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

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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(O-2) 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 (TOP) of 0.6 Cl-2 molecules per second and active site for the HCl oxidation at 650 K and initial partial pressures of p(HCl) = 2 mbar and p(O-2) = 0.5 mbar. The HCl oxidation over RuO2 is therefore considered to be structure insensitive. (C) 2010 Elsevier Inc. All rights reserved.

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Subject classification (UKÄ) – MANDATORY

  • Atom and Molecular Physics and Optics

Keywords

  • RuO2, Reactivity, Stability, Surfaces, Heterogeneous catalysis, In situ SXRD, Deacon process
Original languageEnglish
Pages (from-to)169-175
JournalJournal of Catalysis
Volume272
Issue number1
Publication statusPublished - 2010
Publication categoryResearch
Peer-reviewedYes