Catalytic Conversion of Carbohydrates into 5-Ethoxymethylfurfural by a Magnetic Solid Acid Using γ-Valerolactone as a Co-Solvent

Selective conversion of carbohydrates to fuels and fine chemicals is of great importance for biorefinery. However, development of efficient solid acidic catalysts which perform stably for this process is still challenging. Herein, we reported a novel carbon-based solid acidic catalyst, prepared via hydrothermal carbonization of glucose followed by magnetization of Fe3O4 and sulfonation of H2SO4, which can serve as an efficient and recyclable catalyst in the catalytic dehydration of fructose to 5-hydroxymethylfurfural (HMF) and subsequent etherification of 5-ethoxymethylfurfural (EMF) with ethanol from various carbohydrates. The effects of reaction conditions (temperature, time, solvents, catalyst amount, and gamma-valerolactone (GVL) concentration) were optimized affording to a maximum EMF yield of 67.4 % at 120 degrees C, 55 wt % catalyst loading based on starting fructose and 60 vol.% of GVL in ethanol after 24 h of reaction. Noticeably, GVL promotes the formation of EMF and HMF reducing the extent of side reactions. Recycling experiments showed that the catalyst could be easily separated with a magnet and reused up to 4 consecutive times without significant loss of activity. The present work opens a way to synthesize reusable and cost-effective solid acidic catalysts from biomass wastes and may contribute to a holistic approach for biomass valorization.