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以浸渍法制备了一系列添加CeO2 的Pd Ce/NaZSM 5负载型催化剂 .以CO氧化为模型反应 ,考察了反应温度、Ce含量、预还原、空速及水蒸气等对CO氧化性能的影响 ,并利用XRD和XPS等手段对催化剂体相及表面结构进行了表征 .结果表明 :加入CeO2 作助剂可明显提高催化剂的活性 ,且催化转化率随着反应温度及Ce含量的增加而增加 ;随着空速的增加而降低 ;催化剂对水蒸气不敏感 ,在水蒸气存在的条件下反应可连续进行 72 0h以上保持CO完全转化 ;H2 预还原作用使催化剂活性有所提高 .XRD测试结果表明 ,催化剂中Pd组分处于高分散状态 ,CeO2 的引入促进了Pd物种在NaZSM 5载体上的分散 .表面XPS分析证实催化剂表面Pd物种处于较高的氧化状态 ,且CeO2 与Pd物种间存在协同作用 .Pd的高分散及其与CeO2 的相互作用是催化剂具有高活性的关键
A series of Pd-Ce / NaZSM 5 supported catalysts with CeO 2 were prepared by impregnation method.The effects of reaction temperature, Ce content, pre-reduction, space velocity and water vapor on the oxidation performance of CO were investigated by CO oxidation as model reaction, The phase and surface structure of the catalyst were characterized by XRD and XPS.The results showed that the addition of CeO2 as a promoter can significantly improve the activity of the catalyst and the catalytic conversion rate increases with the increase of reaction temperature and Ce content. The catalyst is not sensitive to water vapor, the reaction can be continuously carried out for more than 72h in the presence of water vapor for complete conversion of CO, and H2 pre-reduction makes the catalyst activity increased.XRD test results show that, The Pd component in the catalyst is highly dispersed and the introduction of CeO2 promotes the dispersion of the Pd species on the NaZSM 5 support.The surface XPS analysis confirms that the Pd species on the catalyst surface is in a higher oxidation state and the synergism between the CeO2 and the Pd species exists. The high dispersion of Pd and its interaction with CeO2 is the key to the high activity of the catalyst