Preparation Of 2,5-furanicarboxylic Acid (FDCA) By Oxidation Of 5-hydroxymethylfurfural (5-HMF)

Biomass resources are abundant in source, cheap in price, environmentally friendly and reproducible, which made them to be an ideal substitute for fossil fuels. 5-hydroxymethylfurfural (5-HMF) and 2,5-furandicarboxylic acid (FDCA) are important biomass platform compounds, and FDCA could be produced from 5-HMF oxidation which is an important intermediate for polyester, fine chemicals and medicine.Herein, Organic solvent-freely 5-hydroxymethyl furfural (HMF) oxidation into 2,5-furandicarboxylic acid (FDCA) with hydrogen peroxide and basic solvent using quaternary ammonium octamolybdate and quaternary ammonium dectungstate was studied. The prepared catalysts were characterizated by FT-IR、XRD and X-ray single crystal diffraction (SXRD). The result showed that the great difference performance of quaternary ammonium octamolybdate and quaternary ammonium dectungstate in HMF oxidation with H2O2 was attributed their different structure. The oxided poducts were analyzed by HPLC with the method of standard addition, and it revealed the main product of 5-HMF is FDCA and the by-product are HMFCA and other byproducts from the oxidative cleavage of 5-HMF furan ring. The optimal reaction conditions were obtained by optimizing the catalytic oxidation process, that is 100℃, 2 h, the mass ratio of the catalyst to 5-HMF is 1:10, and the molar ratio of basicity NaOH to 5-HMF is 2:1. The conversion of 5-HMF reached 98.8%, and the selectivity of FDCA achieved 99.3%.In order to solve the problem of catalyst recovery, herein graphere, nanotube TiO2, fibrous γ-Al2O3 and porous SiO2 were used catalyst supports, and ammonium molybdate and secondary ammonium tungstate were loaded by equal volume impregnation method to prepare MoO3 and WO3 supported catalysts under the conditions of calcination. Reaction studies show that using γ-Al2O3 as catalyst carrier, the catalysts display the excellent catalytic activity on both 5-HMF conversion and FDCA selectivity. The optimized loading amounts of MoO3 and WO3 are 20%, and the conversion of 5-HMF reached 99.1% and 99.5%, and the selecyivity of FDCA achieved 91.4% and 96.5% respectively.