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Ammonia synthesis using a stable electride as an electron donor and reversible hydrogen store

Nature Chemistry volume 4, pages 934–940 (2012)Cite this article

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Abstract

Industrially, the artificial fixation of atmospheric nitrogen to ammonia is carried out using the Haber–Bosch process, but this process requires high temperatures and pressures, and consumes more than 1% of the world's power production. Therefore the search is on for a more environmentally benign process that occurs under milder conditions. Here, we report that a Ru-loaded electride [Ca24Al28O64]4+(e−)4 (Ru/C12A7:e−), which has high electron-donating power and chemical stability, works as an efficient catalyst for ammonia synthesis. Highly efficient ammonia synthesis is achieved with a catalytic activity that is an order of magnitude greater than those of other previously reported Ru-loaded catalysts and with almost half the reaction activation energy. Kinetic analysis with infrared spectroscopy reveals that C12A7:e− markedly enhances N2 dissociation on Ru by the back donation of electrons and that the poisoning of ruthenium surfaces by hydrogen adatoms can be suppressed effectively because of the ability of C12A7:e− to store hydrogen reversibly.

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Figure 1: Ru-loaded C12A7 electride catalyst for ammonia synthesis.
Figure 2: Catalytic performance of Ru/C12A7:e− at atmospheric pressure.
Figure 3: Catalytic performance of Ru/C12A7:e− under high-pressure conditions.
Figure 4: FT-IR and kinetic analyses.
Figure 5: Possible pathway for the ammonia synthesis reaction over Ru/C12A7:e−.

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References

  1. Mittasch, A. Early studies of multicomponent catalysts. Adv. Catal. 2, 81–104 (1950).

    Google Scholar 

  2. Honkala, K. et al. Ammonia synthesis from first-principles calculations. Science 307, 555–558 (2005).

    Article  CAS  Google Scholar 

  3. Ertl, G. Elementary steps in heterogeneous catalysis. Angew. Chem. Int. Ed. Engl. 29, 1219–1227 (1990).

    Article  Google Scholar 

  4. Gambarotta, S. & Scott, J. Multimetallic cooperative activation of N2 . Angew. Chem. Int. Ed. 43, 5298–5308 (2004).

    Article  CAS  Google Scholar 

  5. Pool, A. J., Lobkovsky, E. & Chirik, P. J. Hydrogenation and cleavage of dinitrogen to ammonia with a zirconium complex. Nature 427, 527–530 (2004).

    Article  CAS  Google Scholar 

  6. Spencer, N. D., Schoonmaker, R. C. & Somorjai, G. A. Structure sensitivity in the iron single-crystal catalyzed synthesis of ammonia. Nature 294, 643–644 (1981).

    Article  CAS  Google Scholar 

  7. Aika, K., Takano, T. & Murata, S. Preparation and characterization of chlorine-free ruthenium catalysts and the promoter effect in ammonia-synthesis. 3. A magnesia-supported ruthenium catalyst. J. Catal. 136, 126–140 (1992).

    Article  CAS  Google Scholar 

  8. Jacobsen, C. J. H. et al. Catalyst design by interpolation in the periodic table: bimetallic ammonia synthesis catalysts. J. Am. Chem. Soc. 123, 8404–8405 (2001).

    Article  CAS  Google Scholar 

  9. Ozaki, A. Development of alkali-promoted ruthenium as a novel catalyst for ammonia synthesis. Acc. Chem. Res. 14, 16–21 (1981).

    Article  CAS  Google Scholar 

  10. Tsai, M. C., Seip, U., Bassignana, I. C., Kuppers, J. & Ertl, G. A vibrational spectroscopy study on the interaction of N2 with clean and K-promoted Fe(111) surfaces: π-bonded dinitrogen as precursor for dissociation. Surf. Sci. 155, 387–399 (1985).

    Article  CAS  Google Scholar 

  11. Rosowski, F. et al. Ruthenium catalysts for ammonia synthesis at high pressures: preparation, characterization, and power-law kinetics. Appl. Catal. A 151, 443–460 (1997).

    Article  CAS  Google Scholar 

  12. Bielawa, H., Hinrichsen, O., Birkner, A. & Muhler, M. The ammonia-synthesis catalyst of the next generation: barium-promoted oxide-supported ruthenium. Angew. Chem. Int. Ed. 40, 1061–1063 (2001).

    Article  CAS  Google Scholar 

  13. Rao, C. N. R. & Rao, G. R. Nature of nitrogen adsorbed on transition metal surfaces as revealed by electron spectroscopy and cognate techniques. Surf. Sci. Rep. 13, 221–263 (1991).

