Metal foam supported catalyst and method for the production thereof
The invention relates to methods for producing supported catalysts, comprising: providing a metal foam element A made of nickel; applying an aluminum-containing powder MP to metal foam element A, such that metal foam element AX is obtained; thermally treating metal foam element AX in order to form an alloy between metal foam element A and the aluminum-containing powder MP, such that metal foam element B is obtained; oxidatively treating metal foam element B, such that metal foam element C is obtained; and applying a catalytically active layer, comprising at least one carrier oxide and at least one catalytically active component, to at least one part of the surface of metal foam element C, such that a supported catalyst is obtained. The invention also relates to the supported catalysts obtained according to the method, and to the use thereof in chemical transformations.
1. A process for producing a supported catalyst, comprising the following steps:
(a) providing a metal foam body A consisting of metallic nickel;
(b) applying an aluminum-containing powder MP to metal foam body A so as to obtain metal foam body AX;
(c) thermally treating 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 the range from 680 to 715° C. and the total duration of thermal treatment in the maximum temperature range is between 5 and 240 seconds;
(d) oxidizing the 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 a supported catalyst, and wherein oxidizing the 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 680° 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 6 , wherein the catalytically active component is a transition metal or transition metal compound, the transition metal is selected from the group consisting of iron, ruthenium, osmium, cobalt, rhodium, iridium, nickel, palladium, platinum, cerium, copper, silver, gold, and mixtures thereof.
8. The process of claim 5 , wherein:
a) 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 680° C. in air;
b) 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; and
c) the catalytically active component is a transition metal or transition metal
compound, the transition metal is selected from the group consisting of: iron, ruthenium, osmium, cobalt, rhodium, iridium, nickel, palladium, platinum, cerium, copper, silver, gold, and mixtures thereof.
9. 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 680° C. in air.
10. 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.
11. The process of claim 1 , wherein the catalytically active component is a transition metal or transition metal compound, the transition metal is selected from the group consisting of: iron, ruthenium, osmium, cobalt, rhodium, iridium, nickel, palladium, platinum, cerium, copper, silver, gold, and mixtures thereof.
12. 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.
13. The process of claim 12 , 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 680° C. in air.
14. 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.
15. The process of claim 14 , wherein aluminum hydroxide is formed on the surface by contacting the metal foam body with an aqueous alkali solution.
16. The process of claim 15 , 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.
17. The process of claim 16 , 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 680° C. in air.
18. The process of claim 17 , 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.
19. A supported catalyst prepared by the process of claim 1 , wherein the supported catalyst comprises a metal foam body, wherein the metal foam body comprises an aluminum oxide skin provided with a catalytically active layer.