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分别以镧-铈、铈-镧顺序浸渍和镧铈共浸渍的方式在γ-Al2O3载体上引入助剂La2O3和CeO2,然后担载Pd制备了一系列催化剂.以甲醇分解为探针反应,采用XRD、EXAFS和XPS对催化剂的体相和表面结构进行表征,用BET法测定比表面积,并进行了吸附态CO的FTIR研究.结果表明,La2O3容易进入CeO2的晶格中,促进了CeO2在γ-Al2O3上的分散.但不同的La2O3、CeO2加入方式对活性组分Pd在改性载体上的分散度、优势暴露面及其与CeO2之间的相互作用产生不同的影响.关联甲醇分解性能测试结果说明,Pd在载体上的高度分散以及Pd和CeO2之间通过界面产生的强相互作用是催化剂具有高活性的关键.
La2O3 and CeO2 were introduced into γ-Al2O3 carrier by impregnation with lanthanum-cerium, cerium-lanthanum and co-impregnation with lanthanum-cerium, respectively, and then Pd was used to prepare a series of catalysts. Using methanol decomposition as probe reaction, XRD, EXAFS and XPS were used to characterize the phase and surface structure of the catalyst. The BET surface area was measured by BET method and the FTIR of adsorbed CO was also investigated. The results show that La2O3 can easily enter the lattice of CeO2, -Al 2 O 3 dispersion, but different La 2 O 3 and CeO 2 additions have different effects on the dispersion of the active component Pd on the modified support, the dominant exposure surface and the interaction with CeO 2. The results indicate that the high Pd dispersion on the support and the strong interaction between Pd and CeO2 through the interface are the keys to high activity of the catalyst.