Mild Oxidation of Methane to Oxygenates with O2 and CO on Fluorine Modified TS-1 Supported Rh Single-Atom Catalyst in a Flow Reactor.

Direct catalytic conversion of methane to liquid oxygenates under mild conditions remains a challenge due to high bond energy of symmetric CH₄. Isolated Rh atoms were supported on hydrophobic fluorine modified TS-1 (FTS-1). Single-atom Rh on FTS-1 catalyst was characterized with Ac-HAADF/STEM and CO adsorption FTIR. The aerobic selective conversion of methane to oxygenates was carried out in a fixed bed continuous flow reactor upon co-feeding CO and H₂O at 423 K under relative low pressure (42.3 kPa CH₄, 21.1 kPa CO, 10.6 kPa O₂, 0.476 MPa H₂O). Hydrophobic Rh/FTS-1 catalyst exhibits higher activity (151.9 mol_products/(mol_metalh)) than the activity (36.4 mol_products/(mol_metalh)) over hydrophilic Rh-ZSM-5 (Si/Al = 15) under such reaction conditions. Hydrophobicity of different catalysts were compared by water adsorption test. The catalytic activity of F modified TS-1 supported single-atom Rh (Rh/FTS-1) is higher than that of unmodified Rh/TS-1 which is due to its higher Lewis acidity as shown by pyridine adsorption FTIR and NH₃-TPD. [ABSTRACT FROM AUTHOR]