Copper-Exchanged Omega (MAZ) Zeolite: Copper-concentration Dependent Active Sites and its Unprecedented Methane to Methanol Conversion

摘要

The direct conversion of methane to methanol may provide a way to utilize methane that is otherwise wasted. Here we have explored one of the most promising copper zeolite materials to date, copper-exchanged omega (MAZ) zeolite. With highly crystalline and uniform zeolite omega, we can produce 150 umol-methanol/gram-zeolite under 1bar methane and as high as 200 umol-methanol/gram-zeolite under 30 bar methane, the highest yield ever reported. Furthermore, zeolite omega's ability to convert methane to methanol has a distinct copper-concentration dependent behavior. At lower copper loadings, Cu-MAZ is inactive, and once a minimum copper loading is reached, Cu-MAZ converts methane to methanol more selective than the widely studied Cu-mordenite. With the unprecedented high conversion and selectivity, Cu-MAZ provides insight into the active copper phase and its mechanism which was quantified as two electrons per molecule of methanol produced.