Free-Radical Pathways in the Decomposition of Ketones over Polycrystalline TiO2: The Role of Organoperoxy Radicals

Carter, Emma ORCID: https://orcid.org/0000-0001-6691-2377, Carley, Albert Frederick and Murphy, Damien Martin ORCID: https://orcid.org/0000-0002-5941-4879 2007. Free-Radical Pathways in the Decomposition of Ketones over Polycrystalline TiO2: The Role of Organoperoxy Radicals. ChemPhysChem 8 (1) , pp. 113-123. 10.1002/cphc.200600484

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Abstract

The oxidative decomposition of various ketones (including acetone, 2-butanone, 4-heptanone, cyclopentanone and cyclohexanone) over dehydrated TiO2 (P25) powder is investigated by electron paramagnetic resonance (EPR) spectroscopy. For the first time, a series of thermally unstable radical intermediates are observed both on the activated and reduced TiO2 surface, depending on the adopted experimental conditions. These radical intermediates are identified as organoperoxy-based species of general formula ROO. and RCO3.. They are formed by reaction of photogenerated charge carriers (either trapped electrons or trapped holes) with the adsorbed ketones in the presence of molecular oxygen. The organoperoxy intermediates are thermally unstable and decompose at temperatures in the region of 180–250 K. This work demonstrates that free-radical pathways involving both organoperoxy and superoxide radicals can be responsible for the thermal- and photodecomposition of ketones over polycrystalline TiO2 (P25).

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Chemistry Cardiff Catalysis Institute (CCI)
Subjects:	Q Science > QD Chemistry
Uncontrolled Keywords:	EPR spectroscopy; radical reactions; radicals; reactive intermediates; surface chemistry
Publisher:	Wiley-Blackwell
ISSN:	1439-4235
Last Modified:	16 Oct 2024 10:19
URI:	https://orca.cardiff.ac.uk/id/eprint/1444

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