Method and system for NOx reduction

摘要

A system and method for controlling reductant injection upstream of a selective reduction catalyst (SCR) to overcome NOX inhibiting effects by injecting reductant in an amount proportional to engine out NOX concentration when the NOX concentration is above a predetermined level and injecting predetermined amounts of reductant into the SCR catalyst when engine out NOX concentration is below the predetermined level such as when the engine is idling or decelerating.