Method for removal of NOx and particulate matter

摘要

The invention relates to a method of low temperature NOx reduction without gaseous reductant under absolutely lean conditions using the combination of silver with some transition metals (Co, Ni, Cu, Mn, Fe) or metal oxides of Ce, Pr or Bi as a catalyst-adsorbent. First step is NO oxidation to NO2 using this catalyst at 220-350 DEG C and NO2 thus produced can be converted on the same catalyst from room temperature up to 200 DEG C. These systems are also good adsorbents for NO and NO2 and release basically NO2 during desorption. This NO2 released can be used for simultaneous soot removal. Engine testing of Ag-Ce and Ag-Ce-Co formulations deposited on diesel particulate filter revealed the good activity in soot oxidation and filter regeneration of such a system at 250-350 DEG C using NOx emitted from engine.