Selective aerobic oxidation of glycerol over zirconium phosphate-supported vanadium catalyst

The zirconium phosphate (ZrP)-supported vanadium catalysts have been prepared by the mechanochemical synthesis, and were characterized in detail using various techniques including XRD, SEM, HRTEM, EDX, NH₃-TPD, H₂-TPR, pyridine-absorbed FT-IR and solid ³¹P NMR spectra. XRD, SEM and HRTEM images revealed the vanadium species were highly dispersed on ZrP support. Solid ³¹P NMR technique indicated that there was a strong interaction between vanadium species and ZrP. The calcination temperature affected significantly the distribution for oxidation states of vanadium, and the presence of vanadium (V) species were more favorable to the glycerol oxidation reaction. The resulting catalysts exhibited high catalytic activity for glycerol oxidation and the selectivity to formic acid in glycerol oxidation by using molecular oxygen as the terminal oxidant under the aqueous phase and base-free conditions. Both acid sites and oxidizing sites played a synergistic role in producing the compounds in this work. The reaction can proceed smoothly with high glycerol conversion up to 80–90% and the selectivity towards formic acid to 62%, respectively. After reaction, the catalyst can be facilely recovered and reused with stable activity. On the basis of the above results, the reaction mechanism was proposed accordingly. This study provides a prominent catalytic process for the large scale production of formic acid from biorenewable glycerol.