2,5-Furandicarboxylic acid (FDCA) is a valuable biomass-based monomer with broad market prospects that can replace terephthalic acid (TPA) in all kinds of polymer applications. In this work, the homogeneous catalytic oxidation of 5-hydroxymethylfurfural (HMF) to FDCA was investigated over a Co/Mn/Br catalyst with acetic acid/water as a solvent. On the basis of free radical oxidation reaction mechanisms, one simplified main reaction kinetic model for the oxidation of HMF with six parameters was proposed, which considered the formation of FDCA and the most important intermediates. The effects of catalyst, temperature, and water content on the liquid-phase oxidation kinetics of HMF were investigated. The model fitted the experimental data well, in which only the chain initiation rate constant was found to be dependent on experimental conditions, while other rate constants can be kept constant in the investigated range. Hopefully, the kinetic model in this work can provide valuable insights for the design and optimization of the industrial process of HMF oxidation to FDCA.

2,5-Furandicarboxylic acid (FDCA) is an important monomer for the bio-based degradable polymer polyethylene 2,5-furandicarboxylate. Current kinetic studies on the preparation of FDCA by the liquid-phase oxidation of 5-hydroxymethyl furfural (HMF) have failed to quantitatively consider the effect of the ratio and concentration of Co/Mn/Br ternary catalysts, although they play an important role in the oxidation reaction rate and selectivity. In this work, an effective collision theory was introduced into the kinetic modeling, and then, a kinetic model of HMF oxidation with nine parameters was developed. The fitting results of this model using experimental data of HMF liquid phase oxidation with different catalysts and temperatures were satisfactory. The relative collision frequency coefficients α and β successfully describe the reactivity of Co and Mn, respectively, and they are only influenced by the water content in the solvent and do not vary with temperatures. The chain initiation rate constants are only temperature-dependent, and the other rate constants remain constant over the studied range. The kinetic model developed in this work would bring valuable insights into the synergistic effects of the Co/Mn/Br ternary catalyst components on the oxidation of HMF.

No abstract