Mixed ionic and electronic conducting ceramic membranes for hydrocarbon processing

A gas-impermeable mixed phase ceramic catalytic reactor membrane which comprises about 80% by weight or more of a mixed ionic and electronic conducting first phase and from about 0.1 to about 20% by weight of one or more structurally distinct second phases which impart mechanical strength to the membrane, wherein said second phase or phases is formed from one or more of the same metal elements as the first phase;

• wherein the mixed ionic and electronic conducting first phase has the formula:
• AxA′x′A″2−(x+x′)ByB′y′B″2−(y+y′)O5+z
• where A is an element from the f block lanthanide elements;
• A′ is an element selected from the Group 2 elements;
• A″ is an element from the f block lanthanide or Group 2 elements;
• B is an element selected from Al, Ga, In or mixtures thereof;
• B′ and B″ are different elements and are selected independently from the group of elements consisting of Mg, and the d-block transition elements;
• 0<x<2, 0<x′<2, 0<y<2, 0<y′<2 where x+x′≦2 and y+y′≦2, and z varies to maintain electroneutrality, said membrane being made by forming the first and second phase or phases simultaneously by mixing an off-stoichiometric ratio of the first-phase materials.