Methane Carboxylation Using Electrochemically Activated Carbon Dioxide

Direct synthesis of CH₃COOH from CH₄ and CO₂ is an appealing approach for the utilization of two potent greenhouse gases that are notoriously difficult to activate. In this Communication, we report an integrated route to enable this reaction. Recognizing the thermodynamic stability of CO₂, our strategy sought to first activate CO₂ to produce CO (through electrochemical CO₂ reduction) and O₂ (through water oxidation), followed by oxidative CH₄ carbonylation catalyzed by Rh single atom catalysts supported on zeolite. The net result was CH₄ carboxylation with 100 % atom economy. CH₃COOH was obtained at a high selectivity (>80 %) and good yield (ca. 3.2 mmol g⁻¹_cat in 3 h). Isotope labelling experiments confirmed that CH₃COOH is produced through the coupling of CH₄ and CO₂. This work represents the first successful integration of CO/O₂ production with oxidative carbonylation reaction. The result is expected to inspire more carboxylation reactions utilizing preactivated CO₂ that take advantage of both products from the reduction and oxidation processes, thus achieving high atom efficiency in the synthesis.