| 摘要 |
PURPOSE: To provide a catalyst to effectively purify nitrogen oxides in an exhaust gas from an internal combustion engine which is driven at high air-fuel ratio by depositing a noble metal and oxides of alkaline earth metals containing at least Mg on an inorganic carrier. CONSTITUTION: As an inorganic carrier, a composite oxide of La and β-alumina is used. At least one noble metal among Rh, Pt, Pd, at least one rare earth metal such as Ce, etc., and oxides of alkaline earth metals containing at least Mg are carried on the carrier. A catalyst produced in this manner can effectively purify nitrogen oxides in an exhaust gas discharged out of an internal combustion engine which is driven at high air-fuel ratio. A catalyst having a composition in which, for example, Rh is 0-2wt.% and Pt is 0-5wt.% based on 100 pts.wt. of γ-alumina, and Ce is 0-0.4 mole % and Mg is 0.02-0.18 mole % based on 100 mole % of the inorganic carrier is preferable. |
