Chemical looping conversion of ethane to ethanol via photo-assisted nitration of ethane

Abstract

Ethane is an abundant and cheap hydrocarbon. Selective conversion of ethane to ethanol has economic value but is difficult to achieve due to overoxidation. Here, we report a chemical looping strategy established to selectively convert ethane (C 2 H 6 ) to ethanol (C 2 H 5 OH) using molecular oxygen (O 2 ) as the end oxidant and nitrogen dioxide (NO 2 ) as a relay oxidant. Visible light is used to excite NO 2 to drive a radical reaction with C 2 H 6 to produce ethyl nitrate (C 2 H 5 ONO 2 ) at −10°C with a selectivity of >80% and an ethane conversion of >90%. C 2 H 5 ONO 2 is hydrolyzed to generate C 2 H 5 OH and nitric acid (HNO 3 ), thus completing a chemical loop for the conversion of ethane to ethanol. DFT calculations show that the introduction of light overcomes the barrier of ethane activation at a relatively low temperature and thus avoids ethyl nitrate decomposition and overoxidation, leading to the high selectivity of ethyl nitrate. A chemical looping is proposed to convert ethane to ethanol Selective nitration of ethane produces ethylnitrate in high yields Atmospheric reaction is used for preparative synthesis Photocatalysis is used to activate inert C–H bond at mild conditions The activation of the inert C–H bonds in ethane, an abundant hydrocarbon gas, is an important step in alkane upgrading. He et al. put forward a chemical looping strategy to convert ethane to ethanol via selective photoactivated nitration under mild conditions.