La_(1-x)Ce_xFeO_3钙钛石高变催化剂的XPS研究  

XPS Characterization of La_(1-x)Ce_xFeO_3 Perovski te as High-Temperature Water-Gas Shift Catalysts

作　　者：马红钦[1] 谭欣[1] 朱慧铭[1] 张继炎[1] 张鎏[1] 

机构地区：[1]天津大学化工学院,天津300072

出　　处：《中国稀土学报》2003年第4期445-448,共4页Journal of the Chinese Society of Rare Earths

基　　金：天津市自然科学基金资助项目(003602111)

摘　　要：采用X射线电子能谱(XPS)实验技术,对具有钙钛石结构的稀土铁复合氧化物高变催化剂进行了研究。结果表明:在La1-xCexFeO3钙钛石结构中,铈的价态为正四,镧的价态为正三,而铁为正二、正三混合价态,三价铁和二价铁的摩尔比与稀土镧铈的摩尔比具有很好的一致性;在钙钛石ABO3结构中,A位镧、铈能有效控制B位铁的价态。铁具有混合价态是La1-xCexFeO3催化剂具有较高变换催化活性的主要原因。La1-xCexFeO3表面上存在α吸附氧和β晶格氧两类氧种,随铈含量的增加,表面吸附氧增加。La1-xCexFeO3 perovskite was characterized by X-ray photon-e lectron spectroscopy (XPS). The results show that the valences of cerium and lan thanum in La1-xCexFeO3 structure are +4 and +3 respectively, a nd the iron has a mixed valence, i.e., +2 and +3. The ratio of Fe2+/Fe  3+ in the perovskite structure is in good agreement with that of Ce4+/La 3+; the rare-earth elements can effectively dominate the iron valences. I t is the mixed valence of iron that makes La1-xCexFeO3 perovsk ite have high catalytic activity for water-gas shift reaction. There are two ki nds of oxygen species, α and β oxygen, on La1-xCexFeO3 surfa ce, corresponding to adsorption oxygen with high electron binding energy and lat tice oxygen with low electron binding energy. The quantity of α oxygen species increases with augmentation of cerium in La1-xCexFeO3.

关 键 词：催化化学 X光电子能谱(XPS) 钙钛石结构 高变催化剂 稀土 

分 类 号：TQ113.264.2[化学工程—无机化工] TQ426.84