Optimization of 2,5-Furandicarboxylic Acid (FDCA) Production in a Continuous Packed-Bed Reactor for Sustainable PEF Packaging Applications

2,5-Furandicarboxylic acid (FDCA) is a promising biobased monomer offering a sustainable alternative to polyethylene terephthalate (PET). However, its production remains limited by conventional reactors, which require severe operating conditions and lack optimized reaction parameters, hindering efficiency. This study investigates the synthesis of FDCA from the oxidation of 5-hydroxymethylfurfural (HMF) in a continuous packed-bed reactor using Ru/C as a catalyst and H₂O₂ as an oxidant. The effects of the HMF/NaOH molar ratio and the flow rates of HMF and H₂O₂ on product yield are investigated and analyzed using HPLC. Higher HMF flow rates led to intermediate accumulation due to insufficient contact time, while the lowest flow rate (0.01 mL/min) facilitated the complete conversion to FDCA without intermediates. An increase in the H₂O₂ flow rate (0.05 mL/min) reduced the FDCA yield, likely due to oxidative limitations and catalyst deactivation. Optimal conditions, an HMF/NaOH/H₂O₂ molar ratio of 1:12:8, HMF and H₂O₂ flow rates of 0.03 mL/min, 75 °C, and 1 bar, achieved an FDCA yield of 81.5%. The packed-bed reactor enhanced FDCA production efficiency, yielding an 8.5-fold increase while reducing reaction time compared to a conventional reactor under mild operating conditions. These findings highlight the potential of continuous-flow reactors for efficient and scalable FDCA production.