Photo-reduction of Nitrogen Monoxide with Ammonia

Abstract

Air containing NO and NO₂ was irradiated by a mercury lamp in the presence of various kinds of gaseous compounds such as NH₃, SO₂ and butadiene. NO in the air was rapidly converted into NO₂ by UV irradiation with a high pressure mercury lamp (100 W) at room temperature. By UV irradiadiation, both NO and NO₂ in the air were reduced by the addition of NH₃, SO₂, ethylene, butadiene, isoprene, vinyl chloride and methanol. And they were decomposed more rapidly by the addition of mixture of NH₃ and butadiene than with NH, or butadiene, alone. The photo-reaction between NO and NH₃ in the air brought about the decomposition of O.8 mol of NH₃ and the formation of 1.1 mol of N₂ with respect to the decomposition of unit mole of NO. The photo-reduction of NO in the presence of NH₃ scarcely proceeded in N₂, while that was remarkably accelerated by the addition of a small amount of 0₂. The reaction rate in the air increased with an increase in the concentration of NH₃. The reaction did not depend on reaction temperature in the range of 0 to 80°C. The photo-reduction rate of NO with NH₃ by different light sources was the order with super low>low> high pressure of mercury lamp. The conversion rate of NO to NO₂ by UV irradiation with low pressure mercury lamp was larger than that with high or super low pressure one. On the basis of these results, a mechanism of the photo-reduction of NO with NH₃ in the air was discussed.