Highly efficient K-Fe/C catalysts derived from metal-organic frameworks towards ammonia synthesis


Fe-based catalysts have been discovered as the best elementary metal-based heterogeneous catalysts for the ammonia synthesis in industrial application during the last century. Herein, a novel and scalable strategy is developed to prepare the K-promoted Fe/C catalyst with extremely high Fe loading (> 50 wt.%) through pyrolysis of the Fe-based metal-organic framework (MOF) xerogel. The obtained K-Fe/C catalysts exhibited superior activity and stability towards ammonia synthesis. The weight-specific reaction rate of Fe/C with K2O as promoter can achieve 12.4 mmol·g−1·h−1 at 350 °C and 30.4 mmol·g−1·h−1 at 400 °C, approximately four and two times higher than that of the commercial fused-iron catalyst (3.4 mmol·g−1·h−1 at 350 °C and 16.7 mmol·g−1·h−1 at 400 °C) under the same condition, respectively. The excellent performance of K-Fe/C can be ascribed to the inherited structure derived from the metal-organic frame precursors and the promotion of potassium, which can modify the binding energy of reactant molecules on the Fe surface, transfer electrons to iron for effective activation of nitrogen, prevent agglomeration of Fe nanoparticle (NPs) and restrain side reaction of carbon matrix to methane.

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  1. [1]

    Appl, M. Fundamentals of the synthesis reaction. In Ammonia: Principles and Industrial Practice. Appl, M., Ed.; Wiley-VCH: Weinheim, 2007; pp 9–63.

    Google Scholar 

  2. [2]

    Ertl, G. Molecules at surfaces: 100 years of physical chemistry in berlin-dahlem. Angew. Chem., Int. Ed. 2013, 52, 52–60.

    Article  Google Scholar 

  3. [3]

    Kyriakou, V.; Garagounis, I.; Vasileiou, E.; Vourros, A.; Stoukides, M. Progress in the electrochemical synthesis of ammonia. Catal. Today 2017, 286, 2–13.

    Article  Google Scholar 

  4. [4]

    Licht, S.; Cui, B.C.; Wang, B. H.; Li, F. F.; Lau, J.; Liu, S. Z. Ammonia synthesis by N2 and steam electrolysis in molten hydroxide suspensions of nanoscale Fe2O3. Science 2014, 345, 637–640.

    Article  Google Scholar 

  5. [5]

    Yang, D. S.; Chen, T.; Wang, Z. J. Electrochemical reduction of aqueous nitrogen (N2) at a low overpotential on (110)-oriented Mo nanofilm. J. Mater. Chem. A 2017, 5, 18967–18971.

    Article  Google Scholar 

  6. [6]

    Li, H.; Shang, J.; Ai, Z. H.; Zhang, L. Z. Efficient visible light nitrogen fixation with BiOBr nanosheets of oxygen vacancies on the exposed {001} facets. J. Am. Chem. Soc. 2015, 137, 6393–6399.

    Article  Google Scholar 

  7. [7]

    Medford, A. J.; Hatzell, M. C. Photon-driven nitrogen fixation: Current progress, thermodynamic considerations, and future outlook. ACS Catal. 2017, 7, 2624–2643.

    Article  Google Scholar 

  8. [8]

    Michalsky, R.; Pfromm, P. H.; Steinfeld, A. Rational design of metal nitride redox materials for solar-driven ammonia synthesis. Interface Focus 2015, 5, 20140084.

    Article  Google Scholar 

  9. [9]

    Arashiba, K.; Miyake, Y.; Nishibayashi, Y. A molybdenum complex bearing PNP-type pincer ligands leads to the catalytic reduction of dinitrogen into ammonia. Nat. Chem. 2010, 3, 120–125.

    Article  Google Scholar 

  10. [10]

    Del Castillo, T. J.; Thompson, N. B.; Peters, J. C. A synthetic single-site Fe nitrogenase: High turnover, freeze-quench 57Fe mössbauer data, and a hydride resting state. J. Am. Chem. Soc. 2016, 138, 5341–5350.

    Article  Google Scholar 

  11. [11]

    Nishibayashi, Y. Recent progress in transition-metal-catalyzed reduction of molecular dinitrogen under ambient reaction conditions. Inorg. Chem. 2015, 54, 9234–9247.

