| abstract |
A method to produce a NO x trap composition, and its use in a NO x trap and in an exhaust system for internal combustion engines, is disclosed. The NO x trap composition is produced by heating an iron-containing zeolite in the presence of an inert gas and an organic compound to produce a reductively calcined iron/zeolite. A palladium compound is then added to the reductively calcined iron/zeolite, and the resulting Pd—Fe/zeolite is then calcined at 400 to 600° C. in the presence of an oxygen-containing gas to produce the NO x trap composition. The NO x trap composition shows low temperature NO capacity below 200° C., as well as an additional NO storage temperature window in the 200 to 250° C. range. |