(584a) Investigating Adsorbate Structures of Cyclic C4 Oxygenates from Biomass on Catalytic Metal Surfaces Using Spectroscopic Techniques

Numerous studies have shown that the properties of metal catalysts can in principle be fine-tuned by controlling the composition of the metal surface with high precision. The ability to design catalysts capable of high selectivity towards the conversion of a single functional group in a multifunctional molecule is a major objective for heterogeneous catalysis research. This need for high selectivity toward a single functional group may be of growing importance in efforts to establish biorefining operations, where biomass-derived multifunctional carbohydrates are key ?building block? intermediates and must be converted to commodity chemicals. This work focuses on results from high resolution electron energy loss spectroscopy (HREELS) and temperature programmed desorption (TPD) experiments combined with selective use of density functional theory (DFT) calculations on single-crystal surfaces under ultrahigh vacuum conditions to study structure-property relations for a series of C₄ cyclic oxygenates on Pd and Pt (111) surfaces. The objective of this work is to identify methods to tailor surfaces that are able to selectively react one functional group in the multifunctional molecule.

Two types of cyclic probe molecules have been studied in particular: 3-membered epoxide rings (in which ring-strain is high and the character of the oxygenate function is therefore more reactive) and 5-membered furanone rings (in which the ring is relatively stable). Both the epoxides and furanones contain an unsaturated C=C bond; for many applications (including biorefining applications), it is desired to selectively hydrogenate the olefin while keeping the oxygenate functionality intact. In this contribution, we explore the role of surface structure and composition in dictating the reaction pathways for multifunctional C₄ cyclic oxygenates on key transition metal and bimetallic surfaces. Possible catalyst design strategies for improving selectivity in reactions of these molecules are discussed.