化学链燃烧中Fe氧化过程产物层生长特性

Growth Mechanism of the Product Layer During Fe Oxidation in Chemical Looping Combustion

利用TGA、SEM研究了化学链燃烧中Fe氧化反应过程产物层的生长机理,以及产物层形貌对化学反应动力学的影响。考虑了不同的反应条件,包括氧化时间、反应温度、O_2浓度的影响。实验结果表明,氧化产物呈三维岛状生长,反应初期产物岛较小但密度较大,随着反应的进行,产物岛不断长大,但密度先减小后增加;温度及O_2浓度对产物层生长均有影响。产物岛的成核与生长改变了产物层的表观形貌,减小了表观反应速率。

The growth mechanism of the product layer during Fe oxidation in chemical looping combustion was studied with a thermo-gravimetric analysis （TGA） and a scanning electron microscopy （SEM）. The surface morphology of the product layer and its effect on the reaction kinetics were researched. The oxidation time, reaction temperature, and the oxygen concentration were considered. It was found that the oxidation product appeared as dispersed, three-dimensional shaped islands. At the beginning of the reaction, the islands were small with high density. As the oxidation continued, the size of the islands became larger, while the density decreased at first, then increased. Both temperature and oxygen concentration had influence on the growth of the product layer. The nucleation or growth of the islands changed the surface morphology of the product layer, and thus decreased the apparent reaction rate.