AVS 53rd International Symposium
    Surface Science Monday Sessions
       Session SS1-MoA

Paper SS1-MoA3
Hydrogen Production from Ethanol Over Bimetallic Catalysts

Monday, November 13, 2006, 2:40 pm, Room 2002

Session: Catalysis for the Hydrogen Economy
Presenter: H. Idriss, University of Auckland, New Zealand
Authors: P.Y. Sheng, University of Auckland, New Zealand
A. Yee, University of Auckland, New Zealand
W. Chiu, University of Auckland, New Zealand
H. Idriss, University of Auckland, New Zealand
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Hydrogen is one of the most plausible alternative energy sources that can be widely used in the near future if sustainable ways of generating it are found. This work focuses on the reactions of ethanol, as an example of a bio-fuel, on the surfaces of platinum, palladium and rhodium supported on ceria (of size 10 to 20 nm). The bimetallic compounds: Pt-Rh, Rh-Pd, and Pt-Pd were also investigated. The addition of any of the above metals to CeO@sub2@ was found to suppress the oxidation of ethanol to acetates at room temperature, as there are fewer surface oxygen atoms available to oxidize the ethanol (the remaining oxygen atoms did not produce efficient oxidation). Ethanol dehydrogenation to acetaldehyde was facilitated by the presence of Pt or Pd; at higher temperatures the acetaldehyde condensed to other organic compounds, such as crotonaldehyde. By contrast, in the presence of Rh only traces of acetaldehyde or other organic compounds were seen on the surface, and detectable amounts of CO were found upon ethanol adsorption at room temperature. This indicates the powerful nature of Rh in breaking the carbon-carbon bond in ethanol. The effects of prior reduction were also investigated and clear differences were seen: for example, a shift in reaction selectivity is observed for the bimetallic Rh-containing catalysts. Methane was the dominant hydrocarbon on the reduced catalysts while acetaldehyde was the main product for the non-reduced ones. Hydrogen formation was monitored during steady state ethanol oxidation and Pt-Rh and Rh-Au were found to be the most active catalysts.