(239a) Theoretical Investigation of Ethylene Glycol Reforming Over Pt(111) in Vapor and Aqueous Environments

Faheem, M., University of South Carolina
Heyden, A., University of South Carolina

Catalytic conversion of biomass-derived oxygenates for production of hydrogen and transportation fuels has gained significant attention in recent years. Ethylene glycol has been used as a model molecule to gain mechanistic insights into the reaction mechanism. The main reaction pathway for the production of hydrogen involves cleavage of C-C, C-H, and O-H bonds with subsequent water-gas shift reaction. A parallel pathway leads to the production of alkanes through C-O bond scissions. While the reaction mechanism is to some degree understood at the metal-gas interface, lack of a well-established methodology for describing the influence of a complex liquid on a reaction across a solid-liquid interface with quantum mechanical accuracy has resulted in very little knowledge on the effect of a liquid-phase environment on the reaction mechanism.

In this talk, we present an application of our recently developed iSMS1 methodology to study the mechanism of ethylene glycol reforming over Pt(111) in water. Periodic planewave density functional theory calculations have been performed to obtain optimized structures for all intermediates and to calculate free energies of reaction and activation free energy barriers in the vapor phase. The effect of water has then been described through a combination of Gaussian-type orbital calculations and COSMO-RS calculations as required by iSMS. Finally, detailed microkinetic models have been developed for both vapor and aqueous phases to provide insights into the effect of a liquid phase environment on the reaction mechanism and activity descriptors.

1.             Faheem, M.; Suthirakun, S.; Heyden, A. J. Phys. Chem. C 2012, 116, 22458-22462.