Analysis of the By-Products in the Ammonia Production From Urea by Dielectric Barrier Discharge

Ammonia, which is the main product of urea decomposition, is used as the reducing agent in the gas phase plasma NOx treatment. Urea, because of its cheap price and relatively low decomposition temperature (150^degC ), represents an excellent direct source of ammonia. In a dielectric barrier discharge (DBD), such temperatures can be achieved within a few minutes of applying voltage. This paper deals with the chemical analysis of the by-products formed by urea decomposition at about 150^degC-200^degC in a DBD, since it is well known that, depending on the temperature, urea decomposition by-products can be quite different. It was found that 0.25 g of urea used can be completely decomposed in several minutes at a constant input applied voltage of 9 kV (10 kHz). The main by-products are ammonia, isocyanic acid, and cyanuric acid. Moreover, it was found that dry and humid air showed no difference in the by-products formed.