Energy & Fuels, Vol.34, No.3, 3250-3261, 2020
Impacts of Solvents on the Stability of the Biomass-Derived Sugars and Furans
During the conversion of sugars/furans into the value-added chemicals via acid catalysis, solvent in addition to acid catalyst is deemed as an essential parameter affecting the reaction network. Solvent could not only disperse the reactant/product but also participate in sugars/furans conversion reactions. In this research, the interactions of some commonly used solvents with the typical sugars (fructose, glucose, xylose) and furans (furfural, 5-hydroxymethylfurfural (HMF), furfuryl alcohol (FA)) were investigated at 200 degrees C. The results showed that the solvent reacted or interacted with the sugars/furans in distinct ways. The sugars were more reactive and showed lower stabilities than the furans in either polar or nonpolar solvents, due to their multiple oxygen-containing functionalities and the conversion via dehydration, retro-aldol condensation, polymerization, etc. The furans were relatively stable in the nonpolar and aprotic solvents (i.e., tetrahydrofuran (THF), toluene, ethyl acetate), as the absence of hydrogen ions suppressed the opening of the furan ring via hydration reactions. In addition, the acidity of water, the protection of the reactive functionalities of sugars/furans with ethanol, the cross-polymerization of acetone or guaiacol with the sugars/furans, and the dispersion of sugars in THF/toluene all affected the stabilities/reactivities of the sugars/furans and modified the reaction network.