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化学学报
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化学学报 ›› 1996, Vol. 54 ›› Issue (9): 833-837.    下一篇

研究论文

水煤气变换催化剂Fe~3O~4的亚稳结构

吕光烈;陈林深;刘顺洪;许裕生;徐松   

  1. 杭州大学中心实验室材料结构研究所;苏州大学物理系
  • 发布日期:1996-09-15

Metastable structure of Fe~3O~4 for water-gas shift catalyst

LU GUANGLIE;CHEN LINSHEN;LIU SHUNHONG;XU YUSHENG;XU SONG   

  • Published:1996-09-15

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X射线Rietveld结构修正发现, α-Fe~2O~3与γ-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, γ-Fe~2O~3还原的Fe~3O~4电价明显偏离α-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Mossbauer谱存在明显的差异, α-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γ-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。

关键词: 催化剂, 氧化铁, 催化活性, 穆斯堡尔谱, 亚稳态结构, 水煤气变换, 其它基金, RIETVELD分析

Different oxygen parameters of Fe~3O~4 which were reduced from α-Fe~2O~3 and γ-Fe~2O~3 with water-gas at 400℃ were observed by means of X-ray powder diffraction Rietveld structure refinement. Using bond-valence calculation method, the electrovalences of tetrahedra site A and octahedra site B of Fe~3O~4 reducing from γ-Fe~2O~3 are obviously different from that reducing from α-Fe~2O~3, 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 Fe~3O~4. The first peak and Mossbauer spectrum of Fe~3O~4 reducing from α-Fe~2O~3 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 Fe~3O~4 was obtained from γ-Fe~2O~3, having different electrovalence from normal Fe~3O~4 and having correlating with low-temperature catalytic activity of water-gas shift reaction.

Key words: CATALYST, IRON OXIDE, CATALYTIC ACTIVITY, MOSSBAUER SPECTROSCOPY

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