Potassium promoter in industrial ammonia synthesis catalyst: Studies by surface ionization
作者： K. Engvall , L. Holmlid , A. Kotarba , J.B.C. Pettersson , P.G. Menon
DOI: 10.1016/0926-860X(95)00206-5
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摘要: Abstract Industrial ammonia synthesis catalysts, as fresh (pre-reduced and passivated) used (passivated) flat samples were studied in a molecular beam UHV apparatus, using surface ionization detector. The desorption of the K promoter from catalyst at 870–1080 could be characterized, by measuring angular distributions simultaneous Arrhenius plots, function angle around sample. two activation energies observed for 260 kJ/mol (2.7 eV) 330 (3.4 eV); had only one, much smaller barrier 164 (1.70 eV). chemical state potassium changes stronger bound ionic, probably form FeOK, to weaker, more covalent one during industrial process. A large difference work functions between (3.9 (1.7 was observed. This seems due formation oxides on catalyst, caused enrichment use.
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