Exhaust gas aftertreatment systems

摘要

A method for improving NOx conversion efficiency of a urea base SCR catalyst is presented. Since efficiency is reduced by the presence of hydrocarbons in the catalyst, the method proposes to regenerate the SCR by maintaining its temperature above the boiling point of hydrocarbons for a sufficient period of time to free up catalyst storage sites. The regeneration process is followed by over-injection of ammonia to replenish the ammonia released from the SCR catalyst due to high regeneration temperatures.