Chemical-Looping Combustion of Coal with Metal Oxide Oxygen Carriers

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• 作者：Ranjani Siriwardane ; Hanjing Tian ; George Richards ; Thomas Simonyi ; James Poston
• 刊名：Energy & Fuels
• 出版年：2009
• 出版时间：August 20, 2009
• 年：2009
• 卷：23
• 期：8
• 页码：3885-3892
• 全文大小：399K
• 年卷期：v.23,no.8(August 20, 2009)
• ISSN：1520-5029

文摘

The combustion and reoxidation properties of direct coal chemical-looping combustion (CLC) over CuO, Fe₂O₃, Co₃O₄, NiO, and Mn₂O₃ were investigated using thermogravimetric analysis (TGA) and bench-scale fixed-bed flow reactor studies. When coal is heated in either nitrogen or carbon dioxide (CO₂), 50% of weight loss was observed because of partial pyrolysis, consistent with the proximate analysis. Among various metal oxides evaluated, CuO showed the best reaction properties: CuO can initiate the reduction reaction as low as 500 °C and complete the full combustion at 700 °C. In addition, the reduced copper can be fully reoxidized by air at 700 °C. The combustion products formed during the CLC reaction of the coal/metal oxide mixture are CO₂ and water, while no carbon monoxide was observed. Multicycle TGA tests and bench-scale fixed-bed flow reactor tests strongly supported the feasibility of CLC of coal by using CuO as an oxygen carrier. Scanning electron microscopy (SEM) images of solid reaction products indicated some changes in the surface morphology of a CuO−coal sample after reduction/oxidation reactions at 800 °C. However, significant surface sintering was not observed. The interactions of fly ash with metal oxides were investigated by X-ray diffraction and thermodynamic analysis. Overall, the results indicated that it is feasible to develop CLC with coal by metal oxides as oxygen carriers.