Researchers realize direct methane to acetic acid conversion under mild condition

The direct conversion of methane (CH₄) into high value-added multi-carbon (C₂₊) oxygenates, such as acetic acid (CH₃COOH), under mild conditions offers a promising way for upgrading natural gas into transportable liquid chemicals. However, achieving this transformation efficiently remains a major challenge due to strong C-H bonds in methane, the difficulty of oxygen (O₂) activation, and the low selectivity of C-C coupling reactions.

In a study published in Journal of the American Chemical Society, a research group led by Prof. DENG Dehui, Assoc. Prof. CUI Xiaoju, and Prof. YU Liang from the Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Sciences achieved the direct carbonylation of CH₄ with carbon monoxide (CO) and O₂ into CH₃COOH under mild conditions—including room temperature.

Using a novel MoS₂-confined Rh-Fe dual-site catalyst, researchers obtained an unprecedented CH₃COOH selectivity of 90.3% and a productivity of 26.2 μmol g_cat.^–1 h^–1 at just 25 °C, outperforming previously reported catalytic systems.

Researchers revealed that the confined Fe sites within MoS₂ activate O₂ to form highly reactive Fe=O species, which can dissociate CH₄ into CH₃ species even at room temperature, and these CH₃ species then couple with adsorbed CO on adjacent Rh sites to form the key CH₃CO intermediate, leading to the formation of CH₃COOH.

The unique structure of Rh–Fe sites offered synergistic catalytic properties that effectively balance C–H activation and C–C coupling, addressing the trade-off between activity and selectivity in the carbonylation of CH₄ to CH₃COOH under mild conditions.

"Our study opens up new avenues for designing efficient catalysts for the oxidative carbonylation of methane to acetic acid," said Prof. DENG.