CrOx decoration on Fe/TiO2 with tunable and stable oxygen vacancies for selective oxidation of glycerol to lactic acid

Selective conversion of glycerol to lactic acid requires the synergistic activation of C–H, C–O, and O–H. Herein, we report an inexpensive Fe–Cr/TiO2 catalyst that achieves lactic acid formation with a high selectivity of 60.5%. By changing the Fe/Cr ratios and reduction temperatures, the structures of Vő and Vő-OH were altered, which determined the overall oxidation–dehydration–isomerization process. The in situ ATR-IR experiments confirmed the activation of glycerol by adsorbing the primary −OH, and a series of control experiments verified that Fe was responsible for the cleavage of C–H and O–H, while CrOx catalyzed the activation of C–O and C–H. This work designs a hydrothermal catalyst with multifunctional ability, which may guide the rational catalyst design for the selective oxidation of glycerol to lactic acid.