Ag/Ce0.75Zr0.25O2催化剂中Ag的负载量对碳烟燃烧活性的影响

摘要

开发低温下高催化活性的柴油机碳烟颗粒燃烧催化剂是当前环境催化领域的热点问题.利用共沉淀的方法制备了用于碳烟催化燃烧反应的Ag/Ce0.75Zr0.25O2催化剂.活性评价结果表明,相对于Ce0.75Zr0.25O2催化剂,Ag的引入可显著降低碳烟催化燃烧温度.而且,Ag的负载量存在一个最佳值.以XRD、in-situ XRD、BET、TPR等表征手段探究了该系列催化剂结构性质及其变化产生的影响.结果表明,Ag与Ce物种间的相互作用可显著降低催化剂(特别是CeO2表面氧)的还原温度.该相互作用使Ag/Ce0.75Zr0.25O2催化剂在一定温度下(>200℃)就表现出Ag+的性质.这些性质与该催化剂具有较高的碳烟氧化活性相关.而且,该催化剂也表现出良好的稳定性.%It is still important to develop soot oxidation catalysts with excellent activity under low temperature. Ag/Ce0.75Zr0.25O2 was synthesizedvia coprecipitation method for soot oxidation. Compared with the catalytic performance of Ce0.75Zr0.25O2, the introduction of Ag can lead to the decrease of soot-ignition temperature. Moreover, there is an optimal Ag loading. Subsequently, several methods such as XRD,in-situ XRD, BET, TPR were used to characterize the physicochemical properties of Ag-based catalysts. The results showed that the introduction of Ag resulted in decreasing the reduction temperature of surface oxygen species, being due to the interaction of Ag and Ce. The interaction also brings about the occurrence of Ag+ nature. And the feature is linked with the outstanding activity of soot oxidation for Ag-based catalyst. Furthermore, the Ag-based catalyst possessed fairly good stability in soot oxidation.