Efficient synthesis of 2,5-furandicarboxylic acid from biomass-derived 5-hydroxymethylfurfural in 1,4-dioxane/H2O mixture

The catalytic conversion of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA), a renewably sourced substitution for petroleum-derived terephthalic acid, at a high concentration is highly demanding but challenging. Herein, the efficient conversion of HMF (10–25 wt%) in 1,4-dioxane/H2O was achieved, and a desirable FDCA yield of 98% was obtained from HMF (10 wt%) over commercial Ru/C (2 Equiv. NaHCO3, 4 MPa O2, 3 h, and 140 ℃). In addition, a two-step cascade reaction was developed for FDCA production, in which FDCA was employed as the acid catalyst to promote the dehydration of fructose (10 wt%) to HMF, followed by oxidation in 1,4-dioxane/H2O to FDCA over Ru/C. As compared to pure water or 1,4-dioxane, the better stability of HMF in 1,4-dioxane/H2O with a weak alkaline environment and the enhancement of superoxide radicals (·O2-) in 1,4-dioxane/H2O could ensure high FDCA yield at high HMF concentration.