Kilogram-scale production of high purity 2,5-furandicarboxylic acid via sustainable leap in continuous electrochemical oxidation of 5-hydroxymethylfurfural

Abstract

Electrochemical oxidation of 5-hydroxymethylfurfural (HMFOR) stands out as an efficient and sustainable approach for 2,5-furandicarboxylic acid (FDCA) production. However, despite numerous catalyst advancements, the industrial adoption of this process faces significant challenges, stemming from limitations in scalability and high device costs. To address this gap, we developed a scalable HMFOR process for continuous FDCA production. Key parameters such as electrolyte concentration, anodic and cathodic catalysts, types of sparge gas, and current density were found to be critical to the yield and quality of the isolated FDCA products. NiFeOOH anode and Pt cathode operated at 33.3 mA cm−2 in 0.33 M KOH and O2 environment were chosen as they provided the fastest oxidation kinetic and minimized HMF degradation rate, hence producing FDCA with high yield and purity. Using the optimal conditions identified in a milligram-scale batch reactor, we constructed a 2-liter CSTR with a novel electrode design accommodating 100 A of current. This process achieved an unprecedented FDCA production rate of ∼2 kg per day and space–time yields of up to 295 μmol h−1 cm−2, along with exceptional stability for 48 h. The isolated FDCA demonstrated comparable purity and color to commercial products. This simple and robust continuous reactor design can be applied to other electrochemical biomass valorization processes, potentially replacing conventional electrolyzers.