Multiple Brønsted acidic sites in nitrogen-rich dicyandiamide immobilized on silica gel as a heterogeneous catalyst for efficient conversion of fructose into 5-hydroxymethylfurfural

Abstract

5-Hydroxymethylfurfural (HMF) has received increasing attention as a crucial intermediate for the production of high-value-added chemicals and biofuels. Therefore, strategies for the synthesis of HMF have been widely explored by designing various catalysts. In this study, acidic nitrogen-rich dicyandiamide immobilized on silica gel (SiO₂-DCDA-SO₃H) was synthesized using a simple and practical method to enhance the dehydration of fructose into HMF. Various modern techniques were used to characterize the catalyst. Besides, the effect of temperature, catalyst mass, substrate, initial substrate concentration, and solvent, and its reusability and large-scale production were assessed to find the optimal conditions. The catalyst exhibited excellent catalytic activity with an impressive yield of HMF (95.2% ± 4.3%) from fructose at 160 °C after 120 min in dimethyl sulfoxide (DMSO). Moreover, this catalyst may be exploited as a promising catalyst for laboratory-scale synthesis of HMF and has potential to be implemented in industry given that it demonstrates strong reusability and scalability.