Methods and compositions for assuring reduction of NOx emissions from an engine by selective catalytic reduction

摘要

A reliable SCR system for reducing NOx emissions from a lean-burn internal combustion engine (10) utilizes a chemical tagging reagent to assure proper usage of urea or other NOx-reducing reagent (30). A reagent quality sensor (52) is provided to detect the tagging reagent and authenticate the NOx-reducing reagent (30). The sensor (52) can desirably be used to determine feed rate to assure proper NOx-reducing reagent feed rate, to thus prevent under dosing or over dosing, and can warn of a disruption in feed due to empty tank or stopped up feed line.