Acid-Catalyzed Dehydration of Fructose into 5-Hydroxymethylfurfural by Cellulose-Derived Amorphous Carbon

Carbonaceous solid (CS) catalysts with -SO3H, -COOH, and phenolic -OH groups were prepared by incomplete hydrothermal carbonization of cellulose followed by either sulfonation with H2SO4 to give carbonaceous sulfonated solid (CSS) material or by both chemical activation with KOH and sulfonation to give activated carbonaceous sulfonated solid (a-CSS) material. The obtained carbon products (CS, CSS, and a-CSS) were amorphous; the CSS material had a small surface area (<0.5 m(2)g(-1)) and a high -SO3H group concentration (0.953 mmolg(-1)), whereas the a-CSS material had a large surface area (514 m(2)g(-1)) and a low -SO3H group concentration (0.172 mmolg-1). The prepared materials were evaluated as catalysts for the dehydration of fructose to 5-hydroxymethylfurfural (5-HMF) in the ionic liquid 1-butyl-3-methylimidazolium chloride ([BMIM][Cl]). Remarkably high 5-HMF yields (83%) could be obtained efficiently (80 degrees C and 10 min reaction time). CSS and a-CSS catalysts had similar catalytic activities and efficiencies for the conversion of fructose to 5-HMF in [BMIM][Cl]; this could be explained by the trade-off between -SO3H group concentration (high for CSS) and surface area (high for a-CSS). The cellulose-derived catalysts and ionic liquid exhibited constant activity for five successive recycles, and thus, the methods developed provide a renewable strategy for biomass conversion.