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采用穆斯堡尔谱、X射线衍射和电子显微镜等研究了四种工业用Fe-Cr系中温变换催化剂的结构细节。由这些催化剂的穆斯堡尔谱图表明:它们都具有相似的谱形,即由表征α-Fe_2O_3和γ-Fe_2O_3的磁分裂六线谱和表征超顺磁性Fe_2O_3小晶粒及Fe_2O_3-Cr_2O_3固溶体等中央顺磁峰所组成。结合这些催化剂的制备条件和催化活性,对其和催化剂结构三者之间的关系进行了初步探讨。结果发现:(1)随着助剂K、Cr的含量增加,穆斯堡尔谱图上中央顺磁部分所占比例亦增加;(2)制备方法不同,不只影响Cr的均匀分布,而且也对晶体外形,晶粒
The structural details of four commercial Fe-Cr mid-temperature shift catalysts were investigated by Mossbauer spectroscopy, X-ray diffraction and electron microscopy. The Mossbauer spectra of these catalysts show that all of them have a similar spectral shape, which is characterized by the magnetic split-line characterization of α-Fe_2O_3 and γ-Fe_2O_3 and the characterization of superparamagnetic Fe_2O_3 small grains and Fe_2O_3-Cr_2O_3 solid solution Central paramagnetic peak and other components. According to the preparation conditions and catalytic activity of these catalysts, the relationship between them and the structure of catalysts was discussed. The results showed that: (1) As the content of K and Cr increased, the proportion of central paramagnetic part in Mössbauer spectra also increased; (2) The preparation method not only affected the uniform distribution of Cr but also Crystal shape, grain