Bio-based cellulose benzenesulfonic acid-catalyzed dehydration of fructose to 5-hydroxymethylfurfural

In this work, cellulose benzenesulfonic acid (CBSA) was successfully prepared by chemically modifying cellulose with a 4-chlorobenzenesulfonic acid reagent in toluene, providing mainly Brønsted acid sites, as determined by pyridine-DRIFT, for use as a potential solid acid catalyst. The as-prepared CBSA was characterized by various techniques, and its catalytic performance for the conversion of fructose to 5-HMF was examined in dimethyl sulfoxide. In particular, the effects of reaction temperature and reaction time on its activity were investigated. The results showed that CBSA with a 10 wt% loading exhibited the highest catalytic activity, achieving a fructose conversion of 100% and a 5-HMF yield of approximately 85% when a reaction temperature of 140 °C and a reaction time of 180 min were employed. The reusability of CBSA was moderately satisfactory. A 5-HMF yield of 55% and a fructose conversion of 97% were obtained after a total of 4 runs (3 reuse cycles). According to the XPS results of the spent catalyst, the decrease in catalytic performance was mainly due to the insufficiency or loss of the -SO₃H group as the active site for the catalytic dehydration of fructose. These findings could be beneficial for advancing heterogeneous catalysis in saccharide valorization and the development of bio-based solid Brønsted acid catalysts.