Method of making cerium oxide nanoparticles

• US 9,303,223 B2
• Filed: 11/11/2014
• Issued: 04/05/2016
• Est. Priority Date: 09/05/2006
• Status: Active Grant

• Current Assignee: Cerion, LLC (Revstone Industries LLC)
• Original Assignee: Cerion, LLC (Revstone Industries LLC)
• Inventors: Difrancesco, Albert Gary, Hailstone, Richard K., Reed, Kenneth J., Prok, Gary R.
• Primary Examiner(s): BOS, STEVEN J
• Application Number:
  US14/537,993
• Publication Number:
  US 20150059236A1
• Time in Patent Office: 511 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: B01J 13/0034 Additives, e.g. in view of promoting stabilisation or peptisation
• CPC Class Codes: B01J 13/0047 containing a metal oxide
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: C01F 17/235 Cerium oxides or hydroxides
• CPC Class Codes: C01F 17/32 oxide or hydroxide being the only anion, e.g. NaCeO2 or MgxCayEuO
• CPC Class Codes: C01G 25/00 Compounds of zirconium
• CPC Class Codes: C01G 25/02 Oxides
• CPC Class Codes: C01G 49/0054 containing one rare earth metal, yttrium or scandium
• CPC Class Codes: C01G 49/009 Compounds containing, besides iron, two or more other elements, with the exception of oxygen or hydrogen
• CPC Class Codes: C01G 49/02 Oxides; Hydroxides C01G49/0018 takes precedence
• CPC Class Codes: C01G 55/00 Compounds of ruthenium, rhodium, palladium, osmium, iridium, or platinum
• CPC Class Codes: C01P 2002/30 Three-dimensional structures
• CPC Class Codes: C01P 2002/52 containing elements as dopants
• CPC Class Codes: C01P 2002/72 by d-values or two theta-values, e.g. as X-ray diagram
• CPC Class Codes: C01P 2004/04 obtained by TEM, STEM, STM or AFM
• CPC Class Codes: C01P 2004/51 Particles with a specific particle size distribution
• CPC Class Codes: C01P 2004/52 highly monodisperse size distribution
• CPC Class Codes: C01P 2004/64 Nanometer sized, i.e. from 1-100 nanometer
• CPC Class Codes: C01P 2006/90 Other properties not specified above
• CPC Class Codes: C10G 25/02 with ion-exchange material
• CPC Class Codes: C10L 1/10 : containing additives
• CPC Class Codes: C10L 1/1233 : oxygen containing compounds, e.g. oxides, hydroxides, acids and salts thereof
• CPC Class Codes: C10L 1/1881 : carboxylic group attached to an aliphatic carbon atom
• CPC Class Codes: C10L 10/02 : for reducing smoke development
• CPC Class Codes: C10L 10/06 : for facilitating soot removal
• CPC Class Codes: C10L 2200/0222 : Group IV metals: Ti, Zr, Hf, Ge, Sn, Pb
• CPC Class Codes: C10L 2200/024 : Group VIII metals: Fe, Co, Ni, Ru, Rh, Pd, Os, Ir, Pt
• CPC Class Codes: C10L 2200/0245 : Lanthanide group metals: La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu
• CPC Class Codes: C10L 2200/0254 : Oxygen containing compounds
• CPC Class Codes: C10L 2230/22 : for improving fuel economy or fuel efficiency
• CPC Class Codes: C10L 2250/06 : Particle, bubble or droplet size
• CPC Class Codes: C10L 2270/026 : for diesel engines, e.g. automobiles, stationary, marine
• CPC Class Codes: Y02E 60/50 : Fuel cells
• CPC Class Codes: Y10T 428/2982 : Particulate matter [e.g., sphere, flake, etc.]

Abstract

A process for making cerium-containing oxide nanoparticles includes providing an aqueous reaction mixture containing a source of cerous ion, a source of hydroxide ion, at least one monoether carboxylic acid wherein the molar ratio of said monoether carboxylic acid to cerous ions is greater than 0.2, and an oxidant. The cerous ion is oxidized to ceric ion, thereby forming a product dispersion of cerium-containing oxide nanoparticles CeO_2-δ, wherein δ has a value of about 0.0 to about 0.5.

Claims

1. A method for making a dispersion of cerium oxide nanoparticles, comprising:

a) forming an aqueous reaction mixture comprising;

i) a source of cerous ion;

ii) a source of hydroxide ion;

iii) at least one monoether carboxylic acid, wherein the molar ratio of said monoether carboxylic acid to cerous ions is greater than 0.2; and

iv) an oxidant;

b) oxidizing the cerous ion to ceric ion; and

c) thereby forming in the reaction mixture a dispersion of cerium oxide nanoparticles, CeO_2-δ

, wherein δ

has a value of about 0.0 to about 0.5.

2. The method of claim 1, wherein the nanoparticles have a mean hydrodynamic diameter of about 1 nm to about 50 nm.

3. The method of claim 1, wherein the nanoparticles have a mean hydrodynamic diameter of 1.5 to 8 nm.

4. The method of claim 1, wherein the nanoparticles have a mean hydrodynamic diameter of 2 to 4 nm.

5. The method of claim 1, wherein said source of cerous ion is cerous nitrate.

6. The method of claim 1, wherein said monoether carboxylic acid is selected from the group consisting of ethoxyacetic acid, methoxyacetic acid, 3-methoxypropionic acid, and combinations thereof.

7. The method of claim 6, wherein said monoether carboxylic acid is methoxyacetic acid.

8. The method of claim 1, wherein said oxidant is hydrogen peroxide.

9. The method of claim 1, wherein the molar ratio of monoether carboxylic acid to total metal ions is greater than 0.3.

10. The method of claim 1, wherein the molar ratio of monoether carboxylic acid to total metal ions is greater than 0.6.

11. The method of claim 1, wherein the pH of the reaction mixture is less than or equal to 7.

12. The method of claim 1, wherein the pH of the reaction mixture is less than or equal to 5.

13. The method of claim 1, further comprising adding the cerium oxide nanoparticles to diesel fuel as a fuel additive.

14. The method of claim 1, wherein said nanoparticles are characterized by a crystalline cubic fluorite structure.

15. The method of claim 1, wherein the aqueous reaction mixture is formed by the sequential steps of adding:

1) the at least one monoether carboxylic acid;

2) concurrently adding the source of cerous ion and the source of hydroxide ion; and

3) the oxidant.

16. The method of claim 1, wherein the aqueous reaction mixture is formed by the sequential steps of adding:

1) the at least one monoether carboxylic acid;

2) concurrently adding the source of hydroxide ion and a first portion of the source of cerous ion;

3) the oxidant; and

4) a second portion of the source of cerous ion.

17. The method of claim 1, wherein the aqueous reaction mixture is formed by the sequential steps of adding:

1) the at least one monoether carboxylic acid;

2) concurrently adding the source of hydroxide ion and a first portion of the source of cerous ion;

3) a first portion of the oxidant; and

4) concurrently adding a second portion of the source of cerous ion and a second portion of the oxidant.