A Simple One-Pot Synthesis of a Sulfonated Carbon/Silica Composite Catalyst from Low Value Molasses for 5-HMF Production

Sulfonated silica–carbon composite catalysts (SSC) were synthesized from molasses and K60 silica gel in a one-pot method that simultaneously carbonized and sulfonated the composite. SSC prepared with 12 M sulfuric acid (SSC-12M) demonstrated a fructose to 5-hydroxymethylfurfural (5-HMF) conversion of 83.0% and a yield of 49.1% at 180 °C for 3 h in water. Silica was vital for enhancing the performance; sulfonated carbons with no silica led to lower yields and significant proportions of levulinic and formic acid byproducts. SSC-12 M demonstrated a 47.5% yield of 5-HMF after 3 cycles, while catalysts were easily regenerated via reflux in additional sulfuric acid. Solvent selection revealed that DMSO combined with SSC-12 M demonstrated a 98.2% conversion of fructose with a 62.7% 5-HMF yield (63.8% selectivity). However, the conversion of glucose to 5-HMF under identical conditions resulted in a 98.0% conversion and 70.2% yield (71.6% selectivity). SSC-12 M could lead to new opportunities in solid acid-catalyzed reactions.