Reducing NOx emissions with a staged catalyst

摘要

The conversion of NO_x to nitrogen in the exhaust of a lean burn engine using a hydrocarbon assisted-selective catalytic reduction system is benefited by a two-stage oxidation catalyst-reduction catalyst SCR reactor. The character and quantity of the oxidation catalyst is managed to just activate the hydrocarbon reductant at low temperatures (but not fully burn it at high temperatures) to increase its NO_x reduction efficiency as the exhaust then contacts the larger reduction catalyst stage of the two-stage reactor.