Direct Coupling of CH₄ and CO₂ to C2 Oxygenates over a NiO/Fe₂O₃ Catalyst under Mild Conditions

Converting greenhouse gases CH4 and CO2 into C2 oxygenates under mild conditions has attracted broad attention, but the process is very difficult due to the hard activations of C–H and C═O bonds as well as the low reaction rate. Here, we developed the direct coupling of CH4 and CO2 with H2O to C2 oxygenates (acetic acid and ethanol) over the NiO/Fe2O3 catalyst at 150 °C and atmospheric pressure. The performance results displayed the highest formation rate of C2 oxygenates (3.1 μmol gcat–1·h–1 at 150 °C) over the NiO/Fe2O3 catalyst compared with pure NiO and Fe2O3 catalysts. The physicochemical characterizations revealed that the active acid–base sites of NiFe2O4 and the oxygen vacancy on the NiO/Fe2O3 catalyst ensured the activations of CH4 and CO2, reaching the highest coupling rates of intermediates. In situ diffuse reflectance infrared Fourier transform spectroscopy demonstrated that *OH and *H from H2O activated the cleavages of the C–H and C═O bonds. The couplings between *CH2OH and *COOH with *CH3 produced C2 oxygenates of acetic acid and ethanol. This study provided an attractive route and illustrated a reaction pathway for C2 oxygenate production from direct coupling of CH4 and CO2 under mild conditions.