Aerobic Oxidation of 5-Hydroxymethylfurfural into 2,5-Furandicarboxylic Acid over Gold Stabilized on Zirconia-Based Supports

A series with gold supported on monoclinic (m-), tetragonal (t-) ZrO 2, and Mg-modified zirconia were prepared and used for the catalytic oxidation of biomass-derived 5-hydroxymethylfurfural to 2,5-furandicarboxylic acid (FDCA). The Au stabilized on Mg-modified zirconia calcined at 600 °C (denoted as Au/MZ-600) exhibited a superior catalytic performance with 95% of FDCA yield after 4 h by adapting a two-temperature step reaction. The structure–activity relationship was investigated by using X-ray diffraction, temperature-programmed reduction by H 2, X-ray absorption spectroscopy, temperature-programmed desorption of CO 2, and N 2 adsorption–desorption methods. The results clearly demonstrate that the addition of Mg ions in/on the zirconia support at appropriate calcination temperature plays an important role in optimizing the interaction between gold nanoparticles and the support by fine-tuning the surface base properties of the zirconia supports and creation of oxygen vacancies. Accordingly, tuning these gold–support interactions is essential to achieve high dispersion of small-sized gold nanoparticles with enhanced metallic character, which plays a significant role in enhancing the catalytic activity of the final catalyst.