A chemical kinetic model for the selective reduction of nitric oxide by ammonia

Abstract

A chemical kinetic model has been developed which explains the important features of the reaction between ammonia and nitric oxide in the presence of oxygen. Essential to the model is a chain branching mechanism, initiated by the reaction between amidogen (NH 2) and nitric oxide, which is directly responsible for NO removal and allows the further conversion of ammonia to amidogen. At high temperatures, this process becomes counterproductive, resulting in NO formation; at low temperatures, it is dominated by chain termination steps. Thus there is a narrow temperature window in which nitric oxide reduction is effective. The role of excess oxygen and the effect of adding hydrogen are also explained by the model. Possible products of the NH 2 + NO reaction are discussed in some detail, and it is shown that different product channels can lead to the same effects.