Direct Conversion of Methane to Methanol over Copper-Exchanged Zeolite under Mild Conditions

Abstract

Direct methane-to-methanol (MTM) conversion in a stepwise process under mild conditions has been widely studied. Nevertheless, suitable catalysts and reaction processes for industrial applications have remained elusive. Recently, small-pore copper-exchanged zeolites [copper ion–exchanged mordenite (Cu-MOR)] have been reported as the most effective catalysts for MTM reaction, which necessitates enhancement of active sites in the catalysts and protection of methanol from overoxidation. Herein, we attempt to optimize the catalyst material compositions of Cu-MOR and to optimize the pretreatment and reaction conditions during MTM tests. We investigated effects of copper composition, catalyst activation time, and activation temperature. Rationalizing the catalyst compositions and reaction conditions achieved methanol productivity as high as 0.107 mol/mol Cu (72.63 μ mol/g catalyst). We also simplified the catalyst treatment and reaction procedure, which resulted in methanol yield increase.