Within the biomass processing field, the overarching goal is to synthesize alternatives to oil-based commodities from carbohydrates and lignin, which requires reductive chemistries. The low vapor pressure and high reactivity of the available feedstocks generally dictate condensed phase processing, while their high oxygen content (particularly in the case of sugars) imparts water solubility. Accordingly, aqueous-phase hydro-processing has become a staple of the biomass processing community. As a research community, we frequently set our sights on developing structure-function relations to enable rational selection of both metal and support to affect a particular reactivity, selectivity, or stability; unfortunately, connecting structure and function is non-trivial in condensed media. A common concern is that the structure and number of catalytic active sites can be difficult to precisely describe for catalysts immersed in liquid water.  In general, experimentalists are frequently relegated to <i>ex-situ</i> methods of characterization, which provide only a snapshot of the active material in an idealized state that may or may not be relevant under reaction conditions. Surface reactivity in liquid water is extremely dynamic—transient phenomena often occur on multiple timescales, and a catalyst may never reach an actual steady state structure, coverage, and/or performance in the course of a typical laboratory experiment. Coupled with a lack of detail about the catalyst in its working state, it can be very difficult to extract useful kinetic data from this type of system.  Here, we analyze observed transient phenomena during the hydrogenation of levulinic acid over supported Ru catalysts in water.  In doing so, we decouple activity from stability and attempt to provide meaningful insights regarding both.     <br/>

Trends in activity and stability of supported Ru during aqueous-phase hydrogenation of levulinic acid

256th National Meeting (2018)

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