Tailored sulfonated carbons: unraveling enhanced catalytic dynamics for fructose dehydration under conventional and microwave heating

Abstract

This investigation is centered on the synthesis and evaluation of sulfonated carbons (SCs) employed as catalysts in the transformation of fructose into 5-hydroxymethylfurfural (5-HMF). The sulfonated carbons were synthesized through carbonization and in situ sulfonation in the presence of H₂SO₄, using glycerol and glucose as precursors. Experimental conditions were systematically optimized to achieve an appropriate quantity and density of surface acidic sites, primarily sulfonic and carboxylic groups, pivotal for the fructose dehydration reaction. The catalytic performance of these sulfonated carbons was assessed under both conventional and microwave heating. Notably, the most favorable outcomes were observed in a microwave-assisted system, achieving an 80% conversion at 120 °C within a concise 5 min reaction time. This feat was realized using a 5 wt% fructose solution in dimethylsulfoxide (DMSO) and a 5 wt% catalyst, with selectivity to 5-HMF reaching values as high as 98%. The findings elucidate the impact of the heating mode, alongside the textural properties and surface density of acid groups, providing valuable insights for the optimization of catalysts in fructose conversion processes. This investigation provides pertinent insights into the domain, underscored by the significance of fine-tuning synthesis conditions and reaction parameters for the development of effective catalysts in the context of fructose-to-5-HMF conversion.