Partial oxidation of methane to methyl oxygenates with enhanced selectivity using a single-atom copper catalyst on amorphous carbon support

• Published in: Applied surface science 2023-12, Vol.639, p.158289, Article 158289
• Main Authors: Lee, Hyesung, Kwon, Choah, Vikneshvaran, Sekar, Lee, Sukjun, Lee, Sang-Yup
• Format: Article
• Language: English
• Subjects: Carbon; Catalysis; Copper; Methane; Oxidation
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2023.158289

[Display omitted] •Single-atom CuN4 on the carbon surface was effective for selective CH4 oxidation.•The catalyst showed higher CH3OH selectivity than other single-atom Cu catalysts.•Carbon on the surface involved in the cleavage of C-H bond of CH4.•Size reduction and hydrophilic surface facilitated the CH4 oxidation reaction.•Potential reaction pathways were suggested for the production of methyl oxygenates. In this study, we report a single-atom Cu catalyst on the amorphous carbon support for direct methane partial oxidation. The catalyst was prepared by the carbonization of Cu-doped ZIF-8 to implant single-atom Cu active centers that coordinate with four nitrogen (CuN4) on the amorphous N-doped carbon. Carbonization enhanced the oxidation resistance of the catalyst by preventing the oxidation of Cu-coordinating ligands, leading to a 40% reduction in CO2 production. Our prepared catalyst showed higher methanol selectivity than other single-atom copper catalysts. Mechanistic studies revealed that Cu and the surface carbon atom facilitated the dissociation of H2O2 into OOH and H, which further transformed into Cu–O and led to proton abstraction from methane. We highlight a simple approach to prepare a single-atom catalyst that is supported on amorphous N-doped carbon, derived from a metal-doped ZIF. This catalyst exhibits enhanced selectivity and stability for the partial oxidation of methane.