Furfural (FF) is an important biomass-derived platform chemical, which offers a rich source of derivatives that can be used as promising industrial chemicals and biofuel components such as furfuryl alcohol (FA) and 2-methyl furan (MF)^1,2. For this reason, chemical hydrogenation and hydrogenolysis (CH) of FF has been studied to obtain target products FA and MF extensively. Selective conversion has been mainly obtained over Cu-containing heterogeneous catalysts depending upon reaction conditions such as temperature, pressure, and catalyst loading and partial pressures of H₂ in vapor phase^3-5.   Frequently, the reduction conditions require moderate pressures of hydrogen and moderate reaction temperatures (200 – 300^oC) ^3-5.

As an alternative to CH, electrocatalytic hydrogenation and hydrogenolysis (ECH) allows for furfural reduction without the use of externally supplied hydrogen gas at mild reaction conditions.   Rather, the electrolyte and electrochemical process provide the means to reduce FF.

Similar to the heterogeneous catalysis work, Cu-based electrocatalysts have shown promise in ECH as well. Cu electrodes resulted in higher selectivities towards MF in acidic electrolytes than other metal electrodes investigated in the literature⁶. Additionally, Cu has a  relatively higher hydrogen overpotential compared to noble metals⁷, allowing for ECH to occur rather than the competitive hydrogen evolution reaction.

Our research has focused on the synergistic effects between Cu electrocatalysts and the electrolytes used.  The pH, anions and cations used, and the mixtures of organic and aqueous solutions used all have a significant impact on the selectivity of ECH between MF and FF.  For example, the selectivity of MF was 10 times higher than that of FA in 0.5M H₂SO₄ in 1:4 (vol) acetonitrile:water, but only FA was produced using the same Cu electrode in 0.2M NH₄Cl in 1:4 (vol) acetonitrile:water.  The relationships between electrolyte and product selectivity along with the impact of Cu catalyst morphology will be reported.

References:

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            (2)       Lange, J.-P.; van der Heide, E.; van Buijtenen, J.; Price, R. Furfural—A promising platform for lignocellulosic biofuels. ChemSusChem 2012, 5, 150-166.

            (3)       Rao, R.; Baker, R. T. K.; Vannice, M. Furfural hydrogenation over carbon-supported copper. Catalysis Letters 1999, 60, 51-57.

            (4)       Burnette, L. W.; Johns, I. B.; Holdren, R. F.; Hixon, R. M. Production of 2-methylfuran by vapor-phase hydrogenation of furfural. Industrial & Engineering Chemistry 1948, 40, 502-505.

            (5)       Bremner, J. G. M.; Keeys, R. K. F. The hydrogenation of furfuraldehyde to furfuryl alcohol and sylvan (2-methylfuran). Journal of the Chemical Society (Resumed) 1947, 1068-1080.

            (6)       Nilges, P.; Schröder, U. Electrochemistry for biofuel generation: production of furans by electrocatalytic hydrogenation of furfural. Energy & Environmental Science 2013, 6, 2925-2931.

            (7)       Revie, R. W.; Uhlig, H. H.: Corrosion and corrosion control: an introduction to corrosion science and engineering; 4th Ed. ed.; Wiley-Interscience, 2008.