The Haber–Bosch Process Revisited: On the Real Structure and Stability of “Ammonia Iron” under Working Conditions

Authors

  • Timur Kandemir,

    1. Abteilung Anorganische Chemie, Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin (Germany)
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  • Dr. Manfred E. Schuster,

    1. Abteilung Anorganische Chemie, Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin (Germany)
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  • Dr. Anatoliy Senyshyn,

    1. Forschungsneutronenquelle Heinz Maier-Leibnitz (FRM II), Technische Universität München, Lichtenbergstrasse 1, 85747 Garching (Germany)
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  • Dr. Malte Behrens,

    Corresponding author
    1. Abteilung Anorganische Chemie, Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin (Germany)
    • Abteilung Anorganische Chemie, Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin (Germany)

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  • Prof. Dr. Robert Schlögl

    Corresponding author
    1. Abteilung Anorganische Chemie, Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin (Germany)
    • Abteilung Anorganische Chemie, Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin (Germany)

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  • We thank F. Girgsdies for help with the phase analysis, M. Hölzl and S. Pfanzelt for support at the beamline, Friedrich K. Seitz and Frank Rosowski (BASF SE) for providing the catalyst and for fruitful discussions, and FRM II (Garching) for the allocation of beam time.

Abstract

original image

In situ neutron diffraction was used to study the structural properties of an industrial ammonia synthesis catalyst under working conditions similar to those of the Haber–Bosch process. Despite favorable thermodynamics, no indications of reversible bulk nitridation of the iron catalyst was observed in a self-generated ammonia concentration of 12 vol % at 425 °C and 75 bar after 88 h on stream.

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