    Article  Google Scholar 

  12. [12]

    Han, W. F.; Huang, S. L.; Cheng, T. H.; Tang, H. D.; Li, Y.; Liu, H. Z. Promotion of Nb2O5 on the wustite-based iron catalyst for ammonia synthesis. Appl. Surf. Sci. 2015, 353, 17–23.

    Article  Google Scholar 

  13. [13]

    Sehested, J.; Jacobsen, C. J. H.; Törnqvist, E.; Rokni, S.; Stoltze, P. Ammonia synthesis over a multipromoted iron catalyst: Extended set of activity measurements, microkinetic model, and hydrogen inhibition. J. Catal. 1999, 188, 83–89.

    Article  Google Scholar 

  14. [14]

    Hagen, S.; Barfod, R.; Fehrmann, R.; Jacobsen, C. J. H.; Teunissen, H. T.; Chorkendorff, I. Ammonia synthesis with barium-promoted iron–cobalt alloys supported on carbon. J. Catal. 2003, 214, 327–335.

    Article  Google Scholar 

  15. [15]

    Karolewska, M.; Truszkiewicz, E.; Wściseł, M.; Mierzwa, B.; Kępiński, L.; Raróg-Pilecka, W. Ammonia synthesis over a Ba and Ce-promoted carbon-supported cobalt catalyst. Effect of the cerium addition and preparation procedure. J. Catal. 2013, 303, 130–134.

    Google Scholar 

  16. [16]

    Zeng, H. S.; Inazu, K.; Aika, K. I. Dechlorination process of active carbon-supported, barium nitrate-promoted ruthenium trichloride catalyst for ammonia synthesis. Appl. Catal. A Gen. 2001, 219, 235–247.

    Article  Google Scholar 

  17. [17]

    Banerjee, R.; Phan, A.; Wang, B.; Knobler, C.; Furukawa, H.; O’Keeffe, M.; Yaghi, O. M. High-throughput synthesis of zeolitic imidazolate frameworks and application to CO2 capture. Science 2008, 319, 939–943.

    Article  Google Scholar 

  18. [18]

    Furukawa, H.; Cordova, K. E.; O’Keeffe, M.; Yaghi, O. M. The chemistry and applications of metal-organic frameworks. Science 2013, 341, 1230444.

    Article  Google Scholar 

  19. [19]

    Silva, P.; Vilela, S. M. F.; Tomé, J. P. C.; Almeida Paz, F. A. Multifunctional metal-organic frameworks: From academia to industrial applications. Chem. Soc. Rev. 2015, 44, 6774–6803.

    Article  Google Scholar 

  20. [20]

    Mahmood, A.; Guo, W. H.; Tabassum, H.; Zou, R. Q. Metal-organic frameworkbased nanomaterials for electrocatalysis. Adv. Energy Mater. 2016, 6, 1600423.

    Article  Google Scholar 

  21. [21]

    Sun, J. K.; Xu, Q. Functional materials derived from open framework templates/precursors: Synthesis and applications. Energy Environ. Sci. 2014, 7, 2071–2100.

    Article  Google Scholar 

  22. [22]

    Wang, H. L.; Zhu, Q. L.; Zou, R. Q.; Xu, Q. Metal-organic frameworks for energy applications. Chem 2017, 2, 52–80.

    Article  Google Scholar 

  23. [23]

    Xia, W.; Zhu, J. H.; Guo, W. H.; An, L.; Xia, D. G.; Zou, R. Q. Well-defined carbon polyhedrons prepared from nano metal-organic frameworks for oxygen reduction. J. Mater. Chem. A 2014, 2, 11606–11613.

    Article  Google Scholar 

  24. [24]

    Xia, W.; Zou, R. Q.; An, L.; Xia, D. G.; Guo, S. J. A metal-organic framework route to in situ encapsulation of Co@Co3O4@C core@bishell nanoparticles into a highly ordered porous carbon matrix for oxygen reduction. Energy Environ. Sci. 2015, 8, 568–576.

    Article  Google Scholar 

  25. [25]

    Zhu, Q. L.; Xia, W.; Akita, T.; Zou, R. Q.; Xu, Q. Metal-organic frameworkderived honeycomb-like open porous nanostructures as precious-metal-free catalysts for highly efficient oxygen electroreduction. Adv. Mater. 2016, 28, 6391–6398.

