| 摘要 |
PURPOSE:To enable contact reduction of nitrogen oxide with using hydrocarbon as a reducing agent in the exhaust gas temp. range from 200 to 500 deg.C by incorporating specified catalytic components (a), (b) and (c) described below into the catalyst. CONSTITUTION:At least one metal oxide (a) selected from TiO2 Al2O3, ZrO2, and SiO2, and rare earth oxide (b) are preliminarily mixed, molded by a proper method (e.g. extrusion molding, punching into tablets, or forming into spheres), and then calcined at 300-800 deg.C. The calcined product is then immersed in an aq. soln. of soluble salt of metal selected from Ru, Rh, Pd, Ag and Pt or metal oxide of these (c), dried and calcined at 300-800 deg.C. Further, if required, the product is calcined in a reductive atmosphere to obtain a selective reduction catalyst for nitrogen oxides. The preferable compsn. ratio of (a), (b), and (c) is, by atomic ratio, (a):(b):(c)=(99-70):(1-20):(0.01-10). |
