Metal foam element containing cobalt and method for producing same
The present invention relates to a method for producing supported catalysts, comprising: providing a metal foam element A, which consists of metallic cobalt, an alloy of nickel and cobalt, or an arrangement of layers of nickel and cobalt, lying one over the other; applying an aluminum-containing powder MP to metal foam element A in order to obtain metal foam element AX; thermally treating metal foam element AX to achieve alloy formation between metal foam element A and aluminum-containing powder MP, in order to obtain metal foam element B; oxidatively treating metal foam element B, in order to obtain metal foam element C; and applying a catalytically active layer, comprising at least one support oxide and at least one catalytically active component, to at least part of the surface of metal foam element C, in order to obtain a supported catalyst. The present invention further relates to the supported catalysts that can be obtained using the method and to the use of said supported catalysts in chemical transformations.
1. A process for producing a supported catalyst, comprising the following steps:
(a) providing a metal foam body A made of metallic cobalt, an alloy of nickel and cobalt, or overlying layers of nickel and cobalt;
(b) applying an aluminum-containing powder MP to metal foam body A so as to obtain metal foam body AX;
(c) thermally treating the metal foam body AX to achieve alloy formation between metal foam body A and aluminum-containing powder MP so as to obtain metal foam body B;
wherein the maximum temperature in the thermal treatment of metal foam body AX is within a range from 680 to 715° C. for a total duration of between 5 and 240 seconds;
(d) oxidizing metal foam body B so as to obtain metal foam body C;
(e) applying a catalytically active layer comprising at least one support oxide and at least one catalytically active component to at least part of the surface of metal foam body C so as to obtain the supported catalyst;
wherein the oxidative treatment of metal foam body B in step (d) is selected from the following:
heating of metal foam body B while in contact with an oxidizing gas atmosphere without prior formation of aluminum hydroxide on the surface of the metal foam body; or
heating of metal foam body B while in contact with an oxidizing gas atmosphere after aluminum hydroxide has previously been formed on the surface of the metal foam body.
2. The process of claim 1 , wherein, for the oxidative treatment of metal foam body B in step (d), metal foam body B is heated while in contact with an oxidizing gas atmosphere without prior formation of aluminum hydroxide on the surface of the metal foam body.
3. The process of claim 2 , wherein the heating while in contact with an oxidizing gas atmosphere is carried out for a period of 1 to 60 minutes at a temperature of 200° C. to 700° C. in air.
4. The process of claim 1 , wherein, for the oxidative treatment of metal foam body B in step (d), metal foam body B is heated while in contact with an oxidizing gas atmosphere after aluminum hydroxide has been formed on the surface of the metal foam body.
5. The process of claim 4 , wherein aluminum hydroxide is formed on the surface by contacting the metal foam body with an aqueous alkali solution.
6. The process of claim 5 , wherein the aqueous alkali solution contains sodium hydroxide, potassium hydroxide, lithium hydroxide or combinations thereof, and the metal foam body is contacted with the aqueous alkali solution for a period of not more than 30 minutes.
7. The process of claim 4 , wherein the heating while in contact with an oxidizing gas atmosphere is carried out for a period of 1 to 60 minutes at a temperature of 200° C. to 700° C. in air.
8. The process of claim 1 , wherein the support oxide of the catalytically active layer applied in step (e) is selected from the group consisting of: aluminum oxide, silicon dioxide, titanium oxide, and mixtures thereof.
9. The process of claim 1 , wherein the catalytically active component is a transition metal or transition metal compound, and the transition metal being is selected from the group consisting of: iron, ruthenium, osmium, cobalt, rhodium, iridium, nickel, palladium, platinum, cerium, copper, silver, gold, and mixtures thereof.
10. The process of claim 9 , wherein, for the oxidative treatment of metal foam body B in step (d), metal foam body B is heated while in contact with an oxidizing gas atmosphere without prior formation of aluminum hydroxide on the surface of the metal foam body.
11. The process of claim 10 , wherein the heating while in contact with an oxidizing gas atmosphere is carried out for a period of 1 to 60 minutes at a temperature of 200° C. to 700° C. in air.
12. The process of claim 9 , wherein, for the oxidative treatment of metal foam body B in step (d), metal foam body B is heated while in contact with an oxidizing gas atmosphere after aluminum hydroxide has been formed on the surface of the metal foam body.
13. The process of claim 12 , wherein aluminum hydroxide is formed on the surface by contacting the metal foam body with an aqueous alkali solution.
14. The process of claim 13 , wherein the aqueous alkali solution contains sodium hydroxide, potassium hydroxide, lithium hydroxide or combinations thereof, and the metal foam body is contacted with the aqueous alkali solution for a period of not more than 30 minutes.
15. The process of claim 14 , wherein the heating while in contact with an oxidizing gas atmosphere is carried out for a period of 1 to 60 minutes at a temperature of 200° C. to 700° C. in air.
16. The process of claim 15 , wherein the support oxide of the catalytically active layer applied in step (e) is selected from the group consisting of: aluminum oxide, silicon dioxide, titanium oxide, and mixtures thereof.