【摘要】 用 XRD,TPD MS,SEM,LRS,Mossbauer谱和流动法 TPD 等技术,研究了Fe₂O₃-Cr₂O₃间的SOOI效应,发现这一效应的存在会导致（Fe,Cr）₃O₄催化剂相和表面相结构的变化。当Cr₂O₃>17%时,有新相生成;（Fe,Cr）₃O₄表面结构随Gr₂O₃从4.6增至21.2%时,由氧化性转变为还原性;当（Fe,Cr）₃0₄表面的Fe³⁺与Fe²⁺表面浓度相当时,水煤气变换反应的比活性最好。更多还原

【Abstract】 The strong oxide-oxide interaction (SOOI) between Fe2O3 and Cr2O3 has been studied by XRD, SEM, TPD MS, Laser Raman Spectro-scopy (LRS), Mossbauer spectroscopy and TPD techniques. The results show that the addition of Cr2O3 increases the dispersion degree for water gas shift (WGS) catalyst (Fe,Cr)3O4. Cr atoms get into the lattice of both Fe2O3 and Fe3O4 to form solid solutions (Fe,Cr)2O3 and (Fe,Cr)3O4 with about 17% of Cr2O3 at saturation. The activation energies of desorption and the pre-exponential factors for lattice oxygen are 1.81 kJ/mol, 1.4×1010s-1 and 258 kJ/mol, 5.4×1012 s-1 for (Fe,Cr)2O3-0 and ((Fe, Cr)2O3-21.2 respectively. It implies that the stability of(Fe,Cr)2O3 is higher than that of Fe2O3. The assignation of LRS bands for bond vibrations is as follows: v = 220- 222 cm-1 for Fe-O, v = 387-417 cm-1 for Fe-O-Cr, and v = 155-159cm-1 for Cr-O. The Mossbauer results indicate that the catalytic specific activity is related to the number of ion pair (Fe3+,Fe2+)in octahedral sites. There are two acidic sites, Fe3+ and Fe2+, on the surface of catalysts. The number of Fe2+ sites increases with theincrease of Cr2O3 content. As the Fe3+/Fe2+ ratio on (Fe, Cr)3O4 -14.6 surface approaches unity, its specific WGS activity is the highest. All the results mentioned above reveal the fact that the SOOI between Cr2O3 and Fe2O3 does exist. It makes (Fe,Cr)3O4 catalyst disperse better and makes both the bulk and surface structures of catalyst change synchronously. Since WGS reaction is a redox process, it takes place easily only when the surface redox condition is adequate.更多还原