Electrocatalytic methane direct conversion to methanol in electrolyte of ionic liquid
Haomin Jiang, Luting Zhang, Zhaohui Wang, Zhiwei Han, Lixuan Ma, Ang Li, Yanzhi Sun, Yang Tang, Pingyu Wan, Riguang Zhang, Yongmei Chen, Maohong Fan
Abstract
The direct conversion of methane (CH 4 ) to methanol (CH 3 OH) is of great significance for efficiently utilizing biogas and natural gas, in which the activation of CH 4 under mild conditions with high selectivity of CH 3 OH in products is challenging. The advantage of electrocatalytic system besides CH 4 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]BF 4 as supporting electrolyte was setup, in which superoxide radicals (·O 2 − ) and peroxide anions (O 2 2− ) were generated through oxygen reduction reaction (ORR) on cathode while CH 4 was activated on anode with a V 2 O 5 -based catalyst (Ov-V 2 O 5 ). Methanol and ethanol were identified as the liquid conversion products of CH 4 , and the average formation rate of 352.5 μ mol g cat −1 h − 1 for CH 3 OH with Faraday efficiency of 61.1% were obtained under the optimized conditions. Density function theory (DFT) calculation results suggest that the introduce of V 4+ sites in Ov-V 2 O 5 enhanced the chemisorption of CH 4 molecules on anode surface, and the active oxygen species are involved in the formation of methanol and ethanol.