Method for producing zirconia colloids
View Patent ↗The present invention pertains to a method for producing a colloidal suspension of zirconia particles, comprising the following successive steps: a) subjecting a mixture of zirconium oxychloride and an alkali metal halide in an aqueous solvent to hydrothermal treatment at a temperature above 150° C., so as to obtain a suspension in the form of a two-phase mixture comprising a slurry and a supernatant, b) without first peptizing it, desalting said suspension so as to form a colloidal suspension of zirconia.
1. A method for producing a colloidal suspension of zirconia particles, comprising the following successive steps:
(a) subjecting a mixture of zirconium oxychloride and an alkali metal halide AX in an aqueous solvent to hydrothermal treatment at a temperature above 150° C., so as to obtain a suspension in the form of a two-phase mixture comprising a slurry and a supernatant, and
(b) desalting said suspension, without first peptizing said suspension, so as to form a colloidal suspension of zirconia.
2. The method according to claim 1 , wherein the suspension obtained in step (a) is diluted with water before performing step (b).
3. The method according to claim 2 , wherein the diluted suspension is desalted in step (b) by performing ultrafiltration.
4. The method according to claim 1 , wherein the alkali metal halide is potassium chloride.
5. The method according to claim 1 , wherein zirconium oxychloride and the alkali metal halide are mixed in a molar ratio of AX/ZrOCl 2 from 1/10 to 1/1.
6. The method according to claim 1 , wherein zirconium oxychloride and the alkali metal halide are mixed in a molar ratio of AX/ZrOCl 2 from 1/4 to 1/2.
7. The method according to claim 1 , wherein zirconium oxychloride concentration in said mixture ranges from 0.5 to 4 mol/l.
8. The method according to claim 1 , wherein zirconium oxychloride concentration in said mixture ranges from 1 to 2 mol/l.
9. The method according to claim 1 , wherein the hydrothermal treatment is conducted at a temperature from 150 to 220° C. during at least one day.
10. The method according to claim 1 , wherein the hydrothermal treatment is conducted at a temperature from 160 to 200° C. during at least one day.
11. The method according to claim 1 , wherein the hydrothermal treatment is conducted at a temperature from 175 to 190° C. during at least one day.
12. The method according to claim 1 , wherein the suspension obtained in step (a) is desalted in step (b) by performing dialysis in water.
13. The method according to claim 1 , further comprising a step of solvent-exchange so as to substitute at least one alcoholic solvent for part or all of the aqueous solvent included in the suspension.
14. The method according to claim 13 , wherein solvent exchange is performed by dialysis or diafiltration.
15. The method according to claim 1 , further comprising an intermediate or subsequent step of improving zirconia dispersion, either by adding a dispersant, or by surface modification of the zirconia.
16. The method according to claim 1 , further comprising an intermediate or subsequent step of pH modification by addition of an organic or inorganic base.