The initial activity for the aqueous-phase hydrogenation (APH) of acetaldehyde, propanal, acetone, xylose, furfural, and furfuryl alcohol; and the aqueous-phase hydrogenolysis of tetrahydrofurfuryl alcohol and xylitol, have been measured over a series of alumina-supported monometallic catalysts (Pd, Pt, Ru, Rh, Ni, and Co) in a high throughput reactor.  These oxygenated compounds have the same functionalities that are found in biomass-derived aqueous solutions including pyrolysis oils and aqueous hydrolysis solutions.  The rates of the APH of the carbonyl compounds are dependent on the functionality of the molecule and the catalyst.  Ru is most active for the APH of acetaldehyde, propanal, acetone, and xylose, whereas Pd is most active for the APH of furfural.  The measured rates of APH of carbonyl groups decrease in the order of acetone, acetaldehyde and propanal, xylose, and furfural.  The initial rates of aqueous-phase hydrogenolysis of tetrahydrofurfuryl alcohol and xylitol are much lower than the initial rate for APH of C=O and C=C bonds.  To achieve a mechanistic understanding DFT calculations and microkinetic modeling have been performed for several of the representative compounds.  The measured and predicted rates are compared to validate the proposed reaction mechanisms, following which activity descriptors are identified to facilitate the formulation of new catalysts.

Aqueous-phase hydrogenation and hydrogenolysis of biomass-derived oxygenates over monometallic catalysts

246th National Meeting (2013)

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