Mechanism insights into the upgrading of xylose to furfural over the carbon-based catalysts in aqueous media

Abstract

Exploring low-cost and high-efficient solid acid catalysts and elucidating complete reaction mechanisms are critically important for the sustainable transformation of biomass-derived molecules to bio-fuels and high-value chemicals. Here, we design a renewable strategy to construct carbon-supported solid acid catalysts (M@FRC, M=Sn, Al, Fe, Zn, and Mg) by using biomass waste resources (furfural residue, FR) as the carbon source and tested for dehydration of xylose to furfural (FAL) in the aqueous medium. Kinetic studies revealed the relationship between the main reaction (target product FAL) and the side reaction (other by-products) in the dehydration of xylose under different catalysts. Deuterium-labeling reactions and density functional theory calculations elucidate that the aldehyde carbon of FAL was derived from the C1 of xylose. Furthermore, the C1 of xylose could be broken to form formic acid. While the C1 atom from xylose was converted into formic acid, other carbon atoms could be transformed to tetra-, tri-, di- and mono-carbon compounds. This study offers a prospect for the sustainable catalytic upgrading of biomass by the development of renewable catalytic materials from waste lignocellulosic biomass and an in-depth understanding of the xylose conversion mechanism to develop tailored processes.