The catalytic partial oxidation of ethanol was carried out over three different catalysts at short contact times to identify the effects of alloying with tin and of the support. The platinum-tin catalyst on zirconia produced more hydrogen and carbon oxides than the platinum on zirconia catalyst yet both had similar conversion of ethanol and selectivity to acetaldehyde. X-ray diffraction showed the presence of an equi-molar platinum-tin phase on the bimetallic catalyst. The smaller Pt-Pt bond distance in the bimetallic leads to a higher flux through the decarbonylation of acetaldehyde pathway (carbon-carbon bond breakage) compared to the dehydration of acetaldehyde route to ethylene. On alumina, the bimetallic catalyst exhibits behavior similar to the monometallic platinum on zirconia catalyst except there is more ethylene on the bimetallic. X-ray diffraction shows the presence of tin enriched platinum phases. It is likely that these phases are not active due to enrichment of the surface in tin and that the active sites are actually free platinum not taking part in the alloy. The difference in ethylene and acetaldehyde selectivity can be explained by the ability of zirconia to decompose ethylene/acetaldehyde to carbon, which is oxidized to carbon oxides in the atmosphere present during partial oxidation. (C) 2012 Elsevier Ltd. All rights reserved.