摘要：

Well‐characterized catalyst model compounds of KAlO 2 and KFeO 2 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 KAlO 2 (with the K desorption barrier of 1.76 eV) and covalent on KFeO 2 (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 KAlO 2 and fails for KFeO 2 . This failure indicates a non‐equilibrium desorption process. K Rydberg states are only found to desorb from KFeO 2 , in agreement with the suggestion that such states in some way are responsible for the catalytic activity.

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