Controlling Competitive Side Reactions in the Electrochemical Upgrading of Furfural to Biofuel

Furfural (FF) is obtained from lignocellulosic biomass and is a promising platform chemical that can produce valuable chemicals including furfuryl alcohol (FA) and 2-methylfuran (MF). We synthesized both FA and MF using electrochemical hydrogenation and hydrogenolysis (ECH) of FF in acidic electrolyte using a Cu electrode. We investigated the role of concurrent side reactions including the hydrogen evolution reaction (HER) and polymerization of furanic compounds during ECH, as well as the potential dependence of the reaction pathway for ECH of FE As the magnitude of applied potential increased, both ECH and HER were promoted. Polymerization of furanic compounds was diminished by lowering the initial concentration of FE but at a cost of increased the HER activity. In contrast, higher concentrations of FF suppressed the HER, though excessive initial concentrations of FF resulted in lowering the activity of both ECH and the HER due to a polymeric film being formed on the electrode. The highest mole balances and faradaic efficiencies towards ECH were achieved at -0.5 V, though at the expense of lower conversions of FF than those obtained at greater overpotentials. We also found that the ECH of FF followed two parallel reactions to independently produce FA and MF on Cu in 0.5 M H2SO4 regardless of the applied potential.