| 摘要 |
PROBLEM TO BE SOLVED: To obtain a ternary catalyst excellent in removing effect of harmful materials by impregnating a palladium soln. into alumina, subjecting it to reduction, adding cerium oxide, etc., milling them after pH adjustment with nitric acid, coating a ceramic monolithic carrier with the resultant slurry and carrying out drying and firing. SOLUTION: A palladium soln. is impregnated into alumina and subjected to reduction with 1.5-2.0 ml hydrazine hydrate based on 1 g palladium. The palladium soln. is usuallyprepd. by dissolving palladium chloride in a soluble solvent such as a hydrous alcohol. A soln. contg. cerium oxide and a 3rd catalyst component is then added. After pH adjustment to <=4.5 with nitric acid, they are milled so that particles of 7-9 μm particle size account for >=90% of all particles. A ceramic monolithic carrier is coated with the resultant slurry, dried and fired to obtain the objective palladium ternary catalyst. |
