1/1 overview “catalytic filter, exhaust system, positive ignition engine, and method to maintain simultaneous conversion of carbon monoxide, hydrocarbons, nitrogen oxides and particulate matter exhaust gasâ € catal catalyzed filter for filtering particulate matter from exhaust gas comprising one or more catalyst poisons and emitted from a positive-ignition internal combustion engine said filter comprising a porous substrate having a total substrate length and having inlet surfaces and outlet surfaces, wherein the inlet surfaces are separated from the outlet surfaces by a porous structure containing pores of a first major pore size. wherein the porous substrate is coated with a reactive coating composition comprising a plurality of solid particles, wherein the porous structure of the porous substrate of the reactive coating composition contains pores of a second main pore size, such reactive coating composition being arranged axially on the porous substrate as a first zone comprising the inlet surfaces of a first substrate length less than the total substrate length and the second zone comprising the output surfaces of a second length less than the total substrate length, where the sum of the substrate length in the first zone and the substrate length in the second zone is 100%, wherein the reactive coating composition of at least the second zone is a three-way catalyst reactive coating composition comprising one or more precious metals supported on an area oxide. high surface area, and an oxygen storage component and wherein: (i) a specific surface area of reactive coating composition vo in the first zone than in the second zone; or (ii) the loading of both reactive coating composition and a specific surface area of the reactive coating composition in the first zone is than in the second zone.
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