    Article  CAS  Google Scholar 

  14. Aika, K., Ozaki, A. & Hori, H. Activation of nitrogen by alkali-metal promoted transition-metal. 1. Ammonia synthesis over ruthenium promoted by alkali-metal. J. Catal. 27, 424–431 (1972).

    Article  CAS  Google Scholar 

  15. Hansen, T. W. et al. Atomic-resolution in situ transmission electron microscopy of a promoter of a heterogeneous catalyst. Science 294, 1508–1510 (2001).

    Article  CAS  Google Scholar 

  16. Ertl, G. Reactions at surfaces: from atoms to complexity (Nobel Lecture). Angew. Chem. Int. Ed. 47, 3524–3535 (2008).

    Article  CAS  Google Scholar 

  17. Urabe, K., Aika, K. & Ozaki, A. Activation of nitrogen by alkali metal-promoted transition metal. J. Catal. 38, 430–434 (1975).

    Article  CAS  Google Scholar 

  18. Ommen, J. G., Bolink, W. J., Prasad, J. & Mars, P. The nature of the potassium compound acting as a promoter in iron–alumina catalysts for ammonia synthesis. J. Catal. 38, 120–127 (1975).

    Article  Google Scholar 

  19. Larichev, Y. V. et al. XPS and TEM studies on the role of the support and alkali promoter in Ru/MgO and Ru-Cs+/MgO catalysts for ammonia synthesis. J. Phys. Chem. C 111, 9427–9436 (2007).

    Article  CAS  Google Scholar 

  20. Siporin, S. E. & Davis, R. J. Use of kinetic models to explore the role of base promoters on Ru/MgO ammonia synthesis catalysts. J. Catal. 225, 359–368 (2004).

    Article  CAS  Google Scholar 

  21. Bécue, T., Davis, R. J. & Garces, J. M. Effect of cationic promoters on the kinetics of ammonia synthesis catalyzed by ruthenium supported on zeolite X. J. Catal. 179, 129–137 (1998).

    Article  Google Scholar 

  22. Dye, J. L. Electrides: early examples of quantum confinement. Acc. Chem. Res. 42, 1564–1572 (2009).

    Article  CAS  Google Scholar 

  23. Matsuishi, S. et al. High-density electron anions in a nanoporous single crystal: [Ca24Al28O64]4+(e−)4 . Science 301, 626–629 (2003).

    Article  CAS  Google Scholar 

  24. Sushko, P., Shluger, A., Hayashi, K., Hirano, M. & Hosono, H. Electron localization and a confined electron gas in nanoporous inorganic electrides. Phys. Rev. Lett. 91, 126401-1-4 (2003).

    Article  Google Scholar 

  25. Toda, Y., Kubota, Y., Hirano, M., Hirayama, H. & Hosono, H. Surface of room-temperature-stable electride [Ca24Al28O64]4+(e−)4: preparation and its characterization by atomic-resolution scanning tunneling microscopy. ACS Nano 5, 1907–1914 (2011).

    Article  CAS  Google Scholar 

  26. Hayashi, K. Heavy doping of H− ion in 12CaO·7Al2O3 . J. Solid State Chem. 184, 1428–1432 (2011).

    Article  CAS  Google Scholar 

  27. Kim, S-W. & Hosono, H. Synthesis and properties of 12CaO·7Al2O3 electride: a review of single crystal and thin film growth. Phil. Mag. 92, 2596–2628 (2012).

    Article  CAS  Google Scholar 

  28. Yoon, B. et al. Charging effects on bonding and catalyzed oxidation of CO on Au8 clusters on MgO. Science 307, 403–407 (2005).

    Article  CAS  Google Scholar 

  29. Ricci, D. et al. Paramagnetic defect centers at the MgO surface. An alternative model to oxygen vacancies. J. Am. Chem. Soc. 125, 738–747 (2003).

    Article  CAS  Google Scholar 

  30. Sushko, P. V., Gavartin, J. L. & Shluger A. L. Electronic properties of structural defects at the MgO (001) surface. J. Phys. Chem. B 106, 2269–2276 (2002).

    Article  CAS  Google Scholar 

  31. Toda, Y. et al. Work function of a room-temperature, stable electride [Ca24Al28O64]4+(e−)4 . Adv. Mater. 19, 3564–3569 (2007).

