CO oxidation over Rh dispersed on SiO{sub 2}, Al{sub 2}O{sub 3}, and TiO{sub 2}: Kinetic study and oscillatory behavior

Journal Article · Sun Oct 01 00:00:00 EDT 1995 · Journal of Catalysis

DOI:https://doi.org/10.1006/jcat.1995.1253· OSTI ID:191960

Ioannides, T; Efstathiou, A M; Zhang, Z L ^[1]

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1. Univ. of Patras (Greece); and others

The kinetic behavior of Rh supported on SiO{sub 2}, Al{sub 2}O{sub 3}, and TiO{sub 2} in the CO oxidation reaction has been investigated. It was found that the maximum turnover frequency (TOF) is approximately the same over the three catalysts, although the maximum is shifted to lower CO pressures for Rh/Al{sub 2}O{sub 3} and Rh/TiO{sub 2} than for Rh/SiO{sub 2} catalyst. At high CO pressures, a change from -1 to -0.4 in the reaction order with respect to CO was observed over Rh/Al{sub 2}O{sub 3} while in the case of Rh/TiO{sub 2} a similar change from -1 to -0.2 was observed. These changes are attributed to the contribution of the CO dissociation step to the total oxidation rate. Oscillatory behavior and hysteresis were observed on all catalysts at 393 K. However, the window of oscillation with respect to the CO pressure was much wider on Rh/SiO{sub 2} than on the other catalysts. On-line mass spectrometry was used to follow the precise oscillatory patterns as a function of reaction temperature over the Rh/SiO{sub 2} catalyst. The oxidation/reduction of the rhodium surface is proposed to be the dominant mechanism responsible for the observed oscillatory behavior. 46 refs., 8 figs., 1 tab.

• OSTI ID: 191960
• Journal Information: Journal of Catalysis, Journal Name: Journal of Catalysis Journal Issue: 2 Vol. 156; ISSN JCTLA5; ISSN 0021-9517
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
20 FOSSIL-FUELED POWER PLANTS
33 ADVANCED PROPULSION SYSTEMS
40 CHEMISTRY
ALUMINIUM OXIDES
CARBON MONOXIDE
CATALYST SUPPORTS
CATALYSTS
CHEMICAL REACTION KINETICS
MASS SPECTROSCOPY
OXIDATION
REDUCTION
RHODIUM
SILICA