PNNL

Abstract

Upcoming regulations regarding diesel engine emissions require substantial reduction in particulate matter and nitrogen oxides through aftertreatment methods. Since sulfur oxides in the exhaust greatly reduce the performance of the aftertreatment system, a dedicated trap for removal of sulfur oxides has been considered. Most adsorbents are more effective in removing SO3 than SO2; hence oxidation catalysts have been employed to maximize the concentration of SO3 in the effluent. Although SO2 concentrations are easily measured, SO3 is less easily quantified. As a result, the only figure of merit for the SOx trap performance has been total capacity, provided by post-characterization. In this paper we describe a chromatographic method for measurement of SO2 and SO3 adsorption in real time, which provides adsorbent performance data on breakthrough capacities and sulfur slip, especially important when operating at high space velocities. We also provide experimental measurements of breakthrough capacities for SO2 and SO3 adsorption for some common metal oxide adsorbents using this analytical system.