FIELD: exhaust gas purification.
SUBSTANCE: invention relates to a catalytic product for reducing emissions of harmful substances from an exhaust gas stream containing substrate containing an inlet side and an outlet side, the first zone and the second zone, where the first zone contains an ammonia slip catalyst (hereinafter – ASC) containing platinum group metal on a carrier and the first SCR catalyst, where the second zone contains a catalyst containing a diesel oxidation catalyst (DOC), where the first zone is located upstream in front of the second zone; and where the first zone contains a lower layer containing a mixture of (1) platinum group metal on the carrier and (2) the first SCR catalyst, an upper layer containing the second SCR catalyst, wherein the upper layer is located on top of the lower layer. The invention also relates to a catalytic product for reducing emissions of harmful substances from an exhaust gas stream containing substrate containing an inlet end and an outlet end, the first zone, the second zone and the third zone, while the first zone contains the second SCR catalyst, while the second zone contains an ammonia slip catalyst (ASC) containing a mixture of (1) platinum group metal on a carrier and (2) the first SCR catalyst, while the third zone contains a catalyst (“third zone catalyst”) containing a diesel oxidation catalyst (DOC), and the first zone is located upstream in front of the second zone, and the second zone is located upstream in front of the third zone, wherein ASC is included in the first layer, the third zone catalyst is included in the second layer, which extends from the outlet end to a length that is less than the full length of substrate, while the second layer is located on top of the first layer and has a shorter length than the first layer; and the second SCR catalyst is included in a layer that extends from the inlet end to a length that is less than the full length of substrate, and which at least partially overlaps the first layer. The invention also relates to methods for reducing emissions of harmful substances from the exhaust gas stream, including contacting the exhaust gas stream with the claimed catalytic products.
EFFECT: obtaining a catalyst that provides both the removal of NOx by SCR and the selective conversion of ammonia into nitrogen, and at the same time the conversion of ammonia occurs over a wide temperature range in the driving cycle of the vehicle, and by-products in the form of nitric oxide and nitrous oxide are formed in the minimum amount.
20 cl, 12 dwg, 2 ex