    Article  Google Scholar 

  26. [26]

    Rogge, S. M. J.; Bavykina, A.; Hajek, J.; Garcia, H.; Olivos-Suarez, A. I.; Sepúlveda-Escribano, A.; Vimont, A.; Clet, G.; Bazin, P.; Kapteijn, F. et al. Metal-organic and covalent organic frameworks as single-site catalysts. Chem. Soc. Rev. 2017, 46, 3134–3184.

    Article  Google Scholar 

  27. [27]

    Yin, P. Q.; Yao, T.; Wu, Y.; Zheng, L. R.; Lin, Y.; Liu, W.; Ju, H. X.; Zhu, J. F.; Hong, X.; Deng, Z. X. et al. Single cobalt atoms with precise N-coordination as superior oxygen reduction reaction catalysts. Angew. Chem., Int. Ed. 2016, 55, 10800–10805.

    Article  Google Scholar 

  28. [28]

    Zhao, C. M.; Dai, X. Y.; Yao, T.; Chen, W. X.; Wang, X. Q.; Wang, J.; Yang, J.; Wei, S. Q.; Wu, Y.; Li, Y. D. Ionic exchange of metal–organic frameworks to access single nickel sites for efficient electroreduction of CO2. J. Am. Chem. Soc. 2017, 139, 8078–8081.

    Article  Google Scholar 

  29. [29]

    Lohe, M. R.; Rose, M.; Kaskel, S. Metal-organic framework (MOF) aerogels with high micro- and macroporosity. Chem. Commun. 2009, 0, 6056–6058.

    Article  Google Scholar 

  30. [30]

    Mahmood, A.; Xia, W.; Mahmood, N.; Wang, Q. F.; Zou, R. Q. Hierarchical heteroaggregation of binary metal-organic gels with tunable porosity and mixed valence metal sites for removal of dyes in water. Sci. Rep. 2015, 5, 10556.

    Article  Google Scholar 

  31. [31]

    Ertl, G. Primary steps in catalytic synthesis of ammonia. J. Vac. Sci. Technol. A 1983, 1, 1247–1253.

    Article  Google Scholar 

  32. [32]

    Hibbitts, D.; Iglesia, E. Prevalence of bimolecular routes in the activation of diatomic molecules with strong chemical bonds (O2, NO, CO, N2) on catalytic surfaces. Acc. Chem. Res. 2015, 48, 1254–1262.

    Article  Google Scholar 

  33. [33]

    Kowalczyk, Z.; Jodzis, S.; Raróg, W.; Zieliński, J.; Pielaszek, J. Effect of potassium and barium on the stability of a carbon-supported ruthenium catalyst for the synthesis of ammonia. Appl. Catal. A Gen. 1998, 173, 153–160.

    Article  Google Scholar 

  34. [34]

    Kowalczyk, Z.; Sentek, J.; Jodzis, S.; Diduszko, R.; Presz, A.; Terzyk, A.; Kucharski, Z.; Suwalski, J. Thermally modified active carbon as a support for catalysts for NH3 synthesis. Carbon 1996, 34, 403–409.

    Article  Google Scholar 

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This work was financially supported by the National Key Research and Development Program of China (Nos. 2017YFB0602200 and 2017YFA0206701), National Program for Support of Top-notch Young Professionals, Changjiang Scholar Program and the National Natural Science Foundation of China (Nos. 21725301, 91645115, 21673273, 21473003, 21872104, and 21821004). The XPS experiments were conducted at Lab of Multitechniques Electron & Ion Spectrometer for Surface Analysis of Peking University. We thank Jinglin Xie for XPS data discussion.

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Correspondence to Ruqiang Zou or Ding Ma.

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Yan, P., Guo, W., Liang, Z. et al. Highly efficient K-Fe/C catalysts derived from metal-organic frameworks towards ammonia synthesis. Nano Res. 12, 2341–2347 (2019). https://doi.org/10.1007/s12274-019-2349-0

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  • metal-organic frameworks
  • pyrolysis
  • ammonia synthesis
  • iron nanoparticles
  • K promotion