【摘要】 基于热重分析仪研究了950℃下天然赤铁矿石载氧体与H2还原反应过程中的反应性能,并借助于X射线衍射仪(XRD)和扫描电镜与电子能谱(SEM-EDS)联用,对还原反应固体产物进行了表征。研究表明,950℃下载氧体反应速率最大值出现在转化率为0.11时,此阶段主要是由Fe2O3完全转化为Fe3O4,反应很容易进行。随后反应速率下降,当转化率为0.178时载氧体产物含有的低阶铁氧化物为Fe3O4、FeO;而转化率为0.477时,主要产物有Fe、FeO、Fe3O4存在。SEM-EDS表征结果表明,随转化率增加,载氧体颗粒表面上含Fe元素的晶粒逐渐聚集、长大,并且在Fe、FeO生成区发生了颗粒体积收缩和烧结现象,特别是Fe元素富集区;而SiO2、Al2O3相对含量较高区域依然保持稳定的结构。与铁矿石串行流化床实验对比,铁矿石良好的惰性载体分布有效地缓解了载氧体的烧结程度,使得载氧体在长时间使用过程中反应性能得以维持。更多还原

【Abstract】 Using H2 as a reactant gas,the reaction characterization of hematite oxygen carrier was investigated in a thermogravimetric analyzer(TGA).The solid reduction products were characterized by XRD(X-ray diffraction) and SEM-EDS(Scanning Electron Microscope-Energy Dispersive Spectrometer).The results show that there is a maximum reaction rate when the conversion is 0.11.In this stage,Fe2O3 as an active phase was converted to Fe3O4 and the reduction reaction was easy to happen.Then,there is a decrease of reaction rate.When the conversion degree of hematite oxygen carrier was 0.178,the solid reduction products were composed of Fe3O4 and FeO.When the conversion is 0.477,Fe3O4,FeO and Fe were all found in the reduction products.SEM-EDS results show that the grains at the surface of hematite oxygen carrier were gathered and grown up,and the particle volume shrinkage and sintering effect are observed,especially in the region rich in Fe element.However,a relative stable structure was seen in the region rich in SiO2 or Al2O3 contents.Further,compared with the results based on interconnected beds,the sintering of hematite was alleviated due to a good inert material distribution,which kept a good long-term reactivity of hematite oxygen carrier.更多还原