| 摘要 |
PROBLEM TO BE SOLVED: To effectively carry out reduction of nitrogen oxide in a waste gas even under the presence of oxygen and moisture by permitting a solid acid carrier to carry silver aluminate at a specified rate of carrying in terms of silver and at least one kind selected from the group of Pt and Ir at a carrying rate within a specified range. SOLUTION: A solid acid carrier such as γ-alumina or the like is made to carry silver aluminate at a rate of carrying of 0.01-10 wt.% in terms of silver and at least one kind (platinum group element) selected from the group of Pt and Ir at a rate of carrying within a range of 0.0001-0.2 wt.%. A catalyst structure body, which is prepared by coating an inert support formed in a desired shape in advance with a powdery catalyst thus obtained by a convenient method such as a wash coat method or the like, is used. A catalyst layer is formed on a surface of a structural body such as a honeycomb, spherical or annular body by a wash coat method or the like, and in order to make the surface carry the catalyst, a catalyst layer has to be of a thickness of not smaller than 30 μm from the surface. |
