Electrochemical oxidation of 5-hydroxymethylfurfural with flow electrodes: A novel approach for continuous synthesis of 2,5-furandicarboxylic acid

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Switzerland : 1996), 2025-01, Vol.504, p.158374, Article 158374
• Main Authors: Padligur, Maria C., Westerfeld, Paul, Linkhorst, John, Wessling, Matthias
• Format: Article
• Language: English
• Subjects: 2,5-furandicarboxylic acid; 5-hydroxymethylfurfural; Flow electrode; NiOOH; Slurry electrode
• ISSN: 1385-8947
• DOI: 10.1016/j.cej.2024.158374

[Display omitted] •Electrochemical synthesis of FDCA from HMF is possible with flow electrodes.•The particles in the flow electrode act as a redox mediator.•Prior to the synthesis the catalyst on the particles can be electrically pre-charged.•Synthesis with flow electrodes tolerates fluctuation in HMF and electricity supply.•Energy storage and synthesis can be combined with flow electrodes. Electrochemical processes for chemical production allow the direct utilization of renewable electricity and facilitate using sustainable resources like biomass. A promising biobased product is the polymer furan-2,5-dicarboxylate (PEF), which can be produced from hemicellulosic biomass through intermediates 5-hydroxymethylfurfural (HMF) and 2,5-furandicarboxylic acid (FDCA). The transformation of HMF into FDCA can be achieved through electrochemical oxidation. Electrochemical conversion has the advantage of high efficiencies at low pressures and temperatures. However, the primary constraint of electrochemical processes lies in the limitation of the active area to the electrode surface. In this work, we overcome this limitation by suspending particles coated with NiOOH as a catalyst in the electrolyte. The resulting suspension is called a flow electrode. We show that during electrolysis, the oxidation of HMF to FDCA occurs on the particles and not on the current collector. The reaction mechanism is indirect: HMF reacts to FDCA on the catalyst-coated particles, and the catalyst itself gets reduced. The reduced catalyst, no longer active for oxidation reactions, is regenerated electrochemically on the otherwise inert current collector. Additionally, we show that catalyst regeneration and oxidation of HMF to FDCA can be decoupled. We propose that this system can store energy in the flow electrode to react economically to fluctuating energy prices.