AVS 47th International Symposium
    Surface Science Friday Sessions
       Session SS+MC-FrM

Paper SS+MC-FrM5
Reactions of Acetaldehyde over UO@sub2@(111) Single Crystal Surfaces: Evidence of Benzene Formation

Friday, October 6, 2000, 9:40 am, Room 209

Session: Characterization of Oxides and Thin Films
Presenter: S.V. Chong, The University of Auckland, New Zealand
Authors: S.V. Chong, The University of Auckland, New Zealand
H. Idriss, The University of Auckland, New Zealand
Correspondent: Click to Email
The reactions of aldehydes on metal oxide surfaces have exposed some of the most exquisite chemistry compared to their alcohol and carboxylic acid counterparts. Due to the intermediate oxidation state of the carbonyl carbon on an aldehyde, reactions such as the Cannizzaro reaction (forming alcohol and carboxylate) and Tishchenko reaction (forming ester) have been observed on various metal oxide surfaces. Furthermore, condensation reactions have also been observed on aldehydes possessing alpha-H atom(s) over stoichiometric metal oxide surfaces, while surface defect sites are able to reductively couple two aldehyde adsorbates to yield alkene. Herein, we present the reactions of acetaldehyde over the stoichiometric, electron irradiated, and H@sub2@ reduced surfaces of UO@sub2@(111) single crystal. TPD results over the three surfaces show evidence of benzene formation, and it appears that electron irradiation slightly increases the conversion to benzene, while H@sub2@ reduction doubles it. Thus, the amount of benzene yield might be a novel way to quantify the extent of surface defects. No C@sub4@ hydrocarbon (crotonaldehyde nor butadiene) traces were observed, indicating that the formation of benzene through aldol condensation pathways might be ruled out.