CATALYST, PROCESS FOR PRODUCING THE CATALYST, USE OF THE CATALYST

• US 20140018234A1
• Filed: 07/05/2013
• Published: 01/16/2014
• Est. Priority Date: 07/05/2012
• Status: Active Grant

• Current Assignee: MAN Truck & Bus AG (Volkswagen AG)
• Original Assignee: MAN Truck & Bus AG (Volkswagen AG)
• Inventors: DOERING, Andreas
• Granted Patent: US 9,067,197 B2
• Time in Patent Office: Days
• US Class Current: 502/242
• CPC Class Codes: B01D 2255/1021 Platinum
• CPC Class Codes: B01D 2255/20707 Titanium
• CPC Class Codes: B01D 2255/20776 Tungsten
• CPC Class Codes: B01D 2255/30 Silica
• CPC Class Codes: B01D 2258/01 Engine exhaust gases
• CPC Class Codes: B01D 53/944 Simultaneously removing carbon monoxide, hydrocarbons or carbon making use of oxidation catalysts three-way-catalysts [TWC] B01D53/9445
• CPC Class Codes: B01J 21/063 Titanium; Oxides or hydroxides thereof
• CPC Class Codes: B01J 23/42 Platinum
• CPC Class Codes: B01J 23/44 Palladium
• CPC Class Codes: B01J 23/6527 Tungsten
• CPC Class Codes: B01J 35/023 Catalysts characterised by dimensions, e.g. grain size
• CPC Class Codes: B01J 35/40 characterised by dimensions, e.g. grain size in a colloidal state B01J35/23; crystallite size B01J35/77

Abstract

A catalyst especially for oxidation of exhaust gas constituents, for example nitrogen oxide, preferably nitrogen monoxide, consists of a particulate support material composed of titanium-containing nanoparticles, preferably titanium oxide nanoparticles, especially titanium dioxide nanoparticles coated with platinum, especially platinum particles. A process for producing such a catalyst.

Claims

1. A catalyst for oxidation of exhaust gas constituents including nitrogen oxide, the catalyst comprising:

a particulate support material composed of titanium-containing nanoparticles; and

a platinum coating, wherein the support material is coated with the platinum coating.

2. The catalyst according to claim 1, wherein the catalyst oxidizes nitrogen monoxide, the particulate support material is composed of titanium dioxide nanoparticles, and the platinum coating is composed of platinum particles.

3. The catalyst according to claim 1, further comprising bridges arranged between and joining at least one of a plurality of platinum particles of the platinum layer and to plurality of support material particles of the support material, the bridges contain metal oxide and at least one of silicon and tungsten.

4. The catalyst according to claim 1, wherein the platinum coating is composed of platinum nanoparticles.

5. The catalyst according to claim 1, wherein the catalyst further includes palladium.

6. The catalyst according to claim 1, wherein the catalyst has a platinum concentration in the range of 0.5 mg to 150 mg per 1 gram of catalyst weight.

7. The catalyst according to claim 1, wherein the catalyst has a platinum concentration in the range of 1 mg to 100 mg per 1 gram of catalyst weight.

8. The catalyst according to claim 3, wherein the catalyst has one of:

a titanium;

silicon ratio of 20;

1 to 2;

1; and

a titanium;

tungsten ratio of 80;

1 to 8;

1.

17. The use of a catalyst according to claim 1 for oxidation of exhaust gas constituents including nitrogen oxide downstream of an internal combustion engine.

18. The use of the catalyst according to claim 17 for oxidation of nitrogen monoxide.

19. A coating produced using a catalyst according to claim 1 for application to ceramic or metallic catalyst substrates.

9. A process for producing a catalyst for oxidation of exhaust gas constituents including nitrogen oxide, comprising the following steps:

providing a titanium-containing first precursor material for production of a support material;

providing a second precursor material for production of a catalytically active component, the second precursor material comprising at least one of platinum and palladium;

providing a third precursor material containing at least one of silicon, tungsten, and palladium, for production of a stabilizing material;

introducing the titanium containing first precursor material into a through-flowable reaction zone of a pyrolysis device;

introducing the second precursor material into the reaction zone downstream of where the first precursor material is introduced; and

introducing the third precursor material into the reaction zone one of;

simultaneously with the introduction of the first precursor material;

downstream of where the first precursor material is introduced;

downstream of where the second precursor material is introduced.

10. The process according to claim 9, wherein:

the first precursor material comprises one of titanium halides, titanium acetates, titanium tetraisopropoxide, and titanium alkoxides;

the second precursor material comprises one of Platinum compounds and palladium compounds; and

the third precursor material comprises one of Silicon compounds, tungsten compounds, and palladium compounds including palladium chlorides.

11. The process according to claim 9, wherein:

the first precursor material comprises one of TiCl₄, Ti(NO₃)₂, or Ti(SO₄)₂, titanium acetates, titanium tetraisopropoxide, and titanium tetraethoxide;

the second precursor material comprises one of platinum chlorides, platinum acetates, tetraammineplatinum hydroxide, platinum alkoxides, platinum nitrate, and palladium chlorides; and

the third precursor material comprises one of silicon halides, silicon chlorides, silanes, hexamethyldisiloxane, silicon alkoxides, tungsten halides, tungstates, tungsten alkoxides, tungsten acetates, tungsten nitrate; and

palladium chlorides.

12. The process according to claim 9, wherein the third precursor material is one of a silicon compound and a tungsten compound;

and

at least one of the first and third precursor material is introduced into the reaction zone in or essentially together with an oxidizing atmosphere.

13. The process according to claim 12, wherein the oxidizing atmosphere is obtained by an addition of a gaseous oxidizing agent.

14. The process according to claim 9, wherein the second precursor material is introduced into the reaction zone in or essentially together with a reducing atmosphere.

15. The process according to claim 14, wherein the reducing atmosphere is obtained by an addition of a gaseous reducing agent to the reaction zone.

16. The process according to claim 15, wherein the gaseous reducing agent is one of hydrogen and methane.