MIL-100(Fe), a metal−organic framework containing coordinatively unsaturated iron sites, was prepared by a solvothermal method and utilized in cyclohexane oxidation. Interestingly, the composition and fraction of redox-active Fe(II/III) sites in MIL-100(Fe) could be tuned by using different pretreatment temperatures. The obtained materials were characterized by means of field-emission scanning electron microscopy (FE-SEM), powder X-ray diffraction (PXRD), N2 adsorption-desorption isotherms, and X-ray photoelectron spectroscopy (XPS). Due to the presence of redox-active coordinatively unsaturated sites (CUS) at the iron atoms, MIL-100(Fe) exhibited good performance for cyclohexane oxidation under mild reaction conditions. Oxidation rates were significantly enhanced when reduced FeII sites were generated by high-temperature pretreatments. In either high-temperature or low-temperature pretreatment, the isolated Fe(II/III) sites in MIL-100 were far more reactive in cyclohexane oxidation than were bulk iron oxide materials. Finally, possible reaction pathways were proposed based on radical, Haber-Weiss routes.
Bibliographical noteFunding Information:
This work was supported by the National Research Foundation of Korea under Grant (NRF-2019R1A2C2002313). Also, the authors gratefully acknowledge the financial support from the Inorganometallic Catalyst Design Center, an EFRC funded by the DOE, Office of Basic Energy Sciences (DESC0012702). This research was supported by Human Resources Program in Energy Technology of the Korea Institute of Energy Technology Evaluation and Planning (KETEP), granted financial resource from the Ministry of Trade, Industry & Energy, Republic of Korea (No.20174010201640).
All Science Journal Classification (ASJC) codes
- Physical and Theoretical Chemistry
- Organic Chemistry
- Inorganic Chemistry