<br/>Industrial hydrocarbon and chemical synthesis reactions (aromatic production, selective polar bond hydrogenation, hydrodeoxygenation of oxygenates) often involve shuffling of reactive hydrogen intermediates in their respective catalytic cycle. In order to achieve their intrinsic atomistic efficiency, we first understand the catalytic events and then their kinetic and thermodynamic requirements that lead to the selective attack of reactive hydrogen on specific chemical bonds (e.g., C=O, C-O, C=C, etc.). Using a combined kinetic, isotopic, spectroscopic, and density functional theory methods, we interrogate the molecular details, charge of reactive hydrogen species, and their catalytic function in several classes of reactions on metal, metal oxide, and metal sulfide systems. The specific chemistry and applications are: (1) hydrogen addition to aromatics and C-O bond cleavage in phenolic species during lignin hydrodeoxygenation reactions, (2) hydrogen transfer during the hydrogenation of aromatics, and (3) hydrogenation of polar bonds (C=O) in aldehydes and ketones. We show that, despite the different reaction systems, these catalytic steps and their rates are dictated by the charge of the reactive hydrogen species, and this charge is strongly influenced by not only the active site structure but also the local reaction environments. This mechanistic knowledge allows us to identify key thermodynamic properties as the kinetic descriptors, and formulate site and site environment that transform the potential energy landscape to allow hydrogen transfer reactions to occur effectively and selectively, in order to achieve the required reaction specificity and atomic efficiencies.

Hydrogen shuffling catalysis: A generalized mechanistic interpretation for hydrogenation and hydrodeoxygenation on transition metal clusters

2019 Spring National Meeting

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.