Effect of Ceria on the Sulfation and Desulfation Characteristics of Lean NOx Trap Catalysts
Mark Crocker, University of Kentucky
Y. Ji (a), V. Easterling (a), M. Crocker (a), T.J. Toops (b), J. Theis (c), J. Ura (c), R.W. McCabe (c)
(a) University of Kentucky Center for Applied Energy Research, Lexington, KY 40511, USA;
(b) Fuels, Engines and Emissions Research Center, Oak Ridge National Laboratory, Knoxville, TN 37932, USA;
(c) Chemical Engineering Department, Ford Research and Innovation Center, Dearborn, MI 48121, USA
Several years ago, Theis and co-workers reported that the addition of ceria to lean NOx trap (LNT) catalysts improved their sulfur tolerance . It is well known that ceria is able to store sulfur (as sulfate), which may help to delay the poisoning of the main NOx storage components and thereby extend the time between desulfations. To better understand the role of ceria in alleviating the sulfur deactivation of LNTs, we have investigated the NOx storage capacity of ceria-containing and ceria-free powder LNT catalysts before and during sulfation. The desulfation behavior of the powder catalysts has also been studied and the results compared with those obtained for fully formulated monolithic LNTs.
 J. Theis, J. Ura, C. Jr. Goralski, H. Jen, E. Thanasiu, Y. Graves, A. Takami, H. Yamada, S. Miyoshi, SAE Technical Paper Series 2003-01-1160.