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Direct photo-oxidation of methane to methanol over a mono-iron hydroxyl site

DOI: 10.1038/s41563-022-01279-1 DOI Help

Authors: Bing An (University of Manchester) , Zhe Li (Xiamen University; University of Chicago) , Zi Wang (University of Manchester) , Xiangdi Zeng (University of Manchester) , Xue Han (University of Manchester) , Yongqiang Chen (Oak Ridge National Laboratory) , Alena M. Sheveleva (University of Manchester) , Zhongyue Zhang (Nagoya University) , Floriana Tuna (University of Manchester) , Eric J. L. Mcinnes (University of Manchester) , Mark D. Frogley (Diamond Light Source) , Anibal J. Ramirez-Cuesta (Oak Ridge National Laboratory) , Louise S. Natrajan (University of Manchester) , Cheng Wang (Xiamen University) , Wenbin Li (University of Chicago) , Sihai Yang (University of Nottingham) , Martin Schroeder (University of Manchester)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Nature Materials , VOL 338

State: Published (Approved)
Published: June 2022
Diamond Proposal Number(s): 23782

Abstract: Natural gas, consisting mainly of methane (CH4), has a relatively low energy density at ambient conditions (~36 kJ l−1). Partial oxidation of CH4 to methanol (CH3OH) lifts the energy density to ~17 MJ l−1 and drives the production of numerous chemicals. In nature, this is achieved by methane monooxygenase with di-iron sites, which is extremely challenging to mimic in artificial systems due to the high dissociation energy of the C–H bond in CH4 (439 kJ mol−1) and facile over-oxidation of CH3OH to CO and CO2. Here we report the direct photo-oxidation of CH4 over mono-iron hydroxyl sites immobilized within a metal–organic framework, PMOF-RuFe(OH). Under ambient and flow conditions in the presence of H2O and O2, CH4 is converted to CH3OH with 100% selectivity and a time yield of 8.81 ± 0.34 mmol gcat−1 h−1 (versus 5.05 mmol gcat−1 h−1 for methane monooxygenase). By using operando spectroscopic and modelling techniques, we find that confined mono-iron hydroxyl sites bind CH4 by forming an [Fe–OH···CH4] intermediate, thus lowering the barrier for C–H bond activation. The confinement of mono-iron hydroxyl sites in a porous matrix demonstrates a strategy for C–H bond activation in CH4 to drive the direct photosynthesis of CH3OH.

Journal Keywords: Metal–organic frameworks; Photocatalysis; Porous materials

Diamond Keywords: Photocatalysis

Subject Areas: Chemistry, Materials, Environment

Instruments: B22-Multimode InfraRed imaging And Microspectroscopy

Other Facilities: 10-BM at Advanced Photon Source; BL11S at Aichi Synchrotron Radiation Centre (AichiSR); Spallation Neutron Source

Added On: 01/07/2022 10:24

Discipline Tags:

Earth Sciences & Environment Climate Change Physical Chemistry Catalysis Energy Materials Chemistry Materials Science Metal-Organic Frameworks Metallurgy Organometallic Chemistry

Technical Tags:

Spectroscopy Infrared Spectroscopy Synchtron-based Fourier Transform Infrared Spectroscopy (SR-FTIR)