化学链重整中铈基载氧体的热分析动力学研究

Thermal analysis kinetics of cerium-based oxygen carriers in chemical-looping reforming

采用共沉淀法制备了铈基载氧体Ce7Fe3Oδ,并在相同条件下制备了纯CeO2载氧体作为对照,以H2为还原性气体对两种载氧体进行了热重实验,并在氢气气氛下进行了程序升温还原实验,基于热重分析谱图与氢气程序升温还原谱图的联合法,利用非定温单升温速率法对铈基载氧体还原反应动力学进行了分析。分析结果表明,对于Ce7Fe3Oδ载氧体的还原反应过程,在360~495℃温度范围内由收缩核模型(柱对称)控制,而在495~675℃和675~950℃两个温度范围内由化学反应模型(n=2)控制,并根据模型分别计算出了相应模型的活化能和指前因子。

The cerium-based oxygen carrier Ce7Fe3Oδwas prepared by co-precipitation,and pure CeO2 oxygen carrier was prepared under the same conditions as a contrast.The thermogravimetric analysis(TGA)in hydrogen atmosphere and the temperature-programmed reduction(H2-TPR)of the two oxygen carriers were carried out.Based on the combination of TGA and H2-TPR spectra,the reduction reaction kinetics of the cerium-based oxygen carrier was analyzed by non-constant temperature single heating rate method.The analysis results indicate that the reduction process of Ce7Fe3Oδis controlled by the shrinking core model(column symmetry)in the temperature range of 360-495℃,and is controlled by the chemical reaction model(n=2)in the temperature range of 495-675℃and 675-950℃.And the activation energy and pre-exponential factor of the corresponding model are calculated according to the model.