One-Pot Solvent-Free\nConversion of Furfural and CO<sub>2</sub> into 2,5-Furandicarboxylic\nAcid

2,5-Furandicarboxylic acid is an important biomonomer\nfor the synthesis\nof polyesters, and studies on the synthesis of FDCA mainly focus on\nthe 5-hydroxymethylfurfural and furoic acid routes. The synthetic\nroute starting from furfural has a broader and more economical raw\nmaterial source than the furoic acid route. In this study, the furfural\nroute was used to develop an energy-efficient and one-pot method for\nsynthesizing FDCA from furfural and CO<sub>2</sub> as raw materials.\nUnder solvent-free conditions, the Co–N–C catalyst and\nCsOH·H<sub>2</sub>O were used as catalyst and base, respectively.\nPure furfural was converted to cesium furoate (with a yield of 93%)\nby mechanical ball-milling. Then, without the need for separation\nand purification, CsOH·H<sub>2</sub>O was <i>in situ</i>-transformed into Cs<sub>2</sub>CO<sub>3</sub> at 260 °C under\na flowing CO<sub>2</sub> atmosphere, thereby facilitating the carboxylation\nof furoate to cesium 2,5-furandicarboxylate. The dynamic experiments\nand Matlab data fitting revealed that it followed the iterative steps\nof rapid disproportionation (<i>k</i><sub>1</sub> = 7.53)\nand slow furfuryl alcohol oxidation (<i>k</i><sub>2</sub> = 0.13). Single Co sites improved atomic utilization without using\nany solvent, yielding a fast formation rate of furoic acid (21.6 mol<sub>FA</sub> mol<sub>metal</sub><sup>–1</sup> h<sup>–1</sup>). The renewable biomass furfural and greenhouse gas CO<sub>2</sub> were comprehensively utilized to form a biobased polyester monomer\nFDCA via a green and simple strategy.