The Pd-only close-coupled catalysts of the different loading sequence of CeO₂ and Pd over Al₂O₃ were prepared using consecutive wetness impregnation method. Differences in structural, surface properties and catalytic performance, together with the thermal aging behaviors of catalyst at 1000 °C were investigated systematically by XRD, TPR, XPS, ICP, CO adsorption and TEM. Consequently, the Ce/Pd/Al catalysts loaded Ce after Pd over the alumina show superior structural properties before and after aging treatment, suggesting the Ce/Pd/Al catalysts possess better thermal resistance than Pd/Ce/Al catalysts loaded Pd after Ce. Moreover, the aged Ce/Pd/Al catalysts possess stronger reducible probed by TPR, and HRTEM and CO adsorption show smaller particles size of Pd and higher palladium dispersion. As a result, for Ce/Pd/Al catalysts, more palladium sites play a role as active site, which promotes low temperature conversion of pollutants effectively. The catalytic performance of the catalysts is forcefully subject to palladium dispersion and reduction property, especially for NO conversion, and the light-off temperature of NO over aged Ce/Pd/Al is 27 °C lower than aged Pd/Ce/Al. The results have demonstrated that novel loading sequence is beneficial to catalytic activity which is maintained even after aging treatment.

CeO ₂和Pd在Al ₂ O ₃上的不同加载顺序的仅Pd紧密偶联催化剂使用连续的湿法浸渍法制备。通过XRD，TPR，XPS，ICP，CO吸附和TEM系统研究了结构，表面性能和催化性能的差异，以及催化剂在1000°C时的热老化行为。因此，在氧化铝上的Pd之后负载Ce的Ce / Pd / Al催化剂在时效处理之前和之后显示出优异的结构性能，表明Ce / Pd / Al催化剂具有比在Ce之后负载Pd的Pd / Ce / Al催化剂更好的耐热性。而且，老化的Ce / Pd / Al催化剂具有更强的TPR可还原性，HRTEM和CO吸附显示Pd的粒径较小，钯的分散度较高。结果，对于Ce / Pd / Al催化剂，更多的钯位点充当了活性位点，有效地促进了污染物的低温转化。催化剂的催化性能受制于钯的分散性和还原性，特别是对于NO转化而言，在老化的Ce / Pd / Al上，NO的起燃温度比老化的Pd / Ce / Al低27°C。结果表明，即使在老化处理之后，新的负载顺序也有利于保持催化活性。