Abstract: Three light-duty gasoline vehicles are selected to conduct the emission tests based on WLTC and NEDC cycles to analyze the emission characteristics of regular pollutants and ammonia. The results show that ammonia is a byproduct of oxidation-reduction reactions, which occur when the initial exhaust of engine enters into three-way catalytic converter (TWC). The main condition for ammonia formation is long-duration acceleration, when relatively high concentration of CO provides a relatively strong reduction environment in TWC, leading to the forming of ammonia. The ammonia emission shows a rising trend as the mileage increases and high CO and ammonia emissions are more likely to occur under low temperature environment.

Key words: ammonia emission characteristics, WLTC cycle, NEDC cycle, three-way catalytic converter