Base-free oxidation of 5-hydroxymethyl-2-furfural to 2,5-furan dicarboxylic acid over basic metal oxide-supported ruthenium catalysts under aqueous conditions

Polyethylene terephthalate (PET) is the third-largest globally produced polymer, and many efforts have been made to replace PET with a renewable polymer. One renewable alternative to PET is polyethylene furanoate (PEF), which is prepared using 2,5-furan dicarboxylic acid (FDCA) as a precursor instead of terephthalic acid (TPA). Biomass-derived hydroxymethyl-2-furfural (HMF) can be converted to 2,5-furan dicarboxylic acid (FDCA) through multiple oxidation reactions. Metal oxide-supported Ru catalyst prepared by simple methods for the oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furan dicarboxylic acid (FDCA) in the absence of a base under aqueous conditions is reported. This study clearly explains that the nature of basicity of the support has an important role on the selective oxidation of HMF to FDCA. Among the various materials studied magnesium oxide (MgO)-supported Ru catalyst afforded a 100% HMF conversion and more than 90% FDCA yield with 90 psi of $$\hbox {O}_{2}$$ at 160 $${^{\circ }}\hbox {C}$$ in 4 h and it could be used 5 times without a significant drop of FDCA yields. Metal oxide-supported Ru catalyst prepared by simple methods for the oxidation of 5-Hydroxymethylfurfural (HMF) to 2,5-Furan dicarboxylic acid (FDCA) in the absence of a base under aqueous conditions are reported. Magnesium oxide (MgO)-supported Ru catalyst afforded a 100% HMF conversion and more than 90% FDCA yield.