Ethyl Radical Ejection During Photodecomposition of Butanone on TiO2(110)

Journal Article · Wed Oct 15 00:00:00 EDT 2008 · Surface Science, 602(20):3188-3193

DOI:https://doi.org/10.1016/j.susc.2007.06.079· OSTI ID:947450

Henderson, Michael A

The photodecomposition of acetone and butanone were examined on the (110) surface of rutile TiO2 using temperature programmed desorption (TPD) and photon stimulated desorption (PSD). In both cases, photodecomposition was proceeded by a required thermal reaction between the adsorbed ketone and coadsorbed oxygen resulting in a diolate species. The diolate photodecomposed by ejection of an organic radical from the surface leaving behind a carboxylate species. In the acetone case, only methyl radical PSD was detected and acetate was left on the surface. In the butanone case there was a possibility of either methyl or ethyl radical ejection, with propionate or acetate left behind, respectively. However, only ethyl radical PSD was detected and the species left on the surface (acetate) was the same as in the acetone case. The preference for ethyl radical ejection is linked to the greater thermal stability of the ethyl radical over that of the methyl radical. Unlike in the acetone case, where the ejected methyl radicals did not participate in thermal chemistry on the TiO2(110) surface after photoactivation of the acetone diolate, ethyl radicals photodesorbing at 100 K from butanone diolate showed a preference for dehydrogenation to ethene through the influence of coadsorbed oxygen. These results reemphasize the mechanistic importance of organic radical production during photooxidation reactions on TiO2 surface. Pacific Northwest National Laboratory is operated by Battelle for the US Department of Energy.

• Research Organization: Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 947450
• Report Number(s): PNNL-SA-63867; SUSCAS; 19833; KC0302010; TRN: US0901850
• Journal Information: Surface Science, 602(20):3188-3193, Vol. 602, Issue 20; ISSN 0039-6028
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
ACETATES
ACETONE
CHEMISTRY
DEHYDROGENATION
DESORPTION
ETHYL RADICALS
KETONES
METHYL RADICALS
OXYGEN
PHOTONS
PRODUCTION
RADICALS
RUTILE
STABILITY
VOLATILE ORGANIC-COMPOUNDS
PHOTOCATALYTIC OXIDATION
GAS-PHASE
TITANIUM-DIOXIDE
HETEROGENEOUS PHOTOCATALYSIS
CARBOXYLIC-ACIDS
WATER-VAPOR
TIO2
METHYL
Environmental Molecular Sciences Laboratory