Pd/MgO/γ-Al_2O_3的结构和催化性能的研究

Study on the Structure and Catalytic Performance of Pd/MgO/ γ Al 2O 3

用常规浸渍法和双浸渍法制备了系列ＭｇＯ／γ－Ａｌ２Ｏ３复合氧化物载体负载的钯催化剂．实验结果发现，两种制备方法所得催化剂中，钯在复合载体上沉积的部位不同，从而导致了不同的钯与载体的相互作用，使得活性金属钯的电子密度发生不同程度的变化．钯催化剂对ＣＯ氧化反应活性不仅与钯分散度有关，而且还与催化剂中活泼的晶格氧及钯与载体作用方式有关．钯催化剂随载体中ＭｇＯ含量的变化而呈现的活性变化趋势是以上各因素协同作用的结果．

Palladium catalysts supported on composite MgO/ γ Al 2O 3 were prepared by conventional impregnation(CI) and double impregnation(DI) methods. Several ordinary means were performed for characterization, such as temperature programmed reduction(TPR), in situ IR with CO as probe molecule, H 2 O 2 titration for determining palladium dispersion, and CO oxidation as test reaction. It is found that different deposition sites of palladium on MgO/ γ Al 2O 3 and different mechanisms of palladium support interaction lead to the difference in electron density of palladium in these two kinds of catalysts. Activity of palladium catalysts for CO oxidation relates not only to the palladium dispersion, but also to the active lattice oxygen and the mechanism of palladium support interaction. The high activity of this catalyst is a consequence of the combined effect of these factors.