It has been attempted to obtain the optimum decomposition temperature of ammonium nitrate yielding notrous oxide in a selected temperature range from 240 ℃ to 260 ℃. The difficulty in maintaining a constant reaction temperature in an exothermic decomposition reaction of ammonium nitrate has been dissolved by sampling only a small quantity of ammonium nitrate on a hot stainless steel reactor bottom with a large heat capacity.
A pressure transducer has been mounted atop of hermetically sealed reactor as the means of measuring the reaction rate in terms of total pressure increase in the reactor due to the formation of the product gases.
A device for introducing the solid sample into the reactor was used so that the sample could come in contact with the heated reactor bottom plate and start the reaction only at the desired temperature.
It has been also confirmed by the hand made gas chromatography unit that the reaction, NH₄NO₃ -> N₂O + 2H₂O, has proceeded in a selected temperature range without being accompanied by side reactions to any appreciable extent.
It was concluded that the reaction was definetely a zero order reaction and was proceeded at a nearly constant temperature, and that there was no optimum value of temperature within the selected temperature range.
When nitrous oxide were the disired product, the temperature of reaction should be maintained as low as possible, if the reaction rate were not too much sacrificed. Although the side reactions were not appreciable, the higher the temperature, the more the formation of nitric oxide in the product gases became pronounced as per the gas chromatographical analyses.