Catalytic Reduction of NOx

A system for treating an exhaust gas stream, comprising:

• an oxidation catalyst, a particulate trap downstream of the oxidation catalyst, a reductant fluid injector downstream of the particulate trap, and an SCR catalyst downstream of the reductant fluid injector;
• wherein the oxidation catalyst enhances the NO2 content of the exhaust gas stream such that the ratio of NO to NO2 in the exhaust gas stream exiting the oxidation catalyst is lower than the ratio of NO to NO2 in the exhaust gas stream entering the oxidation catalyst;
• wherein the oxidation catalyst adjusts the ratio of NO to NO2 in the exhaust gas stream such that more particulate matter is combusted in the particulate trap and more NOx is removed from the exhaust gas stream in the SCR catalyst than in the absence of the oxidation catalyst;
• wherein the particulate trap traps particulates contained in the exhaust gas stream;
• and
• wherein the reductant fluid injector injects nitrogenous reductant fluid into the gas stream.