The selective conversion of methane into high-value oxygenates via C–H activation under mild conditions is considered a promising strategy for energy diversification and greenhouse gas mitigation. In situ generation of H2O2 for methane activation offers an attractive alternative to the use of externally supplied H2O2, avoiding its high cost, low utilization efficiency, and transport and storage risks. However, achieving efficient methane oxidation while suppressing overoxidation remains a major challenge, as it requires precise control over the generation rate, local concentration, and reactive oxygen species derived from H2O2, such as ·OH and ·OOH radicals.
In a study published in Angewandte Chemie International Edition, a research team led by Profs. HOU Guangjin and GAO Pan from the Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Sciences (CAS) developed a Na–Auδ⁻ interface structure on MOR nanosheet that enables near-quantitative selectivity for methane oxidation to methanol, acetic acid, and other oxygenates under mild conditions.
Selective methane conversion to methanol and acetic acid via •OH/CH3 radical coupling enabled by Na–Auδ⁻ interfacial sites that generate H2O2 and •OH (Image by Xianquan Li)
The researchers found that the Au/1.2Na-MOR(NS) catalyst achieved nearly 100% selectivity toward hydroxylated oxygenates derived from methane, with a productivity of 2.02 mmol·gcat−1·h−1 under CH4/CO/O2/H2O conditions at 150 °C.
By combining operando spectroscopic characterizations and density functional theory calculations, the team revealed that the Na–Auδ⁻ interfacial sites promote kinetically favored O–O bond cleavage and H2O dissociation. This process enables the controlled in situ generation of H2O2 and •OH radicals, which are essential for methane C-H activation while effectively suppressing overoxidation.
Further mechanistic studies showed that methane oxidation proceeds through *CH3 radicals generated through •OH-mediated methane activation. Coupling of *CH3 with •OH produces methanol, whereas direct coupling with adsorbed CO leads to acetic acid formation. Isotopic labeling experiments confirmed CO serves as the sole carbonyl source, excluding the possibility of methanol carbonylation.
“Our study elucidates the dynamic role of in-situ generated H2O2 in methane activation under mild conditions and demonstrates that electronic microenvironment engineering is an effective strategy for achieving selective and controllable oxidation valorization of methane.
Key words: Methane Oxidation • Electronic Microenvironment Engineering • Interfaces • Hydrogen Peroxide • Heterogeneous Catalysis
Article Link: https://doi.org/10.1002/anie.202525250