Electrocatalytic methane direct conversion to methanol in electrolyte of ionic liquid

Abstract

The direct conversion of methane (CH4) to methanol (CH3OH) is of great significance for efficiently utilizing biogas and natural gas, in which the activation of CH4 under mild conditions with high selectivity of CH3OH in products is challenging. The advantage of electrocatalytic system besides CH4 activation is that could provide active oxygen species in situ. However, whether the sorts of active oxygen species could affect the methane conversion is still unexplored. In this study, a non-diaphragm electrochemical bath with an aprotic ionic liquid [BMIM]BF4 as supporting electrolyte was setup, in which superoxide radicals (·O2−) and peroxide anions (O22−) were generated through oxygen reduction reaction (ORR) on cathode while CH4 was activated on anode with a V2O5-based catalyst (Ov-V2O5). Methanol and ethanol were identified as the liquid conversion products of CH4, and the average formation rate of 352.5 μmol gcat−1h− 1 for CH3OH with Faraday efficiency of 61.1% were obtained under the optimized conditions. Density function theory (DFT) calculation results suggest that the introduce of V4+ sites in Ov-V2O5 enhanced the chemisorption of CH4 molecules on anode surface, and the active oxygen species are involved in the formation of methanol and ethanol.