Method for making high purity metal oxide particles and materials made thereof
View Patent ↗The present invention is directed to a method of making metal oxide and mixed metal oxide particles. The method includes treating a mixture formed from a metal source, such as metal alkoxide, a surfactant, and a first alcohol in an aqueous media at a very high metal oxide yield. The mixture is reacted using a catalyst to form metal oxide particles having a desired particle size in said mixture. The method is particularly suitable for forming silica particles. The metal oxide particles can then be heat treated to form synthetic fused metal oxides such as, for example, synthetic fused silica.
1. A method for making metal-containing particles comprising:
(a) forming a first phase comprising a mixture of water, a metal source, a first catalyst, a first surfactant, and a first alcohol;
b) adding the first phase to a second phase comprising water, a second alcohol, and a second surfactant to form a blend;
(c) treating the blend with a phase enhancer, the phase enhancer being separately added to the blend via a composition other than that of the first phase or the second phase; and
(d) treating the blend from (c) with a second catalyst to form metal-containing particles.
2. The method of claim 1 , wherein the metal source comprises a metal alkoxide, a hydrolyzable organometallic compound, oxo metal oligomers, or mixtures of two or more thereof.
3. The method of claim 1 , wherein the metal source comprises a metal chosen from Si, Ti, Fe, AI, Zr, Nb, Y, a rare earth metal, or a combination of two or more thereof.
4. The method of claim 1 , wherein the metal source comprises a metal alkoxide, and the molar ratio of water to metal alkoxide source in the first phase is from about 0.5 to about 4.0.
5. The method in claim 1 , wherein the first and/or second alcohol comprises a linear alcohol having 1-10 carbon atoms.
6. The method of claim 1 , wherein the first surfactant is a co-surfactant system comprising a non-polar compound and an alcohol.
7. The method of claim 6 , wherein the alcohol of the co-surfactant system is a tertiary alcohol.
8. The method of claim 1 , wherein the second surfactant comprises a nonionic surfactant.
9. The method of claim 8 , wherein the nonionic surfactant is chosen from a polyethoxylate, a polypropoxylate, a phenolate, a polyol having a molecular weight of 300-100,000, or a combination of two or more thereof.
10. The method of claim 1 , comprising adding the first phase to the second phase at a rate such that the addition is completed over a period of about 30 minutes to about 150 minutes.
11. The method of claim 1 , wherein forming the first phase comprises adding the metal source to a mixture comprising water, the first surfactant, and the first alcohol.
12. The method of claim 11 , comprising adding the metal source to the first phase at a rate such that the addition is completed over a period of about 20 to about 120 minutes.
13. The method in claim 1 , wherein forming the first phase comprises (a) adding the metal source to a mixture of water, the first catalyst, and the first alcohol, and (b) adding the first surfactant after the addition of the metal source.
14. The method of claim 1 , wherein the phase enhancer comprises a primary or secondary alcohol.
15. The method of claim 1 , wherein the pH of the blend prior to reacting the blend with the second catalyst is no greater than about 3.5, and the pH of the mixture during the treating operation (d) is no greater than about 6.
16. The method of claim 1 , wherein the first catalyst comprises an acid catalyst or a base catalyst.
17. The method of claim 16 wherein the first catalyst comprises a base catalyst chosen from ammonium hydroxide, quaternary ammonium hydroxides, hydroxylamines, derivatives of hydroxylamines, amino pyridines, or a combination of two or more thereof.
18. The method of claim 17 , wherein the base catalyst is a composition comprising about 0.01% to about 10% by weight of a catalyst material.
19. The method of claim 1 , wherein the metal-containing particles are formed in an aqueous solution for which the amount of water is from about 50% to about 99% by weight.
20. The method of claim 15 wherein primary particles agglomerate to sizes from about 5 microns to about 1000 microns.
21. The method of claim 1 , wherein the metal-containing particles have a primary particle size of about 0.5 microns to about 100 microns.
22. The method of claim 1 , wherein the metal containing-particles comprise primary particles have a mean diameter, and greater than about 80% of the primary particles are within +/−15% of the mean diameter of the primary particles.
23. The method of claim 1 , wherein the metal-containing particles are chosen from metal oxides, metal hydroxides, metal carbonates, or metal oxycarbonates.
24. The method of claim 1 , wherein the metal-containing particles have a total cationic impurity concentration of less than 100 ppb.
25. The method of claim 1 , wherein the metal-containing particles have a total cationic impurity concentration of less than 10 ppb.
26. The method of claim 1 , wherein the phase enhancer comprises an alcohol chosen from an alcohol comprising from 1 to 10 carbon atoms.
27. The method of claim 1 , wherein the phase enhancer comprises an alcohol chosen from butanol, pentanol, isopropanol, isobutanol, and isopentanol.
28. The method of claim 1 , wherein the phase enhancer comprises butanol.