| abstract |
(57) [Summary] (Modified) [Purpose] To provide a method for removing nitrogen oxides emitted from diesel engines. [Composition] In the method of catalytically removing nitrogen oxides using ammonia or urea as a reducing agent, a denitration catalyst layer is installed on the upstream side of the gas flow, and a function of oxidatively decomposing ammonia into nitrogen and nitrogen oxides in the subsequent flow is provided. Have (1 ± 0.6) R 2 O ・ [aM 2 O 3 ・ bAl 2 O 3 ] ・ cMeO ・ y SiO 2 (wherein R is an alkali metal ion and / or a hydrogen ion, M is a group VIII element, a rare earth element, one or more elements selected from the group consisting of titanium, vanadium, chromium, niobium, antimony and gallium, Me is an alkaline earth element), and a crystalline silicate having an X-ray diffraction pattern described in detail in the text as a carrier, and at least one of platinum, palladium, ruthenium, iridium, and rhodium as an active metal. An ammonia decomposition catalyst layer containing various kinds is installed to decompose and remove leaked ammonia. |