水煤气变换催化剂Fe_3O_4的亚稳结构  

Metastable Structure of Fe_3O_4 for Water - Gas Shift Catalyst

作　　者：吕光烈[1] 陈林深[1] 刘顺洪[1] 许裕生[2] 徐松[2] 

机构地区：[1]杭州大学中心实验室材料结构研究所,杭州310028 [2]苏州大学物理系,苏州215006

出　　处：《化学学报》1996年第9期833-837,共5页Acta Chimica Sinica

基　　金：浙江省自然科学基金资助项目

摘　　要：X射线Rietveld结构修正发现,a-Fe_2Q_3与r-Fe_2O_3在400℃用水煤气还原得到的尖晶石型水煤气变换催化剂Fe_3O_4有不同的氧密堆积结构参数.用键价理论估算四面体A位和八面体B位Fe原子电价,r-Fe_2O_3还原的Fe_3O_4电价明显偏离a-Fe_2O_3还原的Fe_3O_4所具有的正常电价,但经600℃热处理后,回复到正常Fe_3O_4的电价.这二种Fe_3O_4的M(?)ssbauer谱存在明显的差异,a-Fe_2O_3还原的Fe_3O_4的第一峰有明显分裂,A位和B位的同质异能位移的变化趋势反映出来的Fe原子电价变化趋势,与用键价理论推算的Fe原子电价变化趋势一致.我们把这种由r—Fe_2O_3还原、电价偏离正常Fe_3O_4、并与水煤气低温变换催化活性有关的Fe_3O_4称为亚稳态Fe_3O_4.Different oxygen parameters of Fe3O4 which were reduced from α - F2O3 and γ -Fe2O3with water - gas at 400℃ were observed by means of X - ray powder diffraction Rietveld structure refinement. Using bond - valence calculation method, the electrovalences of tetrahedrasite A and octahedra site B of Fe3O4 reducing from γ - Fe2O3 are obviously different from thatreducing from α - Fe2Q3 , but they can change into the normal ones after being aged at 600℃　in reducing atmosphere. There are also different in Mossbauer spectra of two types of Fe3O4. The first peak of Mossbauer spectrum of Fe3O4 reducing from a-Fe2O3 occurs splitting. The electrovalence changing directions of Fe deduced from the changes of isomer shift of A site and B site are the same as that bond - valence calculating method. A metastable Fe3O4 was obtained fromγ - Fe2O3, having different electrovalence from normal Fe3O4 and having correlating with low -temperature catalytic activity of water- gas shift reaction.

关 键 词：水煤气 催化剂 氧化铁 亚稳结构 

分 类 号：O643.36[理学—物理化学] TQ542.4[理学—化学]