In this article, the high‐temperature (≥1000 °C) oxidation kinetics of porous magnesium‐manganese oxide structures considered for large‐scale thermochemical energy storage are determined. For this analysis, oxides with Mn/Mg molar ratios of 2/3, 1/1, and 2/1 are synthesized via solid‐state reaction and crushed to a powder with particle sizes ranging from 125 to 180 μm. The powder is thermally reduced at 1500 °C inside a heated alumina tube under argon flow. Subsequently, the resulting porous bed is oxidized at temperatures between 1000 and 1500 °C with an oxygen to argon molar ratio of 1:4 (leading to an oxygen partial pressure of 0.2 atm). An Arrhenius‐type kinetic rate law is derived using the theory of internal oxidation assuming spherical particles. Subsequently, the kinetic rate law parameters are identified by comparing measured oxygen flow at the reactor outlet to the oxygen output computed using a 1D plug flow reactor model incorporating the postulated kinetic model. Results indicate that the derived bulk kinetic rate law describes the measured oxidation kinetics well and is suited for designing thermochemical energy storage modules based on magnesium‐manganese oxides.

中文翻译：

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高温热化学能量存储中镁锰氧化物的氧化动力学

在本文中，确定了考虑用于大规模热化学能量存储的多孔镁锰氧化物结构的高温（≥1000°C）氧化动力学。对于此分析，通过固相反应合成了Mn / Mg摩尔比为2 / 3、1 / 1和2/1的氧化物，并将其粉碎成粒径为125至180μm的粉末。粉末在氩气流下在加热的氧化铝管中于1500°C进行热还原。随后，在1000至1500℃之间的温度下以氧气与氩气的摩尔比为1：4（导致氧气分压为0.2atm）氧化所得多孔床。阿雷尼乌斯型动速率定律是根据假设球形颗粒的内部氧化理论得出的。后来，通过将反应器出口处测得的氧气流量与使用结合了假定动力学模型的一维活塞流反应器模型计算出的氧气输出量进行比较，可以确定动力学速率定律参数。结果表明，推导的整体动力学速率定律很好地描述了测得的氧化动力学，适合于设计基于镁锰氧化物的热化学储能模块。