Au-Fe Separates Enable CO-Assisted Methane Oxidation to Acetic Acid with O2 via Tandem Catalysis

Direct conversion of methane to acetic acid with molecular O2 at room temperature remains as a grand challenge. Herein, we achieved room-temperature oxidation of CH4 into acetic acid with O2 and CO over structurally optimized Au/TiO2 and Fe/ZSM-5 through tandem catalysis. The process decouples H2O2 formation and migration, H2O2 activation to hydroxyl radicals for CH4 oxidation, and carbon-carbon coupling to acetic acid. The physical mixture of Au/TiO2 and Fe/ZSM-5 yielded 55.6 μmol gcat−1 with the acetic acid selectivity in liquid of 64.9% in H2O under 61 bar (CH4:CO:O2 = 15:40:6) at 30 °C for 6 h without any external energy. In situ synchrotron-based vacuum ultraviolet photoionization mass spectrometry demonstrates a closer spatial interval is critical for in situ generated H2O2 migrates from Au/TiO2 to Fe/ZSM-5, which can be readily used by Fe/ZSM-5 to produce hydroxyl radicals, enabling the maximum liquid-phase product accumulation.