Improving Syngas Selectivity of Fe2O3/Al2O3 with Yttrium Modification in Chemical Looping Methane Conversion
Improving Syngas Selectivity of Fe2O3/Al2O3 with Yttrium Modification in Chemical Looping Methane Conversion
复制标题
钇改性提高化学循环甲烷转化中 Fe2O3/Al2O3 合成气的选择性
DOI：
10.1021/acscatal.9b02730
复制
发表时间：
2019-09-01
期刊：
影响因子：
12.9
通讯作者：
Wang, Xiaodong
中科院分区：
文献类型：
--
作者：
Kang, Yu;Tian, Ming;Wang, Xiaodong
铁基载氧体（OCs）具有晶格氧充足、成本低廉、环境相容性好等优点，在甲烷化学链部分氧化反应中提高其合成气选择性具有重要意义。结果表明，Y的加入可使Fe_2O_3/Al_2O_3催化剂的CO选择性提高到98%，而CH_4转化率接近90%。X射线衍射（XRD）和透射电子显微镜（TEM）表征结合穆斯堡尔谱表明，Y的掺入导致Fe物种逐渐从Fe 2 O3转移到石榴石结构（Y3 Fe 2Al 3 O 12），这是一种新形成的相，被发现对合成气的生成具有高度活性。密度泛函理论（DFT）计算结果表明，石榴石中受限Fe物种具有如此高的CO选择性，是由于石榴石结构中可还原的Fe离子与不可还原的Al和Y离子共享晶格氧，从而提高了氧空位形成能（E-ov）.因此，本研究为甲烷部分氧化反应中新材料的筛选提供了有意义的指导。
It is of great significance to improve the syngas selectivity of Fe-based oxygen carriers (OCs), because of their sufficient lattice oxygen, low cost, and environmental compatibility in chemical looping partial oxidation of CH4. In this work, it was found that the addition of Y could remarkably increase CO selectivity of Fe2O3/Al2O3 to 98% with a CH4 conversion of , similar to 90%. X-ray diffraction (XRD) and transmission electron microscopy (TEM) characterizations combined with Mossbauer spectroscopy illustrated that the incorporation of Y led to the Fe species gradually transferring from Fe2O3 into the garnet structure (Y3Fe2Al3O12), a newly formed phase, which was found to be highly active for syngas generation. Density functional theory (DFT) calculations demonstrated that such a high CO selectivity of confined Fe species in garnet originated from enhanced oxygen vacancy formation energy (E-ov), compared with Fe2O3, which resulted from the lattice oxygen shared by not only reducible Fe ions but also nonreducible Al and Y ones in a garnet structure. Therefore, our work provides a meaningful guidance of new materials screening for methane partial oxidation in the chemical looping process.