Effects of zinc on χ-Fe_(5)C_(2) for carbon dioxide hydrogenation to olefins:Insights from experimental and density function theory calculations

作     者：Xianglin Liu Minjie Xu Chenxi Cao Zixu Yang Jing Xu Xianglin Liu;Minjie Xu;Chenxi Cao;Zixu Yang;Jing Xu

作者机构：State Key Laboratory of Chemical EngineeringEast China University of Science and TechnologyShanghai 200237China Maoming Branch R&D InstituteSINOPECMaoming 525000China Key Laboratory of Smart Manufacturing in Energy Chemical ProcessMinistry of EducationEast China University of Science and TechnologyShanghai 200237China 

出 版 物：《Chinese Journal of Chemical Engineering》 (中国化学工程学报（英文版）)

年 卷 期：2023年第54卷第2期

页      面：206-214页

核心收录：

学科分类：083002[工学-环境工程] 0830[工学-环境科学与工程（可授工学、理学、农学学位）] 081704[工学-应用化学] 07[理学] 070304[理学-物理化学(含∶化学物理)] 08[工学] 0817[工学-化学工程与技术] 070303[理学-有机化学] 0703[理学-化学] 

基　　金：the funding support from Shanghai Sailing Program (19YF1411000) National Natural Science Foundation of China (21878080, 21808058) Ningxia Science Foundation (2019AAC03282) 

主　　题：Reaction engineering χ-Fe_(5)C_(2) Zn promoter Carbon dioxide Hydrogenation Density function theory 

摘      要：Production of light olefins from CO_(2), the primary greenhouse gases, is of great importance to mitigate the adverse effects of CO_(2) emission on environment and to supply the value-added products from nonpetroleum resource. However, development of robust catalyst with controllable selectivity and stability remains a challenge. Herein, we report that Zn-promoted Fe catalyst can boost the stable and selective production of light olefins from CO_(2). Specifically, the Zn-promoted Fe exhibits a highly stable activity and olefin selectivity over 200 h time-on-stream compared to the unpromoted Fe catalyst, primarily owing to the preservation of active χ-Fe_(5)C_(2) phase. Structural characterizations of the spent catalysts suggest that Zn substantially regulates the content of iron carbide on the surface and suppresses the reoxidation of bulk iron carbide during the reaction. DFT calculations confirm that adsorption of surface carbon atoms and graphene-like carbonaceous species are not thermochemically favored on Zn-promoted Fe catalyst. Carbon deposition by CAC coupling reactions of two surface carbon atoms and dehydrogenation of CH intermediate are also inhibited. Furthermore, the effects of Zn on antioxidation of iron carbide were also investigated. Zn favored the hydrogenation of surface adsorbed oxygen atoms to H_(2)O and the desorption of H_(2)O, which reduces the possibility of surface carbide being oxidized by the chemisorbed oxygen.