| 摘要 |
PROBLEM TO BE SOLVED: To raise the activity of Pt as an oxidation catalyst and improve the activity at low temperature by controlling the ratio of Pt existing as a single body without oxide coating to be higher than the ratio of the Pt existing as an oxide by forming an oxide coating. SOLUTION: A slurry is produced by adding 10wt.% of hydrated alumina to γ-alumina as activated alumina, a honeycomb support is wash-coated with the resultant slurry, and the obtained honeycomb support is fired for 2 hours at 500 deg.C in air. Then, a prescribed amount (a proper amount to adjust Pt in 3.6wt.% of γ-alumina) of a nitric acid-acidic solution of dinitrodiammineplatinum(II) and a prescribed amount (a proper amount to adjust Pd in 2.2wt.% of y-alumina) of a nitric acid-acidic solution of dinitrodiamminepalladium(II) are mixed, the wash-coat layer on the honeycomb support is impregnated with the mixed solution, and the resultant honeycomb support is dried for 1 hour at 150 deg.C and then fired for 2 hours at 500 deg.C to give a honeycomb catalyst. Further, the obtain honeycomb catalyst is heated for 1 hour at 400 deg.C in a reducing gas flowing atmosphere to give a catalyst for exhaust gas cleaning. |
