AVS 46th International Symposium
    Surface Science Division Monday Sessions
       Session SS1+EM-MoM

Paper SS1+EM-MoM10
Reactions of Acetic Acid, Acetaldehyde and Ethanol on the (111) Surface of Uranium Dioxide Single Crystal

Monday, October 25, 1999, 11:20 am, Room 606

Session: Chemistry on Oxides
Presenter: H. Idriss, 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 three C2 molecules having different functional group and polarity, have been investigated on the (111) surface of uranium dioxide single crystal, which has been characterised by LEED and AES. The adsorption of acetic acid, the most polar among the three molecules, indicates a higher sticking probability on the oxygen terminated UO@sub 2@(111) surface, followed by ethanol then acetaldehyde. Temperature Programmed Desorption (TPD) for these molecules displays a rich chemistry. Acetic acid-TPD on a stoichiometric surface yields ketene (dehydration) as the main product, plus acetaldehyde (reduction) as the minor product. While on an electron beam sputtered surface, two additional products were observed - butene and crotonaldehyde. In the case of acetaldehyde, both sputtered and non-sputtered surfaces yield benzene, with ketene as the additional product on the sputtered surface. The reactions of ethanol on a stoichiometric surface give acetaldehyde and ethylene as the only two products with "equal" amount. The comparison of this latter result with those of other metal oxide single crystals indicates a plausible relationship between the dehydrogenation/dehydration selectivity of primary alcohols and the Madelung potential of the cations. In summary, this investigation has shown the ability of UO@sub 2@(111) single crystal to oxidise, reduce, reductively couple, and trimerise organic molecules.