Solid state oxygen anion and electron mediating membrane and catalytic membrane reactors containing them

A solid state membrane for use in a catalytic membrane reactor which comprises:

• a reduction surface which in operation in a catalytic membrane reactor contacts an oxygen-containing gas and an oxidation surface which in operation in a catalytic membrane reactor contacts a reactant gas, a partial vacuum or an oxygen-depleted gas,
• wherein said membrane is fabricated from a mixed metal oxide having the stoichiometry:
• A.sub.2-x A'.sub.x B.sub.2-y B'.sub.y O.sub.5+z
• where:
• A is an alkaline earth metal ion or mixture of alkaline earth metal ions;
• A' is a metal ion or mixture of metal ions where the metal is selected from the group consisting of the lanthanide series or is yttrium;
• B is a metal ion or mixture of metal ions wherein the metal is selected from the group consisting of 3d transition metals, and the group 13 metals;
• B' is a metal ion or mixture of metal ions where the metal is selected from the group consisting of the 3d transition metals, the group 13 metals, the lanthanides and yttrium;
• x is a number greater than or equal to 0 an less than or equal to 2;
• y is a number greater than or equal to 0 and less than or equal to 2;
• and
• z is a number greater than zero and less than one that renders the compound charge neutral.