| abstract |
A catalyst system for the selective reduction of gaseous NO x in the presence of excess oxygen, having a copper-containing ZSM5 zeolite to which a NO x -containing gas is exposed, and means for introducing a metered volume of finely dispersed, water soluble, oxygen-containing organic compound (alcohol, aldehyde, ketone, ether) into the NO x -containing gas prior to exposure to the Cu-ZSM5 zeolite. n Also, a method of treating automotive exhaust gas emissions, having an excess of oxygen, by the steps of: (a) introducing a water soluble, oxygenated organic compound (steam/oxygenate mixture) into the exhaust gas emissions as a reductant and at a location closely adjacent the source of the exhaust gas generation (in an appropriate amount with respect to the NO x ); (b) substantially immediately exposing the reductantl/emission mixture to a transition metal-exchanged high silica ZSM5 zeolite (SiO₂/Al₂O₃ of between 10-50) catalyst at a space velocity in the range of 20-80 K hr⁻¹; and (c) sequentially exposing the effluent of such zeolite catalyst to an oxidation catalyst. |