FTIR study of the low-temperature water-gas shift reaction on Au/Fe{sub 2}O{sub 3} and Au/TiO{sub 2} catalysts

Journal Article · Mon Nov 15 04:00:00 EST 1999 · Journal of Catalysis

DOI:https://doi.org/10.1006/jcat.1999.2636· OSTI ID:20003856

Boccuzzi, F; Chiorino, A; Manzoli, M; Andreeva, D; Tabakova, T

An FTIR and quadruple mass spectroscopic study of the water-gas shift (WGS), the reverse WGS reactions, and the adsorption of the individual molecules involved has been carried out on Au/Fe{sub 2}O{sub 3} and Au/TiO{sub 2} catalysts. The chemisorptions and the reactions on the two catalysts have been compared with the aim of gaining a better understanding of the role played by the two phases present in these catalysts and of the synergistic interplay between them in gold catalysts tested for a low-temperature water-gas shift reaction. Evidences are reported that H{sub 2} is dissociated already at room temperature on both the catalysts on gold sites, giving rise to hydrogen atoms that can react with adsorbed oxygen atoms or spillover on the supports where they can reduce the support surface sites. It is shown that CO is adsorbed molecularly on different surface sites, on the support cations, on Au{sup 0} sites exposed at the surface of small three-dimensional particles and also on Au{sup {delta}{minus}} sites exposed at the surface of negatively charged clusters. The CO formed in the reverse WGS reaction appears chemisorbed only on the Au{sup 0} sites. The support sites and the Au{sup {delta}{minus}} sites, where the CO appears as more strongly bonded, are present but not accessible to the CO formed by CO{sub 2} reduction, probably because these sites are covered by water. Water and OH groups are adsorbed on the supports, on gold sites, and at the interface between them. The effects of CO coadsorption on water dissociation and of H{sub 2} dissociation on CO{sub 2} reduction have been evidenced. The close similarity of the catalytic activity of the two examined samples indicates that the active sties for hydrogen dissociation and for water-CO reactive interactions are located at the surface of the metallic gold small particles where the reaction can take place by a red-ox regenerative mechanism.

• Research Organization: Univ. degli Studi di Torino (IT)
• OSTI ID: 20003856
• Journal Information: Journal of Catalysis, Journal Name: Journal of Catalysis Journal Issue: 1 Vol. 188; ISSN 0021-9517; ISSN JCTLA5
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
08 HYDROGEN
CARBON MONOXIDE
CATALYTIC EFFECTS
CHEMICAL REACTION KINETICS
CHEMISORPTION
DISSOCIATION
GOLD
HYDROGEN
HYDROGEN PRODUCTION
IRON OXIDES
SHIFT PROCESSES
TITANIUM OXIDES
WATER GAS PROCESSES