Effects of CO2 Atmosphere and K2CO3 Addition on the Reduction Reactivity, Oxygen Transport Capacity, and Sintering of CuO and Fe2O3 Oxygen Carrie

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• 作者：Zhongliang Yu ; Chunyu Li ; Xuliang Jing ; Qian Zhang ; Yitian Fang ; Jiantao Zhao ; Jiejie Huang
• 刊名：Energy & Fuels
• 出版年：2013
• 出版时间：May 16, 2013
• 年：2013
• 卷：27
• 期：5
• 页码：2703-2711
• 全文大小：754K
• 年卷期：v.27,no.5(May 16, 2013)
• ISSN：1520-5029

文摘

Chemical looping combustion (CLC) of coal has received increasing interest in recent years. However, few attempts have been made to examine the effects of CO₂ atmosphere and K₂CO₃ addition on the reduction rate, the oxygen transport capacity (OTC), and the sintering of the oxygen carrier when coal is used directly in CLC. In this work, these issues for Fe₂O₃ and the CuO oxygen carriers were investigated by thermogravimetric analysis (TGA), X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and inductively coupled plasma鈥揳tomic emission spectrometry (ICP-AES). The TGA results indicate that the reduction rates can be increased by either the CO₂ atmosphere or the K₂CO₃ additive due to the enhanced CO₂ gasification of coal char. Detailed analyses demonstrate that the CO₂ atmosphere affects the OTC and the sintering of the oxygen carrier by thermodynamic restrictions. The CO₂ atmosphere has no effect on the OTC of the CuO oxygen carrier, and there are no significant differences in sintering between the residues obtained under CO₂ and N₂ atmospheres. However, the CO₂ atmosphere limits the OTC of the Fe₂O₃ oxygen carrier within the transformation Fe₂O₃鈥揊e₃O₄, and the sintering could be moderated because of the higher sintering resistance of Fe₃O₄. The K₂CO₃ addition does not affect the OTC because the catalyst has no impact on the equilibrium but promotes the sintering of the oxygen carrier due to its low Tammann temperature. Although severe sintering could be caused by the K₂CO₃ addition, the catalytic effect can be observed during several redox cycles.