铈修饰铁基复合载氧体用于化学链甲烷部分氧化重整制合成气研究

Partial oxidation reforming of methane to synthesis gas by chemical-looping using CeO2-modified Fe2O3 as oxygen carrier

  • 摘要: 以Al2O3为惰性载体,利用共沉淀法制备了CeO2-Fe2O3-Al2O3复合载氧体,并对载氧体进行了XRD、SEM表征。在固定床反应器中,考察了程序升温、恒温、多循环等操作条件下,载氧体对甲烷部分氧化重整的反应性能。程序升温实验结果表明,在相同温度下,CeO2含量为30%的载氧体与不含CeO2的载氧体对比,CH4转化率、H2和CO选择性均提高。在恒温实验中,含有CeO2的两种载氧体,CH4转化率、H2和CO选择性上也都明显高于不含CeO2的载氧体,当反应时间小于1 200 s时,无积炭发生。三种载氧体经过15次循环后,CeO2含量为30%的载氧体表现出最佳的循环特性。多循环实验中,当反应温度850 ℃、反应时间945 s时,CH4最大转化率达到91.53%、H2的最大选择性达到86.36%、CO的最大选择性达到85.12%、H2与CO的最佳平均物质的量比为2.03。XRD谱图显示,经过多次循环后,三种载氧体的物相没有发生变化,载氧体表现出了很好的稳定性能。

     

    Abstract: The CeO2/Fe2O3 oxygen carriers were prepared by co-precipitation method and their characterization was carried out using X-ray diffraction (XRD) and scanning electron microscope (SEM). The partial oxidation reforming of methane was tested in a fixed-bed at different operating conditions. The temperature programming results show that 30% CeO2-modified Fe2O3 has rather better effect than pure Fe2O3; the conversion of CH4, the selectivity of H2 and CO are greatly improved. Same results have been observed in isothermal experiments. As the reaction time is less than 1 200 s, there is no carbon deposit formed. After 15 cycles, 30% CeO2-modified Fe2O3 has the best cycling performance at 850 ℃ and the reaction time of 945 s. The conversion of CH4 reaches to 91.53%, the selectivity of H2 and CO reach to 86.36% and 85.12%, respectively and the H2/CO mol ratio in syngas is 2.03. The species of substance in oxygen carriers has no obvious change after 15 cycles.

     

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