SCI和EI收录∣中国化工学会会刊

Chinese Journal of Chemical Engineering ›› 2023, Vol. 54 ›› Issue (2): 206-214.DOI: 10.1016/j.cjche.2022.03.027

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Effects of zinc on χ-Fe5C2 for carbon dioxide hydrogenation to olefins: Insights from experimental and density function theory calculations

Xianglin Liu1,2, Minjie Xu1, Chenxi Cao1,3, Zixu Yang1, Jing Xu1   

  1. 1. State Key Laboratory of Chemical Engineering, East China University of Science and Technology, Shanghai 200237, China;
    2. Maoming Branch R&D Institute, SINOPEC, Maoming 525000, China;
    3. Key Laboratory of Smart Manufacturing in Energy Chemical Process, Ministry of Education, East China University of Science and Technology, Shanghai 200237, China
  • Received:2021-09-03 Revised:2022-03-11 Online:2023-05-11 Published:2023-02-28
  • Contact: Zixu Yang,E-mail:zixu.yang@ecust.edu.cn
  • Supported by:
    The authors greatly acknowledge the funding support from Shanghai Sailing Program (19YF1411000), National Natural Science Foundation of China (21878080, 21808058), Ningxia Science Foundation (2019AAC03282).

Effects of zinc on χ-Fe5C2 for carbon dioxide hydrogenation to olefins: Insights from experimental and density function theory calculations

Xianglin Liu1,2, Minjie Xu1, Chenxi Cao1,3, Zixu Yang1, Jing Xu1   

  1. 1. State Key Laboratory of Chemical Engineering, East China University of Science and Technology, Shanghai 200237, China;
    2. Maoming Branch R&D Institute, SINOPEC, Maoming 525000, China;
    3. Key Laboratory of Smart Manufacturing in Energy Chemical Process, Ministry of Education, East China University of Science and Technology, Shanghai 200237, China
  • 通讯作者: Zixu Yang,E-mail:zixu.yang@ecust.edu.cn
  • 基金资助:
    The authors greatly acknowledge the funding support from Shanghai Sailing Program (19YF1411000), National Natural Science Foundation of China (21878080, 21808058), Ningxia Science Foundation (2019AAC03282).

Abstract: Production of light olefins from CO2, the primary greenhouse gases, is of great importance to mitigate the adverse effects of CO2 emission on environment and to supply the value-added products from non-petroleum 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 CO2. 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-Fe5C2 phase. Structural characterizations of the spent catalysts suggest that Zn substantially regulates the content of iron carbide on the surface and suppresses the re-oxidation 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 C-C 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 H2O and the desorption of H2O, which reduces the possibility of surface carbide being oxidized by the chemisorbed oxygen.

Key words: Reaction engineering, χ-Fe5C2, Zn promoter, Carbon dioxide, Hydrogenation, Density function theory

摘要: Production of light olefins from CO2, the primary greenhouse gases, is of great importance to mitigate the adverse effects of CO2 emission on environment and to supply the value-added products from non-petroleum 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 CO2. 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-Fe5C2 phase. Structural characterizations of the spent catalysts suggest that Zn substantially regulates the content of iron carbide on the surface and suppresses the re-oxidation 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 C-C 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 H2O and the desorption of H2O, which reduces the possibility of surface carbide being oxidized by the chemisorbed oxygen.

关键词: Reaction engineering, χ-Fe5C2, Zn promoter, Carbon dioxide, Hydrogenation, Density function theory