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Structure Sensitivity in CH4 Oxidation: Switching C1 to C2 Selectivity on Mn Single Atoms Versus Nanoparticles
Wenjun Yu1,2, Lulu Chen3,4, Geqian Fang5
1CAS Key Laboratory of Science and Technology on Applied Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China.
Journal of the American Chemical Society
|July 12, 2026
Summary
Highly dispersed MnOx/ZSM-5 catalysts, as single atoms or nanoparticles, selectively oxidize methane to valuable oxygenates. Nanoparticles achieve high acetic acid selectivity, offering a noble-metal-free route for methane valorization.
Area of Science:
- Catalysis
- Materials Science
- Chemical Engineering
Background:
- Direct selective oxidation of methane (DSOM) to high-value oxygenates under mild conditions is a significant catalytic challenge.
- Existing methods often lack selectivity or require harsh conditions, limiting practical applications.
- Developing efficient, noble-metal-free catalysts for methane valorization is crucial for sustainable chemistry.
Purpose of the Study:
- To investigate the use of highly dispersed MnOx/ZSM-5 catalysts for the direct selective oxidation of methane (DSOM).
- To understand the structure-dependent mechanisms of methane activation and oxygenate formation.
- To achieve selective production of C1 and C2 oxygenates, particularly acetic acid, using a noble-metal-free system.
Main Methods:
- Synthesis and characterization of MnOx/ZSM-5 catalysts with single-atom (SACs) and nanoparticle (NP) configurations.
- Evaluation of catalytic performance in the direct selective oxidation of methane (DSOM) using CH4 and O2.
- Utilized density functional theory (DFT) calculations and various characterization techniques to elucidate reaction mechanisms.
Main Results:
- Mn single-atom catalysts (SACs) primarily yielded C1 oxygenates (formic acid, methanol) with ~78.8% selectivity.
- Mn nanoparticle (NP) catalysts exclusively produced liquid oxygenates, achieving an outstanding 81.8% selectivity for acetic acid.
- Distinct methane activation pathways were identified: Mn-O sites on SACs activate CH4 to *CH3 for C1 products, while NPs promote *CH2 formation leading to acetic acid via a non-classical pathway.
Conclusions:
- Catalyst structure (single atoms vs. nanoparticles) dictates the methane activation mechanism and product distribution in DSOM.
- MnOx/ZSM-5 nanoparticles provide a highly selective and stable route to acetic acid from methane, bypassing CO carbonylation.
- This work offers fundamental insights into structure-sensitive methane activation and presents a practical, noble-metal-free strategy for methane valorization.
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