Copper-doped sulfonic acid-functionalized MIL-101(Cr) metal-organic framework for efficient aerobic oxidation reactions

A series of Cr-based metal-organic framework MIL-101-SO3H bearing sulfonic acid functional groups were utilized for the immobilization of catalytically active copper species via a post-synthetic metalation method. The novel materials were fully characterized by scanning electron microscopy, X-ray diffraction, energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), the Brunauer-Emmett-Teller method, and thermogravimetric analysis. XPS and the EDX element map both suggested that Cu2+ is coordinately bonded to the MIL-101-SO3H, which forms the MIL-101-SO3@Cu structure. The obtained copper-doped MIL-101-SO3@Cu-1, MIL-101-SO3@Cu-2, and MIL-101-SO3@Cu-3 catalysts were utilized in the selective oxidation of alcohols and epoxidation of olefins using molecular oxygen as an oxidant. Catalytic aerobic oxidation optimization showed that MIL-101-SO3@Cu-1 is the optimal catalyst and it can be reused ten times without compromising the yield and selectivity.