Effect of Cu doping on morphology and properties of calcium ferrite and its application as oxygen carrier in chemical looping hydrogen production

IF 11.3 1区化学 Q1 CHEMISTRY, PHYSICAL

ACS Catalysis Pub Date : 2024-09-22 DOI:10.1016/j.jclepro.2024.143668

Shuoxin Zhang, Xin Guo

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Abstract

Chemical looping hydrogen production with inherent CO₂ capture has been widely recognized as a clean and efficient approach to high-purity hydrogen production because of the ultra-pure H₂ product without any purification facilities. It is crucial to develop oxygen carriers with better performance to improve fuel conversion and hydrogen production efficiency. The potential of Ca₂Fe₂O₅ in steam converting has been confirmed. However, its lower oxygen transfer capacity, that is, it tends to produce lower fuel conversion in fuel reactors, which will limit its practical application. Here, we report the development of Cu-doped Ca₂Fe₂O₅-based oxygen carriers using sol-gel technology. The effects of B-site substitution of Cu element on the morphological properties and redox properties of Ca₂Fe_2-xCu_xO₅ (x = 0, 0.1, 0.25, 0.5, 1) oxygen carriers were evaluated based on experiments and density functional theory calculations. The results show that Cu doping not only elevated the surface oxygen content and enhanced the oxygen activity of the oxygen carriers, but also increased the Fe³⁺ at the B-site, thus enhanced their binding ability with oxygen molecules. Vacancy formation was a rate-determining step in the chemical looping hydrogen production (CLH), and Cu-doped Ca₂Fe₂O₅ reduced the energy of oxygen vacancy formation. In the CLH process, the doping of Cu significantly improved the hydrogen productivity and fuel conversion rate. The fuel conversion rate was positively correlated with the doping amount of Cu. When x = 1, Ca₂Fe_2-xCu_xO₅ had the maximum fuel conversion rate, and its average conversion was 54.2% more than that of undoped Ca₂Fe₂O₅. Ca₂Fe_2-xCu_xO₅ with x = 0.25 was the most suitable for CLH with the highest H₂ yield, which was 20.3% more than that of Ca₂Fe₂O₅. Moreover, its properties remained stable over multiple redox cycles with high activity and stability for CO-CLH.

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掺杂铜对钙铁氧体形态和性能的影响及其在化学循环制氢中作为氧载体的应用

由于无需任何纯化设施即可获得超纯的氢气产品，化学循环制氢与固有的二氧化碳捕获技术已被广泛认为是一种清洁高效的高纯度制氢方法。开发性能更好的氧气载体对于提高燃料转化和制氢效率至关重要。Ca2Fe2O5 在蒸汽转化方面的潜力已得到证实。然而，其较低的氧气传输能力，即在燃料反应堆中产生较低的燃料转化率，将限制其实际应用。在此，我们报告了利用溶胶-凝胶技术开发的掺铜 Ca2Fe2O5 氧载体。基于实验和密度泛函理论计算，评估了铜元素的 B 位取代对 Ca2Fe2-xCuxO5（x = 0、0.1、0.25、0.5、1）氧载体的形态特性和氧化还原特性的影响。结果表明，Cu 掺杂不仅提高了氧载体的表面氧含量，增强了氧活性，而且增加了 B 位的 Fe3+，从而增强了氧载体与氧分子的结合能力。空位形成是化学循环制氢（CLH）的决定性步骤，而掺铜的 Ca2Fe2O5 降低了氧空位形成的能量。在化学循环制氢过程中，掺杂 Cu 显著提高了氢气生产率和燃料转化率。燃料转化率与 Cu 的掺杂量呈正相关。当 x = 1 时，Ca2Fe2-xCuxO5 的燃料转化率最高，其平均转化率比未掺杂的 Ca2Fe2O5 高 54.2%。x = 0.25 的 Ca2Fe2-xCuxO5 最适合用于 CLH，其 H2 产率最高，比 Ca2Fe2O5 高出 20.3%。此外，其特性在多次氧化还原循环中保持稳定，对 CO-CLH 具有较高的活性和稳定性。

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来源期刊

ACS Catalysis CHEMISTRY, PHYSICAL-

CiteScore

20.80

自引率

6.20%

发文量

1253

审稿时长

1.5 months

期刊介绍： ACS Catalysis is an esteemed journal that publishes original research in the fields of heterogeneous catalysis, molecular catalysis, and biocatalysis. It offers broad coverage across diverse areas such as life sciences, organometallics and synthesis, photochemistry and electrochemistry, drug discovery and synthesis, materials science, environmental protection, polymer discovery and synthesis, and energy and fuels. The scope of the journal is to showcase innovative work in various aspects of catalysis. This includes new reactions and novel synthetic approaches utilizing known catalysts, the discovery or modification of new catalysts, elucidation of catalytic mechanisms through cutting-edge investigations, practical enhancements of existing processes, as well as conceptual advances in the field. Contributions to ACS Catalysis can encompass both experimental and theoretical research focused on catalytic molecules, macromolecules, and materials that exhibit catalytic turnover.