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采用热重分析仪和质谱仪联用对使用机械混合法制备Fe2O3和Al2O3载体的还原反应过程进行研究。还原反应中使用3种10%还原气体(CH4,H2,CO),氧化反应中使用5%氧气以避免较大的温升。从载体的还原失重曲线中可明显地看出铁基载体的还原过程分为3个阶段,且反应速率各不相同。还原的3个阶段中第一阶段的反应速率最快,且燃料能够完全被氧化生成CO2,随着反应进行速率降低,燃料不完全转化程度增加。通过XRD(X射线衍射)分析各个还原阶段的产物,发现与以前认识的载氧体活性相与惰性相不同,Al2O3在反应过程中会参与反应,生成新的化合物FeAl2O4,而此化合物不稳定能够进一步分解,被还原成Fe。3种还原气体中,H2的还原反应速率最快,并且无积碳,而CH4的还原反应中存在较为严重的积碳现象。
Thermogravimetry and mass spectrometry were used to study the reduction reaction process of Fe2O3 and Al2O3 supported by mechanical mixing. Three 10% reduction gases (CH4, H2, CO) are used in the reduction reaction and 5% oxygen in the oxidation reaction to avoid large temperature rise. It can be clearly seen from the reduction weight loss curve of the support that the reduction process of the iron-based support is divided into three stages and the reaction rates are different. In the first three stages of reduction, the reaction rate is the fastest, and the fuel can be completely oxidized to form CO2. As the reaction rate decreases, the degree of incomplete conversion of the fuel increases. By XRD (X-ray diffraction) analysis of the various reduction stages of the product and found that the oxygen carrier and the previously recognized active phase and inert phase is different, Al2O3 in the reaction process will be involved in the reaction to generate a new compound FeAl2O4, and this compound is unstable to Further decomposition, was reduced to Fe. Of the three kinds of reducing gases, the reduction reaction rate of H2 was the fastest, and there was no carbon deposition. However, there was a serious carbon deposition phenomenon in the reduction reaction of CH4.