초록 ▼

This invention provides a method for preparing cerium oxide nanoparticles with a narrow size distribution. The cerium oxide nanoparticles obtained by the method of the invention are nearly all crystalline. The method comprises providing a first aqueous solution comprising cerium nitrate and providin

This invention provides a method for preparing cerium oxide nanoparticles with a narrow size distribution. The cerium oxide nanoparticles obtained by the method of the invention are nearly all crystalline. The method comprises providing a first aqueous solution comprising cerium nitrate and providing a second aqueous solution comprising hexamethylenetetramine. The first and second aqueous solutions are mixed to form a mixture, and the mixture is maintained at a temperature no higher than about 320째 K to form nanoparticles. The nanoparticles that are formed are then separated from the mixture. A further aspect of the present invention is an apparatus for preparing cerium oxide nanoparticles. The apparatus comprises a mixing vessel having a first compartment for holding a first aqueous solution comprising cerium nitrate and a second compartment for holding a second aqueous solution comprising hexamethylenetetramine. The mixing vessel has a retractable partition separating the first and second compartments.

대표청구항 ▼

I claim: 1. A method for preparing cerium oxide nanoparticles comprising the steps of: (a) providing a first aqueous solution comprising cerium nitrate; (b) providing a second aqueous mixture comprising hexamethylenetetramine; (c) rapidly mixing the first aqueous solution with the second aqueous so

