Facile synthesis of sulfonated fructose-derived porous carbon nanosheets for efficient dehydration of fructose to 5-hydroxymethylfurfural in 1,4-dioxane/H₂O

Sulfonated carbon materials are promising heterogeneous Brønsted acid catalysts for biomass valorization, but the facile construction of carbon frameworks with accessible acid sites remains challenging. Herein, a sulfonated fructose-based porous nanosheet carbon (SPC) was synthesized via a facile and energy-efficient two-step strategy involving P 2 O 5 -assisted rapid self-propagating carbonization and concentrated sulfuric acid sulfonation, and subsequently employed for fructose dehydration to HMF in a low-boiling 1,4-dioxane/H 2 O solvent system. During carbonization, P 2 O 5 simultaneously promoted fructose carbonization and directed the formation of a porous nanosheet architecture, avoiding conventional high-temperature activation processes. The resulting porous nanosheets provided abundant sites for -SO 3 H grafting and enhanced Brønsted acid site accessibility. Consequently, SPC exhibited efficient catalytic performance for the selective dehydration of fructose, affording an HMF yield of 70.1% at 140 ℃ for 30 min. Moreover, SPC efficiently converted concentrated fructose (1.0 g fructose) to HMF with a 59.4% yield and exhibited moderate recyclability. This work provides a facile strategy for constructing biomass-derived sulfonated carbon solid acids with effectively utilized Brønsted acid sites for biomass upgrading.