Homogeneous Copper-Catalyzed Conversion of Methane to Methyl Trifluoroacetate in High Yield at Low Pressure

摘要

The direct catalytic oxidation of methane to oxygenates, a reaction that garners significant scientific and industrial interest, is plagued by poor methane-based yields. Some of the best homogeneous catalytic systems reported to date convert methane to methyl esters using catalysts with complex organic ligands to reach high yields at relatively high temperature (423K) and pressure (20-70bar). In our study, we used a simple copper compound, copper(II) oxide, to selectively convert methane to methyl trifluoroacetate at 363K and low pressure (5bar) resulting in yields as high as 63% at a methane conversion of 71%. The catalyst is easily recovered by treating the spent reaction mixture with a base, and the catalytic performance of the recovered material is highly comparable to that of the fresh catalyst. In terms of turnover, copper oxide (TON = 33 for ester yield of 56%) ranks higher than other simple metal compounds and is comparable to catalysts with NHC ligands. Thus, this work demonstrates the possibility of using a simple catalyst devoid of complex ligands to convert methane in high yields at low pressure.