原位拉曼光谱研究CO还原α-Fe_(2)O_(3)过程的晶面效应  

Probing into the crystal plane effect on the reduction ofα-Fe_(2)O_(3) in CO by Operando Raman spectroscopy

作　　者：李培侠 曲龙梅 张彩虹 任晓波 王会香[1] 张建利[3] 穆跃文 吕宝亮[1,3] LI Pei-xia;QU Long-mei;ZHANG Cai-hong;REN Xiao-bo;WANG Hui-xiang;ZHANG Jian-li;MU Yue-wen;LV Bao-liang(State Key Laboratory of Coal Conversion,Institute of Coal Chemistry,Chinese Academy of Sciences,Taiyuan 030001,China;Changzhi Comprehensive Inspection and Testing Center,Changzhi 046000,China;State Key Laboratory of High-Efficiency Utilization of Coal and Green Chemical Engineering,Ningxia University,Yinchuan 750021,China;Key Laboratory of Materials for Energy Conversion and Storage of Shanxi Province,Institute of Molecular Science,Shanxi University,Taiyuan 030006,China)

机构地区：[1]中国科学院山西煤炭化学研究所,煤转化国家重点实验室,山西太原030001 [2]长治市综合检验检测中心,山西长治046000 [3]宁夏大学,省部共建煤炭高效利用与绿色化工国家重点实验室,宁夏银川750021 [4]山西大学分子科学研究所,能量转换与存储材料山西省重点实验室,山西太原030006

出　　处：《燃料化学学报》2021年第10期1558-1566,I0014-I0020,共16页Journal of Fuel Chemistry and Technology

基　　金：supported by National Natural Science Foundation of China (21972158);Research Project Supported by Shanxi Scholarship Council of China (2020-196);Foundation of State Key Laboratory of High-efficiency Utilization of Coal and Green Chemical Engineering (2021-K10);Shanxi Province Science Foundation for Youths (201901D211583);the Doctoral Start-up Foundation of Shanxi Province (SQ2019006)

摘　　要：氧化铁作为铁基费托合成主催化剂的前驱体,其还原活化过程对催化剂整体性能有着至关重要的影响。α-Fe_(2)O_(3)作为一种晶体材料,其暴露晶面对铁基催化剂的还原和活化过程有重要影响,但目前对此仍然缺乏必要的研究。本研究合成了六角片、立方体和菱面体三种不同形貌的α-Fe_(2)O_(3)单晶纳米颗粒,其对应主暴露面分别为(001)、(102)和(104)晶面,然后利用原位拉曼光谱(ORS)研究了CO还原过程中α-Fe_(2)O_(3)晶体结构的转变过程。结果发现,与(104)和(102)晶面相比,(001)晶面具有更好的还原活性。对于三种晶面上的CO吸附和CO_(2)脱附,SEM、TEM和XPS等表征以及DFT理论计算结果表明,CO_(2)脱附是还原过程的决速步骤;(001)晶面对氧原子的束缚能力较弱,导致了其表面CO_(2)更容易脱附,从而促进了整个还原过程。For the Fe-based catalysts in Fischer-Tropsch synthesis,the reduction and activation process ofα-Fe_(2)O_(3)precursor has a significant effect on the catalytic performance.As a crystalline material,the reduction and activation ofα-Fe_(2)O_(3)is assuredly influenced by the exposed crystal plane;however,there is a lack of necessary research in this regard.In this work,α-Fe_(2)O_(3)nanocrystals of three different morphologies,viz.,pseudo-cubic,hexagonal-plate and rhombohedra,were synthesized,which mainly expose the crystal planes of(102),(001)and(104),respectively.The evolution ofα-Fe_(2)O_(3)crystal structure was then investigated in CO atmosphere by using the Operando Raman spectroscopy(ORS).The results show that theα-Fe_(2)O_(3)(001)plane has a better reductive activity in comparison to the(104)and(102)planes.The SEM,TEM,XPS and XRD characterization and DFT calculation results reveal that CO_(2)desorption is a decisive step for the reduction ofα-Fe_(2)O_(3);owing to the weak binding ability of(001)crystal plane to oxygen atoms,the desorption of CO_(2)on the(001)crystal plane is much easier,which can promote the reduction process.

关 键 词：α-Fe_(2)O_(3) 晶面 原位拉曼 还原 

分 类 号：TF533.1[冶金工程—钢铁冶金]