应用失重技术研究了450~600 ℃下氢气还原超细氧化铁粉过程。采用扫描电镜和X射线来分析还原过程中的结构及物相变化。研究结果表明,由于纳米颗粒的尺寸效应，反应初始速率增加。不同温度下，还原速率随着还原程度增加而减小。还原过程的速率控制过程通过反应过程中的部分结构变化、活化能及气固反应数学模型确定。结果表明，H2还原超细氧化铁的初始阶段由化学反应过程控制，在反应后期阶段，反应过程是受化学动力学和内扩散的混合控制。
Microscale iron oxide powders were reduced with hydrogen at 450600 ℃. Experiment was carried out by means of weight loss technique. The structure change and phase transformation in reduction process were examined with scanning electron microscopy and Xray diffraction device. The initial reduction rate was hight due to size effect. The reduction rate was decreased with the increase of reduction degree at different temperature. The rate controlling step was determined by structure change of partially reduced oxide,apparent activation energy and model of gassolid reactions. The reaction of reduction by hydrogen was found to be a complex one,which in the initial stage, is controlled by chemical reaction then by combination of chemical reaction and gas mass diffusion.
参考文献
- 下载量()
- 访问量()
- 您的评分：
-
10%
-
20%
-
30%
-
40%
-
50%