Phosphotungstic acid on activated carbon: A remarkable catalyst for 5-hydroxymethylfurfural production

Phophotungstic acid (HPW) supported on activated carbon (AC) was prepared and used for dehydration of fructose to 5-hydroxymethylfurfural (HMF), a biomass-derived precursor for chemicals and fuels. Different characterization techniques showed that Keggin structure of HPW was maintained after impregnation process by incipient wetness method with ethanol as solvent. The high mass content of the active phase (50 wt%) on the support resulted in accessible acid sites and high acid density, important for the dehydration reaction. The effects of reaction time, catalyst amount, and temperature were investigated. The catalytic system with dimethyl sulfoxide (DMSO) as solvent provided an efficient transformation of fructose to HMF, resulting in high HMF yields (99.3 %) and total fructose conversion after 30 min of reaction at 140 degrees C. Fructose conversion was not significantly affected by the catalyst amount. On the other hand, the increase in temperature resulted in greater and faster conversion. HMF yield was deeply affected by all reaction variables. Moreover, HPW/AC was reused five times without significant loss of activity. Additionally, a kinetic evaluation was performed and the activation energy of fructose conversion to HMF was 109.4 kJmol(-1).