Metal−Organic Framework Supported Gold Nanoparticles as a Highly Active Heterogeneous Catalyst for Aerobic Oxidation of Alcohols

The use of metal−organic frameworks (MOFs), an emerging class of porous materials, as supports for gold nanoparticles (NPs) may bring new opportunities in the development of highly active heterogeneous gold catalysts for a variety of catalytic reactions. Although currently a few examples of MOF-supported nanoparticulate Au have been reported, the preparation of an active Au NPs deposited MOF catalyst in solution is still a challenging research target. In this study, we report a highly efficient heterogeneous gold catalyst, which was deposited on a zeolite-type MOF (MIL-101) by a simple colloidal method with polyvinylpyrrolidone (PVP) as protecting agent using HAuCl4 as the Au precursor. The resulting Au/MIL-101 (CD/PVP) catalyst exhibited extremely high catalytic activities in liquid-phase aerobic oxidation of a wide range of alcohols, which could even efficiently catalyze the oxidation under ambient conditions in the absence of water or base. Moreover, the catalyst was easily recoverable and could be reused several times without leaching of metals or debasing of activity. The high dispersion of Au NPs and the electron donation effects of aryl rings to the Au NPs within the large cages of the MIL-101 support are suggested to be the main reasons for the observed high activities of the Au/MIL-101 (CD/PVP) catalyst in aerobic oxidation of alcohols under base-free conditions.