Synthesis of 5-hydroxymethylfurfural from fructose catalyzed by sulfonated carbon-based solid acid

Sulfonated carbon-based solid acid catalyst (AC-SO3H) was prepared by the sulfhydrylation and sulfonation of activated carbon (AC) with 3-thiol-propyl trimethoxy silane and sulfuric acid successively. The prepared solid acid catalyst was characterized by infrared spectroscopy (IR), thermogravimetric analysis (TGA), elemental analysis (EA), X-ray powder diffraction (XRD), and Brunauer-Emmet-Teller (BET) specific surface area analysis, and the acid density of AC-SO3H was determined by neutralization titration. AC-SO3H was then employed to catalyze the synthesis of 5-hydroxymethylfurfural (5-HMF) via the dehydration of fructose. The influence of the type of support, sulfonating agent and their concentration, catalyst amount, reaction temperature, and time was investigated. It was found that fructose was converted into 5-HMF with excellent selectivity and stability. The yield of 5-HMF reached up to 100% under the optimized conditions. The solid acid catalyst was reused without noticeable deactivation. The yield of 5-HMF was still up to 94.3% after 4 cycles.