Laboratory of Energy Science and Technology, ETH Zurich, Leonhardstrasse 27, 8092 Zurich (Switzerland).
Electrochemical Materials, ETH Zurich, Hönggerbergring 64, 8093 Zurich (Switzerland).
ChemSusChem. 2015 Jun 22;8(12):2055-65. doi: 10.1002/cssc.201403426. Epub 2015 Apr 27.
Chemical looping combustion (CLC) and chemical looping with oxygen uncoupling (CLOU) are emerging thermochemical CO2 capture cycles that allow the capture of CO2 with a small energy penalty. Here, the development of suitable oxygen carrier materials is a key aspect to transfer these promising concepts to practical installations. CuO is an attractive material for CLC and CLOU because of its high oxygen-storage capacity (20 wt %), fast reaction kinetics, and high equilibrium partial pressure of oxygen at typical operating temperatures (850-1000 °C). However, despite its promising characteristics, its low Tammann temperature requires the development of new strategies to phase-stabilize CuO-based oxygen carriers. In this work, we report a strategy based on stabilization by co-precipitated ceria (CeO2-x ), which allowed us to increase the oxygen capacity, coke resistance, and redox stability of CuO-based oxygen carriers substantially. The performance of the new oxygen carriers was evaluated in detail and compared to the current state-of-the-art materials, that is, Al2 O3 -stabilized CuO with similar CuO loadings. We also demonstrate that the higher intrinsic oxygen uptake, release, and mobility in CeO2-x -stabilized CuO leads to a three times higher carbon deposition resistance compared to that of Al2 O3 -stabilized CuO. Moreover, we report a high cyclic stability without phase intermixing for CeO2-x -supported CuO. This was accompanied by a lower reduction temperature compared to state-of-the-art Al2 O3 -supported CuO. As a result of its high resistance towards carbon deposition and fast oxygen uncoupling kinetics, CeO2-x -stabilized CuO is identified as a very promising material for CLC- and CLOU-based CO2 capture architectures.
化学链燃烧（CLC）和化学链氧气分离（CLOU）是新兴的热化学 CO2 捕获循环，可在较小的能量损失下捕获 CO2。在这里，开发合适的氧载体材料是将这些有前途的概念转化为实际装置的关键方面。CuO 是 CLC 和 CLOU 的一种有吸引力的材料，因为它具有高储氧能力（20wt%）、快速反应动力学和在典型操作温度（850-1000°C）下的高氧平衡分压。然而，尽管具有有前途的特性，但 CuO 基氧载体的低德拜温度需要开发新的策略来稳定其相。在这项工作中，我们报告了一种基于共沉淀氧化铈（CeO2-x）稳定化的策略，该策略使我们能够显著提高 CuO 基氧载体的氧容量、抗积碳性和氧化还原稳定性。详细评估了新型氧载体的性能，并与当前最先进的材料（即具有类似 CuO 负载的 Al2O3 稳定的 CuO）进行了比较。我们还证明，CeO2-x 稳定的 CuO 中更高的内在氧吸收、释放和迁移能力导致其抗积碳能力比 Al2O3 稳定的 CuO 高 3 倍。此外，我们报告了 CeO2-x 负载的 CuO 没有相混合的高循环稳定性。这伴随着比最先进的 Al2O3 负载的 CuO 更低的还原温度。由于其对积碳的高抵抗力和快速的氧气分离动力学，CeO2-x 稳定的 CuO 被确定为 CLC 和 CLOU 基 CO2 捕获结构的一种很有前途的材料。
