Boosting 2,5-furancarboxylic acid formation by improving support surface oxygen activity in AuPd/Ce1-xZrxO2 catalysts

To study the influence of the redox properties of oxide supports on the catalytic properties of AuPd catalysts in the 5-hydroxymethylfurfural (5-HMF) oxidation under weak alkaline conditions, a series of Ce1-xZrxO2 supports (x = 0, 0.5 and 1) and the corresponding bimetallic AuPd/Ce1-xZrxO2 catalysts have been prepared. The samples are studied by X-ray fluorescence spectrometry, X-ray diffraction, Raman spectroscopy, temperature-programmed reduction with hydrogen, and temperature-programmed desorption of ammonia and carbon dioxide. The comparative studies of the AuPd/Ce1-xZrxO2 catalysts show that the active surface oxygen of the Ce-based supports plays a significant role in the aerobic HMF oxidation to 2,5-furancarboxylic acid (FDCA) under weak alkaline conditions (NaHCO3, pH ≈ 8) boosting the 2,5-formylfurancarboxylic acid (FFCA) oxidation stage. PdAu/CeO2 and PdAu/CeZrO2 provide the FDCC yields of 86 and 71.5 %, respectively, at 80 °C, while the main reaction product for the PdAu/ZrO2 catalyst is the FFCA intermediate.