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Historical perspective on: The role of potassium in the catalytic synthesis of ammonia [Volume 60, Issue 3, 15 January 1979, Pages 391–394]
Chemical Physics Letters 589 (2013) 17
Contents lists available at ScienceDirect
Chemical Physics Letters journal homepage: www.elsevier.com/locate/cplett
Historical perspective on: The role of potassium in the catalytic synthesis of ammonia [Volume 60, Issue 3, 15 January 1979, Pages 391–394] G. Ertl ⇑, M. Weiss, S.B. Lee Institut für Physikalische Chemie der Universität München, Munich, Germany
Summary by Gerhard Ertl, Nobel prize-winner: Professor Gerhard Ertl. The industrial synthesis of ammonia (Haber–Bosch process) is performed with iron-based catalysts in which small amounts of potassium act as an ‘electronic’ promoter [1]. In the course of our studies on the mechanism of this reaction, along the surface science approach [2], the effect of coadsorbed K on a Fe (1 0 0) single crystal surface on the kinetics of dissociative nitrogen adsorption (which is the rate-determining step of the reaction) was investigated. The observed strong enhancement of the rate of this step was attributed to a local increase of the adsorption energy of N2, whereby the activation energy for dissociation of this species is also lowered. As is reflected in the strong decrease of the work function, K adsorption is associated with a pronounced transfer of electronic
DOI of original article: http://dx.doi.org/10.1016/j.cplett.2013.08.060
⇑ Corresponding author. Fax: +49 30 84135106.
E-mail address: [email protected] (G. Ertl). 0009-2614/$ - see front matter Ó 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.cplett.2013.08.040
charge to the substrate, and a neighbouring N2 molecule will experience a stronger ‘backbonding’ effect from the metal to its p⁄-orbitals, whereby the M–N2 bond will be strengthened and the N–N bond weakened. This electrostatic model was later confirmed by further experiments [3], as well as by theory [4]. References [1] (a) R. Schlögl, in: G. Ertl, H. Knözinger, F. Schüth, J. Weitkamp (Eds.), Handbook of Heterogeneous Catalysis, second ed., Wiley-VCH, Weinheim, 2008, p. 2501; (b) G. Ertl, Encyclopedia of Catalysis, Wiley-VCH, Weinheim, 2010. [2] G. Ertl, Catal. Rev. 21 (1980) 201. [3] G. Ertl, S.B. Lee, M. Weiss, Surf. Sci. 144 (1982) 527. [4] J.K. Nørskov, S. Holloway, N.D. Lang, Surf. Sci. 137 (1984) 65.
Contents lists available at ScienceDirect
Chemical Physics Letters journal homepage: www.elsevier.com/locate/cplett
Historical perspective on: The role of potassium in the catalytic synthesis of ammonia [Volume 60, Issue 3, 15 January 1979, Pages 391–394] G. Ertl ⇑, M. Weiss, S.B. Lee Institut für Physikalische Chemie der Universität München, Munich, Germany
Summary by Gerhard Ertl, Nobel prize-winner: Professor Gerhard Ertl. The industrial synthesis of ammonia (Haber–Bosch process) is performed with iron-based catalysts in which small amounts of potassium act as an ‘electronic’ promoter [1]. In the course of our studies on the mechanism of this reaction, along the surface science approach [2], the effect of coadsorbed K on a Fe (1 0 0) single crystal surface on the kinetics of dissociative nitrogen adsorption (which is the rate-determining step of the reaction) was investigated. The observed strong enhancement of the rate of this step was attributed to a local increase of the adsorption energy of N2, whereby the activation energy for dissociation of this species is also lowered. As is reflected in the strong decrease of the work function, K adsorption is associated with a pronounced transfer of electronic
DOI of original article: http://dx.doi.org/10.1016/j.cplett.2013.08.060
⇑ Corresponding author. Fax: +49 30 84135106.
E-mail address: [email protected] (G. Ertl). 0009-2614/$ - see front matter Ó 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.cplett.2013.08.040
charge to the substrate, and a neighbouring N2 molecule will experience a stronger ‘backbonding’ effect from the metal to its p⁄-orbitals, whereby the M–N2 bond will be strengthened and the N–N bond weakened. This electrostatic model was later confirmed by further experiments [3], as well as by theory [4]. References [1] (a) R. Schlögl, in: G. Ertl, H. Knözinger, F. Schüth, J. Weitkamp (Eds.), Handbook of Heterogeneous Catalysis, second ed., Wiley-VCH, Weinheim, 2008, p. 2501; (b) G. Ertl, Encyclopedia of Catalysis, Wiley-VCH, Weinheim, 2010. [2] G. Ertl, Catal. Rev. 21 (1980) 201. [3] G. Ertl, S.B. Lee, M. Weiss, Surf. Sci. 144 (1982) 527. [4] J.K. Nørskov, S. Holloway, N.D. Lang, Surf. Sci. 137 (1984) 65.