Mechanistic Insight into the Electrocatalytic Hydrogenation and Electroreduction of Furfural

Electrochemical reduction of biomass-derived platform chemicals is an emerging route for biofuels and chemicals production, where renewable electricity drives reactions on electrodes without the need for external hydrogen supply. 1-3 However, the mechanisms governing electrochemical reduction of biomass-derived furanic compounds and its competition with hydrogen evolution reaction (HER) remain unclear. In this talk, we investigate the electrochemical reduction of furfural on copper electrodes for the production of 2-methylfuran (an important potential biofuel additive), furfuryl alcohol (a valuable chemical building block), and dimerization products. Through novel electrochemical techniques, we distinguish between two mechanisms – electrocatalytic hydrogenation (ECH) and outer-sphere electroreduction (ER). Understanding of the underlying mechanisms enables us to tune product selectivity and the competition between ECH, ER, and HER by varying reaction conditions including cathode potential, initial furfural concentration and electrolyte pH. Cyclic voltammetry and bulk electrolysis results clarify the reaction pathways of 2-methylfuran and furfuryl alcohol formation under these conditions. We demonstrate that electrochemical reduction is a promising route for selective furfural conversion and highlight the importance of the underlying mechanisms. These findings can be applied to related biomass-derived platform chemicals including 5-(hydroxymethyl)furfural and other carbonyl-containing compounds. References: 1. Xin, L.; Zhang, Z.; Qi, J.; Chadderdon, D. J.; Qiu, Y.; Warsko, K. M.; Li, W., Electricity storage in biofuels: selective electrocatalytic reduction of levulinic acid to valeric acid or gamma-valerolactone. ChemSusChem 2013 , 6, 674–686. 2. Matthiesen, J. E.; Suástegui, M.; Wu, Y.; Viswanathan, M.; Qu, Y.; Cao, M.; Rodriguez-Quiroz, N.; Okerland, A.; Kraus, G.; Raman, D. Raj; Shao, Z.; Tessonnier, J.-P., Electrochemical Conversion of Biologically Produced Muconic Acid: Key Considerations for Scale-Up and Corresponding Technoeconomic Analysis. ACS Sustainable Chem. Eng. 2016 , 4, 7098–7109. 3. Suástegui, M.; Matthiesen, J. E.; Carraher, J. M.; Rodriguez Quiroz, N.; Okerlund, A.; Cochran, E. W.; Shao, Z.; Tessonnier, J.-P., Combining Metabolic Engineering and Electrocatalysis: Application to the Production of Polyamides from Sugar. Angew. Chem. Int. Ed. 2016 , 55, 2368–2373.