Novel and Efficient Vanadium-Loaded Montmorillonite Catalyst for the Synthesis of 5-Hydroxymethylfurfural from Glucose and Fructose

Abstract

5-Hydroxymethylfurfural (5-HMF), as an important biomass derivative platform compound, has received widespread attention due to its in-depth application in petrochemicals. In this work, a low-cost and efficient vanadium-loaded montmorillonite (V-Mont) catalyst for the transformation of glucose and fructose to 5-HMF was prepared using the ion exchange method, possessing both strong Brønsted acid and Lewis acid sites. The highest 5-HMF yields of 63.33% and 70.02% with almost complete conversion were obtained from glucose at 160 °C for 2 h and from fructose at 170 °C for 20 min in methyl isobutyl ketone (MIBK)/ saturated salt water (Sat•NaCl) biphasic solvent, respectively. The V-Mont catalyst in saturated salt water system also achieved a satisfactory result in 5-HMF synthesis and was recycled for four times with no obvious loss of activity. The mechanism was speculated and validated using density functional theory (DFT) calculations, indicating that the mononuclear pentavalent [VO(OH)2]+ as a dominant species could accelerate the synergetic proton transfer in the glucose isomerization process and reduce the energy barrier with effect, further promoting the positive progression of chemical equilibrium. This study provides a novel and green strategy to further design efficient catalytic system for 5-HMF production.

Keywords: 5-hydroxymethylfurfural, Glucose, Vanadium-loaded montmorillonite, Density functional theory calculation, Mechanism