Effects of Reaction Conditions on Electroreduction of Biomass-Derived Furfural and Its Side Reactions in Acidic Electrolyte
Authors: Jung Sungyup , Karaiskakis Alexandros N , Biddinger Elizabeth J 
Published: February 2020

Current investigations for electrochemical energy storage and generation systems help to dramatically decrease the demand for traditional fossil fuels. However, organic carbon resources, also, need to be replaced with alternatives to totally reduce their demands. In this respect, biomass is a promising sustainable resource for both alternative fuels and organic carbon-based materials [1]. Furfural (FF) is a lignocellulose-derived C­5 chemical platform that can be converted to furfuryl alcohol (FA) and 2-methyl furan (MF), which are an adhesive intermediate and a promising fuel candidate, respectively [2]. Traditionally, catalytic hydrogenation and hydrogenolysis (CH) is used for the conversion of FF to FA and MF, but it requires externally supplied hydrogen gas, high pressure and high temperature for the reaction[1, 2].
In contrast, electrochemical hydrogenation and hydrogenolysis (ECH) facilitates the conversion of FF at ambient conditions with no H2 gas. ECH of FF can use atomic hydrogen, supplied from the aqueous electrolyte. These advantages led to emerging studies for ECH of biomass, but it has not been broadly studied [3]. The relationships between electrochemical reaction conditions and results will greatly contribute to broadening the ECH of FF.
In our previous study, FA and MF yield increased as a current density increased when the equivalent amount of charge was applied to the reaction in acidic solutions [4]. Also, we found that furanic compounds participate in homogeneous side reactions in pH ≤ 1 solution that can decrease mole balance and products yield as reaction time increase [4]. Another concurrent side reaction that undesirably consumes electrons is the hydrogen evolution reaction[5].
Here, we focus on the effects of applied potentials and Cu electrocatalysts, combined with rapid evaporation of MF, produced from ECH of FF. This is to investigate the product yield and electrochemical efficiency for products as well as side reactions at multiple applied potentials in 0.5 M sulfuric acid (pH 0). Also, rapid evaporation of MF with N2 gas flowing is used for avoiding its homogeneous side reactions at pH 0 [4]. Bare Cu foil and micro-sized Cu supported on Cu have been used as electrocatalysts.
Rapid N2 gas flowing enhanced the mole balance and MF yield. FF conversion and MF yield increased when applied potential increased, but electrochemical efficiency for FA and MF production increased as applied potential decreased. Micro-sized Cu electrocatalysts had higher conversion of FF and yield of MF than bare Cu foil.
[1] G.W. Huber, S. Iborra, A. Corma, Synthesis of transportation fuels from biomass: chemistry, catalysts, and engineering, Chemical Reviews, 106 (2006) 4044-4098.
[2] Y. Nakagawa, M. Tamura, K. Tomishige, Catalytic reduction of biomass-derived furanic compounds with hydrogen, ACS Catalysis, 3 (2013) 2655-2668.
[3] Y. Kwon, K.J.P. Schouten, J.C. van der Waal, E. de Jong, M.T.M. Koper, Electrocatalytic conversion of furanic compounds, ACS Catalysis, 6 (2016) 6704-6717.
[4] S. Jung, E.J. Biddinger, Electrocatalytic hydrogenation and hydrogenolysis of furfural and the impact of homogeneous side reactions of furanic compounds in acidic electrolytes, ACS Sustainable Chemistry & Engineering, 4 (2016) 6500-6508.
[5] R. Parsons, The rate of electrolytic hydrogen evolution and the heat of adsorption of hydrogen, Transactions of the Faraday Society, 54 (1958) 1053-1063.