High resolution electron energy loss spectroscopy (HREELS) and temperature programmed desorption (TPD) were employed to study the decomposition of 1-epoxy-3-butene (EpB) and 2-butenal (crotonaldehyde, CrHO) on Pd(111). HREELS investigations indicate that both EpB and CrHO decompose through a common surface aldehyde intermediate that is distinct from molecular CrHO. The surface aldehyde intermediate decomposes to yield the gas phase decarbonylation products CO and propylene, as well as H2. Comparison with previous studies suggests that Pd is unique compared to previously studied surfaces in its reactivity with EpB and CrHO.

The thermal surface chemistry of 2(5H)-furanone (25HF) on Pd(111) and Pt(111) was studied using high-resolution electron energy loss spectroscopy (HREELS) and temperature-programmed desorption (TPD). After adsorbing 25HF on each surface at <140 K, increasing the temperature above 300 K resulted in opening and decomposition of the furanone ring. On both surfaces, 25HF undergoes decarbonylation and dehydrogenation to form CO and H2 as the principal desorption products. A key difference between Pd(111) and Pt(111) reactivity is the relatively high amount of CO2 produced from Pt(111), suggesting that 25HF decomposition proceeds in part through an additional surface intermediate on Pt(111). HREELS provides further indications that the reactions proceed through distinct pathways. On Pd(111), direct decarbonylation to surface CO and ethylidyne is observed. On Pt(111), two reaction pathways are proposed. One pathway is similar to the reaction pathway for Pd(111) and produces CO during TPD, and the other proceeds through an intermediate that retains the OCO functional group and results in CO2 as a desorption product.

High-resolution electron energy loss spectroscopy (HREELS) and temperature-programmed desorption (TPD) were used to study the adsorption and thermal chemistry of 2,3-dihydrofuran (2,3-DHF) and 2,5-dihydrofuran (2,5-DHF) on Pd(111). The results, paired with earlier computational results, indicate that 2,3-DHF and 2,5-DHF both adsorb on Pd(111) primarily via their respective olefin functional groups at low temperature (<170 K). Both molecules undergo dehydrogenation by 248 K to form species that produce furan in a reaction limited process above 300 K. The furan-producing intermediate intermediate can also undergo decomposition to form C(3)H(x) and CO. In addition, benzene resulting from C-C coupling reactions is detected on the surface and as a desorption product from both species, at about 520 K. A key difference between the two species is that 2,3-DHF can be hydrogenated to produce tetrahydrofuran at about 330 K, whereas 2,5-DHF is more likely to dehydrogenate, producing furan in an additional low-temperature channel at approximately 320 K. The results point to the importance of the position of the olefin functional group in relation to the ether function in determining the reactivity of cyclic oxygenates.

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A combination of experimental surface science techniques and density functional theory calculations has been employed to understand the adsorption and surface chemistry of a variety of C 4 cyclic oxygenates on the (111) surface of Pd. These C 4 cyclic oxygenates represent important probe molecules for production of chemicals from biomass-derived carbohydrates. The surface level studies of these intermediates reveal that adsorption and reactivity trends are determined by ring size/strain, degree of unsaturation, nature of the oxygenate function, and composition of the metal surface.