Catalytic Valorization of Expired Fructan-Rich Food into the Biofuel 5-Ethoxymethylfurfural via a Restaurant Food Waste-Derived Carbonaceous Solid Acid

Valorization of food waste into value-added fuels or chemicals is of considerable significance. Herein, an efficient catalytic approach was developed for transforming expired fructan-rich food (probiotics beverage powder, onion powder and garlic powder that have expired) into the biofuel, 5-ethoxymethylfurfural (EMF), via a carbonaceous solid acid synthesized by hydrothermal carbonization and sulfonation of restaurant food waste. The as-prepared restaurant food waste-derived carbonaceous solid acid catalyst (FW-SO 3 H) was well-characterized by a series of model physical and chemical technologies, and its catalytic performances were evaluated by the ethanolysis of expired fructan-rich food for EMF synthesis. The effects of reaction process variables were investigated. A considerable EMF yield of 52.1% from expired probiotics beverage powder was obtained in DMSO/ethanol medium at 140 °C for 4 h. EMF yields of 20.4% and 11.7% were achieved from expired onion powder and expired garlic powder, respectively. This work provides a valorization strategy for both expired fructan-rich food and restaurant food waste. Graphic Abstract