Active oxygen center in oxidative coupling of methane on La_(2)O_(3) catalyst

作     者：Xiaohong Zhou Yaoqi Pang Zebang Liu Evgeny I.Vovk Alexander Pvan Bavel Shenggang Li Yong Yang Xiaohong Zhou;Yaoqi Pang;Zebang Liu;Evgeny I.Vovk;Alexander P.van Bavel;Shenggang Li;Yong Yang

作者机构：School of Physical Science and TechnologyShanghai Tech UniversityShanghai 201210China Shanghai Institute of Optics and Fine MechanicsChinese Academy of SciencesShanghai 201800China University of Chinese Academy of SciencesBeijing 100049China Shell Technology Centre AmsterdamP.O.Box 380001030 BN AmsterdamNetherlands CAS Key Laboratory of Low-Carbon Conversion Science and EngineeringShanghai Advanced Research InstituteChinese Academy of SciencesShanghai 201210China 

出 版 物：《Journal of Energy Chemistry》 (能源化学（英文版）)

年 卷 期：2021年第30卷第9期

页      面：649-659页

核心收录：

学科分类：0820[工学-石油与天然气工程] 081702[工学-化学工艺] 0808[工学-电气工程] 08[工学] 0817[工学-化学工程与技术] 0807[工学-动力工程及工程热物理] 0805[工学-材料科学与工程（可授工学、理学学位）] 080502[工学-材料学] 0827[工学-核科学与技术] 0703[理学-化学] 

基　　金：the Key Projects of Shanghai Science and Technology Commission (18JC1412100) the National Natural Science Foundation of China (No. 91745105, 22072092, 92045301) the startup funding provided by Shanghai Tech University for funding their participation in this work funding provided through The Shell Foundation Grants (No. PT66201) the support from Analytical Instrumentation Center (contract no. SPSTAIC10112914), SPST, Shanghai Tech University。 

主　　题：In-situ XPS Online MS DFT Oxidative coupling of methane High C_(2)selectivity Active oxygen center La_(2)O_(3)catalyst 

摘      要：La_(2)O_(3) catalyzed oxidative coupling of methane(OCM) is a promising process that converts methane directly to valuable C_(2)(ethylene and ethane) products. Our online MS transient study results indicate that pristine surface without carbonate species demonstrates a higher selectivity to C_(2) products, and a lower light-off temperature as well. Further study is focused on carbonate-free La_(2)O_(3) catalyst surface for identification of active oxygen species associated with such products behavior. XPS reveals unique oxygen species with O 1 s binding energy of 531.5 e V correlated with OCM catalytic activity and carbonates removal. However, indicated thermal stability of this species is much higher than the surface peroxide or superoxide structures proposed by earlier computation models. Motivated by experimental results,DFT calculations reveal a new more stable peroxide structure, formed at the subsurface hexacoordinate lattice oxygen sites, with energy 2.18 e V lower than the previous models. The new model of subsurface peroxide provides a perspective for understanding of methyl radicals formation and C_(2) products selectivity in OCM over La_(2)O_(3) catalyst.