Extremely low sulfuric acid catalyst system for synthesis of methyl levulinate from glucose

A comprehensive experimental and kinetic investigation on the synthesis of methyl levulinate from glucose in methanol medium under mild conditions (<= 473 K) catalyzed by extremely low sulfuric acid (<= 0.01 mol L-1) was performed in this study. Glucose was rapidly and almost quantitatively converted into methyl glucosides as a key and stable intermediate product, and a high methyl levulinate yield of ca. 50 mol% can be achieved after the completion of reaction. Based on the detected compounds, a plausible reaction pathway for the acid-catalyzed conversion of glucose in methanol medium was proposed. The generation of methyl levulinate from glucose via methyl glucosides as a function of the process variables was modelled using a simplified first-order kinetic model, and a good fit between experimental data and the kinetic model was obtained. An advantage of this catalyst system is that negligible undesired dimethyl ether formed from the side reaction for the dehydration of methanol that was used as reaction medium, the equipment corrosion was slight, and less spent acid need to be addressed after the reaction. Overall, this catalytic strategy is efficient, economical and environmentally benign for the conversion of carbohydrates into high value-added chemicals and fuels. (C) 2012 Elsevier B.V. All rights reserved.