A nanoarchitecture of sulfuric acid-decorated magnetic g-C3N4 nanohybrid for upgrading biosugars to 5-hydroxymethylfurfural in solvent-free conditions

Abstract

5-Hydroxymethylfurfural (5-HMF), as a key platform compound for the conversion of biomass into various fine chemicals and biofuels, has attracted immense attention. In this study, graphitic carbon nitride (g-C3N4) was decorated with magnetite nanoparticles (Fe3O4) and subsequently functionalized with 1,4-butane sultone to afford Fe3O4@g-C3N4@n-butyl-SO3H. The structural integrity of the synthesized nanohybrid was confirmed through FTIR, XRD, VSM, EDX, BET, TGA, ICP, SEM, TEM, DLS, and acid–base titration analyses. The nanohybrid, as a magnetically recoverable solid acid catalyst, illustrated high catalytic activity in the conversion of biomass-derivatized carbohydrates (sucrose, fructose, and fructose/sucrose) into the more valuable chemical 5- HMF under solvent-free conditions. Under the optimized reaction conditions, Fe3O4@g-C3N4@n-butyl-SO3H provided HMF yields of 80 %, 95 %, and 98 % from sucrose, fructose, and sucrose/ fructose, respectively. Moreover, the developed nanohybrid catalyst could be easily separated from the reaction mixture by utilizing a magnet due to the presence of Fe3O4 nanoparticles. In this manner, the catalyst was easily recovered from the reaction mixture and reused nine times without loss of catalytic activity. Overall, the resulting catalyst offers the potential for improved catalytic performance under solvent-free conditions, ease of separation, and multiple recycling cycles, thereby enhancing the overall efficiency and sustainability of the synthesis process.