CATALYTICALLY EFFECTIVE COMPOSITION HAVING A LARGE CO SURFACE AREA
The present invention relates to a method for producing a catalytically effective composition for catalysts, to the compositions obtained in the method, and to catalysts containing the composition.
1 . A method for producing a catalytically effective composition for catalysts, comprising:
a) providing a first oxidic substrate material;
b) providing a noble metal salt solution containing one or more noble metal salts, wherein a concentration of noble metal in the solution is 0.01 wt. % or less, relative to the total solution being 100 wt. %;
c) producing a suspension by contacting the first oxidic substrate material with the noble metal salt solution; and
d) introducing a second oxidic substrate material into the suspension obtained in step c).
2 . The method according to claim 1 , wherein the first and the second oxidic substrate materials may be the same or different from each other.
3 . The method according to claim 1 , wherein at least one of the first and the second oxidic substrate materials is selected from the group consisting of aluminum oxide, cerium-zirconium oxide, barium oxide, tin oxide, and titanium oxide.
4 . The method according to claim 1 , wherein a total amount of noble metal is in a range of 0.01 to 10 wt. %, relative to the total amount of first oxidic substrate material and noble metal being 100 wt. %.
5 . The method according to claim 1 , wherein the one or more noble metal salts is a salt of a platinum group metal.
6 . The method according to claim 1 , wherein the one or more noble metal salts is a nitrate salt.
7 . The method according to claim 1 , wherein a pH value of the suspension is set to a range of 4 to 10.
8 . The method according to claim 7 , wherein the pH value is set to a range of 4 to 7.
9 . The method according to claim 1 , wherein a pH value of the suspension is set using at least one of ammonia and an aqueous sodium carbonate solution.
10 . The method according to claim 9 , wherein the pH value is set using an aqueous sodium carbonate solution.
11 . The method according to claim 1 , wherein steps a) to d) are performed at a temperature in a range of 10° C. to 90° C.
12 . The method according to claim 1 , further comprising filtering the suspension obtained in step d).
13 . A catalytically effective composition obtained by the method according to claim 1 , wherein the composition has a CO surface area of 6 m 2 /g or more.
14 . A multilayer catalyst comprising the catalytically effective composition according to claim 13 .
15 . A vehicle comprising the multilayer catalyst according to claim 14 .