1,4-Dioxane Intervention Enables Simultaneous Valorization of Biomass-Based C5 and C6 Sugars to Furfural Over Hβ Zeolite

Abstract

The simultaneous valorization of biomass-based C5 and C6 sugars to furfural, a versatile intermediate, is of great significance to fully utilize biomass components. Inability to effectively transform C6 sugars remains a major barrier toward this challenging goal. We herein report the 1,4-dioxane-mediated solvent system with Hβ zeolite catalyst for the transformation of glucose giving high yield to furfural (57%). The maintenance of intrinsic balanced Lewis and Brønsted acid sites from Hβ zeolite that is credited to the positive solvent effect of 1,4-dioxane is highly conductive to the selective C-C bond cleavage of glucose. Also importantly, the introduction of proper amount of H2O into the reaction system results in a high formation rate and an improved selectivity toward furfural due to the induction of highly reactive acyclic glucose. Glucose-to-furfural through 3-deoxyglucose should be more favorable than that via fructose. Impressively, the developed protocol can also be adapted to C5 sugars dehydration, and the one-pot conversion of glucose and xylose mixtures gains a furfural yield as high as 63%. The activation energy barrier for furfural production is higher from glucose compared to xylose. This work not only develops a promising protocol for furfural production simultaneously from C5 and C6 sugars but also provides insights into the mechanistic role of the solvent 1,4-dioxane to availably manipulate the acid-catalyzed conversion of C6 sugars.

Keywords: Glucose, Xylose, Furfural, 1, 4-Dioxane, Hβ zeolite