| 摘要 |
<p>A catalytic trap (10) for the treatment of exhaust generated by lean-burn or partial lean-burn engines is resistant to deactivation by high temperature, lean operating conditions aging. The catalytic trap (10 or 10') comprises a carrier member (12 or 12/12') on which is coated a catalytic trap material (20), optionally in discrete layers (20a, 20b) comprising a NOx sorbent and a refractory metal oxide support on which is dispersed a palladium catalytic component in an amount of at least 25 g/ft3 Pd up to about 300 g/ft3 Pd. A platinum and/or a rhodium catalytic component may also be present. The NO¿x? sorbent may be one or more basic oxygenated compounds of an alkali metal and/or an alkaline earth metal, e.g., of cesium and/or barium. A method of making includes applying the NOx sorbent by a post-dipping technique. A method of use includes alternating lean and stoichiometric or rich periods of operation and optionally oxidizing hydrocarbons in the exhaust prior to contacting the exhaust with the catalytic trap (10).</p> |
