Photo-Driven Aerobic Methane Nitration.

Conversion of methane to liquid oxygenates is challenging but of great value. Here, we report the oxidation of methane (CH 4 ) to methanol (CH 3 OH) assisted by nitrogen dioxide (NO 2 ) as a photo-mediator and using molecular oxygen (O 2 ) as the terminal oxidant. Similar photoreactions are widely studied in atmospheric chemistry but were not previously used in preparative methane conversion. We used visible light to excite NO 2 generated by heating aluminum nitrate Al(NO 3 ) 3 and drove its reaction with methane and O 2 to produce methyl nitrate (CH 3 ONO 2 ), which is then hydrolyzed to CH 3 OH. Nitric acid (HNO 3 ) and nitrate (NO 3 - ) were produced and recycled back to Al(NO 3 ) 3 , completing a chemical loop. HCl can catalyze this photochemical process via relay hydrogen atom-transfer reactions, with up to 17% methane conversion and 78% CH 3 ONO 2 selectivity. This simple photochemical system provides new opportunities in selective methane transformation.