Kinetic Modeling of Homogenous Catalytic Oxidation of 5-Hydroxymethylfurfural to 2,5-Furandicarboxylic Acid

Abstract

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.

Understanding the Co/Mn/Br Synergistic Catalysis in Liquid Phase Oxidation of 5-Hydroxymethyl Furfural to 2,5-Furandicarboxylic Acid Based on the Effective Collision Theory

“…From eqs , , α and β do not vary with temperatures, and so, α and β can be kept constant at different temperatures. Preliminary model fitting results show that model parameters do not vary significantly with temperatures except for k 1 and k b , which is consistent with our previous work in PX, MX, and HMF oxidation. In hydrocarbon liquid-phase oxidation reactions, due to the high activity of peroxyl radicals, their reaction activation energies for H-atom abstraction from α-C atoms are very low, typically 4–12 kcal/mol .…”

“…Herein, a semi-continuous experimental setup was used to carry out the preparation of FDCA by liquid-phase oxidation of HMF, a detailed description of which can be found in our previous work. ,, As briefly described here, the reactants (HMF), solvent (HOAc/H 2 O), and catalyst [Co­(CH 3 COO) 2 (H 2 O) 4 , Mn­(CH 3 COO) 2 (H 2 O) 4 , and NaBr] were added to the titanium reactor in one pot before the start of the experiment. Then, the reactor was charged with chromatographic grade nitrogen to the specified pressure to avoid unnecessary reactions during the temperature rise.…”

“…The initial conditions are According to the fact that the free radical chain reaction mechanism of PX, 22 MX, 11 and HMF 15 oxidation has been successfully modeled in our previous work, the chain propagation and chain termination rate constants vary very little over the range of catalyst concentrations studied, and it is feasible to treat them as constants in kinetic modeling. Therefore, k 2 −k 6 is considered as constant in this model over the range of the studied catalyst concentrations.…”

“…Therefore, k 2 −k 6 is considered as constant in this model over the range of the studied catalyst concentrations. So, these parameters, i.e., k 2 − k 6 obtained in our previous work 15 for HMF oxidation can be used in this work. The effect of the catalyst on the reaction is mainly reflected in the chain initiation steps, where Br• abstracts α-H from reactants to initiate the chain reaction.…”

“…14 Wei et al proposed a simplified reaction kinetic model based on the free radical oxidation reaction mechanism. 15 The kinetic model fitted experimental data well, in which there was only one adjustable parameter, i.e., chain initiation rate constant corresponding to various temperatures, while other parameters were kept constant. However, in these kinetic models mentioned above, the influences of Co/Mn/Br were dealt with the empirical power-law model, and the synergistic mechanism of catalyst components was not well explained.…”