Hydrogen transfer pathways in the oxidation of methanol on Pd(100)

Methanol oxidation was studied using temperature programmed reaction spectroscopy and electron energy loss vibrational spectroscopy in order to determine the reaction paths of the two chemically distinct hydrogen groups in the molecule. It was determined that the alcohol hydrogen is transferred through-space to adsorbed oxygen, forming a hydroxyl and a methoxyl group, while the methyl hydrogens are primarily stripped by the surface and later scavenged by oxygen. Methyl hydrogens can also participate in some through-space transfer reactions. The directly transferred hydrogen gives rise to a low temperature water peak (below 220 K) characteristic of hydroxyl recombination, while the hydrogen transferred via the surface always yields water above 300 K due to atomic recombination. Through-space transfer of the methyl hydrogen in the methoxyl intermediate leads to the formation of formaldehyde and methyl formate.