Patent attributes
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):A1−xA′xB1−(y+z)B′yNzO3 (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.
