Acidic zeolite L as a highly efficient catalyst for dehydration of fructose to 5-hydroxymethylfurfural in ionic liquid

Zeolite L was synthesized by the hydrothermal method and post-treated by NH4-exchange to adjust its acidity. The samples were systematic characterized by various techniques including XRD, XRF, N2 adsorption-desorption, SEM, Py-IR, and NH3-TPD. The results demonstrate that the NH4-exchange post-treatment increase the surface areas, micropore volume, and acidity of zeolite L. The catalytic performances of the samples were tested in the dehydration of fructose to 5-hydroxymethylfurfural (HMF) in ionic liquid (1-butyl-3-methylimidazolium bromide ([bmim]Br)). 99.1% yield of HMF was achieved when using the KL-80°C-1h sample (KL zeolite treated with 1M NH4NO3 solution at 80°C for 1h). The high efficiency could be attributed to the appropriate acid property. The catalyst could be reused for four recycles without obvious decrease in the activity.