Lee Deuk Ki, Cho Jeong Shik, Yoon Wang Lai
Department of Environmental Engineering, Gwangju University, Jinwold-dong 592-1, Gwangju 503-703, Korea.
Chemosphere. 2005 Oct;61(4):573-8. doi: 10.1016/j.chemosphere.2005.03.011. Epub 2005 Apr 26.
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.
阐明了催化剂的作用以及在水相中Ru（3wt.%）/TiO₂催化剂上氨催化氧化反应中优先生成N₂的原因。已证实反应中的催化剂与N₂的选择性生成没有直接关系，仅负责氧化水溶液中的氨NH₃(aq)，最终生成一分子亚硝酸。通过实验证明，由于亚硝酸解离出的NO₂⁻与NH₄⁺离子在水相中的均相反应，N₂得以优先生成。即使在高氧化条件下，只要溶液中有NH₄⁺，NO₂⁻与NH₄⁺反应生成N₂的可能性远大于在催化剂上被氧化为NO₃⁻。
