Sulfur Tolerance of Selective Partial Oxidation of NO to NO2 in a Plasma

Abstract

<div class="htmlview paragraph">Several catalytic aftertreatment technologies rely on the conversion of NO to NO<sub>2</sub> to achieve efficient reduction of NO<sub>x</sub> and particulates in diesel exhaust. These technologies include the use of selective catalytic reduction of NO<sub>x</sub> with hydrocarbons, NO<sub>x</sub> adsorption, and continuously regenerated particulate trapping. These technologies require low sulfur fuel because the catalyst component that is active in converting NO to NO<sub>2</sub> is also active in converting SO<sub>2</sub> to SO<sub>3</sub>. The SO<sub>3</sub> leads to increase in particulates and/or poison active sites on the catalyst. A non-thermal plasma can be used for the selective partial oxidation of NO to NO<sub>2</sub> in the gas-phase under diesel engine exhaust conditions. This paper discusses how a non-thermal plasma can efficiently oxidize NO to NO<sub>2</sub> without oxidizing SO<sub>2</sub> to SO<sub>3</sub>.</div>