Influence of oxidation and reduction conditions upon the morphology of silica-supported polycrystalline silver catalysts

Millar, Graeme J., Metson, James B., Bowmaker, Graham A., & Cooney, Ralph P. (1995) Influence of oxidation and reduction conditions upon the morphology of silica-supported polycrystalline silver catalysts. Journal of the Chemical Society, Faraday Transactions, 91(1), pp. 133-139.

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Abstract

The effect of oxidation and reduction conditions upon the morphology of polycrystalline silver catalysts has been investigated by means of in situ Fourier-transform infrared (FTIR) spectroscopy. Characterization of the sample was achieved by inspection of the νas(COO) band profile of adsorbed formate, recorded after dosing with formic acid at ambient temperature. Evidence was obtained for the existence of a silver surface reconstructed by the presence of subsurface oxygen in addition to the conventional family of Ag(111) and Ag(110) crystal faces.

Oxidation at 773 K facilitated the reconstruction of silver planes due to the formation of subsurface oxygen species. Prolonged oxygen treatment at 773 K also caused particle fragmentation as a consequence of excessive oxygen penetration of the silver catalyst at defect sites. It was also deduced that the presence of oxygen in the gas phase stabilized the growth of silver planes which could form stronger bonds with oxygen. In contrast, high-temperature thermal treatment in vacuum induced significant sintering of the silver catalyst.

Reduction at 773 K resulted in substantial quantities of dissolved hydrogen (and probably hydroxy species) in the bulk silver structure. Furthermore, enhanced defect formation in the catalyst was also noted, as evidenced by the increased concentration of formate species associated with oxygen-reconstructed silver faces.

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ID Code: 62057
Item Type: Journal Article
Refereed: Yes
Keywords: silver, catalyst, formaldehyde, oxidation, reduction
DOI: 10.1039/FT9959100133
ISSN: 1364-5455
Subjects: Australian and New Zealand Standard Research Classification > CHEMICAL SCIENCE (030000) > PHYSICAL CHEMISTRY (INCL. STRUCTURAL) (030600) > Catalysis and Mechanisms of Reactions (030601)
Divisions: Current > Schools > School of Chemistry, Physics & Mechanical Engineering
Current > Institutes > Institute for Future Environments
Current > QUT Faculties and Divisions > Science & Engineering Faculty
Deposited On: 25 Aug 2013 23:24
Last Modified: 25 Aug 2013 23:35

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