Engine off nh3 based selective catalytic reduction nox adsorber

An exhaust treatment system for an engine, comprising:

• a selective catalyst reduction (SCR) treatment module that controls a valve and an air pump to deliver air to an SCR catalyst in response to the engine turning off;
• an SCR loading module that controls the valve and the air pump to deliver air to an exhaust manifold and controls a dosing system to deliver a dosing agent upstream of the SCR catalyst when a temperature of the SCR catalyst is less than a temperature threshold and the SCR catalyst is not saturated with ammonia;
• and
• a decomposition determination module that controls the valve and the air pump to deliver air to the exhaust manifold and controls the dosing system to deliver a dosing agent upstream of the SCR catalyst when the temperature of the SCR catalyst is less than the temperature threshold and the dosing agent is decomposing.