초록 ▼

A process and apparatus for reducing the nitrogen oxide content in oxygen-containing emissions is provided, particularly for internal-combustion engines, particularly of diesel engines and directly injecting Otto engines for motor vehicles. The nitrogen oxides contained in the exhaust gas are reduce

A process and apparatus for reducing the nitrogen oxide content in oxygen-containing emissions is provided, particularly for internal-combustion engines, particularly of diesel engines and directly injecting Otto engines for motor vehicles. The nitrogen oxides contained in the exhaust gas are reduced by a suitable reducing agent, such as hydrogen or hydrocarbons, on a DENOX catalyst. For achieving an improved conversion rate for the nitrogen oxides, a combination of hydrogen and hydrocarbons are used as reducing agents. In different operating ranges of the internal-combustion engine only hydrogen, only hydrocarbons, or hydrogen and hydrocarbons are added. Preferably, for this purpose, the quantity of supplied hydrogen or hydrocarbons is reduced or increased with an increasing engine load and/or catalyst temperature and/or rotational engine speed.

대표청구항 ▼

[ What is claimed is:] [1.] The process for reducing nitrogen oxide content in oxygen-containing emissions of internal-combustion engines, the nitrogen oxide content being reduced on a catalyst by means of a reducing agent added in a metered manner to the exhaust gas as a function of operating tempe

[ What is claimed is:] [1.] The process for reducing nitrogen oxide content in oxygen-containing emissions of internal-combustion engines, the nitrogen oxide content being reduced on a catalyst by means of a reducing agent added in a metered manner to the exhaust gas as a function of operating temperatures, said process comprising:operating the engine in a first operating range with only hydrogen being supplied as a reducing agent to the exhaust gas upstream of the catalyst,operating the engine in a second operating range with both hydrogen and hydrocarbons being supplied as reducing agents to the exhaust gas upstream of the catalyst, andoperating the engine in a third operating range with only hydrocarbons being supplied as a reducing agent to the exhaust gas upstream of the catalyst.