Facile Production of 2,5-Furandicarboxylic Acid via Oxidation of Industrially Sourced Crude 5-Hydroxymethylfurfural

The oxidation of 5-hydroxymethylfurfural (HMF) produces value-added chemicals such as 2,5-diformylfuran (DFF) and 2,5-furandicarboxylic acid (FDCA). In this work, FDCA production was achieved by oxidation of crude HMF solution containing around 45 % HMF and unwanted byproducts such as 5,5 '-[oxy-bis(methylene)]bis-2-furfural (HMF dimer) and polymers. At optimized reaction conditions similar to the Mid-Century process, homogeneous oxidation of the crude HMF (up to 20 wt% in the feed) by Co/Mn/Br catalyst in acetic acid solution produced FDCA at >95 % yield. The solid FDCA product contained <4000 ppm 5-formyl-2-furancarboxylic acid (FFCA). Such high yields were observed because the impurities in crude HMF were also converted to FDCA, as confirmed by the facile oxidation of HMF dimer to FDCA under reaction conditions. The successful demonstration of crude HMF as feed, obviating the need for HMF purification, suggests potential for cost-effectively producing FDCA in existing terephthalic plants.