Direct one-pot conversion of monosaccharides into high-yield 2,5-dimethylfuran over a multifunctional Pd/Zr-based metal–organic framework@sulfonated graphene oxide catalyst
A one-pot conversion of monosaccharides (fructose and glucose) into high-yield 2,5-dimethylfuran (2,5-DMF) is demonstrated over a multifunctional catalyst obtained by loading Pd on a Zr-based metal–organic framework (UiO-66) that is deposited on sulfonated graphene oxide (Pd/UiO-66@SGO). The Brønsted acidity associated with UiO-66@SGO activates the fructose dehydration to form 5-hydroxymethylfurfural (5-HMF), while the Pd nanoparticles further convert 5-HMF to 2,5-DMF by hydrogenolysis and hydrogenation. The results show that under the optimized reaction conditions of 160 °C and 1 MPa H2 in tetrahydrofuran for 3 h, the yield of 2,5-DMF is as high as 70.5 mol%. This value is higher than the previously reported values, and the direct conversion of fructose can be achieved without additional purification of 5-HMF from the reaction mixture. In addition, for the first time, glucose is converted to 2,5-DMF with a high yield of 45.3 mol%. A recyclability test suggests that the 4.8 wt% Pd loaded on the UiO-66@SGO catalyst can be re-used up to five times.