From Microfluidic Screening to Pre‐Pilot‐Scale: TEMPO‐Mediated Electrooxidation of Furfural to Furoic Acid

This study demonstrates the stepwise development and scale‐up of TEMPO‐mediated furfural electrooxidation to furoic acid as a biobased route to a specialty chemical of growing industrial relevance. Initial screening in a microfluidic electrochemical flow cell identified acetamido‐TEMPO as an effective mediator for selective furfural oxidation on graphite felt under alkaline conditions, enabling high furoic acid selectivity at relatively low anodic potentials while limiting overoxidation through appropriate control of cell potential and substrate supply. Subsequent laboratory‐scale batch‐recirculation experiments confirmed stable mediator performance, near‐complete per‐pass selectivity, and Faradaic efficiencies typically above 75%–90%. Translation to a bench‐scale cell further validated the robustness of the process, producing approximately 50 g of furoic acid with closed mass balance, near‐complete selectivity, and stable operation under continuous substrate and base dosing. Further scale‐up to a five‐cell stack configuration demonstrated successful pre‐pilot operation. Improvements in cell architecture and flow‐through electrode design reduced ohmic losses and enhanced electrode utilization, enabling the production of approximately 450 g of furoic acid with concentrations up to 1.9 M in the electrolyte. These results highlight the importance of cell architecture, flow distribution, pH control, and ion transport during scale‐up, while demonstrating the practical potential of mediated electrochemical synthesis for sustainable furoic acid production.