In situ observation of structural changes in polycrystalline silver catalysts by environmental scanning electron microscopy

Millar, Graeme J., Nelson, Megan L., & Uwins, Philippa J.R. (1998) In situ observation of structural changes in polycrystalline silver catalysts by environmental scanning electron microscopy. Journal of the Chemical Society, Faraday Transactions, 94(14), pp. 2015-2023.

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Morphology changes induced in polycrystalline silver catalysts as a result of heating in either oxygen, water or oxygen-methanol atmospheres have been investigated by environmental scanning electron microscopy (ESEM), FT-Raman spectroscopy and temperature programmed desorption (TPD). The silver catalyst of interest consisted of two distinct particle types, one of which contained a significant concentration of sub-surface hydroxy species (in addition to surface adsorbed atomic oxygen). Heating the sample to 663 K resulted in the production of 'pin-holes' in the silver structure as a consequence of near-surface explosions caused by sub-surface hydroxy recombination. Furthermore, 'pin-holes' were predominantly found in the vicinity of surface defects, such as platelets and edge structures. Reaction between methanol and oxygen also resulted in the formation of 'pin-holes' in the silver surface, which were inherently associated with the catalytic process. A reaction mechanism is suggested that involves the interaction of methanol with sub-surface oxygen species to form sub-surface hydroxy groups. The sub-surface hydroxy species subsequently erupt through the silver surface to again produce 'pin-holes'.

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ID Code: 62039
Item Type: Journal Article
Refereed: Yes
Keywords: silver, catalyst, formaldehyde, methanol, ESEM
DOI: 10.1039/A802674B
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
Copyright Owner: Copyright 1998 Royal Society of Chemistry
Copyright Statement: Restrictions on further re-use and further distribution
Deposited On: 26 Aug 2013 00:27
Last Modified: 26 Aug 2013 00:27

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