| 摘要 |
<p>The present invention is directed to a lean NOx trap diesel oxidation catalyst for the treatment of exhaust gas emissions, such as the oxidation of unburned hydrocarbons (HC), and carbon monoxide (CO) and the trapping and reduction of nitrogen oxides (NOx). Catalytic composites can comprise a catalytic material on a carrier, the catalytic material comprising a first NOx trap layer that comprises a NOx sorbent and one or more precious metal components located on the carrier and a second NOx trap layer containing hydrocarbon trapping functionality located over the first NOx trap layer that comprises a NOx sorbent, one or more precious metal components, and a zeolite, for example a beta zeolite, wherein the zeolite is substantially free of framework aluminum. Such zeolites are characterized by high crystallinity and/or by being substantially free of framework aluminum to minimize surface acidity.</p> |
