Catalyst composition
A catalyst composition which prevents deterioration due to grain growth of Rh and/or Pt, includes a perovskite-type composite oxide represented by the following general formula (1): A 1−x A′ x B 1−(y+z) B′ y N z O 3 (1) wherein A represents at least one element selected from alkaline earth metals; A′ represents at least one element selected from rare earth elements; B represents at least one element selected from Ti, Zr, and Hf; B′ represents at least one element selected from transition elements (excluding rare earth elements, Ti, Zr, Hf, Rh, and Pt) and Al; N represents at least one element selected from Rh and Pt; x represents an atomic ratio satisfying the following condition: 0≦x≦0.4; y represents an atomic ratio satisfying the following condition: 0≦y<0.5; z represents an atomic ratio satisfying the following condition: 0<z≦0.5; and X represents 0 when N represents Pt alone.
1. A catalyst composition comprising a perovskite-type composite oxide represented by the following general formula (1):
A 1−x A′ x B 1−(y+z) B′ y N z O 3 (1)
wherein A represents at least one element selected from the group consisting of alkaline earth metals;
A′ represents at least one element selected from the group consisting of rare earth elements;
B represents Ti;
B′ represents at least one element selected from the group consisting of transition elements (excluding rare earth elements, Ti, Rh, and Pt) and Al;
N represents at least one element selected from the group consisting of Rh and Pt;
x represents an atomic ratio satisfying the following condition: 0≦x≦0.4;
y represents an atomic ratio satisfying the following condition: 0≦y<0.5;
z represents an atomic ratio satisfying the following condition: 0<z≦0.5; and
x represents 0 when N represents Pt alone;
wherein A represents at least one element selected from the group consisting of Ca, Sr, and Ba in the general formula (1); and
wherein y represents 0 in the general formula (1).
2. A catalyst composition comprising a perovskite-type composite oxide represented by the following general formula (2):
AB 1−z N z O 3 (2)
wherein A represents at least one element selected from the group consisting of Ca, Sr and Ba;
B represents Ti;
N represents at least one element selected from the group consisting of Rh and Pt; and
z represents an atomic ratio satisfying the following condition: 0<z≦0.5.
3. A catalyst composition comprising a perovskite-type composite oxide represented by the following general formula (3):
AB 1−z Rh z O 3 (3)
wherein A represents at least one element selected from the group consisting of Ca, Sr and Ba;
B represents Ti; and
z represents an atomic ratio satisfying the following condition: 0<z≦0.5.
4. A catalyst composition comprising a perovskite-type composite oxide represented by the following general formula (4):
AB 1−z Pt z O 3 (4)
wherein A represents at least one element selected from the group consisting of Ca and Ba;
B represents Ti; and
z represents an atomic ratio satisfying the following condition: 0<z≦0.5.