Diesel oxidation catalyst

A method for treating a diesel engine exhaust gas stream, the method comprising contacting an exhaust gas stream with an oxidation catalyst composite, and passing the exhaust gas stream through a downstream SCR catalyst, 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 at least one platinum group metal (PGM) and a first refractory metal oxide, wherein the first oxidation component is substantially free of zeolite;
• a NOx storage component comprising one or more of alumina, silica, titania, ceria, and manganese;
• and
• a second oxidation component comprising a second refractory metal oxide, a zeolite, and at least one PGM.

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 an 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 at least one platinum group metal (PGM) and a first refractory metal oxide, wherein the first oxidation component is substantially free of zeolite;
• a NOx storage component comprising one or more of alumina, silica, titania, ceria, and manganese;
• and
• a second oxidation component comprising a second refractory metal oxide, a zeolite, and at least one PGM.