Patent ID: 8067330

Claim:
A catalyst to purify an exhaust gas component, said catalyst comprising: a particulate filter as a catalyst support substrate having thereon a catalyst layer which contains a composite oxide, wherein the composite oxide does not contain cerium and does contain zirconium (Zr) and neodymium (Nd) as essential components and a rare-earth metal R other than cerium (Ce) and neodymium (Nd); each of said zirconium, neodymium and rare-earth metal R constituting said composite oxide is contained, in the form of an oxide, in such a manner that a ratio of Nd 2 O 3 /(ZrO 2 +Nd 2 O 3 +RO) is 3 mol % or more, a ratio of (Nd 2 O 3 +RO)/(ZrO 2 +Nd 2 O 3 +RO) is 33 mol % or less, and a ratio of RO/(ZrO 2 +Nd 2 O 3 +RO) is 12 mol % or more, wherein an oxide of rare-earth metal R is expressed as RO; and platinum (Pt) is supported on the composite oxide.