Exhaust gas cleaner and method for cleaning exhaust gas

摘要

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.