Glucose dehydration to 5-hydroxymethylfurfural on zirconium containing mesoporous MCM-41 silica catalysts

The selective dehydration of glucose to hydroxymethylfurfural (HMF) in a biphasic medium (water/methylisobuthylketone) has been studied by using different catalysts based on mesoporous MCM-41 silica containing ZrO2. These catalysts have been: (a) MCM-41 silica doped with Zr in the synthesis step and activated at 550 and 750 °C, (b) this solid impregnated with sulphuric acid and activated at 750 °C, and (c) MCM-41 impregnated with zirconium sulphate and calcined at 750 °C. All these catalysts exhibit acidic properties (282–563 μmol of NH3 desorbed g−1) and high surface areas (359–635 m2 g−1), being active in the dehydration of glucose to HMF at 175 °C and 150 min of reaction time. Catalysts are quite selective, since only fructose and HMF were detected, whereas levulinic acid was absent. The most active catalyst was obtained after incorporation of zirconium into a MCM-41 silica in the synthesis gel (Zr-MCM-550), achieving a HMF yield of 23%. Moreover, the activity of the spent catalyst is fully recovered after calcination at 500 °C during 2 h. TOF values of these catalysts vary between 1.3 and 1.8 mmol of HMF g-1 h-1, being the catalytic performance well correlated with the acidity and textural characteristics of catalysts.