초록 ▼

A method of purifying the lean exhaust gas of lean mix engines or diesel engines. The exhaust gas is first contacted with a permanent reduction catalyst and subsequently contacted with a nitrogen oxide storage catalyst. This procedure yields a uniformly good conversion of pollutants of the exhaust g

A method of purifying the lean exhaust gas of lean mix engines or diesel engines. The exhaust gas is first contacted with a permanent reduction catalyst and subsequently contacted with a nitrogen oxide storage catalyst. This procedure yields a uniformly good conversion of pollutants of the exhaust gases under differing operating conditions both as regards the air ratios and the exhaust gas temperatures.

대표청구항 ▼

[ What is claimed is:] [1.] A method of purifying lean exhaust gas, from a lean mix engine or a diesel engine, containing hydrocarbons, carbon monoxide and nitrogen oxides, the method comprising;conducting said exhaust gas through a cold start, three-way pre-catalyst positioned close to the engine;t

[ What is claimed is:] [1.] A method of purifying lean exhaust gas, from a lean mix engine or a diesel engine, containing hydrocarbons, carbon monoxide and nitrogen oxides, the method comprising;conducting said exhaust gas through a cold start, three-way pre-catalyst positioned close to the engine;thereafter conducting said exhaust gas through a permanent reduction catalyst, thereby reducing nitrogen oxides with the aid of hydrocarbons and carbon monoxide as reducing agents; and thereafterconducting said exhaust gas through a nitrogen oxides storage catalyst, to trap residual nitrogen oxides leaking from the permanent reduction catalyst.