    Article  CAS  Google Scholar 

  32. Michaelson, H. B. The work function of the elements and its periodicity. J. Appl. Phys. 48, 4729–4733 (1977).

    Article  CAS  Google Scholar 

  33. Matsuishi, S. et al. Direct synthesis of powdery inorganic electride [Ca24Al28O64]4+(e−)4 and determination of oxygen stoichiometry. Chem. Mater. 21, 2589–2591 (2009).

    Article  CAS  Google Scholar 

  34. Liang, C., Wei, Z., Xin, Q. & Li, C. Ammonia synthesis over Ru/C catalysts with different carbon supports promoted by barium and potassium compounds. Appl. Catal. A 208, 193–201 (2001).

    Article  CAS  Google Scholar 

  35. Kowalczyk, Z. et al. Carbon-supported ruthenium catalyst for the synthesis of ammonia. The effect of the carbon support and barium promoter on the performance. Appl. Catal. A 184, 95–102 (1999).

    Article  CAS  Google Scholar 

  36. Raróg-Pilecka, W. et al. Carbon-supported ruthenium catalysts for NH3 synthesis doped with caesium nitrate: activation process, working state of Cs–Ru/C. J. Catal. 239, 313–325 (2006).

    Article  Google Scholar 

  37. Kadowaki, Y. & Aika, K. Promoter effect of Sm2O3 on Ru/Al2O3 in ammonia synthesis. J. Catal. 161, 178–185 (1996).

    Article  CAS  Google Scholar 

  38. Kubota, J. & Aika, K. Infrared spectra of adsorbed dinitrogen on ruthenium metal supported on alumina and magnesium oxide. J. Chem. Soc. Chem. Commun. 1544–1545 (1991).

  39. Kubota, J. & Aika, K. Infrared studies of adsorbed dinitrogen on supported ruthenium catalysts for ammonia synthesis: effects of the alumina and magnesia supports and the cesium compound promoter. J. Phys. Chem. 98, 11293–11300 (1994).

    Article  CAS  Google Scholar 

  40. You, Z., Inazu, K., Aika, K. & Baba, T. Electronic and structural promotion of barium hexaaluminate as a ruthenium catalyst support for ammonia synthesis. J. Catal. 251, 321–331 (2007).

    Article  CAS  Google Scholar 

  41. Aika, K. et al. Support and promoter effect of ruthenium catalyst. Ш. Kinetics of ammonia synthesis over various Ru catalysts. Appl. Catal. A 28, 57–68 (1986).

    Article  CAS  Google Scholar 

  42. Hagen, S. et al. Ammonia synthesis with barium-promoted iron–cobalt alloys supported on carbon. J. Catal. 214, 327–335 (2003).

    Article  CAS  Google Scholar 

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Acknowledgements

We deeply appreciate K. Aika for his suggestions. Discussions with K. Nakajima and Y. Toda are acknowledged. We thank T. Yoshizumi, S. Nakamura and D. Lu for their technical assistance. This work was supported by a Funding Program for World-Leading Innovative R&D on Science and Technology from the Japan Society for the Promotion of Science. A part of this work was supported by a fund from the Element Strategy Initiative Project of the Ministry of Education, Culture, Sports and Science for Technology in Japan.

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  1. Sung-Wng Kim

    Present address: Present address: Department of Energy Science, SungKyunKwan University, Suwon, Korea,

Authors and Affiliations

  1. Materials and Structures Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, 226-8503, Yokohama, Japan

    Masaaki Kitano, Yasunori Inoue, Youhei Yamazaki, Shinji Kanbara, Michikazu Hara & Hideo Hosono

  2. Frontier Research Center, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, 226-8503, Yokohama, Japan

    Fumitaka Hayashi, Satoru Matsuishi, Toshiharu Yokoyama, Sung-Wng Kim & Hideo Hosono

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  1. Masaaki Kitano
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Contributions

H.H. proposed the idea behind this research and M.H. and H.H. directed the entire project. M.K., Y.I., Y.Y., F.H., S.M., S.K., T.Y. and S-W.K. performed the synthesis, characterization and catalytic testing of Ru/C12A7:e−. All the authors discussed the results and commented on the study. M.K., M.H. and H.H. co-wrote the manuscript.

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Correspondence to Michikazu Hara or Hideo Hosono.

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The authors declare no competing financial interests.

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Kitano, M., Inoue, Y., Yamazaki, Y. et al. Ammonia synthesis using a stable electride as an electron donor and reversible hydrogen store. Nature Chem 4, 934–940 (2012). https://doi.org/10.1038/nchem.1476

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  • DOI: https://doi.org/10.1038/nchem.1476

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