Conversion of glucose into 5-hydroxymethylfurfural by carbonaceous solid acid catalysts loaded with Brønsted acid and Lewis acid in biphasic system

Biomass-derived 5-Hydroxymethylfurfural (HMF) is a vital platform compound for synthesizing biofuel and various high-value chemicals. This work prepared carbonaceous solid acid catalysts with Brønsted acid and Lewis acid using pine biomass as raw materials through chloride salts impregnation, carbonization and sulfonation. The obtained catalysts were characterized by XRD, FTIR, SEM–EDS, BET, and Py-IR. The catalysts were applied to convert glucose into HMF in a biphasic system involving NaCl solution and γ-valerolactone. The results showed that the catalyst of PC-Al-SO3H exhibited larger microspheres and pore sizes compared with the sulfonated catalyst of PC-SO3H without AlCl3 impregnation. Effects of key variables such as reaction temperature, reaction time on conversion of glucose into HMF were examined. By using PC-2Al-SO3H with stronger Lewis acid, glucose conversion and HMF yield achieved 86.53 mol% and 59.62 mol% at 160 °C and 6 h. The cyclic experiments revealed that PC-2Al-SO3H exhibited relatively stable activity.