摘要 |
<p>Methods of reducing agent control in an exhaust gas aftertreatment system of a combustion engine with an exhaust gas pipe in which in the direction of flow of the exhaust gas there is an SCR catalyzer. A reducing agent generating system has an NOx and CO/H2 generating unit, an oxidation catalyzer, and a combined NOx storage/ammonia generating unit in the standard gas path of the reducing agent generating system. Ammonia is introduced as a reducing agent for the reduction of nitric oxides before the SCR catalyzer of the reducing agent generating system. Precursor materials for generation of ammonia are directed at least temporarily to the NOx and CO/H2 generating unit through a fuel feed and an air feed. A CO/H2 reducing agent stream is temporally modulated during a rich phase. A CO/H2 concentration is primarily held constant at a high level.</p> |