Improved Catalyzed Soot Filter

摘要

A catalyzed soot filter, in particular for the treatment of Diesel engine exhaust, comprises a coating design which ensures soot particulates filtration, assists the oxidation of carbon monoxide (CO), and produces low H2S emissions during normal engine operations and regeneration events.

主权项

1. A catalyzed soot filter, comprising
a wall flow substrate comprising an inlet end, an outlet end, a substrate axial length extending between the inlet end and the outlet end, and a plurality of passages defined by internal walls of the wall flow filter substrate; wherein the plurality of passages comprise inlet passages having an open inlet end and a closed outlet end, and outlet passages having a closed inlet end and an open outlet end; wherein the internal walls of the inlet passages comprise an inlet coating comprising at least one layer, and the inlet coating extends from the inlet end to an inlet coating end, thereby defining an inlet coating length, wherein the inlet coating length is x % of the substrate axial length, with 25≦x≦100; and wherein the internal walls of the outlet passages comprise an outlet coating comprising at least one layer, and the outlet coating extends from the outlet end to an outlet coating end, thereby defining an outlet coating length, wherein the outlet coating length is y % of the substrate axial length, with 25≦y≦100; wherein the inlet coating length defines an upstream zone of the catalyzed soot filter and the outlet coating length defines a downstream zone of the catalyzed soot filter; wherein the wall flow substrate comprises at least one layer comprising at least one oxidation catalyst and at least one layer comprising at least one H2S suppressing material; wherein said at least one oxidation catalyst and said at least one H2S suppressing material are separated by the internal walls of the wall flow filter substrate; characterized in that the total coating length is x+y, and x+y≧100.