摘要
用共沉淀法制备Mn-CeO2复合氧化物,实验发现了Mn掺杂的CeO2在经过N2吹扫的预处理后吸附Hg0的能力会受到较大损失。为解释上述现象,建立了Mn掺杂的CeO2(111)表面模型,通过H原子的附加使得表层获得电子补偿趋于稳定,计算考虑了Ce-4f、Mn-3d电子间强关联作用的GGA+U方案,以此研究了表层O原子失去前后Hg的吸附能力的变化。研究结果表明,Hg在失去一个表层O原子的掺杂表面仅为微弱的物理吸附,说明在N2吹扫之后可能会丢失表层的活性O物质,导致Hg0的吸附性能降低。
Mn doped CeO2 was prepared by co-precipitation method. Through the mercury adsorption experiment, a great reduction was found in performance while the composite oxide was pretreated in a stream of nitrogen. To understand this phenomenon, a Mn substituted CeO2 （ 111 ） slab model was built and H atom was inserted for better surface stability, the mercury adsorption before and after removing a topmost oxygen atom was studied using density functional theory, corrected for on-site Coulomb interactions （GGA ＋ U ）. It was found that Hg bounded to the active oxygen atoms favourably but could only physisorb on the doping surface with oxygen vacancy, suggesting the pretreatment in nitrogen stream may bring in oxygen defect on the surface, which resulted in the performance degradation for mercury adsorption.
出处
《能源工程》
2013年第4期43-48,共6页
Energy Engineering
