| 摘要 |
PROBLEM TO BE SOLVED: To effectively remove nitrogen oxides contained in an exhaust gas by using a catalyst for cleaning nitrogen oxides used in the coexistence of a hydrocarbon or an organic compound containing oxygen, formed of silica alumina as a porous heat-resistant carrier and silver or silver compounds as an active component borne by the carrier. SOLUTION: This catalyst for cleaning nitrogen oxides is for cleaning an exhaust gas from a lean burn gasoline engine by removing and making harmless nitrogen oxides contained in an exhaust gas from a lean burn gasoline engine, and is used in the presence of hydrocarbons or an organic compound containing oxygen. Silica alumina containing 0.5-15wt.% of silica is used as a porous heat- resistant carrier, and at least, one selected from silver and silver compounds is borne by this carrier as an active component. The silver compounds are silver halogenide such as silver chloride or silver bromide, or silver sulfate, silver phosphate or silver oxide. The amount of these active components to be borne by the porous heat-resistant carrier is equivalent to the preferable range of 0.01-20.0wt.% in terms of silver. |
