In situ studies of the oxidation of HCl over RuO2 model catalysts : stability and reactivity

S. Zweidinger, J.P. Hofmann, O. Balmes, E. Lundgren, H. Over

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    Abstract

    Structure–activity experiments were performed for the HCl oxidation reaction (Deacon-like process) over RuO2 model catalysts – RuO2(1 1 0) and RuO2(1 0 0) – applying in situ surface X-ray diffraction (SXRD) combined with on-line mass spectrometry. The studied model catalysts turned out to be long-term stable under reaction conditions with gas feed ratios p(HCl):p(O2) ranging from 1:4 to 4:1 in the mbar pressure regime and temperatures as high as 685 K. Even pure HCl exposure in the mbar regime was not able to reduce RuO2 below 600 K; above 650 K chemical reduction of the oxide sets in. Under strongly oxidizing reaction conditions, the (surface) oxides grow slowly in thickness. On-line reactivity experiments of both types of model catalysts in a batch reactor yield a mean turn-over frequency (TOF) of 0.6 Cl2 molecules per second and active site for the HCl oxidation at 650 K and initial partial pressures of p(HCl) = 2 mbar and p(O2) = 0.5 mbar. The HCl oxidation over RuO2 is therefore considered to be structure insensitive.
    Original languageEnglish
    Pages (from-to)169-175
    Number of pages7
    JournalJournal of Catalysis
    Volume272
    Issue number1
    DOIs
    Publication statusPublished - 2010

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