Fe₂O₃/Al₂O₃ oxygen carriers for chemical looping combustion of methane: Influence of Fe₂O₃ loadings and preparation methods

A series of Fe₂O₃/Al₂O₃ oxygen carriers with different Fe₂O₃ loading were prepared by different methods and characterized by means of XRD, H₂-TPR, CH₄-TPR, O₂-TPD and BET technologies. The effects of the preparation methods on the Fe₂O₃/Al₂O₃ oxygen carrier structure, activity and the selectivity for CO₂ were also investigated. An obvious effect of Fe₂O₃ loading on the reactivity for methane oxidation and the CO₂ selectivity is observed. Lower Fe₂O₃ loading results in a lower reactivity of oxygen carrier and more CO content in the product gas. The reactivity of Fe₂O₃/Al₂O₃ is also affected by the preparation method of oxygen carrier. The Fe₂O₃/Al₂O₃ oxygen carrier with a Fe₂O₃ loading of 60% (mass ratio) has the best activity and redox stability for methane oxidation. Methane can be quickly converted to CO₂ and H₂O with higher selectivity at 850℃ for 15 min. After redox cycling in alternant methane/air atmosphere for 30 times, no decline in the conversion of methane and the formation of CO₂ is observed.