| 摘要 |
PROBLEM TO BE SOLVED: To obtain a catalyst for purifying catalyst suppressed in the degradation of catalytic purifying performance due to the reaction of Rh with alumina even at a high temp. atmosphere of >=900 deg.C and improved in heat resistance. SOLUTION: The catalyst for purifying waste gas has a carrier base material, a 1st coated layer 2 carrying at least one kind of Pt and Pd on the surface of the base material and a 2nd coated layer 3 formed on the surface of the 1st coated layer and carrying Rh and the 2nd coated layer 3 consists essentially of θ-alumina having 50-100 m<2> /g specific surface area. The θ-alumina is stable against a temp of 900-1000 deg.C, Rh hardly forms a solid solution in the alumina crystal and the sintering of Rh in accordance with the phase change or the grain growth of alumina is suppressed. |
