(555a) Fundamental Investigation of C-C Coupling of Carbonyl Compounds on Ceria

Ceria is an abundant and widely used technological material owing to its ability to readily store and release oxygen and change oxidation state. There is a growing body of evidence indicating that ceria can promote a variety of reactions for organic compounds, including dehydrogenation/hydrogenation, deoxygenation, and C-C coupling, depending on the extent of surface reduction and crystalline orientation of the surface. This suggests that ceria can be a promising heterogeneous catalyst in its own right for the conversion of organic compounds, including the upgrading of pyrolysis and fermentation products, if its reactivity can be understood and tailored at the atomic level. In this talk we will present mechanistic insights generated from surface science experiments and theoretical modeling based on density functional theory calculations into how two representative organic oxygenates, acetaldehyde and acetic acid, interact with the CeO₂(111) surface and undergo self C-C coupling. This is accomplished in part by modeling and predicting the identity of surface reaction intermediates in comparison to infrared vibrational spectroscopy and the thermal decomposition and reaction events observed in temperature programmed desorption experiments. Our work sheds light on the intrinsic reactivity of this ceria surface toward the formation of the most closely related C₄ products, crotonaldehyde and acetone, and highlight the rate-limiting steps in the respective thermal conversion processes.