Eco-friendly Method for Efficient Conversion of Cellulose into Levulinic Acid in Pure Water with Cellulase-Mimetic Solid Acid Catalyst

Abstract

Microcrystalline cellulose could be effectively converted into levulinic acid in pure water at 180 °C in 12 h without additives in a maximum yield of 51.5% with a cellulase-mimetic solid acid catalyst prepared without the use of sulfuric acid. Ball-milling pretreatment of cellulose improved levulinic acid yields by only a few percent, showing that the cellulose binding sites (−Cl) and catalytic sites (−SO3H) of the catalyst are key to the activity of the catalyst. The spent catalyst could be regenerated with H2O2 solution after recycling for 5 times to maintain more than 95% of its catalytic activity. Glucose used as starting material under the same reaction conditions and with the same cellulase-mimetic solid acid gave a yield of 61.5% levulinic acid. The conversion route for carbohydrates to levulinic acid in pure water with the biomimetic catalyst prepared with a H2SO4-free method provides an environmentally friendly method for producing biobased-platform chemicals from renewable resources.