A method for reducing the emission of nitrogen dioxide in a motor vehicle with a lean-burn engine

摘要

The invention relates to a method for reducing the emission of nitrogen dioxide (NO 2) in a motor vehicle having an exhaust gas purification system with an SCR catalytic converter (5). In an SCR catalytic converter (5), which has adsorption centers for nitrogen oxides, an exhaust gas enriched with ammonia is fed to the SCR catalytic converter (5) above an operating temperature. Below the operating temperature, the exhaust gas supplied to the SCR catalytic converter (5) is enriched with a substance such that adsorption of nitrogen oxides at corresponding adsorption centers of the SCR catalytic converter (5) is inhibited. It is envisaged that in order to lower the total NOx emission below a predeterminable first amount, an exhaust gas enriched with ammonia is fed to the SCR catalytic converter (5) and the NO 2 fraction of the total NOx emission is reduced below a prescribable second level by NO 2 is reacted with in the SCR catalyst (5) stored hydrocarbons.