Synthesis of colloidal precious metals nanoparticles with controlled size and morphology

Patent metadata

Field	Value
Publication number	US-10493433-B2
Application number	US-201515511271-A
Country	US
Kind code	B2
Filing date	Oct 7, 2015
Priority date	Oct 7, 2014
Publication date	Dec 3, 2019
Grant date	Dec 3, 2019

Abstract

The present invention relates to colloidal dispersions comprising a plurality of precious group nanoparticles, wherein about 90% or more of the precious group metal is in fully reduced form; a dispersion medium comprising a polar solvent; a water-soluble polymer suspension stabilizing agent; and a reducing agent, wherein the nanoparticle concentration is at least about 2 wt. % of the colloidal dispersion, wherein the nanoparticles have an average particle size of about 1 to about 6 nm and at least 95% of the nanoparticles have a particle size within this range; and further wherein the colloidal dispersion is substantially free of halides, alkali metals, alkaline earth metals and sulfur compounds. Methods of preparing, further processing, and using such colloidal dispersions are also provided herein.

First claim

What is claimed:

1. A colloidal dispersion comprising:
a) a plurality of precious group metal nanoparticles selected from the group consisting of Pt, Pd, Au, Ag, Ru, Rh, 1 r , Os, alloys thereof, and mixtures thereof, wherein about 90% or more of the precious group metal is in fully reduced form;
b) a dispersion medium comprising a polar solvent;
c) a water-soluble polymer suspension stabilizing agent; and
d) a reducing agent,
wherein the nanoparticle concentration is at least about 2 wt. % of the total weight of the colloidal dispersion,
wherein the nanoparticles have an average particle size of 1 to 8 nm and at least 95% of the nanoparticles have a particle size within this range;
and further wherein the colloidal dispersion contains less than about 10 ppm each of halides, alkali metals, alkaline earth metals and sulfur compounds.

2. The colloidal dispersion of claim 1 , wherein the precious group metal nanoparticles are selected from the group consisting of Pt, Pd, alloys thereof, and combinations thereof.

3. The colloidal dispersion of claim 1 , wherein the water-soluble polymer suspension stabilizing agent is selected from the group consisting of polyvinylpyrrolidone, a copolymer comprising vinylpyrrolidone, a fatty acid-substituted or unsubstituted polyoxyethylene, and combinations thereof.

4. The colloidal dispersion of claim 1 , wherein the reducing agent is selected from the group consisting of hydrogen, hydrazine, hydroxyethylhydrazine, formic hydrazide, urea, formaldehyde, formic acid, ascorbic acid, citric acid, glucose, sucrose, xylitol, meso-erythritol, sorbitol, glycerol, maltitol, oxalic acid, methanol, ethanol, 1-propanol, iso-propanol, 1-butanol, 2-butanol, 2-methyl-propan-1-ol, allyl alcohol, diacetone alcohol, ethylene glycol, propylene glycol, diethylene glycol, tetraethylene glycol, dipropylene glycol, tannic acid, garlic acid, and combinations thereof.

5. The colloidal dispersion of claim 1 , wherein the polar solvent is selected from the group consisting of water, alcohols, dimethylformamide, and combinations thereof.

6. The colloidal dispersion of claim 1 , wherein the nanoparticles have an average particle size of 1 to 5 nm and at least 95% of the nanoparticles have a particle size within this range.

7. The colloidal dispersion of claim 1 , wherein at least 95% of the nanoparticles have a particle size of within 50 percent of the average particle size.

8. The colloidal dispersion of claim 1 , wherein the nanoparticle concentration is about 2 wt. % to about 80 wt. % of the total weight of the colloidal dispersion.

9. The colloidal dispersion of claim 1 , wherein the dispersion is shelf stable for at least about six months at ambient temperature.

10. The colloidal dispersion of claim 1 , where the nanoparticles are not separated from the colloidal dispersion when the dispersion is centrifuged at 4,000 rpm for 10 minutes at ambient temperature.

