsible only for the oxidation of aqueous ammonia, NH(3)(aq), finally giving a molecule of nitrous acid. The preferential production of N(2) was experimentally demonstrated due to the homogeneous aqueous phase reaction of the nitrous acid-dissociated NO(2)(-) with NH(4)(+) ions. Even under the highly oxidizing condition, NO(2)(-) was much more likely to react with NH(4)(+) to form N(2) than being oxidized over the catalyst to NO(3)(-) as long as NH(4)(+) was available in solution.
Lee
Deuk Ki
DK
Department of Environmental Engineering, Gwangju University, Jinwold-dong 592-1, Gwangju 503-703, Korea. dklee@gwangju.ac.kr
Cho
Jeong Shik
JS
Yoon
Wang Lai
WL
D000641:Ammonia / Q000737:chemistry / Q000302:isolation & purification*; D002384:Catalysis; D006863:Hydrogen-Ion Concentration; D009566:Nitrates / Q000737:chemistry; D009573:Nitrites / Q000737:chemistry; D009584:Nitrogen / Q000737:chemistry*; D010084:Oxidation-Reduction; D012428:Ruthenium / Q000737:chemistry; D014025:Titanium / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000302:isolation & purification*; D018508:Water Purification
D009566:Nitrates; D009573:Nitrites; D014874:Water Pollutants, Chemical; C009495:titanium dioxide; D000641:Ammonia; D012428:Ruthenium; D014025:Titanium; D009584:Nitrogen