The one-step transformation of fructose to 2,5-diformylfuran over Ru metal supported on montmorillonite

In this work, the synthesis of a catalyst with Ru metal supported on a montmorillonite (MMT) support was performed and the prepared catalyst was characterized via different characterization techniques such as: SEM, XRD, XPS, EDX, TEM, and TGA. The catalytic effect of the prepared Ru-MMT with various wt% of Ru metal were determined for the dehydration reaction of fructose to 5-hydroxymethylfurfural (HMF), and for the efficient oxidation of HMF into 2,5-diformylfuran (DFF). HMF conversion occurred completely in 4 h of reaction time to obtain DFF with a 96% yield at 120 °C and an oxygen pressure of 3 bar in dimethyl sulfoxide (DMSO) solvent with 2 wt% of the Ru-MMT catalyst. A one-pot, two-step reaction produced a yield of 89% DFF with 100% conversion of fructose, however an 81% yield of DFF was achieved from a one-pot, one-step reaction using the 2 wt% Ru-MMT catalyst. The catalyst can be isolated easily after the completion of the reaction and successfully reused up to five times with no substantial loss of catalyst activity. The practical applicability of the developed catalyst was successfully demonstrated for the direct transformation of various carbohydrates (glucose, inulin, sucrose, starch, raffinose, and maltose) to DFF in moderate to good yields (35–64% yield). Overall, the 2 wt% Ru-MMT catalyst demonstrated excellent catalytic activity for the one-pot transformation of fructose to DFF showing an excellent yield of DFF in a short reaction time, and afforded wide substrate applicability, good recyclability and catalyst stability.