A transient kinetic study of the CO/H[sub 2] reaction on Rh/Al[sub 2]O[sub 3] using FTIR and mass spectroscopy

Journal Article · Fri Jul 01 04:00:00 EDT 1994 · Journal of Catalysis; (United States)

DOI:https://doi.org/10.1006/jcat.1994.1204· OSTI ID:6859048

Efstathiou, A M; Bennett, C O ^[1]; Chafik, T; Bianchi, D ^[2]

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1. Univ. of Connecticut, Storrs, CT (United States)
2. Universite Claude Bernard Lyon, Villeurbanne (France)

The evolution of surface species (their chemical composition and surface coverage) formed during the CO/H[sub 2] reaction at 220[degrees]C on 1 wt% Rh/Al[sub 2]O[sub 3] catalyst was studied by transient isotopic and various hydrogen titration techniques using both in situ mass spectrometry and FTIR. There is a very small amount of active carbon, CH[sub x] ([theta][sub CH], < 0.03), and a large amount of surface linear and bridged CO species ([theta][sub CO] = 0.93) which participate in the formation of CH[sub 4] during reaction. Their amounts stay practically constant with reaction time in CO/H[sub 2] even after 1 h on stream. Also present on the Rh surface are some C[sub x]H[sub y] (alkyl chains) species which largely grow with reaction time (during the first hour on stream) but do not participate in the reaction mechanism of CH[sub 4] formation (spectator species). In addition, formate and carbonate (spectator species) build slowly on the alumina support surface even after 1 h of reaction. The surface coverage of hydrogen, [theta][sub H], is found to be very small, a result consistent with the coverages of CO, CH, and C[sub x]H[sub y] species. CO dissociation over the present 1 wt% Rh/Al[sub 2]O[sub 3] (1.5-nm Rh particles) appears to largely control the overall rate of methane formation, a result similar to that previously reported over the 5 wt% Rh/Al[sub 2]O[sub 3] (9.0-nm Rh particles) catalyst. 60 refs., 11 figs., 4 tabs.

• OSTI ID: 6859048
• Journal Information: Journal of Catalysis; (United States), Journal Name: Journal of Catalysis; (United States) Vol. 148:1; ISSN 0021-9517; ISSN JCTLA5
• Country of Publication: United States
• Language: English

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37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
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ABSORPTION SPECTROSCOPY
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
CARBON COMPOUNDS
CARBON MONOXIDE
CARBON OXIDES
CATALYST SUPPORTS
CATALYSTS
CATALYTIC EFFECTS
CHALCOGENIDES
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
ELEMENTS
HYDROGEN
KINETICS
MASS SPECTROSCOPY
METALS
NONMETALS
OXIDES
OXYGEN COMPOUNDS
PLATINUM METALS
REACTION KINETICS
RHODIUM
SPECTROSCOPY
TRANSITION ELEMENTS