Activation of Molecular Oxygen for Alcohol Oxidation over Vanadium Carbon Catalysts Synthesized via the Heterogeneous Ligand Strategy
Li Zhao, Piaoping Yang, Song Shi, Guozhi Zhu, Xiao Feng, Weiqing Zheng, Dionisios G. Vlachos, Jie Xu
Abstract
Activation of molecular oxygen to realize selective oxidation is challenging. We employ a heterogeneous ligand method to prepare a vanadium carbon catalyst (V–C catalyst) of high efficiency in alcohol oxidation via oxygen activation. Principal component analysis revealed that the chemisorbed oxygen and pentavalent vanadium oxide are crucial in catalyst performance. Isotopic labeling, electron paramagnetic resonance, and control experiments confirmed that the V–C catalyst activates molecular oxygen to singlet oxygen or its analogue and carries out the reaction. A kinetic study and in situ React-IR spectra illustrated that the main reaction route is the O2 activation to 1O2 or its analogue and oxidizes the substrate through C–H bond activation. We demonstrate the efficiency of the V–C catalyst in selectively oxidizing the hydroxyl group in other substrates, including benzyl alcohols, methyl lactate, and ethyl lactate biomass-based alcohols. This will guide the development of highly active nonprecious metal catalysts for activating O2 for aerobic oxidation.