| 摘要 |
PROBLEM TO BE SOLVED: To obtain a catalyst for purifying exhaust gas which can improve an NOx purification capacity even in a low temperature area and in a low HC/NOx ratio and control deterioration even under high temperature hydrothermal conditions, and to provide a method for purifying exhaust gas. SOLUTION: A catalyst containing zeolite is arranged in a preceding stage to an exhaust gas flow, and a catalyst which consists of a first catalyst layer containing at least one component selected from the group consisting of platinum(Pt), palladium(Pd), and rhodium(Rh) and at least one component selected from the group consisting of alkali metals, alkaline earth metals, and rare earth metals, a second catalyst layer containing alumina and/or silica, and a third catalyst layer containing a copper (Cu) component and/or a cobalt (Co) component and in which the first, second, and third catalyst layers are overlaid in turn, is arranged in a succeeding stage to the exhaust gas flow. Appropriately, a catalyst for purifying exhaust gas is used for an internal combustion engine in which the air/fuel ratio of exhaust gas is at the lowest 14.7, an oxygen concentration is at the lowest 5%, and an HC/NOx ratio is at the highest 10. |
