Abstract: An exhaust gas after treatment system includes a diesel particulate filter unit arranged downstream of a diesel engine, a NO2 reduction catalyst arranged downstream of said diesel particulate filter, a selective catalytic reduction (SCR) arrangement arranged downstream of said NO2 reduction catalyst, a first injector for feeding reducing agent into the exhaust gas arranged downstream said particulate filter and upstream said NO2 reduction catalyst, a second injector for feeding reducing agent into the exhaust gas arranged downstream said NO2 reduction catalyst and upstream said selective catalytic reduction (SCR) arrangement. An exhaust gas after treatment method is also provided.

Abstract: A system and an on-board-diagnosis method is provided for an exhaust aftertreatment system of an engine including a diesel particulate filter unit which encompasses a particulate filter in which soot can be oxidized by NO2 and constituents of the exhaust gas are deoxidized in a nitrogen-oxides reduction unit arranged downstream of the diesel particulate filter unit, wherein the exhaust gas flows from the diesel particulate filter unit to the nitrogen-oxides reduction unit. The on-board-diagnosis method includes estimating an NO2 content upstream of the nitrogen-oxides reduction unit, measuring at least one of an NOx or NO2 content upstream of the nitrogen-oxides reduction unit, performing a comparison between the estimated and the measured contents, and, based on the result of the comparison deciding on at least one conditioning step of the diesel particulate filter unit.

Abstract: A system and a method are provided for operating an exhaust aftertreatment system of an engine in which one or more constituents of the exhaust gas are oxidized in an oxidation catalyst and one or more constituents of the exhaust gas are deoxidized by means of a group of possible chemical reactions of different type between the one or more constituents of the exhaust gas and catalytic material arranged in a selective-catalytic-reduction catalyst, wherein the exhaust gas flows from the oxidation catalyst to the selective-catalytic-reduction catalyst, wherein the steps are performed: (a) adjusting at least one desired ratio among one or more pairs of the one or more constituents by varying a space velocity of the exhaust gas in at least the oxidation catalyst; (b) varying the space velocity of the exhaust gas by varying one or more operation parameters of the engine; and (c) establishing the ratio to a value at least approaching the desired ratio among the one or more pairs of the one or more constituents at th

Abstract: A system and a method are provided for operating an exhaust aftertreatment system of an engine in which one or more constituents of the exhaust gas are oxidized in an oxidation catalyst and one or more constituents of the exhaust gas are deoxidized by means of a group of possible chemical reactions of different type between the one or more constituents of the exhaust gas and catalytic material arranged in a selective-catalytic-reduction catalyst, wherein the exhaust gas flows from the oxidation catalyst to the selective-catalytic-reduction catalyst, wherein the steps are performed: (a) adjusting at least one desired ratio among one or more pairs of the one or more constituents by varying a space velocity of the exhaust gas in at least the oxidation catalyst; (b) varying the space velocity of the exhaust gas by varying one or more operation parameters of the engine; and (c) establishing the ratio to a value at least approaching the desired ratio among the one or more pairs of the one or more constituents at th

Abstract: An exhaust gas after treatment system includes a diesel particulate filter unit arranged downstream of a diesel engine, a NO2 reduction catalyst arranged downstream of said diesel particulate filter, a selective catalytic reduction (SCR) arrangement arranged downstream of said NO2 reduction catalyst, a first injector for feeding reducing agent into the exhaust gas arranged downstream said particulate filter and upstream said NO2 reduction catalyst, a second injector for feeding reducing agent into the exhaust gas arranged downstream said NO2 reduction catalyst and upstream said selective catalytic reduction (SCR) arrangement. An exhaust gas after treatment method is also provided.

Abstract: A system and an on-board-diagnosis method is provided for an exhaust aftertreatment system of an engine including a diesel particulate filter unit which encompasses a particulate filter in which soot can be oxidized by NO2 and constituents of the exhaust gas are deoxidized in a nitrogen-oxides reduction unit arranged downstream of the diesel particulate filter unit, wherein the exhaust gas flows from the diesel particulate filter unit to the nitrogen-oxides reduction unit. The on-board-diagnosis method includes estimating an NO2 content upstream of the nitrogen-oxides reduction unit, measuring at least one of an NOx or NO2 content upstream of the nitrogen-oxides reduction unit, performing a comparison between the estimated and the measured contents, and, based on the result of the comparison deciding on at least one conditioning step of the diesel particulate filter unit.