| Diesel vehicles in recent years by means of its good power, economy and durability advantages win people's favor, and its exhaust control technology has developed rapidly. As the important and basic part of diesel exhaust treatment systems, the lean-burn DOC technology not only can promote most of the SOF catalytic conversion, but also shows higher performance on the oxidation of the HC,CO and NO, thereby provides the qualified atmosphere and energy supply. In a word the DOC catalyst technology has double significances: the environment improvement and CO2 emissions reduction.In this paper, Pd supported on four carriers are prepared by incipient wetness impregnation, which Pd loading is 1%, 3%, 5% and 7%. Both fresh and aged samples are tested on home-made dynamic OSC measure instrument and DOC activity equipment for their dynamic OSC and DOC performance. Structure analysis are also done by Brunnauer-Emmett-Teller (BET), pore size distribution test, X-ray diffraction (XRD). Meanwhile, the effects of different Pd loading and Pd-support interaction on OSC and DOC activity are also investigated.Three types of CeO2 materials display different textures and different optimal temperature ranges to show their comparatively higher OSC activities. After aging treatment, 3% Pd-loaded samples perform the comparable OSC activity and BET areas to the samples with even higher loading ratios. In contrast to Pd/Ce100, the Pd/Ce45 and Pd/Ce28 samples display excellent OSC on higher temperature.Activity evaluation results show the different optimal temperature range with regard to differ gases and carriers, of which Pd/Ce100 sample showes the best CO oxidation activity, while with the C3H6,C3H8 and C10H22 oxidation Pd/Ce45 and Pd/Ce28 are better. The activities of aged samples decrease a bit. Of all the Pd / Al sample, 5% Pd shows the best catalytic activity. Further research found that the DOC catalytic activity show the temperature-dependence of their OSC properties. |
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