Diesel oxidation catalyst

A system for treatment of a lean burn engine exhaust gas stream comprising hydrocarbons, carbon monoxide, nitrogen oxides, particulate matter, and other exhaust components, the system comprising:

• an exhaust conduit in fluid communication with a lean burn engine via an exhaust manifold;
• an oxidation catalyst composite;
• and
• a catalyzed soot filter and a selective catalytic reduction (SCR) catalyst located downstream from the oxidation catalyst composite;
• wherein the oxidation catalyst composite comprises:
• a carrier substrate;
• and
• a catalytic coating on at least a portion of the carrier substrate, the catalytic coating including:
• a first oxidation component comprising a platinum (Pt) component, a palladium (Pd) component and a refractory metal oxide, wherein the first oxidation component is substantially free of zeolite;
• a NOx storage component comprising ceria and one or more of alumina, silica, titania, and manganese;
• and
• a second oxidation component comprising a second refractory metal oxide, a zeolite, and platinum (Pt) component,
• wherein the first oxidation component comprises the Pt component to the Pd component in a weight ratio of about 0:1 to 4:1,
• wherein the NOx storage component is substantially free of platinum, palladium, and zirconia,
• wherein the NOx storage component comprises a ceria in a range from about 80-99.8 wt. %, alumina in a range from about 0.1 to 10 wt. %, and silica in a range from about 0.1 to 10 wt. % based on a weight of the NOx storage component,
• wherein the second oxidation component is substantially free of palladium, wherein the first oxidation component is in an under layer on the carrier substrate, the NOx storage component is in a middle layer on the under layer, and the second oxidation component is in an upper layer on the middle layer.