Catalytic Conversion of Fructose and 5-Hydroxymethylfurfural into 2,5-Furandicarboxylic Acid over a Recyclable Fe 3 O 4 –CoO x Magnetite Nanocatalyst

A nano-Fe 3 O 4 –CoO x catalyst was prepared via a simple wet impregnation method. The nano-Fe 3 O 4 –CoO x catalyst showed good catalytic performance for the conversion of 5-hydroxymethylfurfural into 2,5-furandicarboxylic acid (FDCA) with t -BuOOH as the oxidant. Several important reaction parameters were explored, with the highest FDCA yield of 68.6% obtained from HMF after 15 h at a reaction temperature of 80 °C. One-pot conversion of fructose into FDCA was also successful via two steps. Catalytic conversion of fructose over Fe 3 O 4 @SiO 2 –SO 3 H yielded 93.1% HMF, which was oxidized in situ into FDCA with a yield of 59.8%. Furthermore, recycling of nano-Fe 3 O 4 –CoO x was accomplished with the help of a magnetic field. Nano-Fe 3 O 4 –CoO x showed high stability in the reaction process. The use of nonprecious metals and no requirement of a base additive made this method much more economical and environmentally friendly.