Efficient Selective Oxidation of 5-Hydroxymethylfurfural with Oxygen over a ZnCrAl Mixed Oxide Catalyst Derived from Hydrotalcite-like Precursor

Cr-doped ZnAl mixed oxide catalysts (Zn0.75CrAl-x-c) were obtained via calcining the Zn0.75CrAl-x hydrotalcite precursors and were applied in the selective oxidation of 5-hydroxymethylfurfural (5-HMF) to 2,5-furandicarboxylic acid (FDCA). Cr doping significantly enhanced the catalytic activity. A 95.1% 5-HMF conversion with an 88.1% FDCA selectivity was achieved over the Zn0.75CrAl-6-c catalyst at 130 °C under 0.6 MPa oxygen for 4 h. The good performance was associated with the high specific surface area and high oxygen vacancy concentration. Moreover, the Zn0.75CrAl-6-c catalyst was used for five cycles without a significant activity loss indicating excellent stability.