Novel and efficient vanadium-loaded montmorillonite catalyst for the synthesis of 5-hydroxymethylfurfural from glucose and fructose

5-Hydroxymethylfurfural (5-HMF), as an important biomass derivative, has received widespread attention due to its ability to be converted into numerous high value-added chemicals. 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, 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 among the three calculation models, the energy barrier crossed by the [VO(OH)2]+ catalytic reaction was the lowest, further demonstrating the mononuclear pentavalent [VO(OH)2]+ as a dominant species could accelerate the synergetic proton transfer in the glucose isomerization process and promote the positive progression of chemical equilibrium. This study provides a novel and green strategy to further design efficient catalytic system for 5-HMF production.