High-stability, high-capacity oxygen carriers: Iron oxide-perovskite composite materials for hydrogen production by chemical looping
High-stability, high-capacity oxygen carriers: Iron oxide-perovskite composite materials for hydrogen production by chemical looping
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DOI：
10.1016/j.apenergy.2015.05.062
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发表时间：
2015-11-01
期刊：
影响因子：
11.2
通讯作者：
Metcalfe, Ian
中科院分区：
文献类型：
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作者：
Dueso, Cristina;Thompson, Claire;Metcalfe, Ian
氧化铁因其良好的热力学性质而被广泛用作化学环法制氢的氧气载体材料。尽管如此，氧化铁在氧化还原循环后失去了大部分活性，主要是由于烧结和团聚。钙钛矿，如La0.7Sr0.3FeO3-Delta(LSF731)，由于其良好的氧传输性能和循环稳定性，已被认为是潜在的氢气制备材料。然而，对于类似的载体重量，每个循环产生的氢气比使用氧化铁要低。这项工作提出了使用嵌入在LSF731基质中的氧化铁团簇组成的复合OCM。钙钛矿基质在防止团聚的同时，促进了氧向氧化铁团簇的传输。采用机械混合和改进的Pechini法两种制备方法制备了不同氧化铁质量分数(11%和30%)的复合材料。在热重分析仪上研究了这些OCM的反应性。在微反应器中研究了25个氧化还原循环中的产氢和载体稳定性，同时周期性地向一氧化碳和水进料，以便在不同的流中产生二氧化碳和氢气。LSF731和用改进的Pechini法生产的氧化铁含量为30wt%的复合OCM的产氢在25个循环中是稳定的，但单独的氧化铁颗粒的产氢随着循环而减少。在第25个循环中，复合材料的产氢量是单独氧化铁的8倍，是LSF731的4倍。因此，氢气产量也高于氧化铁和LSF731单独简单组合的预期，表明LSF731在以复合材料的形式存在时可能具有更高的有效氧容。(C)2015年提交人。爱思唯尔有限公司出版。
Iron oxide has been widely used as an oxygen carrier material (OCM) for hydrogen production by chemical looping due to its favourable thermodynamic properties. In spite of this, iron oxide loses much of its activity after redox cycling mainly due to sintering and agglomeration. Perovskites, such as La0.7Sr0.3FeO3-delta (LSF731), have been suggested as potential candidate OCMs for hydrogen production due to their excellent oxygen transport properties and stability under cycling. However, hydrogen production per cycle for a similar carrier weight is lower than with iron oxide. This work proposes the use of composite OCMs made of iron oxide clusters embedded in an LSF731 matrix. The perovskite matrix facilitates oxygen transport to the iron oxide clusters while preventing agglomeration. Two preparation methods, mechanical mixing and a modified Pechini method, were used to obtain composite materials with different iron oxide weight fractions, 11 and 30 wt.%. The reactivity of these OCMs was studied in a thermogravimetric analyser. Hydrogen production and carrier stability were investigated in a microreactor over 25 redox cycles while periodically feeding carbon monoxide and water in order to produce carbon dioxide and hydrogen in separate streams. Hydrogen production was stable over 25 cycles for LSF731 and the composite OCM with 30 wt.% iron oxide produced by the modified Pechini method but iron oxide particles alone underwent a decrease in the hydrogen production with cycling. The hydrogen production during the 25th cycle was eight times higher for the composite material than for iron oxide alone and four times higher than for LSF731. The hydrogen production was therefore also higher than that expected from a simple combination of the iron oxide and LSF731 alone, indicating a synergetic effect whereby the LSF731 may have a higher effective oxygen capacity when in the form of the composite material. (C) 2015 The Authors. Published by Elsevier Ltd.