| 摘要 |
PROBLEM TO BE SOLVED: To optimize the pore radius distribution of a rhodium catalyst containing at least rhodium and aluminum out of rhodium, aluminum, zirconium and gallium by adjusting the main peak value of the pore radius distribution at a specified value or below. SOLUTION: An aqueous solution in which rhodium nitrate, gallium nitrate, and zirconium nitrate are mixed so that the ratio in the number of atoms of rhodium, gallium, zirconium, and aluminum is about 1:20:60:80 is prepared. Ammonia water is dropped into the aqueous solution, and an aqueous solution containing the produced coprecipitate is allowed to stand at room temperature for about 17 hr. The aqueous solution is heated at about 80 deg.C for about 5 hr. After that fine powder is obtained through filtration, washing, and drying operations. The fine powder is burned at about 800 deg.C for about 5 hr to synthesize an oxidation catalyst in which the main peak value of a pore radius distribution is controlled to be 2.3 nm or below. In this way, nitrogen oxides can be removed in high activity. |
