Kinetic modeling of solvent partitioning effect on the production of 5-hydroxymethylfurfural from glucose in biphasic solvent system
Xu Han, Zhihao Bi, Xinyu Cui, Lili Qian, Lingzhao Kong, Niko Samec, Milan Vujanović, Yang Guo
Abstract
The distribution characteristics of 5-hydroxymethylfurfural (5-HMF) in solution significantly affect its yield and separation/purification during its production process from glucose, but there is currently a lack of quantitative correlation with the reaction kinetics. In this paper, a systematic kinetic study was conducted on the catalytic conversion of glucose to 5-HMF using a porous carbon catalyst that possesses both Lewis and Brønsted acid sites in a biphasic solvent system composed of NaCl-H 2 O and Methyl isobutyl ketone (MIBK). The addition of NaCl was found to enhance the extraction of 5-HMF into the organic phase, with the highest yield of 84.5% achieved under 10 wt% NaCl concentration. Excessive NaCl increases the solubility of 5-HMF in the aqueous phase, thereby causing a reduction in yield. Kinetic study reveals that higher NaCl concentrations suppress glucose isomerization, humins formation, and direct dehydration to 5-HMF. Excess NaCl also facilitated side reactions, such as 5-HMF rehydration. Changes in solubility equilibrium constants and partition coefficient of 5-HMF were positively correlated, and sensitivity analysis highlighted the impact of NaCl on solubility equilibrium of 5-HMF between aqueous and organic phases. By introducing the parameter of polar activation energy ( E c ), the impact of NaCl on the rate constants of various reaction pathways was quantified, confirming that NaCl altered the physicochemical properties of solvent and potentially catalyzed the reaction. These findings provide valuable insight into the mechanisms and kinetics of glucose isomerization and dehydration in biphasic solvent systems, laying the foundation for the design and regulation of solvent properties to optimize these reactions.