초록 ▼

An exhaust gas cleaner is constituted of an Ag catalyst carrying an Ag component and a base metal catalyst carrying a Cu component and optionally W, V, Mo components, and a noble metal catalyst carrying a noble metal component. The base metal catalyst and the noble metal catalyst may be physically m

An exhaust gas cleaner is constituted of an Ag catalyst carrying an Ag component and a base metal catalyst carrying a Cu component and optionally W, V, Mo components, and a noble metal catalyst carrying a noble metal component. The base metal catalyst and the noble metal catalyst may be physically mixed to form a mixed catalyst. Another exhaust gas cleaner is constituted of the first Ag catalyst carrying an Ag component, the second Ag catalyst carrying an Ag component, a base metal catalyst carrying a Cu component and optionally W, V, Mo components, and a noble metal catalyst carrying a noble metal component. The second Ag catalyst carries the Ag component in an amount larger than that of the first Ag catalyst. The noble metal catalyst is physically mixed with the base metal catalyst to form a mixed catalyst. The exhaust gas cleaner can effectively remove nitrogen oxides in a wide temperature range of exhaust gas.

대표청구항 ▼

[ What is claimed is:] [1.] An exhaust gas cleaner for removing nitrogen oxides by reduction from an exhaust gas containing nitrogen oxides and oxygen in an amount larger than its stoichiometric amount relative to unburned components in said exhaust gas, wherein said exhaust gas cleaner consists ess

[ What is claimed is:] [1.] An exhaust gas cleaner for removing nitrogen oxides by reduction from an exhaust gas containing nitrogen oxides and oxygen in an amount larger than its stoichiometric amount relative to unburned components in said exhaust gas, wherein said exhaust gas cleaner consists essentially of:(a) a silver catalyst consisting essentially of a first porous inorganic oxide supporting 0.2-15 weight % of at least one silver component selected from the group consisting of silver and compounds of silver;(b) a base metal catalyst consisting essentially of a second porous inorganic oxide supporting 0.2-30 weight % of at least one copper component selected from the group consisting of oxides and sulfates of copper, and optionally supporting 30 weight % or lese of at least one component selected from the group consisting of oxides and sulfates of vanadium and oxides and sulfides of tungsten and molybdenum; and(c) a noble metal catalyst consisting essentially of a third porous inorganic oxide supporting 0.01-5 weight % of at least one component selected from the group consisting of platinum, palladium, ruthenium, rhodium, iridium, and gold, the weight percentages being expressed on a metal basis and being based upon the amount of each porous inorganic oxide, and said silver catalyst, said base metal catalyst, and said noble metal catalyst being disposed in this order from inlet side to outlet side of said exhaust gas cleaner.