US EPA

1691801 

Journal Article 

Laboratory studies of the reaction between nitrogen dioxide and ammonia in the temperature range of 288-357 K 

Pagsberg, P; Sillesen, A; Brudnik, K; Ratajczak, E 

2001 

49 

4 

299-304 

WOS:000176691900005 

The title reaction has been studied by infrared tunable diode laser spectroscopy which allows for the detection of both reactant and product molecules. The decay rate of ammonia in the presence of nitrogen dioxide was found to be second order with respect to the concentration of NO2. The simultaneous formation of water was found to occur with a relative yield of Delta[H2O] = -0.5Delta[NH3]. The formation of aerosols containing crystalline ammonium nitrate implies that nitric acid is also a primary reaction product in the overall reaction 2NO(2) + 2NH(3)-->N-2 + H2O + NH4NO3. A reaction mechanism involving asym-N2O4 reacting with NH3 has been tested by detailed computer modelling which was used to account for all of the observed kinetic and mechanistic features. For the rate controlling step 2NO(2) + M-->asym- N2O4 + M (1) we have determined an apparent bimolecular rate constant of k(1) 2.30 x 10(-4) x exp(3838 +/- 360/T)M(-1)s(-1) at a total pressure of 30 mbar. 

kinetics; mechanism; IRTDL spectroscopy; dinitrogen tetroxide