The synergetic effect of metal oxide support on Fe₂O₃ for chemical looping combustion: A theoretical study

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• 作者：Wu Qin ; Yang Wang ; Changqing Dong ; Junjiao Zhang ; Qiuluan Chen ; Yongping Yang
• 关键词：Chemical-looping combustion ; CO ; DFT
• 刊名：Applied Surface Science
• 出版年：2013
• 出版时间：1 October, 2013
• 年：2013
• 卷：282
• 期：Complete
• 页码：718-723
• 全文大小：1430 K

文摘

This study deals with the synergetic effect of Al₂O₃ on Fe₂O₃ for chemical-looping combustion (CLC) of CO, in comparison with the synergetic effects of ZrO₂ and MgO reported in our previous works. Property analysis of Fe₂O₃/Al₂O₃ shows that new bonds form cross the interface making Fe₂O₃ less prone to agglomerate on Al₂O₃, and 0.129 e transfers from Al₂O₃ to Fe₂O₃ to activate the electronic state of Fe₂O₃. Al₂O₃ [ZrO₂ and MgO] favors the thermal stability of Fe₂O₃ by preventing the phase transformation, markedly regulates charge populations on the O-Fe bonds and their overlaps and hence tunes the redox properties of Fe₂O₃. The reaction mechanism analysis demonstrates that Al₂O₃ [ZrO₂ and MgO] activates Fe₂O₃ for oxidizing CO into CO₂ (accompanied by the reduction of Fe₂O₃) in the fuel reactor, which decrease the height of barrier energy (E_a), and the E_a follows clearly Fe₂O₃ > Fe₂O₃/Al₂O₃ > Fe₂O₃/MgO > Fe₂O₃/ZrO₂. However, these supports usually increase the E_a for oxidizing Fe₂O₂ into Fe₂O₃ by O₂ in the air reactor, and the E_a follows clearly Fe₂O₃/ZrO₂ > Fe₂O₃/Al₂O₃ > Fe₂O₃/MgO > Fe₂O₃. It is argued that different supports could be applied to a given CLC system of different thermodynamic properties.