Microwave-assisted catalytic alcoholysis of fructose to ethoxymethylfurfural (EMF) over carbon-based microwave-responsive catalyst

Ethoxymethylfurfural (EMF) is a promising fuel additive and biofuel which can be produced via catalytic direct alcoholysis of fructose. In this work, microwave-responsive catalysts were prepared by carbonization of cellulose (via either hydrothermal treatment or calcination) then functionalized with SO₃H group (via impregnation using concentrated sulfuric acid), which exhibit remarkable performances in one-pot catalytic conversion of fructose to EMF with ethanol. After a 8 h reaction under microwave irradiation at 75 °C, about 80.3% fructose conversion was achieved with the EMF yield of 61.2% for the carbon catalyst prepared by the hydrothermal treatment, which is much higher than that achieved by the catalysis promoted by conventional heating. Further investigation showed that with a microwave-responding catalyst, microwave irradiation encourages the formation of local hot-spots on the catalyst surface, thus facilitating the collision of reactant molecules with catalysts to improve the catalytic efficiency. This work demonstrates the potential of microwave-responsive heterogeneous catalysts for process intensification of valorization of bio-derived chemicals under microwave irradiation.