Integrated Biphasic Electrochemical Oxidation of Hydroxymethylfurfural to 2,5-Furandicarboxylic Acid

Production of biobased platform chemicals and polymersvia electrochemicalroutes enables the direct utilization of electrical energy from renewablesources. To date, the integration of electrochemical conversions inprocess chains remains largely unexplored, and the reactions are oftenstudied using synthetic solutions. This work demonstrates the biphasicelectro-oxidation of hydroxymethylfurfural (HMF) to 2,5-furandicarboxylicacid (FDCA) and couples the electrochemical oxidation with the biphasicdehydration of fructose to HMF. The integrated approach eradicatesthe intermediate HMF purification as the HMF-rich organic productphase is fed directly into the electrochemical flow-cell reactor.Here, HMF is extracted into the aqueous phase and oxidized to FDCAon a Ni-(OH)-2/NiOOH catalyst in a 0.1 M KOH solution at pH 13. TheFDCA then remains in the aqueous phase, enabling direct recirculationof the HMF-containing organic phase. We demonstrate a FDCA yield ofclose to 80% with a feed from HMF synthesis. Further, we analyze theinfluence of the phase ratio (organic to aqueous) and current densityfor biphasic electrochemical oxidation. By adjusting the gap width,we were able to decrease the average cell voltage from 7 V down to3 V at a current density of 30 mA cm(-1). This work presents a promising integrated process for the synthesisof green platform chemicals and provides insight into biphasic solutionsin electrochemical conversions. This work exploresthe biphasic electrochemical oxidationof HMF to FDCA and demonstrates the direct electrochemical conversionof the raw organic product phase of HMF synthesis to FDCA.

Automated summary

The electrochemical conversion of hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA) is demonstrated in this work, along with the biphasic dehydration of fructose to HMF. The integrated approach eliminates the need for intermediate purification as the HMF-rich phase is directly fed into the electrochemical reactor. The results show a promising synthesis process for green platform chemicals and provide insights into biphasic solutions in electrochemical conversions.