A series of ion-conducting perovskites of the form [La(1-x)A(x)] [Co0.
2Fe0.8]O3-delta (x = 0.4, 0.6 for A = Sr; x = 0.8 for A = Ba) were inv
estigated for their use as a catalytic membrane for the oxidative coup
ling of methane (OCM). A-site cations consisting of La0.4Sr0.6 and La0
.2Ba0.8 produce materials with the highest oxygen fluxes and result ac
hieved with a powdered catalyst in a packed-bed reactor configuration.
Selectivities in these materials appear to be limited by high oxygen
ion recombination rates that compete for oxygen with the desired coupl
ing reaction(s). The results also indicate that oxygen fluxes are not
limited by diffusion, but by surface exchange rates at the oxygen-lean
side of the membrane. The study on stability of these materials showe
d that all three perovskites could be reduced in a pure methane or eth
ane stream at 1,023 K but they were totally stable under reaction cond
itions where oxygen is present.