(545c) Determining the Effects of Oxygen On Multifunctional Alcohol Decomposition On Pd(111)

To aid in developing more selective catalysts for biorefining applications, we have studied the surface chemistry of multifunctional alcohols using surface science techniques.  In this contribution, we describe the effects of adsorbed oxygen on the decomposition pathways of a variety of alcohols, including benzyl alcohol and furfuryl alcohol, on Pd(111) via temperature programmed desorption (TPD) and high resolution electron energy loss spectroscopy (HREELS) experiments. On clean Pd(111), furfuryl alcohol and benzyl alcohol proceed through competing reaction pathways of deoxygenation or decarbonylation.  It was found that  deoxygenation is favored at high coverage, with  a bimolecular reaction between adsorbed multifunctional alcohols accelerating the deoxygenation pathway.  The reaction mechanisms for decomposition of a variety of alcohols has also been elucidated in the presence of oxygen, utilizing carefully selected isotopes to track particular C-H and O-H bonds, with TPD and HREELS. Our results show that pre-adsorbed oxygen strongly influences decomposition activation barriers, the selectivity of C-C and C-O scission, desorption products, and the overall extent of alcohol decomposition.  The relative coverages of the alcohol and oxygen play a significant role in the reaction chemistry. The results indicate that interactions between adsorbed oxygen and alcohol-derived intermediates play a major role in the selective oxidation of functional alcohols on Pt-group catalysts.