Elementary steps involved in the hydrogenation of the linear CO species adsorbed on a Ru/Al2O3 catalyst

Citation
M. Nawdali et al., Elementary steps involved in the hydrogenation of the linear CO species adsorbed on a Ru/Al2O3 catalyst, J MOL CAT A, 162(1-2), 2000, pp. 247-256
Citations number
31
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Physical Chemistry/Chemical Physics
Journal title
JOURNAL OF MOLECULAR CATALYSIS A-CHEMICAL
ISSN journal
1381-1169 → ACNP
Volume
162
Issue
1-2
Year of publication
2000
Pages
247 - 256
Database
ISI
SICI code
1381-1169(20001120)162:1-2<247:ESIITH>2.0.ZU;2-O
Abstract
The adsorption of CO on a reduced 3.5% Ru/Al2O3 catalyst in the temperature range (300-478 K) leads mainly to the formation of a linear CO species (de noted by L) adsorbed on Ru sites characterized by an IR band at 2047 cm(-1) at 300 K. The Linear CO species is hydrogenated to CH4 in the temperature range 443-478 K in a flow of pure hydrogen. The rate of appearance of CH4 a s a function of the time in hydrogen follows a decreasing exponential profi le which indicates that a limiting elementary step at the surface controls the overall process. It is shown that this step is the hydrogen-assisted di ssociation of CO, while the other elementary steps leading to CH4 are fast. In the course of the hydrogenation reaction, the hydrogen surface concentr ation does not change significantly with the removal of the L species (no c ompetition between the L species and hydrogen). This is due to the fact tha t in the presence of adsorbed CO on the surface, hydrogen is adsorbed in an amount similar to that determined on a surface without any adsorbed CO but the sites involved are different. (C) 2000 Elsevier Science B.V. All right s reserved.