Over the past few decades, natural gas production in the US has increased due to shale gas and tight oil production, and is projected to continue to increase . This increase in availability and production has driven prices down and prompted research into new ways to use methane, the main component in natural gas. Methane can be directly converted to C2 products using oxidative coupling (OCM), where CH3radicals are formed using oxygen on a catalyst surface then couple in the gas phase to form ethane or ethylene . In previous literature, both conventional fixed bed reactors as well as membrane reactors have been tested for this process. Fixed bed reactors suffer from relatively low yields (>30%) because the oxygen is limited to about 20 mol% of the feed in order to maintain reasonable selectivity . Membrane reactors have desirable characteristics for this type of reaction, but they also suffer from low yield. However, many prior studies have used thick membranes (~1mm) and no additional catalyst, which limits oxygen anion flux, and thus the conversion.
In this study, we are using solid oxide fuel cell (SOFC) technology to fabricate very thin (~20 μm), dense membrane layers from mixed conducting metal oxides including lanthanum gallate doped with strontium, magnesium, and nickel (Ni-LSGM) and lanthanum ferrite doped with strontium and cobalt (LSCF). We will discuss the reasoning for the materials and catalyst choices that we have made, and additionally, we will show results from our packed bed and solid oxide membrane reactor experiments.
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