Wet chemical and plasma methods of forming stable PTPD catalysts

• US 9,433,938 B2
• Filed: 11/19/2015
• Issued: 09/06/2016
• Est. Priority Date: 02/23/2011
• Status: Expired due to Fees

• Current Assignee: Umicore AG & Company KG (Umicore S.A.)
• Original Assignee: SDC Materials,Inc.
• Inventors: Van Den Hoek, Willibrordus G. M., Biberger, Maximilian A.
• Primary Examiner(s): Nguyen, Cam N
• Application Number:
  US14/946,689
• Publication Number:
  US 20160144352A1
• Time in Patent Office: 292 Days
• Field of Search: 502/5, 502/262, 502/263, 502/327, 502332-334, 502/339, 502/355, 502/415, 502/439, 977/773, 977/775, 977/896, 977/900
• US Class Current: 1/1
• CPC Class Codes: B01J 23/42 Platinum
• CPC Class Codes: B01J 23/44 Palladium
• CPC Class Codes: B01J 35/23 in a colloidal state
• CPC Class Codes: B01J 35/393 Metal or metal oxide crystallite size
• CPC Class Codes: B01J 35/396 Distribution of the active metal ingredient
• CPC Class Codes: B01J 35/397 Egg shell like
• CPC Class Codes: B01J 35/40 characterised by dimensions, e.g. grain size in a colloidal state B01J35/23; crystallite size B01J35/77
• CPC Class Codes: B01J 37/349 making use of flames, plasmas or lasers
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: B82Y 40/00 Manufacture or treatment of nanostructures

Abstract

A nano-particle comprising: an interior region comprising a mixed-metal oxide; and an exterior surface comprising a pure metal. In some embodiments, the mixed-metal oxide comprises aluminum oxide and a metallic pinning agent, such as palladium, copper, molybdenum, or cobalt. In some embodiments, the pure metal at the exterior surface is the same as the metallic pinning agent in the mixed-metal oxide in the interior region. In some embodiments, a catalytic nano-particle is bonded to the pure metal at the exterior surface. In some embodiments, the interior region and the exterior surface are formed using a plasma gun. In some embodiments, the interior region and the exterior surface are formed using a wet chemistry process. In some embodiments, the catalytic nano-particle is bonded to the pure metal using a plasma gun. In some embodiments, the catalytic nano-particle is bonded to the pure metal using a wet chemistry process.

Claims

1. A method of forming nano-particles, the method comprising:

forming a plurality of aluminum-palladium carrier nano-particles using a plasma gun, wherein the aluminum-palladium carrier nano-particles comprise an interior region and an exterior surface, the interior region comprising a mixed-metal oxide that includes aluminum oxide and palladium, and the exterior surface comprising pure metallic palladium; and

affixing platinum nano-particles to the pure metallic palladium on the aluminum-palladium carrier nano-particles using a wet chemistry process;

wherein forming the plurality of aluminum-palladium carrier nano-particles using the plasma gun comprises;

loading a quantity of aluminum oxide material and a quantity of palladium material into the plasma gun in a desired ratio, wherein the aluminum oxide material and the palladium material are in powder form;

vaporizing the quantity of aluminum oxide material and the quantity of palladium material using the plasma gun, thereby forming a vapor cloud comprising vaporized aluminum oxide and vaporized palladium; and

quenching the vapor cloud, thereby condensing the vaporized aluminum oxide and the vaporized palladium into carrier nano-particles.

2. The method of claim 1, wherein the step of vaporizing the quantity of aluminum oxide material and the quantity of palladium material comprises:

flowing a working gas into a reactor of the plasma gun;

delivering energy to the working gas, thereby forming a plasma stream; and

flowing the quantity of aluminum oxide material and the quantity of palladium material into the plasma stream.

3. The method of claim 2, wherein the working gas comprises argon and H₂.

4. The method of claim 2, wherein the palladium in the interior region extends to and is bonded with the pure metallic palladium at the exterior surface.

5. The method of claim 1, wherein the palladium in the interior region extends to and is bonded with the pure metallic palladium at the exterior surface.

6. The method of claim 1, wherein the aluminum-palladium carrier nano-particles have an average grain size of 10 nanometers or less.

7. The method of claim 1, wherein the platinum nano-particles have a diameter of 1 nanometer or less.

8. The method of claim 1, wherein the platinum nano-particles have a diameter of approximately 0.5 nanometer.

9. The method of claim 1, wherein the mixed-metal oxide forms a center core of the aluminum-palladium carrier nano-particles.

10. The method of claim 9, wherein the mixed-metal oxide consists only of aluminum oxide and palladium.

11. The method of claim 1, wherein the wet chemistry process comprises:

mixing a platinum solution with the aluminum-palladium carrier nano-particles; and

bonding platinum nano-particles formed from the platinum solution to the pure metallic palladium on the aluminum-palladium carrier nano-particles.

12. The method of claim 11, wherein the platinum solution is a platinum nitrate solution or a platinum chloride solution.

13. A method of forming a catalyst, the method comprising:

providing a support structure;

forming a plurality of aluminum-palladium nano-particles using a plasma gun; and

bonding the plurality of nano-particles to the support structure;

wherein forming the plurality of aluminum-palladium carrier nano-particles using the plasma gun comprises;

loading a quantity of aluminum oxide material and a quantity of palladium material into the plasma gun in a desired ratio, wherein the aluminum oxide material and the palladium material are in powder form;

vaporizing the quantity of aluminum oxide material and the quantity of palladium material using the plasma gun, thereby forming a vapor cloud comprising vaporized aluminum oxide and vaporized palladium; and

quenching the vapor cloud, thereby condensing the vaporized aluminum oxide and the vaporized palladium into carrier nano-particles.

14. The method of claim 13, wherein:

the support structure is a porous ceramic material; and

the nano-particles are disposed within the pores of the ceramic material.

15. The method of claim 13, wherein the aluminum-palladium carrier nano-particles have an average grain size of 10 nanometers or less.

16. The method of claim 13, wherein the platinum nano-particles have a diameter of 1 nanometer or less.

17. The method of claim 13, wherein the platinum nano-particles have a diameter of approximately 0.5 nanometer.