Perovskite oxide is widely used in many important technological fields due to the excellent characteristics. In this work, the performances of the LaFeO3 as oxygen carrier in biomass chemical looping gasification were investigated. It is found that there is no significant decrease in CO and H2 yield with the increase in oxygen carrier cycle number. No obvious change of syngas yield with the increase in LaFeO3 mass is observed, indicating the stability of LaFeO3. The volume fraction of water vapor should be controlled as 39.9%. The DFT calculation results show that CO desorption is identified to be the rate-limiting step with an activation barrier of 0.648 eV for CO molecule formation. For CO oxidation, formation of COO* complex is the rate-limiting step with energy barrier of 0.368 eV. During the process of H2 formation, the pathway of H2 production over surface Fe site is more favorable with the calculated activation energy of 0.428 eV. Formations of H2O and H2 are competing reactions during chemical looping process. However, the relatively low activation energy barriers of H2O dissociation (0.141 eV or 0.081 eV) and H2 formation (0.428 eV) suggest that H2 formation is more competitive. For comparison, performances of Fe2O3 as oxygen carrier were also investigated. The calculation results show a relatively high energy barrier (1.314 eV) of CO formation and relatively low energy barrier (0.434 eV) of CO oxidation.

中文翻译：

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LaFeO3用于生物质化学循环气化的性能及机理研究

钙钛矿氧化物由于其优异的特性被广泛应用于许多重要的技术领域。在这项工作中，研究了 LaFeO3 作为氧载体在生物质化学循环气化中的性能。发现随着氧载体循环次数的增加，CO和H2的产率没有显着降低。没有观察到随着 LaFeO3 质量的增加合成气产率的明显变化，表明 LaFeO3 的稳定性。水蒸气的体积分数应控制在39.9%。DFT 计算结果表明，CO 解吸被确定为限速步骤，CO 分子形成的活化势垒为 0.648 eV。对于 CO 氧化，COO* 复合物的形成是限速步骤，能量势垒为 0.368 eV。在 H2 形成过程中，表面 Fe 位点产生 H2 的途径更有利，计算的活化能为 0.428 eV。H2O 和 H2 的形成是化学循环过程中的竞争反应。然而，H2O 解离（0.141 eV 或 0.081 eV）和 H2 形成（0.428 eV）的相对较低的活化能垒表明 H2 的形成更具竞争力。为了比较，还研究了 Fe2O3 作为氧载体的性能。计算结果表明，CO形成的能垒相对较高（1.314 eV），而CO氧化的能垒相对较低（0.434 eV）。141 eV 或 0.081 eV) 和 H2 形成 (0.428 eV) 表明 H2 形成更具竞争力。为了比较，还研究了 Fe2O3 作为氧载体的性能。计算结果表明，CO形成的能垒相对较高（1.314 eV），而CO氧化的能垒相对较低（0.434 eV）。141 eV 或 0.081 eV) 和 H2 形成 (0.428 eV) 表明 H2 形成更具竞争力。为了比较，还研究了 Fe2O3 作为氧载体的性能。计算结果表明，CO形成的能垒相对较高（1.314 eV），而CO氧化的能垒相对较低（0.434 eV）。