NO _x storage and reduction properties of ceria-promoted lean NO _x trap catalysts

As part of our investigations into the function of ceria in lean NOx trap catalysts, this study focuses on the use of ceria as a NOx storage component and as a support material. Model power catalysts were prepared in which ceria functioned either as a support for the main Ba NOx storage phase, or as the main NOx storage component itself. Relative to a ceria-free Pt/BaO/Al ₂O ₃ reference catalyst, catalysts containing both Ba and CeO ₂ were found to exhibit superior NO _x storage capacity at 200 and 300 °C, while analytical data indicated that the use of CeO ₂ as a support afforded more a highly dispersed Ba phase in comparison to Al2O ₃. In addition, regeneration behavior at low temperature was greatly improved by the presence of CeO ₂. These factors contributed to the superior NO _x storage-reduction performance exhibited by the CeO ₂-containing catalysts under lean-rich cycling conditions in the temperature range 200-300 °C.