MgO-ZrO2 Mixed Oxides as Effective and Reusable Base Catalysts for Glucose Isomerization into Fructose in Aqueous Media

MgO-ZrO2 mixed oxides prepared with different Mg/Zr atomic ratios (denoted as xMZ: where x is the atomic ratio of Mg/Zr) are investigated for the glucose isomerization to fructose in water at 95 degrees C. The highest fructose yield of 33 % is obtained over 0.76MZ with approximate to 74 % selectivity after 3 h. To gain insight into the structure-activity relationships, the prepared catalysts are characterized by N-2 physisorption, XRD, FTIR and CO2-TPD. The results indicate that the addition of MgO drastically changed the textual property of ZrO2 and increased the number of basic sites. The kinetic studies revealed that the Lewis basic sites (cus-O2-) generated from the highly dispersed MgO are the active sites responsible for the enhanced isomerization activity. Notably, MZ is reusable for four runs without a significant decrease in catalyst activity. Accordingly, this study provides an easily prepared, cheap, and recyclable catalyst that may hold great potential for fructose production.