Molecular Origin of the Selectivity Differences between Palladium and Gold-Palladium in Benzyl Alcohol Oxidation: Different Oxygen Adsorption Properties

The same mechanism and microkinetic model used for benzyl alcohol oxidation over Pd/C was shown to apply to benzyl alcohol oxidation over AuPd/C. Almost all of the selectivity differences could be explained by a decrease in oxygen adsorption on AuPd. After isolating oxygen adsorption as being the origin of the selectivity differences, density functional theory was used to investigate the oxygen adsorption properties of a pure Pd surface, a pure Au surface, and an alloyed AuPd surface. The calculations showed that Au-Pd alloying decreased the oxygen adsorption properties relative to pure Pd, which explained the selectivity differences, consistent with the microkinetic modeling.