| abstract |
Low back pressure by a method of catalyzing a filter used in the exhaust system of a spark ignition engine, thereby reducing the total volume of the exhaust system component compared to a separate filter and catalyst substrate component A filter is provided. The filter includes a NOx absorbent catalyst washcoat composition or selective catalytic reduction wherein the inlet surface is separated from the outlet surface by a first porous structure comprising pores of a first average pore size and comprising at least one noble metal. (SCR) The porous substrate is coated with a washcoat composition that is a catalyst washcoat composition, the second porous structure of the washcoated porous substrate includes pores of a second average pore size, The average pore diameter of 2 is smaller than the first average pore diameter. [Selection] Figure 3 |