| Abstract:A global model of Rh only three way catalytic（TWC） suitable for a stoichiometric natural gas engine was established, and the effects of exhaust temperature and composition on the generation characteristics of side-products N2O and NH3 were investigated. The results show that N2O is primarily formed during light-off and low temperature period（400K～605K）, which proceeds via reduction of NO by CO. NH3 is observed at high temperature（＞850K） via reduction of NO by H2, and the H2 required to produce NH3 is generated via steam reforming and water gas-shift reactions over the catalysts. The increase of H2 concentration promotes the production of N2O and NH3. At high temperature, the N2O production will react with H2, and the higher the H2 concentration, the lower the N2O generation. The effect of H2O and CH4 on the formation of N2O and NH3 varies with temperature. Within a certain temperature range, as the O2 concentration increases, the NH3 production decreases and the N2O production increases. At high temperature, the N2O production decreases when the O.2 concentration is too high and under 4000×10-6 O2 concentration, the zero emission of N2O and NH3 can be achieved by controlling the exhaust temperature at 580K～850K range. |