| 摘要 |
PROBLEM TO BE SOLVED: To provide an exhaust gas purifying catalyst being direct decomposition type catalyst having a brown millerite type crystal structure, the crystal structure of which is restrained from being decomposed without missing the catalytic activity by narrowing an interval between the crystal lattices as an alkaline-earth metallic element is used so that carbon dioxide is restrained from approaching to the alkaline-earth metallic element. SOLUTION: This exhaust gas purifying catalyst has the compositional ratio of any of general formulae A3B4O9 and A2B2O5 (A and B are two constituent elements), has the grown millerite type crystal structure and decomposes directly nitrogen oxides contained in exhaust gas. This catalyst contains at least one of the element groups of alkaline-earth metallic elements as constituent element A and at least one of the element groups of Sc, Y, Dy, Ho, Er, Tm, Yb and Lu as constituent element B. |
