不同载体负载的Pd催化剂上CO氧化性能比较

Comparison of CO Oxidation Performance on Various Supported Pd Catalysts

采用沉淀-沉积法制备了一系列不同载体负载的纳米Pd催化剂。以CO氧化为模型反应,考察了载体差异对催化剂CO催化氧化性能的影响。结果发现,载体对Pd催化剂的CO催化氧化性能影响较大,以分子筛为载体的Pd催化剂的活性明显优于金属氧化物担载的催化剂。同时,考察了反应温度、时间、空速及加湿条件等对催化剂CO氧化活性的影响,并利用XRD和XPS等测试手段对催化剂体相结构和表面状态进行了表征。结果表明:催化剂的活性随着反应温度的升高而增加,随着空速的增加而降低。XRD和XPS结果证实不同载体负载的催化剂其表面活性Pd物种的状态有较大差异,分子筛载体利于活性Pd物种向催化剂表面迁移,这种作用以及Pd物种的高分散与催化剂的活性直接相关。

Series of nano-palladium catalysts supported on different carriers were prepared by the method of deposition-precipitation （DP） Taking CO oxidation as a model reaction, the effects of the various carriers on the activity of CO oxidation were investigated. The results show that the activities are strongly dependent on the carriers. The activities of the zeolite supported catalysts are superior to those of the metal oxide supported ones. The influences of reaction temperature, reaction time, space velocity and moisture on the catalytic activity for CO oxidation were investigated. These catalysts were characterized by means of XRD and XPS techniques to verify the species and the geometry of the catalysts. It is found that the catalytic activity increases with the increase of the reaction temperature. The high space velocity results in the lower activity for CO oxidation. XRD and XPS results prove that the surface active Pd species of these catalysts are different. The support of zeolite is beneficial for Pd species moving towards the surface of the catalyst, which, as well as the high Pd dispersion, is directly related to the catalytic activity of the catalysts.