I claim: 1. A method for preparing cerium oxide nanoparticles comprising the steps of: (a) providing a first aqueous solution comprising cerium nitrate; (b) providing a second aqueous mixture comprising hexamethylenetetramine; (c) rapidly mixing the first aqueous solution with the second aqueous solution to form a mixture; (d) maintaining the mixture at a temperature no higher than about 320째 K to form nanoparticles in the mixture; and (e) separating the nanoparticles formed in the mixture from the mixture. 2. The method of claim 1, wherein the first aqueous solution is provided in a first compartment of a mixing vessel, and the second aqueous solution is provided in a second compartment of the mixing vessel, the first and second compartments being separated by retractable partition, and wherein the mixing step comprises retracting the retractable partition of the mixing vessel to cause mixing of the first aqueous solution with the second aqueous solution to form the mixture. 3. The method of claim 1, wherein one of the first and second aqueous solutions is provided in a mixing vessel having at least one inlet, and the other of the first and second aqueous solutions is pumped into the mixing vessels through the at least one inlet to cause rapid mixing of the first and second aqueous solutions to form the mixture. 4. The method of claim 1, wherein the first aqueous solution has a concentration of cerium nitrate in the range of about 0.005 M to about 0.04 M. 5. The method of claim 1, wherein the second aqueous solution has a concentration of hexamethylenetetramine in the range of about 0.05 M to about 1.5 M. 6. The method of claim 5, wherein the concentration of hexamethylenetetramine is in the range of about 0.5 M to about 1.5 M. 7. The method of claim 1, further comprising the step of stirring the mixture while the mixture is maintained at a temperature no higher than about 320째 K. 8. The method of claim 2, wherein the mixing vessel includes a mechanical stirrer and the mixture is stirred with the mechanical stirrer. 9. The method of claim 8, wherein the mechanical stirrer comprises a vertical stirring rod having a plurality of stirring elements attached thereto. 10. The method of claim 9, wherein the vertical stirring rod has a first aperture for fitting a first inlet feed for introducing the first aqueous solution and a second aperture for fitting a second inlet feed for introducing the second aqueous solution, wherein the first inlet feed leads into the first compartment and the second inlet feed leads into the second compartment of the mixing vessel when the retractable partition is in place. 11. The method of claim 10, wherein the vertical stirring rod further includes an outlet drain for the removal of liquid from the mixing vessel. 12. The method of claim 1, wherein the mixture is maintained at a temperature no higher than about 320째 K for a time period between about 2 hours and about 24 hours. 13. The method of claim 12, wherein the time period is between about 5 hours and about 24 hours. 14. The method of claim 12, wherein the time period is between about 12 hours and about 24 hours. 15. The method of claim 1, further comprising the step of sintering the nanoparticles separated in step (e) in air at a temperature in the range of about 400째 C. to about 800째 C. 16. The method of claim 1, wherein step (e) comprises centrifuging the mixture to separate the nanoparticles from the mixture. 17. The method of claim 2 or 3, wherein the step of separating the nanoparticles from the mixture comprises the steps of positioning the mixing vessel inside a centrifuge and centrifuging the mixture in the mixing vessel. 18. The method of claim 1, wherein the cerium oxide nanoparticles include single crystalline cerium oxide nanoparticles. 19. The method of claim 2, wherein retracting the retractable partition takes place in about 0.1 seconds to about 5 seconds. 20. The method of claim 1, 7, or 12, wherein the mixture is maintained at a temperature of about 300째 K to form nanoparticles in the mixture. 21. A method for preparing cerium oxide nanoparticles, comprising the steps of: (a) providing a first aqueous solution comprising cerium nitrate in a mixing vessel; (b) rapidly adding a second aqueous solution comprising hexamethylenetetramine to the first aqueous solution in the mixing vessel to form a mixture; and (c) maintaining the mixture at a temperature no higher than about 320째 K to form the nanoparticles in the mixture; and (d) separating the nanoparticles formed in step (c) from the mixture. 22. The method of claim 21, wherein the mixing vessel has at least one inlet, and step (b) comprises rapidly pumping the second aqueous solution through the at least one inlet into the mixing vessel containing the first solution to form the mixture. 23. A method for preparing cerium oxide nanoparticles, comprising the steps of: (a) providing a first aqueous solution comprising hexamethylenetetramine in a mixing vessel; (b) rapidly adding a second aqueous solution comprising cerium nitrate to the first aqueous solution in the mixing vessel to form a mixture; (c) maintaining the mixture at a temperature no higher than about 320째 K to form the nanoparticles in the mixture; and (d) separating the nanoparticles formed in step (c) from the mixture. 24. The method of claim 23, wherein the mixing vessel has at least one inlet, and step (b) comprises rapidly pumping the second aqueous solution through the inlet into the mixing vessel containing the first solution to form the mixture. 25. The method of claim 21 or 23, wherein the step of separating the nanoparticles from the mixture comprises centrifuging the mixture. 26. The method of claim 21 or 23, wherein the step of separating the nanoparticles from the mixture comprises positioning the mixing vessel inside a centrifuge, and centrifuging the mixture in the mixing vessel. 27. The method of claim 21 or 23, wherein the mixture is maintained at a temperature of about 300째 K to form nanoparticles in the mixture. 28. An apparatus for the preparation of cerium oxide nanoparticles, comprising a centrifuge and a mixing vessel, wherein the mixing vessel is adapted to be positioned inside the centrifuge, the mixing vessel having (a) a first compartment for holding a first aqueous solution comprising cerium nitrate; (b) a second compartment for holding a second aqueous solution comprising hexamethylenetetramine; and (c) a retractable partition separating the first and second compartments, wherein when the retractable partition is retracted, rapid mixing of the first and second aqueous solutions takes place to form a mixture, and the mixture in the mixing vessel is maintained at a temperature no higher than 320째 K to form nanoparticles therein. 29. The apparatus of claim 28, wherein the retractable partition is a vertical partition. 30. The apparatus of claim 28, wherein the mixing vessel further comprises a mechanical stirrer for stirring the mixture. 31. The apparatus of claim 30, wherein the mechanical stirrer comprises a rotatable vertical stirring rod having a plurality of stirring elements attached thereto. 32. The apparatus of claim 31, wherein the vertical stirring rod has a first aperture for fitting a first inlet feed and a second aperture for fitting a second inlet feed, wherein the first aqueous solution is provided through the first inlet feed into the first compartment and the second aqueous solution is provided through the second inlet feed into the second compartment. 33. The apparatus of claim 32, wherein the vertical stirring rod further comprises an outlet drain for the removal of liquid from the mixing vessel. 34. The apparatus of claim 28, wherein the mixing vessel is maintained at a temperature of about 300째 K to form nanoparticles therein. 35. A method for preparing cerium oxide nanoparticles containing a metal selected from the group consisting of platinum, gold, palladium, copper and nickel, wherein the method comprises the steps of: (a) providing a first aqueous solution comprising cerium nitrate; (b) providing a second aqueous solution comprising hexamethylenetetramine; (c) mixing the first and second aqueous solutions to form a mixture; (d) maintaining the mixture at a temperature no higher than about 320째 K, to form nanoparticles therein; (e) separating the nanoparticles formed in step (d) from the mixture; and (f) soaking the nanoparticles separated from the mixture in a solution comprising ions or complex ions of the metal. 36. The method of claim 35, wherein the metal comprises platinum, and step (f) comprises soaking the nanoparticles in a solution comprising chloroplatinic acid. 37. The method of claim 35, wherein the mixture is maintained at a temperature of about 300째 K to form nanoparticles therein.