Evaluation of the Reactivity of Hematite Oxygen Carriers Modified Using Alkaline (Earth) Metals and Transition Metals for the Chemical Looping Conversion of Lignite
Evaluation of the Reactivity of Hematite Oxygen Carriers Modified Using Alkaline (Earth) Metals and Transition Metals for the Chemical Looping Conversion of Lignite
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DOI：
10.3390/en16062662
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发表时间：
2023-03
期刊：
影响因子：
3.2
通讯作者：
H. Lee;Jiahui Xiong;Xinfei Chen;Haitao Wang;Daheoi Song;Jinlong Xie;Yan Lin;Ya Xiong;Zhen Huang;Hongyu Huang
中科院分区：
文献类型：
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作者：
H. Lee;Jiahui Xiong;Xinfei Chen;Haitao Wang;Daheoi Song;Jinlong Xie;Yan Lin;Ya Xiong;Zhen Huang;Hongyu Huang
化学循环（CL）技术是一种清洁高效的能源利用新技术。氧载体（OCs）是化学发光技术的基石。开发低成本、高性能的有机氧化物是化学发光转化应用的关键。赤铁矿是天然铁基OC之一，具有几个优点（例如，成本低、环境友好），但其较低的反应活性限制了其在化学发光中的应用。对赤铁矿的某些活性组分进行改性可以有效地改善其性能。本研究探讨了通过添加碱（土）金属（K，Na和Ca）和过渡金属（Ni，Cu和Mn）来改善赤铁矿的反应性。利用X射线衍射（XRD）对有机碳的晶相进行了表征，结果表明金属的加入显著改变了原始赤铁矿的晶相。K-Fe-O和Na-Fe-O活性固溶体对褐煤半焦的转化具有较强的催化活性。CaO的加入促进了褐煤的挥发分的释放，而低反应活性的CaFe 2 O 4固体溶液的形成抑制了晶格氧的释放。Cu改性样品中CuO/CuFe 2 O 4的存在可以释放少量的游离O2以促进挥发分转化。Ni改性后的氧化物中存在NiO和NiFe 2 O 4高活性相，可提高赤铁矿的反应活性。然而，在Mn改性的OC中生成了具有低反应活性的MnFeO 3相，降低了Mn改性的OC与褐煤焦的反应速率。
Chemical looping (CL) technology is a novel technology for the clean and efficient use of energy. Oxygen carriers (OCs) are the cornerstone of CL technology. The development of low–cost, high–performance OCs is crucial for the application of CL conversion. Hematite, one of the natural Fe–based OCs, has several advantages (e.g., low cost and environmental friendliness), but its low reactivity limits its application in CL. The performance of hematite can be effectively improved by modifying some of its active components. This study explored the improvement of hematite reactivity by adding alkaline (earth) metals (K, Na, and Ca) and transition metals (Ni, Cu, and Mn). The crystal phases of the OCs were characterized using X-ray diffraction (XRD), and the results revealed that the addition of metals significantly changed the phase of the original hematite. The active solid solution of K–Fe–O and Na–Fe–O species exhibited strong catalytic activity to facilitate lignite char conversion. The addition of CaO promoted the devolatilization of lignite, while the formation of a solid CaFe2O4 solution with low reactivity inhibited the lattice oxygen release. The presence of CuO/CuFe2O4 in the Cu–modified sample could release a small amount of free O2 to promote volatile conversion. The high activity phases of NiO and NiFe2O4 in the Ni–modified OCs could improve the reaction activity of hematite. However, the MnFeO3 phase with low reaction activity was generated in the Mn–modified OC, decreasing the reaction rate of the Mn–modified OC with lignite char.