摘要
本文用X射线衍射相分析和透射电子显微镜观察,证明了共沉淀法制备的Fe-Cr系中变催化剂的主体相是α-Fe_2O_3和γ-Fe_2O_3的两相混合物。若采用混沉淀法则能得到单一的γ-Fe_2O_3相。这种单一的γ-Fe_2O_3催化剂的低温活性、耐热性和强度都比较好。对影响晶型的混沉淀工艺条件进行了试验和讨论。
Crystalline phases of the water-gas shift Fe-Cr catalysts prepared by co-precipitation and mix-precipitation have been studied by X-ray diffraction(XRD) analysis and transmission electron microscopy (TEM). The results show that the catalyst prepared by co-precipitation is always composed of two main phases a-Fe2O3 and r-Fe2O3.But the catalyst prepared by mix-precipitation contains a single y-Fe,O3 phase which has higher low-temperature catalytic activity, better heat-resistivity and higher strength.For mix-precipitation, the effect of CrO3 amount added and pH value on the crystalline phases of the catalysts was studied and discussed. It is found that in order to obtain single Y-Fe2O3, pH 7.0-7.5 and Cr2O3 content9-13% are appropriate. When Cr2O3 content is higher than 11.0%,a small amount of a-Fe2O3 coexists with y-Fe2O3 in the catalyst.
