Zn-Al共掺杂La_(2)O_(3)催化剂在甲烷氧化偶联中的性能  

Performance of Zn-Al co-doped La_(2)O_(3) catalysts in the oxidative coupling of methane

作　　者：黎营涛 牛鹏宇 王强 贾丽涛[1] 林明桂[1] 李德宝[1,3] LI Ying-tao;NIU Peng-yu;WANG Qiang;JIA Li-tao;LIN Ming-gui;LI De-bao(State Key Laboratory of Coal Conversion,Institute of Coal Chemistry,Chinese Academy of Sciences,Taiyuan 030001,China;University of Chinese Academy of Sciences,Beijing 100049,China;Dalian National Laboratory for Clean Energy,Dalian 116023,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]中国科学院大学,北京100049 [3]中国科学院洁净能源创新研究院,辽宁大连116023

出　　处：《燃料化学学报》2021年第10期1458-1467,共10页Journal of Fuel Chemistry and Technology

基　　金：山西省科技计划揭榜招标项目(20191101012);煤转化国家重点实验室自主研究课题(2020BWZ003)资助。

摘　　要：采用柠檬酸溶胶凝胶法制备了Zn掺杂和Zn-Al共掺杂的La_(2)O_(3)催化剂,运用原位表征技术研究了该催化剂在甲烷氧化偶联(OCM)反应中的构效关系。原位XRD表征结果发现,La_(2)O_(3)晶体在高温下沿c轴发生热膨胀。H2-TPR结果显示,La_(2)O_(3)基催化剂中含有两种类型的氧物种,即强结合氧和弱结合氧;XPS结果表明,强结合氧归属于为O−。Zn掺杂的La_(2)O_(3)催化剂在高温下形成更多的氧空位,能活化氧气产生更多的强结合氧,因而在OCM反应中表现出较好的催化性能。Al的共掺杂能促进Zn在La_(2)O_(3)中的分散,进一步增加强结合氧数量,提升OCM反应C_(2+)烃的选择性。Zn-doped and Zn-Al co-doped La_(2)O_(3)catalysts were prepared by citric acid sol-gel method and characterized by a series of in situ technologies,to investigate the structure-activity relationship of La_(2)O_(3)-based catalysts in the oxidative coupling of methane(OCM).The in situ XRD results reveal a thermal expansion of the La_(2)O_(3)crystal along the c-axis at high temperature.The H2-TPR results show two types of oxygen species on the La_(2)O_(3)-based catalysts,viz.,the strong-binding oxygen species and weak-binding oxygen species;in addition,the XPS results indicate that the strong-binding oxygen species is probably attributed to anion radical O−.The doping with Zn can significantly increase the number of oxygen vacancies in the Zn-doped La_(2)O_(3)catalysts,which can promote the activation of oxygen and generate more strong-binding oxygen species;as a result,the Zn-doped La_(2)O_(3)catalyst shows better performance in OCM in comparison with the unmodified La_(2)O_(3)catalyst.Moreover,the co-doping with Al can promote the dispersion of Zn in La_(2)O_(3)and further raise the number of strong-binding oxygen species in the Zn-Al co-doped La_(2)O_(3)catalysts,which is beneficial to enhance the selectivity to C_(2+)hydrocarbons in the OCM reaction.

关 键 词：Zn-Al共掺杂 La_(2)O_(3) 氧空位 晶体结构 甲烷氧化偶联 

分 类 号：O643[理学—物理化学]