(243f) Methane Conversion to Ethane and Ethylene Using Solid Oxide Membrane Reactors

Over the past few decades, natural gas production in the US has increased due to shale gas, 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 is currently reformed to produce synthesis gas, a mixture of CO, CO₂ and H₂, which is then used to make other chemicals and fuels.  Although these processes are economical, they rely on large economies of scale, resulting in very large chemical plants and little use for stranded sources of natural gas.  In contrast, direct conversion of methane to chemicals such as ethylene could create an economical use for natural gas that is currently flared.

Methane can be directly converted to C₂ products using oxidative coupling, where CH₃ radicals are formed using oxygen on a catalyst surface then couple to form ethane or ethylene.  In this work membrane reactors are fabricated which can control oxygen anion flux through a membrane. These devices consist of three layers of solid oxide and perovskite materials.  First a porous layer which dissociates oxygen from air, then a very thin solid layer that conducts oxygen anions, and finally another porous layer which facilitates methane activation.  We will show conversion and selectivity results for these devices using several different membranes including: yttria stabilized zirconia (YSZ), scandia stabilized zirconia (ScSZ), and gadolinium doped ceria (GDC).  We will also show results for factors that influence methane activation including the addition of transition metals.