Enhanced sintering resistance of Fe2O3/CeO2 oxygen carrier for chemical looping hydrogen generation using core-shell structure
Enhanced sintering resistance of Fe2O3/CeO2 oxygen carrier for chemical looping hydrogen generation using core-shell structure
复制标题
利用核壳结构增强 Fe2O3/CeO2 氧载体的烧结抗性，用于化学循环制氢
DOI：
10.1016/j.ijhydene.2019.01.167
复制
发表时间：
2019-03-08
影响因子：
7.2
通讯作者：
Xiang, Wenguo
中科院分区：
文献类型：
--
作者：
Ma, Shiwei;Chen, Shiyi;Xiang, Wenguo
ceo2负载的Fe2O3是化学环制氢（CLHG）的理想氧载体。但烧结问题制约了其氧化还原反应性和稳定性的进一步提高。本文在固定床上研究了溶胶-凝胶法制备的核-壳结构Fe2O3/CeO2（标记为Fe2O3@CeO2）氧载体。以Fe2O3/CeO2均相复合样品为对照，研究了核壳结构对烧结性能和氧化还原性能的影响。结果表明：Fe2O3@CeO2的氧化还原活性和稳定性明显高于无CO和CO2的Fe2O3/CeO2，但由于烧结严重，Fe2O3/CeO2的产氢率随着氧化还原循环次数的增加而降低。Fe2O3@CeO2令人满意的性能可归因于其高抗烧结性能，因为核壳结构抑制了Fe阳离子从体向表面的向外迁移。另一方面，Fe阳离子的迁移和随后在颗粒表面的富集导致Fe2O3/CeO2严重烧结。Fe2O3和CeO2在氧化还原循环中的晶粒尺寸演变进一步表明Fe2O3@CeO2具有较高的抗烧结性能。此外，颗粒尺寸分布（PSD）结果表明，循环后Fe2O3/CeO2发生了团聚。此外，CeO2壳层可以促进氧离子在氧化铁纳米粒子核和壳表面之间的传递。因此，纳米级Fe2O3包覆CeO2壳层不仅没有降低Fe2O3@CeO2的氧化还原活性和稳定性，反而促进了其氧化还原活性和稳定性，但生成的CeFeO3氧离子导电性较差。(C) 2019氢能源出版有限责任公司，由爱思唯尔有限公司出版。版权所有。
CeO2-supported Fe2O3 is a satisfactory oxygen carrier for chemical looping hydrogen generation (CLHG). However, the sintering problem restrains its further improvement on redox reactivity and stability. In the present work, a core-shell-structured Fe2O3/CeO2 (labeled Fe2O3@CeO2) oxygen carrier prepared by the sol-gel method was studied in a fixed bed. The effect of the core-shell structure on the sintering resistance and redox performance was investigated with a homogenous composite sample of Fe2O3/CeO2 as a reference. The results showed that the Fe2O3@CeO2 exhibited much higher redox reactivity and stability than the Fe2O3/CeO2 with no CO or CO2 observed in the generated hydrogen, while the hydrogen yield for Fe2O3/CeO2 decreased with redox cycles due to serious sintering. The satisfactory performance of Fe2O3@CeO2 can be ascribed to its high sintering resistance, since the core-shell structure suppressed the outward migration of Fe cations from the bulk to the surface of the particles. On the other hand, the migration of Fe cations and their subsequent enrichment on the particle surface led to the serious sintering of Fe2O3/CeO2. The crystallite size evolution of Fe2O3 and CeO2 in redox cycles further demonstrated the higher sintering resistance of Fe2O3@CeO2. Further, the particle size distribution (PSD) results indicated the agglomeration of Fe2O3/CeO2 after cycles. In addition, the CeO2 shell could facilitate the transport of oxygen ions between the iron oxide nanoparticle core and the shell surface. Therefore, the coating of nanoscale Fe2O3 with a CeO2 shell did not reduce the redox reactivity and stability of Fe2O3@CeO2, but rather promoted it, though less oxygen-ionic-conductive CeFeO3 was generated. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.