Efficient 5-hydroxymethylfurfural synthesis from carbohydrates and food wastes in aqueous-natural deep eutectic solvent (A-NADES) with robust Al2O3 or Al(OH)3

Abstract

HMF synthesis in A-NADES : High yield of HMF could be obtained in a cheap and green A-NADES system with robust Aluminum-based solid catalyst using glucose, different starches, and food wastes as materials. The in-situ change of Al 2 O 3 to AlO(OH) obviously improves the HMF synthesis efficiency. We report a green and efficient method to utilize carbohydrate resources for HMF production in a sustainable A-NADES system. • Robust aluminum-based catalysts including Al 2 O 3 and Al(OH) 3 were used as the effective catalysts for the HMF synthesis. • High yield of HMF was obtained with starch and food wastes as a cheap and abundant substrate. • Aqueous-Natural Deep Eutectic Solvent (A-NADES) was designed as a novel and sustainable reaction system with a high concentration of carbohydrates. • Both the A-NADES system and Al 2 O 3 catalyst showed good reusability. As one of the essential building blocks for bio-chemicals and bio-fuels, the 5-Hydroxymethylfurfural (HMF) production is still challenging in a green and cheap way. This work developed a bio-derived aqueous-natural deep eutectic solvent (A-NADES) to synthesize HMF using α-Al 2 O 3 or Al(OH) 3 as robust catalysts, obtaining high yields of 67.1% and 63.6% HMF from glucose under mild reaction reactions, respectively. Different kinds of starches and starchy food waste also exhibited high conversion efficiency in the A-NADES system. The mechanistic study indicated that the in-situ formed Al (III) site of α-Al 2 O 3 during the reaction was critical for converting glucose-based carbohydrates. A-NADES could be effectively reused six times with a more convenient direct reuse method without significant activity loss. This study suggested a novel A-NADES reaction media in the synergistic reaction with robust aluminum-based catalysts for HMF synthesis, and proposed a novel process of food waste utilization in green solvents.