Mn-Fe_2O_3载氧体作用下CO化学链燃烧特性及动力学研究

Characteristics and kinetics of chemical looping combustion of Mn-doped Fe_2O_3 oxygen carrier with CO

采用共沉淀法制备不同物质的量比Mn掺杂的铁基载氧体(Mn-Fe2O3),并进行XRD、BET和TEM表征。开展不同温度下Mn-Fe2O3与CO的化学链燃烧实验,研究载氧体的反应特性,确定较优的掺杂量和反应温度。结果表明,适量的Mn掺杂有助于改善铁基载氧体的反应活性,Fe∶Mn物质的量为50∶1时燃烧反应转化率最高。多循环化学链燃烧实验证实了载氧体稳定性较好。不同升温速率(30、40、50℃/min)下反应动力学分析表明,Mn-Fe2O3与CO的化学链燃烧还原反应均属于随机成核和随后生长的Avrami-Erofeev方程模型,并依据模型分别计算出了该模型的活化能和频率因子。

Mn-doped Fe2 O3 oxygen carriers with different molar ratios of Fe to Mn were prepared by co-precipitation method, which were characterized by XRD, BET and TEM. Chemical looping combustion tests between Mn-Fe2 O3 and CO at different temperatures were performed to investigate the reaction characteristics, and to determine the optimized Mn doping amount and reaction temperature. The results reveal that a rational Mn doping could enhance the reactivity of iron-base oxygen carrier, and the optimal Fe/Mn molar ratio is 50. Multi-cycle experiments confirm the high stability of the optimized oxygen carrier. Furthermore, the reaction kinetic analysis at heating rates of 30, 40, 50℃/min shows that the Avrami-Erofeev model is suitable for the reactions, and the activation energy and pre-exponential factor can be calculated according to the kinetic model.