氧缺陷影响铁基载氧体氧化-还原行为的分子动力学模拟

Molecular dynamics simulation of the influence of oxygen deficiency on the oxidation-reduction behavior of iron-based oxygen carriers

中文关键词: 密度泛函理论  还原  积碳  氧化

英文关键词: density function theory  reduction  carbon deposits  oxidation

中文摘要:

      铁基载氧体是化学链燃烧中最受青睐的金属载氧体。构造了氧化铁载氧体的S完整表面和S1*、S2*、S3*三种代表性缺陷表面，基于密度泛函理论（Density Function Theory，DFT），首先计算分析了氧缺陷对CO在α-Fe2O3表面上吸附反应的影响，即对比了完整和缺陷α-Fe2O3(0 0 1)表面上CO的吸附和生成物CO2的解离；其次将反应后的载氧体构型表面进行O2吸附反应的模拟；继而对此载氧体一个循环及过程中铁基载氧体表面的积碳趋势进行了模拟分析。通过吸附能、反应能垒和反应能等参数的比较，得到的主要结论为，在铁基载氧体表面还原、积碳、氧化反应中，S1*类氧缺陷具有更好的反应活性和抗积碳性能，具有良好的循环反应性能。该模拟研究为缺陷类型铁基载氧体的制备及其反应条件的确定提供指导。

英文摘要:

      The iron-based oxygen carrier is the most popular metal oxygen carrier in chemical looping combustion. In this paper, the complete surface (shown as S) of the iron oxide carrier and the other three representative defect surfaces as S1*, S2*, and S3* are constructed. Based on the density functional theory (DFT) calculations, Firstly, the effect of oxygen defect on CO adsorption reaction on α-Fe2O3 surface is calculated and analyzed. That is, the adsorption of CO, the dissociation of CO2 on intact and defective α-Fe2O3(0 0 1) surfaces were compared. Secondly, the oxygen carrier structure surface after the reaction is simulated with O2 adsorption reaction. Then the carbon accumulation trend of a cycle of the oxygen carrier and the surface of the iron-based oxygen carrier in the process is simulated and analyzed. From the comparison of adsorption energy, oxygen vacancy formation energy, reaction energy barrier, reaction energy and other parameters, the preliminary conclusions show that the reduction, carbon deposition, and oxidation reactions, S1* oxygen defects have better reactivity and resistance to carbon deposition, and have good cyclic reaction performance, which provides directional guidance for the preparation and construction of iron-based oxygen carriers.