With worldwide petroleum resources dwindling and greenhouse gas emissions rising, it is urgent to find renewable replacements for petroleum-derived products. A biomass-derived chemical with high potential as a platform intermediate, ?-valerolactone (GVL), can be readily synthesized by hydrogenation of levulinic acid (LA), itself a common biomass intermediate, using supported Ru catalysts.  To date the literature on the hydrogenation of LA to GVL has focused more on the process and less on the catalyst. The goal of this work is derive fundamental synthesis-structure-function relationships of Ru catalysts for LA hydrogenation using carbon and alumina supported Ru nanoparticles which have been synthesized in a rational, repeatable, scalable way.  We have demonstrated that the method of strong electrostatic adsorption (SEA) yields well dispersed, homogeneously distributed Ru particles with tight particle size distributions over both types of supports.  SEA synthesis of well dispersed nanoparticles results in higher activity than commercial Ru catalysts with higher Ru loadings.  The dramatic, beneficial effect of potassium doping is reported for the first time.  The carbon support yields higher inherent activity than alumina. Activity as a function of particle size appears sharp volcano shape and to go through a maximum at about 1.5 nm, which indicates hydrogenation of LA is very structure sensitive on Ru particle size. This is supported by FTIR of adsorbed CO on Ru particles of different size. Catalyst deactivation after 24 h occurs to significant extents (8 � 58%) mainly by nanoparticle sintering, but also by minor amounts of K loss in K-doped samples.

Rational nanoparticle synthesis to study the effects of ruthenium particle size, supports, and potassium dopant for levulinic acid hydrogenation to ?-valerolactone

248th National Meeting (2014)

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