Theoretical Insights in to the Influence of the Solvent on Heterogeneous Catalytic Hydrogenation and Hydrogenolysis Reactions

The catalytic conversion of renewable chemical intermediates into high value chemicals and fuel precursors, the synthesis of fine chemical and pharmaceutical intermediates, and the electrocatalytic oxidation of fuels and reduction of oxygen operative in polymer electrolyte fuel cell systems are important processes that can be significantly influenced by the reaction medium (i.e. solvent, solution) in which they are carried out. Solvent effects are often described by the stabilization or destabilization of the transition state by the dielectric constant of the medium in which the reaction is carried out. While such effects are clearly important, the solvent can also be involved in a more intimate manner with the reacting molecules via the formation of hydrogen bonding and unique structural and electronic environments near the active site, or by directly participating in actual catalytic reactions. We have used first principle quantum mechanical calculations to examine the role of solvent on the kinetics and mechanisms of specific metal-catalyzed hydrogenation and hydrogenolysis reactions of oxygenate intermediates important in many of the aforementioned processes.;More specifically, we carry out density functional theoretical calculations to examine the effect of solvent on the: (a) hydrogenation of aldehydes and ketones over different transitional metal surfaces, (b) hydrogenolysis of propionic acid over Ru, Re, and RuRe bimetallic, and (c) hydrogenolysis of glycerol over Ru(0001). The metal-water interface provides a unique environment where metal-catalyzed steps as well as the reactions in the bulk solvent can occur simultaneously.