(745c) Effects of Water on the Kinetics of Acetone Hydrogenation over Metal Catalysts

Authors: 
Demir, B., University of Wisconsin-Madison
Dumesic, J. A., University of Wisconsin-Madison
Chemburkar, A., University of Minnesota
Kropp, T., University of Wisconsin-Madison
Mavrikakis, M., University of Wisconsin-Madison
Neurock, M., University of Minnesota
We will present results exploring the effects of the presence of water on the kinetics of acetone hydrogenation catalyzed by metal and bi-metallic catalysts. These effects are elucidated by intrinsic reaction kinetics experiments and by computational studies. The reaction kinetics experiments at different vapor-liquid concentrations are carried out by adjusting the reactor pressure with inert gas while holding the partial pressures of acetone, water and hydrogen constant. As a result, various reaction kinetics trends are developed in the liquid-only, vapor-liquid and vapor-only regimes. With the oxophilic metal catalyst, Ru/C, the existence of water in the gas phase enhances the rate of the acetone hydrogenation. Moreover, the reactivity further increases when the reaction is carried out in the presence of liquid water environment in the reactor. In contrast, the reactivity for acetone hydrogenation over a supported Pt catalyst does not change with the presence of water in gas phase or as liquid. However, the promotional effect of liquid water is observed when oxophilic promoters, such as Mo and Fe, are incorporated into the Pt catalyst. These experimental trends are supported by density functional theory calculations. We demonstrate that the energy barrier for the acetone hydrogenation over oxophilic metal catalysts is mitigated by the existence of water molecules on the surface under aqueous conditions, resulting in enhanced rates of acetone hydrogenation. The fundamental reactivity studies on acetone hydrogenation are valuable and promising for providing insights in understanding the hydrogenation of biomass-derived oxygenates and play a role in developing selective solvent environments for metal-catalyzed biomass conversion reactions.
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