Toward selective electrooxidation of HMF to FDCA: Suppressing non-Faradaic transformations via low temperature electrolysis

Abstract

Electrooxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA) is a promising strategy for biomass valorization. However, a significant challenge arises from the substantial carbon loss due to spontaneous HMF degradation in alkaline electrolytes, particularly at high concentrations. In this study, we present a straightforward approach to mitigating carbon loss during the electrochemical conversion of HMF to FDCA by suppressing non-Faradaic degradation through low-temperature electrolysis. Notably, under conventional room temperature conditions, carbon losses of up to 25 % can occur, whereas our low-temperature electrolysis method reduces carbon loss to negligible levels (< 1 %) even at high HMF concentrations (up to 500 mM) in highly alkaline electrolyte (2.0 M KOH). This strategy effectively addresses the long-standing challenge of balancing the enhanced kinetics of HMF electrooxidation with the accelerated degradation of HMF as its concentration increases in alkaline media. Our findings highlight the critical role of suppressing non-Faradaic degradation in the efficient conversion of HMF and demonstrate that low-temperature electrolysis offers a viable solution to the challenges of industrial-scale electrochemical biomass valorization.