Glucose conversion to methyl levulinate catalyzed by metal ion-exchanged montmorillonites

Various metal ion-exchanged montmorillonite catalysts were prepared, characterized, and evaluated in the conversion of glucose to methyl levulinate in methanol. The bulk and surface features of these catalysts were investigated using X-ray fluorescence spectroscopy, inductively coupled plasma optical emission spectroscopy , powder X-ray diffraction, Fourier-transform infrared (FT-IR) spectroscopy, thermogravimetric analysis , scanning electron microscopy, N 2 adsorption–desorption, temperature-programmed NH 3 desorption, and pyridine adsorption FT-IR spectroscopy. Al 3   + -exchanged montmorillonite had the best activity and maximum methyl levulinate selectivity because of presence of a large number of acid sites and a good balance of Brønsted and Lewis acid sites on the catalyst. The montmorillonite catalyst can be easily recovered from the reaction mixture by filtration, and reused at least five times without any loss of activity and selectivity after treatment with H 2 O 2 solution to remove carbon species deposited on the catalyst surface .