Abstract
The behaviors of NH3 and N2O in NH3-O2-N2 and NH3-N2O-O2-N2 mixture were studied under UV irradiation at room temperature. NH3 in NH3-O2-N2 mixture decomposed to N2, N2O and H2O under a high pressure mercury lamp irradiation. The selectivity of N2O formation was constant independent of O2 concentration in the presence of excess O2 and was approximately 14 % of the amount of NH3 decomposed. The decomposition rate of NH3 was independent of O2 concentration and proportional to the concentration of NH3. While, under a low pressure mercury lamp irradiation, NH4NO3 formed with N2, N2O and H2O. The decomposition rate increased remarkably with increasing the concentration of O2 and expressed by the following equation
- d (NH3) /dθ= k [NH3] + k' [O2] 1/2 [θ = W/F (watt⋅min⋅l-1) ]
The selectivity of N2O formation increased with increasing the concentration of O2 and decreased rapidly with further increasing over than 10 %. The results may be caused by the oxidative consumption of the intermediate HNO for N2O formation to give NH4NO3. No effect of N2O was observed in the decomposition of NH3 in NH3-O2-N2 mixture under a high and low pressure mercury lamp irradiation. N2O increased a little by the oxidative decomposition of NH3 in N2O-NH3-O2-N2 mixture under a high pressure mercury lamp irradiation and in the early stage under a low pressure mercury lamp irradiation, while decreased in the later stage under a low pressure mercury lamp irradiation. The decomposition rate of N2O was not affected by the presence of NH3.