11. The colloidal dispersion of claim 1 , wherein the plurality of precious group metal nanoparticles are selected from the group consisting of Pt, Pd, Ag, Ru, Rh, Ir, Os, alloys thereof, and mixtures thereof.

12. The colloidal dispersion of claim 1 , wherein the plurality of precious group metal nanoparticles are selected from the group consisting of Pt, Pd, Ru, Rh, Ir, Os, alloys thereof, and mixtures thereof.

13. The colloidal dispersion of claim 1 , wherein the nanoparticles have an average particle size of 1 to 6 nm and at least 95% of the nanoparticles have a particle size within this range.

14. A method of making a precious group metal nanoparticle colloidal dispersion of claim 1 , comprising:
a) preparing a solution of precious group metal precursors selected from salts of Pt, Pd, Au, Ag, Ru, Rh, Ir, Os and alloys thereof in the presence of a dispersion medium and a water soluble polymer suspension stabilizing agent, wherein the precious group metal precursors contain less than about 10 ppm each of halides, alkali metals, alkaline earth metals and sulfur compounds; and
b) combining the solution with a reducing agent to provide a precious group metal nanoparticle colloidal dispersion wherein the nanoparticle concentration is at least about 2 wt. % of the total weight of the colloidal dispersion and wherein at least about 90% of the precious group metal in the colloidal dispersion is in fully reduced form.

15. The method of claim 14 , wherein the precious group metal precursors are salts of Pt, Pd, or alloys thereof.

16. The method of claim 14 , wherein the precious group metal precursors are selected from the group consisting of alkanolamine salts, hydroxy salts, nitrates, carboxylic acid salts, ammonium salts, and oxides.

17. The method of claim 14 , wherein the precious group metal precursors are selected from the group consisting of monoethanolamine Pt(IV) hexahydroxide, dihydrogen hexahydroxyplatinate, Pd(OH)2, Ir(OH)4, Rh nitrate, Pt nitrate, Pt citrate, Pd(II) nitrate, Pd(II) citrate, and Pd (II) ammonia hydroxide complex.

18. The method of claim 14 , further comprising applying the nanoparticle dispersion to a solid support material.

19. The method of claim 18 , wherein the solid support material is selected from the group consisting of silica, alumina, silica/alumina, titania, zirconia, CeO2, rare earth oxides, zeolites, clay materials, carbon, and combinations thereof.

20. The method of claim 14 , for preparing a platinum nanoparticle dispersion,
wherein step a) comprises: preparing a solution of platinum precursor in a dispersion medium, in the presence of a water soluble polymer suspension stabilizing agent, wherein the solution is substantially free of halides, alkali metals, alkaline earth metals and sulfur compounds; and
step b) comprises combining the solution with ethylene glycol as a reducing agent to provide a platinum nanoparticle colloidal dispersion, wherein the platinum nanoparticle concentration is at least about 2 wt. % of the total weight of the colloidal dispersion and wherein at least about 90% of the platinum in the colloidal dispersion is in fully reduced form, and wherein the platinum nanoparticles have an average particle size of 1 to 6 nm, wherein at least 95% of the nanoparticles have a particle size within this range.

21. The method of claim 20 , wherein the platinum nanoparticles have an average particle size of 5 nm.

22. A catalyst comprising:
a) a solid support material; and
b) precious metal group nanoparticles associated with the support material, wherein the nanoparticles are prepared according to the method of claim 14 .

23. The catalyst of claim 22 , wherein the solid support material is selected from the group consisting of silica, alumina, silica/alumina, titania, zirconia, CeO2, rare earth oxides, zeolites, clay materials, carbon, and combinations thereof.

Assignees

• Basf Corp

Inventors

• Xu Xiaoming
• Liu Xinsheng

Classifications

• B01J23/48

  Silver or gold · CPC title

• B01J23/42 Primary

  Platinum · CPC title

• B01J23/464 Primary

  Rhodium · CPC title

• B01J37/16

  Reducing · CPC title

• B01J23/44

  Palladium · CPC title