Fe_2O_3/Al_2O_3氧载体用于甲烷化学链燃烧:负载量与制备方法的影响

Fe_2O_3/Al_2O_3 oxygen carriers for chemical looping combustion of methane:Influence of Fe_2O_3 loadings and preparation methods

以不同方法制备了系列Fe2O3/Al2O3氧载体,采用XRD、H2-TPR、CH4-TPR、O2-TPD和BET等分析技术对氧载体进行了表征。研究了不同Fe2O3负载量氧载体的甲烷化学链燃烧性能,考察了不同制备方法对Fe2O3/Al2O3氧载体结构、反应性和产物选择性的影响。结果表明,Fe2O3负载量对氧载体活性及产物中CO2选择性的影响较大,负载量较低时氧载体活性较低且引起甲烷部分氧化产物CO含量增加。制备方法亦对氧载体与甲烷的反应活性有所影响,整体上共沉淀法制备的质量分数60%Fe2O3/Al2O3氧载体具有较高的氧化活性和化学链循环稳定性。其在反应温度850℃、反应时间15 min、30次循环后甲烷转化率及产物中CO2选择性均未见明显降低。

A series of Fe2O3/Al2O3 oxygen carriers with different Fe2P3 loading were prepared by different methods and characterized by means of XRD, H2-TPR, CH4-TPR, 02-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 Fe203 loading on the reactivity for methane oxidation and the CO2 selectivity is observed. Lower Fe203 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 carder 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 HzO 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.