CO chemisorption and hydrogenation of surface carbon species formed after CO/He reaction on Rh/MgO: A transient kinetic study using FTIR and mass spectroscopy

Journal Article · Sun May 01 00:00:00 EDT 1994 · Journal of Catalysis; (United States)

DOI:https://doi.org/10.1006/jcat.1994.1111· OSTI ID:7036616

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

---

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

The chemisorption of CO and hydrogenation of surface adsorbed carbon species formed after reaction of CO/He with Rh/MgO catalyst in the range 300-573 K were studied by transient methods employing both FTIR and mass spectroscopy in separate flow and reactor systems. Exposure of Rh/MgO to CO/He at 523 K results in a rapid formation of linear and bridged CO species. It was found that formation of gem-dicarbonyl CO species during CO chemisorption at 300 K is strongly affected by CO/He treatment at 523 K and H[sub 2] reduction conditions. Experiments with labelled CO ([sup 13]CO and C[sup 18]O) indicate that linear and bridged CO species readily exchange with gaseous CO species. Transient hydrogenation results for adsorbed carbon-containing species formed after CO/He reaction at 523 K provide evidence that H[sub 2] chemisorption decreases after cycles of reaction in CO/He at 523 K followed by H[sub 2] reduction at 673 K. However, the surface coverages of adsorbed CO species are not affected by such treatments. Oxygen pretreatment of the catalyst at 623 K followed by H[sub 2] reduction, after CO/He reaction at 523 K, greatly affects the transient kinetics of hydrogenation of adsorbed CO species at 523 K but not their respective surface coverages. This result is related to a change in the hydrogen chemisorption sites by oxygen treatment which resulted in the removal of inactive carbon not hydrogenated at 723 K. A kinetic model for the hydrogenation of the various adsorbed carbon-containing species is proposed which accounts for the interpretation of the CH[sub 4] transient responses obtained. 46 refs., 13 figs.

• OSTI ID: 7036616
• Journal Information: Journal of Catalysis; (United States), Journal Name: Journal of Catalysis; (United States) Vol. 147:1; ISSN 0021-9517; ISSN JCTLA5
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
010408 -- Coal
Lignite
& Peat-- C1 Processes-- (1987-)
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
ALKALINE EARTH METAL COMPOUNDS
CARBON COMPOUNDS
CARBON MONOXIDE
CARBON OXIDES
CATALYST SUPPORTS
CATALYTIC EFFECTS
CHALCOGENIDES
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
CHEMISORPTION
ELEMENTS
HYDROGENATION
KINETICS
MAGNESIUM COMPOUNDS
MAGNESIUM OXIDES
METALS
OXIDES
OXYGEN COMPOUNDS
PLATINUM METALS
REACTION KINETICS
RHODIUM
SEPARATION PROCESSES
SORPTION
TRANSITION ELEMENTS