Catalysis Letters

, Volume 67, Issue 2–4, pp 129–134 | Cite as

Stability and excitation of potassium promoter in iron catalysts – the role of KFeO2 and KAlO2 phases

  • Andrzej Kotarba
  • Andrzej Barański
  • Stanisław Hodorowicz
  • Jerzy Sokołowski
  • Andrzej Szytuła
  • Leif Holmlid
Article

Abstract

Well‐characterized catalyst model compounds of KAlO2 and KFeO2 are investigated by thermal desorption of potassium from the material. The desorbing fluxes of ions, atoms and highly excited states (field ionizable Rydberg states) were studied with surface and field ionization detectors in a vacuum apparatus. From the Arrhenius plots the activation energies for desorption of K and K+ were determined. The chemical state of potassium at the surfaces is concluded to be: ionic on KAlO2 (with the K desorption barrier of 1.76 eV) and covalent on KFeO2 (barrier of 2.73 eV). These results agree with the data obtained earlier for industrial catalysts for ammonia and styrene production. They are interpreted in terms of the Schottky cycle, which is completed for KAlO2 and fails for KFeO2. This failure indicates a non‐equilibrium desorption process. K Rydberg states are only found to desorb from KFeO2, in agreement with the suggestion that such states in some way are responsible for the catalytic activity.

potassium desorption stability excitation iron catalyst Rydberg atoms 

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Copyright information

© Kluwer Academic Publishers 2000

Authors and Affiliations

  • Andrzej Kotarba
    • 1
  • Andrzej Barański
    • 2
  • Stanisław Hodorowicz
    • 1
  • Jerzy Sokołowski
    • 1
  • Andrzej Szytuła
    • 3
  • Leif Holmlid
    • 4
  1. 1.Faculty of ChemistryJagiellonian UniversityKrakowPoland
  2. 2.Regional Laboratory of Physicochemical Analyses and Structural ResearchJagiellonian UniversityKrakowPoland
  3. 3.Institute of PhysicsJagiellonian UniversityKrakowPoland
  4. 4.Department of Chemistry, Reaction Dynamics GroupGöteborg UniversityGöteborgSweden

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