Fig. 5: Selective oxidation of CH4 to CH3OH. | Nature Communications

Fig. 5: Selective oxidation of CH4 to CH3OH.

From: High-spin surface FeIV = O synthesis with molecular oxygen and pyrite for selective methane oxidation

Fig. 5

a Performance of selective CH4 oxidation into CH3OH in the aqueous Fe…Fe@FeS2/CH4 and Fe…Fe@FeS2/CH4/O2 systems. b The schematic diagram of selective CH4 oxidation within a binary solution containing perfluorohexane (PFH) and water in a designed reactor, where the gas inlet and outlet balance the pressure of mixture gas (CH4 and O2) at 1 bar, and the condensate inlet and outlet control the reaction temperature to room temperature of 25 °C. c Performance of selective CH4 oxidation into CH3OH in the Fe…Fe@FeS2/CH4/O2 system using 5 mL H2O and 5 mL PFH. d Comparative analysis of TOF and CH3OH selectivity in the Fe…Fe@FeS2/CH4/O2 system versus other gas-liquid-solid three-phase catalytic systems with O2 or H2O2 as the oxidant. e Multi-cycled oxidation of CH4 to CH3OH in the PFH aqueous Fe…Fe@FeS2/CH4/O2 system within 180 min. f Isotopic detection of CH3OH in the Fe…Fe@FeS2/CH4/O2, Fe…Fe@FeS2/13CH4/O2 and Fe…Fe@FeS2/CH4/18O2 systems. Reaction condition: 10 mg Fe…Fe@FeS2, 10 mL solution containing 5 mL H2O and 5 mL PFH, 1 bar gas (CH4 + O2 with a stoichiometric ratio), room temperature. g EPR spectra of *DMPO-•CH3 adducts in the Fe…Fe@FeS2/CH4/O2 system. h Theoretical CH4 molecules adsorption on the high-spin surface FeIV = O of Fe…Fe@FeS2. The charge density difference after CH4 adsorption is also provided. The blue and red iso-surfaces represent charge accumulation and depletion in the space, respectively, with an iso-value of 0.010 au. Mulliken charge calculations were used to determine the number of transferred electrons. i Free energy changes plotted against the reaction coordinate for activation and oxidation of CH4 by high-spin surface FeIV = O on Fe…Fe@FeS2.

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