Activation of methane using solid oxide membranes

Dense membranes of mixed-conducting perovskite-type oxides Lao.sSro.4Co,,8Fe,,,0~ and Lac,aBa&oo.aFe,,,O~ were used for methane coupling by application of pressure-driven O2 permeation. High operating temperatures, typically above 8OO”C, were needed to obtain reasonable oxygen fluxes. Conversions were small (l-3%). Both compositions showed comparable C2 selectivities at low methane partial pressures. At higher pressures the selectivity to Cz hydrocarbons for L~.~Sr,,,Co~.~Fe~.~O~ increased to 67%, whereas LaasBa92Coo,8Fe,,,0~ showed small C, selectivities. Strong surface segregation of Sr and Ba was shown by SEM for both compositions.