Composite oxygen ion transport membrane
A composite oxygen ion transport membrane having a dense layer, a porous support layer, an optional intermediate porous layer located between the porous support layer and the dense layer and an optional surface exchange layer, overlying the dense layer. The dense layer has electronic and ionic phases. The ionic phase is composed of scandia doped, yttrium or cerium stabilized zirconia. The electronic phase is composed of a metallic oxide containing lanthanum, strontium, chromium, manganese and vanadium and optionally cerium. The porous support layer is composed of zirconia partially stabilized with yttrium, scandium, aluminum or cerium or mixtures thereof. The intermediate porous layer, if used, contains the same ionic and electronic phases as the dense layer. The surface exchange layer is formed of an electronic phase of a metallic oxide of lanthanum and strontium that also contains either manganese or iron and an ionic phase of scandia doped zirconia stabilized with yttrium or cerium.
1. A composite oxygen ion transport membrane comprising:
a dense layer having an electronic phase and an ionic phase;
said electronic phase is (La u Sr v Ce 1−u−v ) w Cr x Mn y V z O 3−5 , where u is from about 0.7 to about 0.9, v is from about 0.1 to about 0.3 and (1−u−v) is greater than or equal to zero, w is from about 0.94 to about 1, x is from about 0.67 to about 0.77, y is from about 0.2 to about 0.3, z is from about 0.015 to about 0.03, and x+y+z=1;
said ionic phase is Zr x′ Sc y′ A z′ O 2−δ , where y′ is from about 0.08 to about 0.15, z′ is from about 0.01 to about 0.03, x′+y′+z′=1 and A is Y or Ce or mixtures of Y and Ce;
a porous support layer, said porous support layer formed of Zr x″ A y″ O 2−δ , where y″ is from about 0.03 to about 0.05, x″+y″=1, A is Y or Sc or Al or Ce or mixtures of Y, Sc, Al and Ce.
2. The composite ion transport membrane of claim 1 , further comprising:
a porous intermediate layer between the dense layer and the porous support layer; and
the porous intermediate layer composed of the electronic phase and the ionic phase.
3. The composite ion transport membrane of claim 2 , further comprising:
a surface exchange layer, overlying the dense layer so that the dense layer is located between the surface exchange layer and the porous intermediate layer;
said surface exchange layer composed of a further electronic conductor composed of (La x′″ Sr 1−x′″ ) y′″ MO 3−δ , where x′″ is from about 0.2 to about 0.8, y′″ is from about 0.95 to 1, M=Mn, Fe and a further ionic conductor composed of Zr x iv Sc y iv A z iv O 2−δ , where y iv is from about 0.08 to about 0.15, z iv is from about 0.01 to about 0.03, x iv +y iv +z iv =1 and A=Y, Ce.
4. The composite ion transport membrane of claim 3 , wherein:
the ionic phase constitutes between about 35 percent and 65 percent by volume of each of the dense layer and the intermediate porous layer, remainder the electronic phase; and
the further ionic conductor constitutes between about 35 percent and about 65 percent by volume of the surface exchange layer, remainder the further electronic conductor.
5. The composite ion transport membrane of claim 4 , wherein:
the ionic phase constitutes about 50 percent by volume of each of the dense layer and the intermediate porous layer, remainder the electronic phase; and
the further ionic conductor constitutes between about 50 percent by volume of the surface exchange layer, remainder the electronic conductor.
6. The composite ion transport membrane of claim 1 , wherein:
the electronic phase is (La 0.825 Sr 0.175 ) 0.97 Cr 0.76 Mn 0.225 V 0.015 O 3−δ ; and
the ionic phase is Zr 0.89 Sc 0.1 Y 0.01 O 2−δ .
7. The composite ion transport membrane of claim 2 , wherein:
the electronic phase is (La 0.825 Sr 0.175 ) 0.97 Cr 0.76 Mn 0.225 V 0.015 O 3−δ ; and the ionic phase is Zr 0.89 Sc 0.1 Y 0.01 O 2−δ .
8. The composite ion transport membrane of claim 6 or claim 7 , wherein said porous support layer is formed of Zr 0.97 Y 0.03 O 2−δ .
9. The composite ion transport membrane of claim 5 , wherein:
the electronic phase is (La 0.825 Sr 0.175 ) 0.97 Cr 0.76 Mn 0.225 V 0.015 O 3−δ ; the ionic phase is Zr 0.89 Sc 0.1 Y 0.01 O 2−δ ;
said porous support layer is formed of Zr 0.97 Y 0.03 O 2−δ ; the further ionic conductor is Zr 0.89 Sc 0.1 Y 0.01 O 2−δ ; and the further electronic conductor is La 0.8 Sr 0.2 FeO 3−δ .
10. The composite ion transport membrane of claim 9 , wherein:
the porous intermediate layer has a first thickness of between about 20 micron and about 60 micron, a first average pore size of between about 0.1 mic and about 0.5 mic and a first porosity of between about 40 percent and about 60 percent;
the porous support layer has a second thickness of between about 1 mm and about 2.5 mm, a second average pore size of between about 2 micron and about 5 micron and a second porosity of between about 40 percent and about 60 percent; and
said overlying porous support layer has a third thickness of between about 10 micron and about 25 micron, a third average pore-size of between about 0.1 micron and about 0.5 micron and a third porosity of between about 40 percent and about 60 percent.