Acidic ionic liquid decorated boehmite as an efficient catalyst for conversion of fructose to 5-hydroxymethylfurfural.

An efficient and simple acidic catalyst, B-IL, is developed for the conversion of fructose to 5-hydroxymethylfurfural. To this purpose, Boehmite, a low-cost and abundant naturally occurring clay, is successively functionalized with (3-chloropropyl) triethoxysilane, imidazole, and chlorosulfonic acid to graft an acidic ionic liquid onto its surface. Characterization of the catalyst confirmed that conjugation of the ionic liquid improved the acidity and catalytic activity of Boehmite. To achieve the highest yield of the product, the effects and interactions of the reaction variables, i.e. reaction time, temperature and catalyst loading, were studied using the Response Surface Method. According to the results, the use of 35 wt% B-IL catalyst at 95 °C for 85 min resulted in a 97% yield of 5-hydroxymethylfurfural from fructose. Gratifyingly, the catalyst was highly recyclable and maintained its activity for three successive runs, while further recycling led to a slight loss of its performance. The heterogeneous nature of the catalysis was also affirmed through the Hot filtration test. The kinetic study exhibited that the activation energy was 13.29 kJ/mol. Besides, thermodynamic parameters, i.e. enthalpy, entropy, and Gibbs free energy were calculated as 10.34 kJ/mol, -241.5 J/mol and 99.21 kJ/mol, respectively.