Ga Modified Zeolite Based Solid Acid Catalyst for Levulinic Acid Production

Gallium modified zeolite (mordenite), a solid acid catalyst, was prepared using the sonochemical method. The catalyst (Ga@mordenite) was characterized using XRD, SEM, TEM, EDS, FT-IR, DSC TGA, TPD and XPS analysis. Uniform distribution of Ga on the zeolite surface was confirmed from the SEM-EDS analysis. The catalyst was further used for the production of levulinic acid (LA) from carbohydrates (glucose, starch, and cellulose) in a hydrothermal process. Reaction conditions (time, 6 h; temperature, 175 °C) for the optimum yield of LA (59.9 wt. %) were deduced. The reaction products were analyzed qualitatively using ¹³C NMR and quantified using HPLC analysis. Synergistic effect of the Lewis acid sites of Ga³⁺ generated in situ and the Bronsted acid sites of mordenite were found to be crucial for the activity of Ga@mordenite for the conversion of glucose to levulinic acid.