Selective mild oxidation of methane to methanol or formic acid on Fe-MOR catalysts

Zhihao Fang, Haruno Murayama, Qi Zhao, Bing Liu, Feng Jiang, Yuebing Xu, Makoto Tokunaga, Xiaohao Liu

Research output: Contribution to journalArticlepeer-review

8 Citations (Scopus)

Abstract

Controllable methane oxidation directly into value-added products under mild conditions remains a challenge. Herein, an active Fe/MOR catalyst was synthesized via simple solid-state ion exchange, and its activity in the selective oxidation of methane with H2O2 in the aqueous phase was intensively investigated. The octahedral dimeric Fe3+ species [Fe2(μ-O)2] in the extra framework was confirmed as the initial active site by X-ray photoelectron spectroscopy, X-ray absorption near-edge structure and extended X-ray absorption fine structure, UV-vis diffuse-reflectance spectroscopy, and high-angle annular dark-field scanning transmission electron microscopy in combination with DFT calculations. The DFT calculations indicated that methanol formation via methyl peroxide (CH3OOH∗) on [Fe2(μ-OH)2O2] is the most favorable pathway compared to the direct formation of methanol via CH3O∗. The formed CH3OH is easily further oxidized by hydroxyl radicals (OH) resulting in non-selective methane oxidation. In contrast, the Fe/MOR catalyst could lead to a high methanol selectivity of 71.3% in the presence of homogeneous Cu2+ precursor, which efficiently suppressed the over-oxidation of methanol, and a high formic acid selectivity up to 81-82% at a slightly higher reaction temperature by mildly shifting the oxidation of methanol and formaldehyde to the target product.

Original languageEnglish
Pages (from-to)6946-6956
Number of pages11
JournalCatalysis Science and Technology
Volume9
Issue number24
DOIs
Publication statusPublished - 2019

All Science Journal Classification (ASJC) codes

  • Catalysis

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